IFR 2945A Service manual

Contains

Operating Manual

for

COMMUNICATIONS
SERVICE MONITOR

2945A

Part number 46882-311

Issue 5

Creation date 27-Mar-00

COMMUNICATIONS
SERVICE MONITOR

2945A

 IFR Ltd. 2000

No part of this book may be reproduced or transmitted in any form

or by any means, electronic or mechanical, including photocopying,

or recorded by any information storage or retrieval system, without

permission in writing by IFR Ltd.

Printed in the UK

Manual part no. 46882-311

Issue 5

27 March 2000

i

This manual explains how to use the Communications Service Monitor 2945A. It applies to
instruments fitted with main software version 4.xx and cellular software version 4.xx.

Intended audience

People who need to test mobile radio systems and associated equipment.

Structure

Chapter 1

General information and performance specification.

Chapter 2

Gives installation instructions, including connection of peripheral equipment.

Chapter 3

Operating instruc tions. Setting up and use.

Chapter 4

Brief technical description.

About this manual

Chapter 5

Acceptance testing procedure for the Service Monitor.

Appendix A

Use of the Directional Power Heads, 54421/002 and 54421/003.

Appendix B

Use of the Light-weight Directional Power Heads 54421/016 and 54421/018.

Document conventions

The following conventions appl y thr oughout this manual:-

[Tx TEST] Hard key titles are shown verbatim, using normal lettering in

square brackets.

[Tx freq] Soft key titles are shown verbatim using italic lettering in square

brackets.

RF IN/OUT Titles on the instrument panels are shown verbatim using capital

letters.

Text displayed on screen. See below

†

References to text displayed on the screen of the Service Monitor are given verbatim, using

a font that resembles the displayed text. e.g.

Associated publications

Other manuals that cover specific aspects of this service monitor are:-

• Programming Manual (46882-318) provides programming information for remote

control of the Service Monitor using MI-BASIC and GPIB.

• Maintenance Manual (46882-310) provides servicing information for the

Communications Service Monitor 2945A and Avionics Communication Service
Monitor 2946A.

contd./...

†

GEN FREQ:

Ref Level:

,

, 0G+:

ii 46882-311

About this manual (continued)

Associated publications (continued)

Operating manual supplements provide operating details for specific system test software.

• EDACS Repeater (46882-300)

• AMPS Supplement (46882-313)

• PMR Supplement (46882-315)

• MPT1327 Supplement (46882-317)

• EDACS Radio Supplement (46882-301)

• TACS Supplement (46882-314)

• NMT Supplement (46882-316)

iii

Contents

Precautions ........................................................................................................................................................v

Chapter 1 GENERAL INFORMATION..................................................................................................1-1

Performance data..................................................................................................................... 1-7

Chapter 2 INSTALLATION.....................................................................................................................2-1

Chapter 3 LOCAL OPERATION.............................................................................................................3-1

Using the test modes...............................................................................................................3-15

Chapter 4 TECHNICAL DESCRIPTION...............................................................................................4-1

Chapter 5 ACCEPTANCE TESTING......................................................................................................5-1

Acceptance Test Results Tables............................................................................................5-30

Appendix A DIRECTIONAL POWER HEADS........................................................................................ A-1

Appendix B LIGHT-WEIGHT DIRECTIONAL POWER HEADS.........................................................B-1

Index .............................................................................................................................................Index-1

iv 46882-311

Precautions

These terms have specific meanings in this manual:

WARNING

information to prevent personal injury.

information to prevent damage to the equipment.
important general information.

Hazard symbols

The meaning of hazard symbols appearing on the equipment is as follows:

Symbol Description

General hazard

Dangerous voltage

Toxic hazard

Hot surface

General conditions of use

This product is designed and tested to comply with the requirements of IEC/EN61010-1 ‘Safety
requirements for electrical equipment for measurement, control and laboratory use’, for Class I
portable equipment and is for use in a pollution degree 2 environment. The equipment is designed
to operate from an installation category I or II supply.

Equipment should be protected from the ingress of liquids and precipitation such as rain, snow, etc.
When moving the equipment from a cold to a hot environment, it is important to allow the
temperature of the equipment to stabilise before it is connected to the supply to avoid condensation
forming. The equipment must only be operated within the environmental conditions specified in
Chapter 1 ‘Performance data’, otherwise the protection provided by the equipment may be
impaired.

This product is not approved for use in hazardous atmospheres or medical applications. If the
equipment is to be used in a safety-related application, e.g. avionics or military applications, the
suitability of the product must be assessed and approved for use by a competent person.

WARNING

46882-311 v

Electrical hazards (AC supply voltage)

This equipment conforms with IEC Safety Class I, meaning that it is provided with a protective
grounding lead. To maintain this protection the supply lead must always be connected to the
source of supply via a socket with a grounded contact.

Be aware that the supply filter contains capacitors that may remain charged after the equipment is
disconnected from the supply. Although the stored energy is within the approved safety
requirements, a slight shock may be felt if the plug pins are touched immediately after removal.

Do not remove covers, no user serviceable parts inside. See list of IFR Ltd International Service
Centres at rear of manual.

PRECAUTIONS

Fuses

Note that the internal supply fuse is in series with the live conductor of the supply lead. If
connection is made to a 2-pin unpolarized supply socket, it is possible for the fuse to become
transposed to the neutral conductor, in which case, parts of the equipment could remain at supply
potential even after the fuse has ruptured.

WARNING

Fire hazard

WARNING

Toxic hazards

WARNING

Lithium

Make sure that only fuses of the correct rating and type are used for replacement.
If an integrally fused plug is used on the supply lead, ensure that the fuse rating is commensurate

with the current requirements of this equipment. See under ’Performance Data’ in Chapter 1 for
power requirements.

Some of the components used in this equipment may include resins and other materials which give
off toxic fumes if incinerated. Take appropriate precautions, therefore, in the disposal of these
items.

A Lithium battery (or a Lithium battery contained within an IC) is used in this equipment:
As Lithium is a toxic substance, the battery should in no circumstances be crushed, incinerated or

disposed of in normal waste.
Do not attempt to recharge this type of battery. Do not short circuit or force discharge since this

might cause the battery to vent, overheat or explode.

WARNING

Beryllium copper

WARNING

Lead-acid battery pack

Battery usage

Some mechanical components within this instrument are manufactured from beryllium copper.
This is an alloy with a beryllium content of approximately 5%. It represents no risk in normal use.

The material should not be machined, welded or subjected to any process where heat is involved.

It must be disposed of as “special waste”.
It must NOT be disposed of by incineration.

A lead-acid battery pack is supplied with the instrument as an accessory. This contains both lead
and sulphuric acid. Lead is a toxic substance and sulphuric acid is corrosive and a skin irritant
which can cause chemical burn damage to exposed skin. The battery pack should in no
circumstances be disposed of in normal waste.

vi 46882-311

Do not charge at an ambient temperature of greater than 40°C.
Do not dispose of in a fire. Do not short circuit. Do not crush, puncture, open, dismantle or

otherwise mechanically interfere with. Do not store at temperatures in excess of 60°C.
Do observe the correct polarity and connect correctly.
During normal service, small quantities of hydrogen and oxygen may be vented from the battery

pack. Adequate ventilation must be provided around the instrument to allow these gases to
disperse naturally.

The battery pack must only be charged using the charging facility in the instrument, or by using an
approved sealed lead-acid battery charger.

The normal ’End of Life’ condition is reached when capacity of the battery pack falls to 50% of its
rated capacity. This is shown in the performance specification in Chapter 1 of this manual. Battery
packs should be withdrawn from service when this condition is reached.

Battery storage

Any sealed lead-acid battery naturally self-discharges when in storage. Its service life and capacity
may be adversely affected if it becomes over-discharged. Refer to the performance specification in
Chapter 1 of this manual for storage time and conditions.

Stored battery packs should be periodically ’Top Charged’ to optimize performance and service life.
Before ’Top Charging’, the open circuit voltage must be measured, and if this is below the
minimum shown in the performance specification in chapter 1 of this manual, the battery pack must
not be recharged.

OPERATING MANUAL 2945A

WARNING

Hot Surfaces

WARNING

RF hazard

WARNING

Tilt facility

Take care when touching the RF Input Type N connector after the application of high levels of
continuous power. If 50 W is exceeded for a prolonged period, the temperature of the connector
can become excessive.

When measuring high VSWR ratios, hazardous voltages may be present on the line due to standing
waves. Under these conditions, it is dangerous to operate the equipment with the covers removed.

When the equipment is in the tilt position, it is advisable, for stability reasons, not to stack other
equipment on top of it.

Suitability for use

This equipment has been designed and manufactured by IFR Ltd. to measure the performance to
specification of radio communication apparatus and to generate low power HF, VHF and UHF
signals to facilitate such measurements. The performance data section of this operating manual
shows the operating limits. IFR Ltd. has no control over the use of this equipment and cannot be
held responsible for events arising from its use other than for its intended purpose.

vii

PRECAUTIONS

Precautions

Les termes suivants ont, dans ce manuel, des significations particulières:

WARNING

contient des informations pour éviter toute blessure au personnel.

contient des informations pour évit er les dommages aux équipements.

contient d'importantes informations d'ordre général.

Symboles signalant un risque

La signification des symboles liés à cet équipement est la suivante:

Symbole Nature du risque

Risques généraux

Tension dangereuse

Danger produits toxiques

Surfaces chaudes

Conditions générales d'utilisation

WARNING

Sécurité électrique (tension d’alimentation alternative)

Ce produit a été conçu et testé pour être conforme aux exigences des normes CEI/EN61010-1
« exigences de sécurité des équipements électriques pour la mesure, le contrôle et l'usage en
laboratoire », pour des équipements Classe I portables et pour une utilisation dans un
environnement de pollution de niveau 2. Cet équipement est conç u pour fonctionner à parti r d'une
alimentation de catégorie I ou II.

Cet équipement doit être protégé de l’introduction de liquides ainsi que des précipitations d’eau, de
neige, etc... Lorsqu’on transporte cet équipement d’un environnement chaud vers un
environnement froid, il est important de laisser l’équipement se stabiliser en température avant de
le connecter à une alimentation afin d’éviter toute formation de condensation. L'appareil doit être
utilisé uniquement dans le cadre des conditions d'environnement spécifiées au chapitre 1
"Performance data", toute autre utilisation peut endommager les systèmes de protection.

Ce produit n’es t pas garanti po ur fonctionner dans des atmosphères dangereuses ou pour un usage
médical. Si l'équipement doit être utilisé pour des applications en relation avec la sécurité, par
exemple des applications militaires ou aéronautiques, la compatibilité du produit doit être établie et
approuvée par une personne compétente.

Cet appareil est protégé conformément à la norme CEI de sécurité Classe 1, c’est-à-dire que sa
prise secteur comporte un fil de protection à la terre. Pour maintenir cette protection, le câble
d’alimentation doit toujours être branché à la source d’alimentation par l’intermédiaire d’une prise
comportant une borne de terre.

viii 46882-311

Fusibles

OPERATING MANUAL 2945A

Notez que les filtres d’alimentation contiennent des condensateurs qui peuvent encore être chargés
lorsque l’appareil est débranché. Bien que l’énergie contenue soit conforme aux exigences de
sécurité, il est possible de ressentir un léger choc si l’on touche les bornes sitôt après
débranchement.

Ne pas enlever les capots, aucune pièce réparable ne se trouve à l'intérieur. Contacter un des
Centres de Maintenance Internationaux de IFR Ltd dans la liste jointe à la fin du manuel.

Notez que le fusible d’alimentation interne est en série avec la phase du câble d’alimentation. Si la
prise d’alimentation comporte deux bornes non polarisées, il est possible de connecter le fusible au
neutre. Dans ce cas, certaines parties de l’appareil peuvent rester à un certain potentiel même après
coupure du fusible.

WARNING

Risque lié au feu

WARNING

Danger produits toxiques

WARNING

Lithium

Lors du remplacement des fusibles vérifiez l'exactitude de leur type et de leur valeur.
Si le câble d'alimentation comporte une prise avec fusible intégré, assurez vous que sa valeur est

compatible avec les besoins en courant de l'appareil. Pour la consommation, reportez-vous au
Chapitre 1 "Spécifications".

Certains composants utilisés dans cet appareil peuvent contenir des résines et d'autres matières qui
dégagent des fumées toxiques lors de leur incinération. Les précautions d'usages doivent donc être
prises lorsqu'on se débarrasse de ce type de composant.

Une pile au Lithium ou un CI contenant une pile au Lithium est utilisé dans cet équipement.
Le Lithium est une substance toxique; en conséquence on ne doit l'écraser, l'incinérer ou la jeter

dans la "poubelle".
Ne pas essayer de la recharger, ne pas la court-circuiter, une forte décharge rapide risque de

provoquer une surchauffe voire l'explosion de celle-ci.

WARNING

ix

Bronze au béryllium

Dans cet équipement,certaines pièces mécaniques sont à base de bronze au béryllium. Il s'agit d'un
alliage dans lequel le pourcentage de béryllium ne dépasse pas 5%. Il ne présente aucun danger en
utilisation normale.

Toutefois, cet alliage ne doit pas être travaillé, soudé ou soumis à un processus qui implique
l'utilisation d'une source de chaleur.

En cas de destruction, il sera entreposé dans un container spécial. IL ne devra pas être détruit par
incinération.

PRECAUTIONS

WARNING

Pack batterie au plomb

Utilisation de la batterie

Stockage de la batterie

Un pack batterie au plomb est disponible en accessoire. Celui-ci contient à la fois du plomb et de
l'acide sulfurique. Le plomb est une substance toxique tandis que l'acide sulfurique est corrosif et
irritant pour la peau, pouvant causer des brûlures chimiques. Ce pack batterie ne doit en aucun cas
être jeté dans une poubelle normale.

Ne chargez pas la batterie à une température supérieure à 40°C.
Ne pas jeter la batterie dans le feu. Ne pas court-circuiter. Ne pas écraser, transpercer, ouvrir,

démonter ou intervenir mécaniquement de quelque façon que ce soit. Ne pas stocker à une
température supérieure à 60°C.

Respecter la polarité et brancher correctement.
Au cours de l'utilisation, de faibles quantités d'oxygène et d'hydrogène peuvent s'échapper de la

batterie. Il est alors nécessaire de bien ventiler l'appareil afin d'assurer la dispersion de ces gaz.
Le pack batterie ne doit être chargé qu'avec le chargeur intégré à l'instrument ou en utilisant un

chargeur adapté à ce type de batterie.
Les conditions normales de "fin de vie" sont atteintes lorsque la capacité de la batterie ne dépasse

plus 50% de sa capacité nominale. Celle-ci est décrite dans le chapitre 1 "spécification" de ce
manuel. Les packs batterie doivent être retirés du service lorsqu'ils ont atteint ce niveau d'usure.

Toute batterie de ce type, scellée, au plomb, se décharge naturellement pendant le stockage. Sa
durée de vie et sa capacité peuvent être affectées défavourablement lorsqu'elle se trouve en sous­charge. Reportez-vous au Chapitre 1 des "Spécifications" de ce manuel pour les durées et
conditions de stockage.

Les packs batterie doivent être régulièrement chargés de façon nominale afin d'optimiser les
performances et la durée de vie. Avant toute opération de charge, il faut mesurer la tension en
circuit ouvert et, si elle est inférieure au minimum indiqué dans les spécifications, la batterie ne
doit plus être rechargée.

WARNING

WARNING

WARNING

Position inclinée

Surfaces chaudes

Faire attention ,lors de la manipulation d'un connecteur "N", après l'injection de haute puissance en
continu sur l'entrée RF de ce connecteur: Si une puissance supérieure à 50 W est envoyée pendant
une longue durée, la température du connecteur peut être très élevée.

Danger RF

Lors de la mesure de T.O.S. de valeur importante, des tensions dangereuses dues aux ondes
stationnaires peuvent apparaître sur l’alimentation. Dans ces conditions il est dangereux de faire
fonctionner l’appareil sans ses capots de protection.

Lorsque l’appareil est dans une position inclinée, il est recommandé, pour des raisons de stabilité,
de ne pas y empiler d’autres appareils.

x 46882-311

OPERATING MANUAL 2945A

Vorsichtsmassnahmen

Diese Hinweise haben eine bestimmte Bedeutung in diesem Handbuch:

WARNING

dienen zur Vermeidung von Verletzungsrisiken.

dienen dem Schutz der Geräte.

enthalten wichtige Informationen.

Gefahrensymbole

Die Gefahrensymbole auf den Geräten sind wie folgt:

Symbol Gefahrenart

Allgemeine Gefahr

Gefährliche Spannung

Warnung vor giftigen Substanzen

Heiße Oberfläche

Allgemeine Hinweise zur Verwendung

WARNING

Elektrische Schläge (Wechselspannungsversorgung)

Dieses Produkt wurde entsprechend den Anfo rderungen von
IEC/EN61010-1"Sicherheitsanforderungen für elektrische Ausrüstung für Meßaufgaben, Steuerung

und Laborbedarf", Kl asse I transpo rtabel zur Verwendung in einer Gr ad 2 verunreinigten
Umgebung, entwickelt und get estet. Dieses Gerät ist für Netzversorgung Klasse I oder II
zugelassen.

Das Gerät sollte vor dem Eindringen von Flüssigkeiten sowie vor Regen, Schnee etc. geschützt
werden. Bei Standortänderung von kalter in wärmere Umgebung sollte da s Gerät wegen der
Kondensation erst nach Anpassung an die wärmere Umgebung mit dem Netz verbunden werden.
Das Gerät da rf nur in Umgebungsbedingungen wie in Kapitel 1 "Leistungsdaten (Performance
data)" b eschrieben, betrieben werden; a nsonsten wird der vom Ger ät vorgesehene Schutz des
Anwenders beeinträchtigt.

Dieses Produkt ist nicht für den Einsatz in gefährlicher Umgebung (z.B. Ex-B ereich) und für
medizinische Anwendungen geprüft. Sollte das Gerät für den Einsat z in sicherheitsrelevanten
Anwendungen wie z.B. im Flugverkehr oder bei militaerischen Anwendungen vorgesehen sein, so
ist dieser vo n einer für diesen Bereich zuständigen Person zu beurteilen und genehmigen.

Das Gerät entspricht IEC Sicherheitsklasse 1 mit einem Schutzleiter nach Erde. Das Netzkabel
muß stets an eine Steckdose mit Erdkontakt angeschlossen werden.

Filterkondensatoren in der internen Spannungsversorgung können auch nach Unterbrechung der
Spannungszuführung noch geladen sein. Obwohl d ie darin gespe i cherte Energie innerhalb der

xi

PRECAUTIONS

Sicherungen

Sicherheitsmargen liegt, kann ein le i chter Spannungsschlag bei Berührung kurz nach der
Unterbrechung erfolgen.

Entfernen Sie keine G ehäuseabdeckunge n, es befinden sich keine austauschbaren Teile im Gerät .
Eine Liste der IFR Servicestellen finden Sie auf der Rückseite des Handbuches.

Die interne Sicherung in der Spannungszuführung ist in Reihe mit der sp annungsführenden
Zuleitung geschaltet. Bei Verbindung mit einer zweiadrigen, nicht gepo lten Steckdose kann die
Sicherung in der Ma sseleitung liegen, so daß auch bei geschmol zener Sicherung Ger äteteile immer
noch auf Spannungspot ential sind.

WARNING

Feuergefahr

WARNING

Warnung vor giftigen Substanzen

WARNING

Lithium

Es dürfen nur Ersatzsicherungen vom gleichen Typ mit den korrekten Spezifikat ionen entsprec hend
der Stromaufnahme des Gerätes verwendet werden. Siehe hierzu die Leistungsdaten (Performance
Data) in Kapitel 1.

In einigen Bauel ementen dieses Geräts können Epo xyhar ze oder andere Materialien enthalten sein,
die im Brandfall giftige Gase erze ugen. Bei der Entsorgung müssen deshalb entsprechende
Vorsichtsmaßnahmen getroffen werden.

Eine Lithium Batterie oder eine Lithium Batterie innerhalb eines IC ist in diesem Gerät eingebaut.
Da Lithium ein giftiges Material ist, sollte es als Sondermüll entsorgt werden.
Diese Batterie darf auf keinen Fall geladen werden. Nicht kurzschließen, da sie dabei überhitzt

werden und explodieren kann.

WARNING

xii 46882-311

Beryllium Kupfer

In diesem Gerät sind einige mechanische Komponenten aus Berylium Kupfer gefertigt. Dies ist
eine Verbindung welche aus einem Berylliumanteil von ca. 5 % besteht. Bei nor maler Verwendung
besteht kein Gesundheitsrisiko.

Das Metall darf nicht bearbeitet, geschweißt oder sonstiger Wärmebehandlung ausgesetz t werden.
Es muß als Sondermüll entsorgt werden.
Es darf nicht durch Verbrennung entsorgt werde n.

OPERATING MANUAL 2945A

WARNING

Blei/Säure-Batterie

Verwendung der Batterieoption

Lagerung des Akkus

Als Zubehör zum Funkmeßplatz ist ein Blei-Säure Akku lieferba r. Dieser enthält Blei und
Schwefelsäure. Blei i st eine giftige Substanz , Schwefelsäure verursacht bei Berührung mit der
Haut Verätzungen. Der verbrauchte Blei-Säure Akku sollte unter keinen Umständen mit normalem
Abfall entsorgt werden.

Laden Sie den Akku nicht bei Tempera t uren über 40 Grad Celsius.
Werfen Sie den Akku nicht i n ein Feuer. Schließ en Sie Ihn nicht kurz. Que tschen Sie ihn nicht,

durchlöcher n, öffnen Sie ihn nicht und vermeiden Sie mechanische Beschädigungen. Lagern Sie
den Akku nicht bei Temperaturen über 60 Grad Celsius.

Achten Sie auf die richtige Polari t ät und schließen Sie ihn ordnungsgemäß an.
Während normalem Betrieb kö nnen kleine Mengen von Wasserstoff und Sauerstoff freige setzt

werden. Für eine ausr eichende Belüftung um da s Gerät ist daher zu sorgen.
Der Blei-Säure Akku darf nur mit de r im Gerät befindlichen Ladeeinrichtung oder mit einem

speziell für geschlossene Blei-Sä ure Akkus zugelassenen Ladegerät gelade n werden.
Das Ende der Lebensdauer des Akkus ist erreicht wenn die Kapazität unte r 50 % der spezifizierten

Kapazität abfällt. Siehe Kapitel 1 in diesem Handbuch. Ist dieser Fall eingetr eten, sollte der Akku
nicht mehr verwendet werd en.

Jeder Blei-Säure Akku entlädt sich während der Lagerung. Die Lebensdauer und Kapazität der
Batterie verschlechtern sic h durch zu starke E ntladung. Bezüglich Lagerzustand si ehe auch Kapitel
1 in diesem Handbuch.

Gelagerte Akkus sollten zur Er haltung ihrer Leistungsfähigkeit und Lebensdauer regelmäßig voll
aufgeladen werden. Vor Aufladung muß die Leerlaufspannug gemessen werden. Sollte diese den
Wert wie im Kapitel 1 in diesem Handbuch be schrieben, unterschritten ha ben darf der Akku nicht
mehr geladen werden.

WARNING

Heiße Oberfläche

WARNING

Hochfrequenz

WARNING

Schrägstellung

Vorsicht bei Berührung der H F Eingangsbuchse Typ N nach Einspeisen hoher Dauerleistung. Falls
über längere Zeit 50 Watt überschritten wird, kann die Temperatur der Buchse über Normal
steigen.

Bei Messung von hohen Stehwellenverhältnisse n können sich auf der Le itung gefährliche
Spannungen aufbauen. In solchen Fällen d arf das Gerät ni cht bei geöffnete m Gehäuse betrieben
werden.

Bei Schrägstellung des Geräts sollten aus Stabilitätsgründen keine and e ren Geräte darauf gestellt
werden.

xiii

PRECAUTIONS

Precauzioni

Questi termini vengono utilizzati in questo manuale con significati specifici:

WARNING

riportano informazioni atte ad evitare possibili pericoli alla persona.

riportano informazioni per evitare possibili pericoli all’apparec-chiatura.

riportano importanti informazioni di carattere generale.

Simboli di pericolo

Significato dei simboli di pericolo utilizzati nell’apparato:

Simbolo

Tipo di pericolo

Pericolo generico

Tensione pericolosa

Pericolo sostanze tossiche

Superfici ad alta temperatura

Condizioni general i d’uso.

Questo prodotto è stato progettato e collaudato per rispondere ai requisiti della direttiva
IEC/EN61010-1 'Safety requirements for electrical equipment for measurement, control and
laboratory use' per apparati di classe I portatili e per l'uso in un ambiente inquinato di grado 2.
L'apparato è stato progettato per essere alimentato da un alimentatore di categoria I o II.

Lo strumento deve essere protetto dal possibile ingresso di liquidi quali, ad es., acqua, pioggia,
neve, ecc. Qualora lo strumento venga portato da un ambiente freddo ad uno caldo, è importante
lasciare che la temperatura all’interno dello strumento si stabilizzi prima di alimentarlo per evitare
formazione di condense. Lo strumento deve essere utilizzato esclusivamente nelle condizioni
ambientali descritte nel capitolo 1 ‘Performance data’, in caso contrario le protezioni previste nello
strumento potrebbero risultare non sufficienti.

Questo prodotto non è stato approvato per essere usato in ambienti pericolosi o applicazioni
medicali. Se lo strumento deve essere usato per applicazioni particolari collegate alla sicurezza
(per esempio applicazioni militari o avioniche), occorre che una persona o un istituto competente
ne certifichi l'uso.

WARNING

Pericoli da elettricità (alimentazione c.a.)

Quest ’apparato è provvisto del collegamento di protezione di terra e rispetta le norme di sicurezza
IEC, classe 1. Per mantenere questa protezione è necessario che il cavo, la spina e la presa
d’alimentazione siano tutti provvisti di terra.

Il circuito d’alimentazione contiene dei filtri i cui condensatori possono restare carichi anche dopo
aver rimosso l’alimentazione. Sebbene l’energia immagazzinata è entro i limiti di sicurezza,

xiv 46882-311

Fusibili

OPERATING MANUAL 2945A

purtuttavia una leggera scossa può essere avvertita toccando i capi della spina subito dopo averla
rimossa.

Non rimuovere i coperchi, utilizzare solo parti di scorta originali. Vedi elenco internazionale dei
Centri di Assistenza in fondo al manuale.

Notare che un fusibile è posto sul filo caldo del cavo di alimentazione. Qualora l’alimentazione
avvenga tramite due poli non polarizzati, è possibile che il fusibile vada a protezione del neutro per
cui anche in caso di una sua rottura, l’apparato potrebbe restare sotto tensione.

WARNING

Pericolo d’incendio

WARNING

Pericolo sostanze tossiche

WARNING

Litio

Assicurarsi che, in caso di sostituzione, vengano utilizzati solo fusibili della portata e del tipo
prescritti.

Se viene usata una spina con fusibili, assicurarsi che questi siano di portata adeguata coi requisiti di
alimentazione richiesti dallo strumento. Tali requisiti sono riportati nel cap. 1 "Performance data".

Alcuni dei componenti usati in questo strumento possono contenere resine o altri materiali che, se
bruciati, possono emettere fumi tossici. Prendere quindi le opportune precauzioni nell'uso di tali
parti.

Quest'apparato incorpora una batteria al litio o un circuito integrato contenente una batteria al litio.
Poiché il litio è una sostanza tossica, la batteria non deve essere mai né rotta, né incenerita, né

gettata tra i normali rifiuti.
Questo tipo di batteria non può essere sottoposto né a ricarica né a corto-circuito o scarica forzata.

Queste azioni possono provocare surriscaldamento, fuoriuscita di gas o esplosione della batteria.

WARNING

WARNING

xv

Rame berillio

Alcuni componenti meccanici in questo strumento sono realizzati in rame berillio. Si tratta di una
lega con contenuto di berillio di circa il 5%, che non presenta alcun rischio in usi normali.

Questo materiale non deve essere lavorato, saldato o subire qualsiasi processo che coinvolge alte
temperature.

Deve essere eliminato come "rifiuto speciale". Non deve essere eliminato tramite "inceneritore".

Pacco batterie al piombo

Uso della batteria

Lo strumento può essere corredato di un pacco batteria, fornibile come accessorio contenente
piombo e acido solforico.

PRECAUTIONS

Immagazzinamento della batteria

Il piombo è una sostanza tossica, l’acido solforico è corrosivo ed irritante e, se viene a contatto con
la pelle, può causare bruciature di natura chimica.

Il pacco batteria in qualsiasi circostanza:

- non deve essere ricaricato in ambiente con temperatura superiore a 40°C;

- non deve essere posto sul fuoco;

- non deve essere corto-circuitato;

- non deve essere aperto o rotto né deve subire alcuna violazione meccanica;

- non deve essere conservato a temperatura superiore a 60°C;
Osservare sempre la corretta polarità ed il corretto collegamento.
Durante il normale uso, piccole quantità di idrogeno ed ossigeno possono fuoruscire, per cui

occorre che, intorno allo strumento, vi sia una ventilazione sufficiente alla dispersione di questi gas
in modo naturale.

Il pacco batteria deve essere ricaricato solo attraverso lo strumento o attraverso un carica-batterie
approvato per batterie al piombo sigillate.

La batteria può considerarsi esaurita quando la sua capacità scende al di sotto del 50% del valore di
targa. Tale valore è riportato nelle specifiche tecniche al capitolo 1 di questo manuale.

Il pacco batteria, una volta esaurito, dovrebbe essere prontamente sostituito.

Qualsiasi batteria al piombo sigillata si scarica naturalmente nel tempo. La sua vita e la sua
capacità possono ridursi in caso di completa scarica. Far riferimento alle specifiche tecniche
riportate nel capitolo 1 di questo manuale per quanto riguarda tempo e condizioni
d’immagazzinamento.

Le batterie tenute in magazzino dovrebbero essere periodicamente ricaricate per migliorare la loro
durate. Prima di ricaricare la batteria misurare la tensione a circuito aperto e se essa è inferiore al
limite riportato nelle specifiche tecniche vedi capitolo 1 di questo manuale, non bisogna procedere
all ricarica.

WARNING

WARNING

WARNING

Posizionamento inclinato

Superfici ad alta temperatura

Fare attenzione nel toccare il connettore d'ingresso di tipo N dopo aver applicato una potenza
elevata e co nt inua. Una pote nza superiore a 50 W pe r tempi prolungati può port are il connett ore
ad una temperatura molto elevata.

Rischio a RF

Durante la misura di ROS di valori elevati, la presenza di onde stazionarie può causare tensioni
pericolose. In queste condizioni è quindi rischioso usare lo strumento coi coperchi rimossi.

Quando lo strumento è in posizione inclinata è raccomandato, per motivi di stabilità, non
sovrapporre altri strumenti.

xvi 46882-311

OPERATING MANUAL 2945A

Precauciones

Estos términos tienen significados específicos en este manual:

WARNING

contienen información referente a prevención de daños personales.

contienen información referente a prevención de daños en equipos.

contienen información general importante.

Símbolos de peligro

Los significados de los símbolos de peligro que aparecen en los equipos son los siguientes:

Símbolo

Naturaleza del peligro

Peligro general

Voltaje peligroso

Aviso de toxicidad

Superficies a altas temperaturas

Condiciones generales de uso

WARNING

Nivel peligroso de electrici dad (tensi ón de red)

Este producto ha sido diseñado y probado para cumplir los requerimientos de la normativa
IEC/EN61010-1 "Requerimientos de la normativa para equipos eléctricos de medida, control y uso
en laboratorio", para equipos clase I portátiles y para uso en un ambiente con un grado de
contaminación 2. El equipo ha sido diseñado para funcionar sobre una instalación de alimentación
de categorías I o II.

Debe protegerse el equipo de la entrada de líquidos y precipitaciones como nieve, lluvia, etc.
Cuando se traslada el equipo de entorno frío a un entorno caliente, es importante aguardar la
estabilización el equipo para evitar la condensación. Sólo debe utilizarse el aparato en las
condiciones ambientales especificadas en el capítulo 1 “Especificaciones” o “Performance data”,
en caso contrario la propia protección del equipo puede resultar dañada.

Este producto no ha sido aprobado para su utilización en entornos peligrosos o en aplicaciones
médicas. Si se va a utilizar el equipo en una aplicación con implicaciones en cuanto a seguridad,
como por ejemplo aplicaciones de aviónica o militares, es preciso que un experto competente en
materia de seguridad apruebe su uso.

Este equipo cumple las normas IEC Seguridad Clase 1, lo que significa que va provisto de un cable

de protección de masa. Para mantener esta protección, el cable de alimentación de red debe de
conectarse siempre a una clavija con terminal de masa.

Tenga en cuenta que el filtro de red contiene condensadores que pueden almacenar carga una vez
desconectado el equipo. Aunque la energía almacenada está dentro de los requisitos de seguridad,

xvii

PRECAUTIONS

Fusibles

pudiera sentirse una ligera descarga al tocar la clavija de alimentación inmediatamente después de
su desconexión de red.

No quitar las tapas, en el interior no existen piezas reemplazables por el usuario. Vea la lista de
Centros de Servicios Internacionales en la parte trasera del manual.

Se hace notar que el fusible de alimentación interno está enserie con el activo del cable de
alimentación a red. Si la clavija de alimentación de red cuenta con sólo dos terminales sin
polaridad, el fusible puede pasar a estar en serie con el neutro, en cuyo caso existen partes del
equipo que permanecerían a tensión de red incluso después de que el fusible haya fundido.

WARNING

Peligro de incendio

WARNING

Aviso de toxicidad

WARNING

Litio

Asegúrese de utilizar sólo fusibles del tipo y valores especificados como repuesto.
Si se utiliza una clavija con fusible incorporado, asegúrese de que los valores del fusible

corresponden a los requeridos por el equipo. Ver sección de especificaciones del capítulo 1 para
comprobar los requisitos de alimentación.

Alguno de los componentes utilizad os en este equipo pudieran incluir resinas u otro tipo de
materiales que al arder produjeran sustancias tóxicas, Por tanto, tome las debidas precauciones en
la manipulación de esas piezas.

En este equipo se utiliza una batería de litio (o contenida dentro de un CI).
Dada que el litio es una substancia tóxica las baterías de este material no deben ser aplastadas,

quemadas o arrojadas junto a basuras ordinarias.
No trate de recargar este tipo de baterías. No las cortocircuite o fuerce su descarga ya que puede

dar lugar a que la esta emita gases, se recaliente o explote.

WARNING

xviii 46882-311

Berilio-cobre

Algunos componentes mecánicos contenidos en este instrumento incorporan berilio-co bre en su
proceso de fabricación. Se trata de una aleación con un contenido aproximado de berilio del 5%, lo
que no repr esenta ningún riesgo durante su uso nor mal.

El material no debe ser manipulad o, soldado, ni sometido a ningún proceso que implique la
aplicación de calor.

Para su eliminación debe tratarse como un "residuo especial". El material NO DEBE eliminarse
mediante incineración.

OPERATING MANUAL 2945A

WARNING

Paquete de baterías de plomo-ácido

Baterías de plomo-acido

Junto con el equipo se suministra como accesorio una batería de plomo-ácido que contienen plomo
y ácido sulfúrico. El plomo es una sustancia tóxica y el ácido sulfúrico es corrosivo e irritable para
la piel y puede causar sobre la piel expuesta al mismo, heridas por quemadura química. La batería
no debe tir arse en ningún caso a l a basura convencional.

No cargar la batería a temperatura superior a los 40°C.
No la tire al fuego, no la cortocircuite. No la aplaste, ni perfore, ni abra, ni desmonte, ni

interfiera mecánicamente con ella de ninguna manera.

No almacenar a temperaturas superiores a los 60°C.
Fíjese en la polaridad correcta y conéctale correctamente.

Es posible que durante el funcionamiento normal de la batería se produzcan pequeñas fugas de

gases hidrógeno y oxígeno. Es preciso permitir la ventilación adecuada del entorno del
instrumento con el fín de permitir la dispersión natural de dichos gases.

La batería sólo debe ser recargada utilizando la función de carga del instrumento o empleando

un cargador adecuado para baterías de plomo-ácido.

La vida normal de la batería se considera terminada cuando su capacidad cae por debajo del

50% de su capacidad nominal. Esta capacidad nomina aparece en el capitulo 1 de este
manual. Las baterías que alcancen esta condición deben dejar de ser utilizadas.

Almacenamiento de la batería

WARNING

Superficies a altas temperaturas

WARNING

Riesgo de RF

Cualquier batería de plomo-ácido se descarga de forma natural durante su almacenamiento. Su
vida útil y su capacidad pueden verse seriamente afectadas si la batería se descarga completamente.
Vea en el capitulo 1 del manual el tiempo y las condiciones de almacenamiento.

Las baterías almacenadas deben ser recargadas periódicamente para optimizar su rendimiento y su
vida útil. Antes de recargarlas es necesario medir la tensión en bones en circuito abierto y en caso
de encontrarse por debajo del mínimo indicado en las especificaciones del capitulo 1 de este
manual, la batería no debe recargarse.

Tenga cuidado al tocar el conector de entrada RF tipo N tras la aplicación continuada de altos
niveles de potencia. La temperatura del conector puede llegar a ser excesiva si se sobrepasan 50 W
durante un periodo prolongado de tiempo.

Cuando se miden valores elevados de ROE, pueden existir tensiones elevadas debido a ondas
estacionarias. Bajo estas condiciones resulta peligroso operar con el equipo sin las tapas puestas.

WARNING

Tener en cuenta con el equipo inclinado

xix

Si utiliza el equipo en posición inclinada, se recomienda, por razones de estabilidad, no apilar otros
equipos encima de él.

Contents

Chapter 1

GENERAL INFORMATION

Purpose and features...................................................................................................................... 1-2

Transmitter testing.................................................................................................................. 1-2

Receiver testing ...................................................................................................................... 1-3

Duplex testing......................................................................................................................... 1-4

Systems testing ....................................................................................................................... 1-5

Spectrum analyzer...................................................................................................................1-5

AF testing ............................................................................................................................... 1-6

Performance data......................................................................................................................... 1-7

Receiver measurements .......................................................................................................... 1-7

Audio analyzer........................................................................................................................ 1-8

Transmitter measurements.................................................................................................... 1-10

RF spectrum analyzer ........................................................................................................... 1-11

Tracking generator................................................................................................................ 1-12

Audio generators...................................................................................................................1-12

General features.................................................................................................................... 1-13

Frequency standard............................................................................................................... 1-13

General ................................................................................................................................. 1-13

Options and accessories........................................................................................................ 1-14

List of figures

Fig. 1-1 Transmitter test setup...................................................................................................... 1-2

Fig. 1-2 Receiver test setup........................................................................................................... 1-3

Fig. 1-3 One port duplex test setup............................................................................................... 1-4

Fig. 1-4 Two port duplex test setup .............................................................................................. 1-4

Fig. 1-5 Cellular radio-telephone test setup.................................................................................. 1-5

Fig. 1-6 AF test setup.................................................................................................................... 1-6

46882-311 1-1

GENERAL INFORMATION

Purpose and features

2945A is a portable Communications Service Monitor for carrying out production, routine and
maintenance testing on radio transmitters, receivers and two way radio communication equipment.
The Service Monitor contains modules to provide facilities equivalent to the following
instruments:-

RF generator, two audio generators, specialised tones generator, RF power meter, modulation
meter, RF counter, AF counter, AF voltmeter, distortion meter, large screen digital oscilloscope,
spectrum analyzer and monitoring receiver.

Distortion measuring filters, AF post demodulation filters and IF passband filters, are built in for
inclusion in relevant measurement paths.

The signal obtained from the demodulators, when in Tx test mode, is fed to an AF amplifier and
can be monitored on the built-in loudspeaker, on headphones connected to the accessory socket, or
taken from the DEMOD OUT connector to other equipment.

The monitor has a wide range of test capabilities including base station, mobile and transponder
commissioning and servicing, radio telephone system and radio pager testing, as well as production
testing to all of the above.

The selection of a test mode configures the modules into set-ups ready for connection to the
equipment to be tested and produces the appropriate set-up screen on the display. The set-up
screen shows the settings of the active modules, records changes to settings as they are made and
gives readouts of test results both digitally and on barcharts.

The modules of the monitor can each be used to perform as individual test instruments.
A hard copy of most screens can be made to a suitable printer using the screen capture feature.

This is one of the functions accessed after pressing the [DISPLAY HOLD] key on the front panel.
See Front panel layout, DISPLAY HOLD key, in Chapter 3.

A memory facility allows instrument settings and test results to be stored within the instrument.
With the memory card option fitted, these can be stored on memory cards. This also allows
settings to be exchanged between instruments.

The memory card option also includes a real time clock which provides date/time stamping to
stored results and to screen-capture printouts.

The RS232 control facility permits operation of the instrument by remote or automatic control as
an alternative or supplement to the conventional front panel local control.

IEEE 488.2 GPIB remote control is available as an option.
RS232 and GPIB control facilities are detailed fully in the Programming Manual supplied.
The test modes are outlined in the following descriptions, with interconnection diagrams showing

the principles of the test procedures.

Transmitter testing

Service Monitor

MODULATED RF SIGNAL

AF GENERATOR
OUTPUT

Fig. 1-1 Transmitter test setup

1-2 46882-311

Tx

Under

Test

AF (MODULATION)
INPUT

C3240

OPERATING MANUAL 2945A

The transmitter test procedure uses:-

The AF generators, to provide a source of modulation for the transmitter under test.
The RF power meter, to measure the mean output power level of the transmitter.
The RF counter, to obtain the mean RF frequency of the transmitter output.
The modulation meter, to measure the modulation depth or the deviation level and to

provide a demodulated output signal. Single sideband transmissions can be demodulated
when the SSB option is implemented.

The AF counter, to measure the frequency of the demodulated signal.
The distortion meter, to obtain the signal to noise level, the modulation distortion percentage

or the modulation SINAD level of the transmitter.
The oscilloscope, to view the demodulated signal and to measure the modulation levels.
The tones generator, to modulate transmitters of systems using tone calling.
The tones decoder, to demodulate tones generated by the transmitter.
The AF amplifier and loudspeaker, to monitor the demodulated signal.

Cellular radio-telephones can be tested using the SYSTEMS mode. (See ’System testing’).
The spectrum analyzer facility, which is a separate operating mode (SPEC ANA), can be used to

study the sidebands and any harmonics produced by the transmitter, either by direct connection or
by off-air monitoring.

Receiver testing

The receiver test procedure uses:-

The RF generator and the AF generators, to produce a transmission with defined parameters.
The AF voltmeter, to measure the level of the demodulated signal from the receiver.
The distortion meter, to obtain signal-to-noise ratio, SINAD levels and distortion percentage

figures.
The tone generator and tone detector, to produce and decode specialised calling tones to test

tone recognition circuits.
The oscilloscope, to view and measure the demodulated signal or other waveforms.

The RF signal from the Service Monitor is coupled to the receiver and the demodulated signal from
the receiver taken to the AF input of the Service Monitor. By measuring the levels of the AF signal
from the receiver, the sensitivity of the receiver can be checked. The distortion levels introduced
by the receiver can be measured.

Service Monitor

MODULATED RF TEST SIGNAL

DEMODULATED AF SIGNAL

Fig. 1-2 Receiver test setup

Rx

Under

Test

C3241

46882-311 1-3

GENERAL INFORMATION

During all of the above procedures, the RF levels, the distortion levels and modulation levels can
be displayed on bar charts as well as being provided as a digital read-out. The AF waveforms can
also be studied using the digital oscilloscope facility.

Duplex testing

Service Monitor

Service Monitor

MODULATED

RF TEST

SIGNAL

DEMODULATED AF SIGNAL

AF GENERATOR OUTPUT

RF SIGNAL
FROM RADIO
UNDER TEST

Fig. 1-3 One port duplex test setup

MODULATED RF TEST SIGNAL

MODULATED RF SIGNAL

DEMODULATED AF SIGNAL

Rx/Tx

Under

Test

Rx/Tx

Under

Test

C3242

AF GENERATOR OUTPUT

Fig. 1-4 Two port duplex test setup

Using the Duplex test facility, parameters for transmitter testing and receiver testing can be set-up
and displayed on one screen. This gives the capability to study the performance of duplex
transceivers. Both one port and two port units can be tested.

C3243

1-4 46882-311

OPERATING MANUAL 2945A

Systems testing

Cellular and trunked radio-telephone systems

Service Monitor

AF OUT

!

!

AF IN

RF

SERVICE

+

CONNECTION

DC

SUPPLY

C3253

Fig. 1-5 Cellular radio-telephone test setup

With the appropr iate cellular or trunked mobile telephone option include d, the monitor has built-in
software to generat e and interroga t e signals of the vario us cellular or trunked telephone systems.
This gives the facility for testing all aspects of these systems.

Inbuilt test programs and user programming facilities give speed and flexibility to these tests.
Operating instructions for each of the SYSTEM test options is given in separate supplements to

this manual. These supplements are supplied, as appropriate, with instruments fitted with
SYSTEM testing options.

Spectrum analyzer

The SPEC ANA mode allows ‘off air’ and directly coupled RF signals to be studied and
monitored.

Sideband spread, harmonic levels and RF interference can be examined.
The frequency range of the spectrum analyzer is from 100 kHz to 1.0 GHz with the start and stop

frequencies of the sweep infinitely variable from within this range.
The tracking generator permits frequency response tests to be made to frequency dependent circuits

and the frequency offset facility extends this capability into the area of frequency shifting circuits,
such as mixers.

The ‘Look and Listen’ function gives the ability to demodulate a signal displayed on the spectrum
analyzer and monitor the signal obtained on the built-in loudspeaker, on headphones or other data
output equipment.

46882-311 1-5

GENERAL INFORMATION

AF testing

Service Monitor

AUDIO

AUDIO

Fig. 1-6 AF test setup

Amplifier

Under

Test

C3244

The AF testing mode allows the dual AF generators and the tones generator to be used as a signal
source. The AF voltmeter, distortion meter, bar chart displays and the AF counter can all be used
to provide data relating to signals applied to the AF input connector. The digital oscilloscope is
also available for studying AF waveforms.

1-6 46882-311

OPERATING MANUAL 2945A

Performance data

Receiver measurements

RF signal generator

Frequency

Range 400 kHz to 1.05 GHz
Resolution 10 Hz
Indication 10 digit display
Setting Keyboard entry, delta inc rem ent / decrement function and rotary

Accuracy As frequency standard

Output Level

Range Rx Test:

Resolution 0.1 dB
Indication 4 digits plus sign (dBm, dBµV, µV, mV, PD/EMF).
Accuracy ± 2 dB for level above −127 dBm on N-Type socket up to 1 GHz

control

N-Type socket: −141 dBm to −21 dBm
BNC socket: −115 dBm to +5 dBm. (usable to +7 dBm)

Reverse Power Protection N-Type: 50 W for 10 minutes, normal operat i on. 150 W for

Output Impedance Nominally 50 Ω

VSWR N-Type Better than 1.2:1 up t o 500 M Hz

VSWR BNC Better than 2.2:1 up to 1.05 GHz

Spectral Purity

Residual FM Less than 15 Hz RMS (0.3 to 3. 4 kHz) up to 500 MHz.

Harmonics Better than −20 dBc
Spurious signals Better than −30 dBc (±10 kHz to 1.5 MHz offset from carrier

SSB phase noise (20 kHz offset) Better than −95 dBc / Hz up to 1 GHz
RF carrier leakage Less than 0.5 µV PD generated in a 50 Ω load by a 2 turn loop

Amplitude Modulation - Internal

Frequency range 400 kHz to 1.05 GHz
AM depth range 0 to 99 %
Resolution 1 %
Indication 2 digits
Setting Keyboard entry, delta inc rem ent / decrement function and rotary

1 minute at 20°C.
Overload indicated by audible and v i sual warning.

BNC: 5 W Tripping indicated by audibl e and visual warning.

Better than 1.35:1 up to 1.05 GHz

Less than 20 Hz RMS (0.3 to 3.4 kHz) up to 1000 MHz (with

OCXO)

Less than 22 Hz RMS (0.3 to 3.4 kHz) up to 1000 MHz, over the

range 18 to 28°C (with TCXO)

frequency or over range 600-700 MHz).

Better than −40 dBc from 400 k Hz to 1 GHz

25 mm from the case. Output l evel less than −40 dBm into a
sealed 50 Ω load.

control

46882-311 1-7

GENERAL INFORMATION

Accuracy ±7% ±1 digit, for mod freq of 1 kHz,

Distortion Less than 2% at 1 kHz for 30%, CCITT Wei ghted
Modulation Frequency Range 20 Hz to 20 kHz

Amplitude Modulation - External

Input impedance Nomi nal l y 10 kΩ in parallel with 40 pF
Frequency Range As internal AM
Modulation Frequency Range As internal AM
Sensitivity 1.0 V RMS for 0 to 100% AM

Frequency Modulation - Internal

Frequency range 400 kHz to 1.05 GHz
Maximum deviation 75 kHz
Indication 3 digits
Setting Keyboard entry, delta inc rem ent / decrement function and rotary

Accuracy † ±5% ± 10 Hz at 1 kHz modulating frequency
±10% at modulating frequencies from 50 Hz to 15 kHz.
Distortion Less than 1% at 1 kHz for deviati on of 5 kHz, CCITT Weighted.
Resolution 25 Hz
Pre-emphasis 750 µs selectable
Mod Frequency Range 20 Hz - 25 kHz

Frequency Modulation - External

Input impedance Nomi nal l y 10 kΩ in parallel with 40 pF
Frequency Range As internal FM
Modulation Frequency Range DC to 100 kHz
Pre-emphasis 750 µs selectable
Sensitivity 1 V RMS for 0 to 75 kHz devi at i on

Microphone Input

Input Level 2 mV to 200 mV (AGC levelled)
Input Impedance Nominally 150 Ω
Press To Talk (PTT) When using the optional microphone in Tx Tes t mode, the PTT

CW 1.5 MHz to 400 MHz.

±10% ±1 digit for mod freq of 50 Hz to 5 kHz,

CW 1.5 MHz to 400 MHz.

±15% ±1 digit, for mod f req of 50 Hz to 15 kHz,

CW 1.5 MHz to 400 MHz.

control

will switch instrument to Rx Test.

† At low modulation levels t he residual AM / FM may becom e significant

Audio analyzer

Audio Voltmeter

Input Impedance Nominally 1 MΩ i n paral l el wi th 40 pF
Frequency Range DC and 20 Hz to 50 kHz

Level Ranges 0-100 mV to 0-100 V RMS in a 1,3,10 s equence
Resolution 1 mV or 1% of reading
Indication 3 digits and barchart
Accuracy ±3% ±3 mV ± resolution

1-8 46882-311

AC only 20 Hz to 50 kHz
Polarized DC (below 1 Hz)

OPERATING MANUAL 2945A

50 mV (100 mV for 40 dB SINAD). Readi ng suppressed if audio

Audio Frequency Meter

Frequency Range 20 Hz to 20 kHz
Resolution 0.1 Hz, less than 10 kHz

Indication 5 digits
Accuracy As frequency standard ± 1 digi t ± resolution
Sensitivity 50 mV

Audio SINAD Meter

Frequency 1 kHz
Range 0 to 18 dB and 0 to 50 dB
Resolution 0.1 dB
Indication 3 digits and barcharts
Accuracy ± 1 dB
Sensitivity

Audio Distortion Meter

Frequency 1 kHz
Range 0 to 10 %, 0 to 30 % and 0 to 100 %
Resolution 0.1 % distortion
Indication 3 digits and barcharts
Accuracy ± 5 % of readi ng ± 0.5 % distortion
Sensitivity 50 mV (100 mV for 1 % distort i on). Reading suppressed if audio

Audio S/N Meter

Range 0 to 30 dB and 0 to 100 dB
Resolution 0.1 dB
Indication 3 digits and barchart
Accuracy ± 1 dB
Sensitivity 50 mV (100 mV for 40 dB S/N). Reading suppressed if audio

Audio Oscilloscope

Operating Modes Single or repetitive sweep
Frequency Range DC to 50 kHz, 3 Hz to 50 kHz A C coupled
Voltage Range 10 mV to 20 V per division in a 1,2,5 s equence
Voltage Accuracy ±5 % of full scale
FM Ranges ±75, 30, 15, 6, 3 and 1.5 kHz devi ation full scale, ±10 %

AM Ranges 20, 10 and 5 % per division, ±10 % accuracy
Timebase 50 µs/div to 5 s/div in a 1,2, 5 sequence
Graticule 10 Horizontal by 6 Vertical di visions
Special features Built in antialiasing circuit ry

Audio Barcharts

Barchart Displays AF Voltage, SINAD, Distort i on, S/N
Vertical Resolution 2 % of full scale
Ranging Autoranging, range hold or manual selection 1, 2, 5, sequence

1 Hz, at 10 kHz and above

voltage is less than 5 m V

voltage is less than 5 m V

voltage is less than 5 m V

accuracy

with hysteresis

46882-311 1-9

GENERAL INFORMATION

Audio and Modulation Filters

300 Hz Lowpass
300 Hz Highpass
3 kHz Lowpass
300 Hz to 3.4 kHz Bandpass
15 kHz Lowpass
750 µs de-emphasis. (NOT available in Audio M ode)

Transmitter measurements

RF Frequency Meter

Frequency Range 100 kHz to 1.05 GHz
Resolution 1 Hz or 10 Hz, selectable
Indication Up to 10 digits
Accuracy As frequency standard ±resolution
Acquisition Time Less than 1 second (manual).

Sensitivity Autotuned: 5 mW (N-Type) 0.05 mW BNC (antenna port)

VSWR N Type <1.2:1 to 500 MHz

RF Power Meter (Broadband)

Frequency Range 200 kHz to 1.05 GHz
Dynamic Range 5 mW to 150 W (N-Type)

Indication Units Watts, dBm or dBW
Indication 3 digits or barchart
Resolution 0.1 dB
Accuracy ±10 % ±resolution (N-Type)

Maximum Power Handling N-Type: 150 W for limited periods, typically 1 minute at 20°C.

Maximum Continuous Power 50W at 20°C (Note N-Type connector tem perature may exceed

Typically 3 seconds (autotune),
operates over 10 MHz - 1.0 GHz

Manual Tuned: −34 dBm (N-Type), −60 dBm BNC (antenna
port)

<1.25:1 to 1000 MHz

BNC (antenna port) <3:1 to 1000 MHz

0.05 mW to 250 mW BNC (antenna port)

BNC (antenna port) specification is typically as for N-Type
specification.

70°C after typically 10 minutes.)
Overload indicated by audible and v i sual warning.
BNC (antenna port) input 5 W maximum.

Harmonic Measurement Displays 1st to 5th harmonic of the carrier.

Max. harmonic frequency 1050 MHz
Dynamic range 0 to −60 dBc (depends on filter b/ w selected).

Transient Power Analysis Displays power profile agains t time.

Frequency range 1 to 1050 MHz
Dynamic range 60 dB below spectrum analyzer reference level.
Scale (power) 10 dB/div.
Scale (time) 50 µs/div to 5 s/div.
Trigger level Adjustable over full dynamic range +ve or −ve trigger.
Pre-trigger 0, 25%, 50%, 75% or 100% of di splayed period.

1-10 46882-311

OPERATING MANUAL 2945A

Modulation Meter

Sensitivity Autotuned: 5 mW (N-Type) 0.05 mW BNC (antenna port)

Audio filters 300 Hz Lowpass

Amplitude Modulation

Frequency Range 100 kHz to 1.05 GHz
Modulation Frequency Range 10 Hz to 15 kHz
AM Depth Range 0 to 99% (manually tuned)

Resolution 1% AM
Indication 2 digits and barchart
Accuracy † ± 5% ±1 digit at 1 kHz
± 8.5% ±1 digit from 50 Hz t o 10 kHz
Demodulation Distortion † Less than 2 %, at 1 kHz & 30% AM, (CCITT Weighted)
Residual AM Less than 1 % (300 Hz to 3.4 kHz)

Frequency Modulation

Frequency Range 100 kHz to 1.05 GHz
Modulation Frequency Range 10 Hz to 15 kHz
Deviation Range 0 t o 75 kHz
Resolution 10 Hz below 2 kHz deviation,

Indication 3 digits and barchart

Accuracy † ± 5 % ±resolution at 1 kHz m odul ation frequency

Demodulation Distortion Less than 2 % at 1 kHz and 5 kHz FM, (CCITT Weighted)
Residual FM Less than 30 Hz (300 Hz to 3.4 k Hz)
Demodulation Output Socket

(de-emphasis function available)

Manual Tuned:−34 dBm(N-Type) −60 dBm BNC (ant enna port )

300 Hz Highpass
3 kHz Lowpass
300 Hz to 3.4 kHz Bandpass
15 kHz Lowpass
750 µs de-emphasis

0 to 90% below 100 MHz
0 to 80% from 100 to 400 MHz

1% above 2 kHz deviation

± 7.5 % ±resolution for modulation frequencies 50 Hz to 10 kHz

200 mV peak to peak ±10 % per 1 kHz deviation

† At low modulation levels t he residual AM / FM may becom e significant

RF spectrum analyzer

Frequency Range 100 kHz to 1.0 GHz
Spans Continuously variable,

Resolution Bandwidth 300 Hz, 3, 30, 300 kHz, 3 MHz
Reference Level (top of screen) −50 dBm to +52 dBm
On screen dynamic range 80 dB
On Screen Linearity Typically ± 2 dB ±resoluti on (10 dB/div)

Vertical resolution 0.1 dB on 2 dB / division

Level Flatness ± 1 dB ±resolution over 50 MHz span

46882-311 1-11

1 kHz / division to 100 M Hz / division.
1,2,5,10 increments.
Start / Stop frequency entry.

(10 dB above the noise floor)

0.5 dB on 10 dB / division

GENERAL INFORMATION

Intermodulation Distort i on Better than 70 dB for two signal s at −30 dBm into first mixer
Sweep speeds 10 ms/div mini m um (Optimum sweep speed and bandwidth

Update Rate Using “AUTO” resolution B/W selection

SPAN
10 kHz

100 kHz

10 MHz
100 MHz
1000 MHz

Marker Indication Single marker for frequency and level display

Features Simultaneous 'Look and Listen'

Tracking generator

Tracking Generator Offset 0-999 MHz
Output Level N-Type socket: −141 dBm to −21 dBm

selected according to s pan)

RES B/W UPDATE

300 Hz 5 SWEEP/sec

1 MHz

Function for ∆ level and ∆ frequency from centre.

Span 100 kHz, 200 kHz, 500 kHz, 1 MHz
2µV Sensitivity

BNC socket: −115 dBm to +5 dBm

3 kHz 9 SWEEP/sec

30 kHz 9 SWEEP/sec

300 kHz 9 SWEEP/sec
300 kHz 5 SWEEP/sec

3 MHz 5 SWEEP/sec

Audio generators

Frequency

Frequency Range 10 Hz to 25 kHz
Waveform Sine or square wave
Setting Keyboard entry, delta inc rem ent / decrement function and rotary

Indication 5 digits
Resolution 0.1 Hz below 3.25 kHz

Accuracy 0.01 Hz ± frequency st andard <180 Hz

Level

Level Range 0.1 mV to 4 V RMS
Setting Keyboard entry, delta inc rem ent / decrement function and rotary

Indication 4 Digits
Resolution 0.1 mV below 409 mV

Accuracy ±5% ±resolution 50 Hz - 15 kHz
Output impedance Nominally 5 Ω (Minimum load impedance 25 Ω)
Signal Purity
Distortion Less t han 0.5 % at 1 kHz

Signalling Encoder / Decoder

Sequential Tones Functions Encodes and decodes up to 40 tones.

control

1 Hz above 3.25 kHz

0.1 Hz ± frequency standard >180 Hz

control

1 mV above 409 mV

Less than 1 % from 50 Hz to 15 kHz

CCIR, ZVEI, DZVEI, EEA, EIA or user defined.
Any of the tones may be ex tended.
Continuous, burst and single step modes available.

1-12 46882-311

OPERATING MANUAL 2945A

Demodulated signals and audio signal s may be monitored via the

User Defined Tones

DTMF Generation and decoding of DTMF tones.
DCS Generation and decoding of Digitally Coded Squelch, DCS.
POCSAG Generation of POCSAG code CCIR No. 1 Rec 584. Bit rates

Audio Monitor

General features

Keyboard and Display Logical colour c oded keyboard with bright high resoluti on LCD

Display size 160 x 85 m m

RS232C

Connector 9 way male ’D’ Type

Frequency standard

Internal Frequency Standard (TCXO)

Frequency 10 MHz
Temperature stability Better than 0.5 in 10
Ageing Rate Better than 1 in 10
Warm up 1 minute to s pecified accuracy

External Frequency Standard Input

Frequency 1, 2, 5 and 10 MHz
Input Level Greater than 1 V peak to peak
Input Impedance Nominally 1 kΩ

Up to two sequential tones frequency plans may be defined and

stored within the Service Monitor. Any of the s tandard tone

frequency plans may be copi ed t o user defined and modified.
Tone length 20 ms to 1 s.
Standard tone frequencies may be selected from a menu.

from 400 to 4800 bit/s. Inversion available.

internal loudspeaker and via the ac cessory socket output on

the front panel.

RS232C interface is provided for printing or remote instrument

control.

6

, 0 to 50 °C

6

per year

General

Power Requirements

AC Supply Voltage 90 V to 265 V 90 V to 132 V
AC Supply Frequency 45 Hz to 67 Hz 45 Hz to 440 Hz
Maximum AC Power 190 VA
DC Supply Voltage 11 to 32V
Maximum DC Power 100W
Low battery indicator Indication of low battery voltage provided.
Charge Output 13.8V at 6A max t o charge a 12V sealed lead acid battery

Electro-Magnetic Compatibility Conforms with the protect i on requi rem ents of the EEC Council

Safety

Directive 89/336/EEC.
Complies with the limi t s specified in the fol l owi ng standards:

EN 55011 Class B CISPR 11

EN50082-1 IEC 801-2,3,4

EN60555-2 IEC 555-2.
This instrument is des i gned to comply with the requirement s of

EN61010-1 / IEC61010-1, for Class 1 P ortable equipment and

is for use in a pollution degree 2 envi ronm ent. The equipment

is designed to operate from an ins tallation categories 1 or 2

supply.

46882-311 1-13

GENERAL INFORMATION

Environmental

Rated range of use 0°C to 50°C and up to 95% relative humidity at 40°C

Storage and transport

Temperature −40°C to +71°C
Altitude Up to 2500m (pressurised freight at 27 kPa differential)

Dimensions and Weight

Height 178 mm
Width 380 mm
Depth 457 mm (including handle, feet and covers)
Weight Less than 11.4 kg, (Less than 25 lb)

Options and accessories

Options

Option 1
Option 2
Option 3
Option 4
Option 5
Option 6
Option 8
Option 10
Option 11
Option 12
Option 13
Option 14
Option 15
Option 16

Option 21
Option 22
Option 23
Option 24
Option 30

600 Ω Matching Unit (Option 1)

Features

600 Ω Matching Unit
Analog Systems Card
High Stability OCXO
Parallel Interface
GPIB Interface
Memory Card Drive and Date/Time Stamp

SSB Demodulator
NMT
AMPS
TACS
MPT1327
PMRTEST
EDACS Radio Test
EDACS Repeater Test

Demodulation filters
POCSAG decode
CCITT Filter
CMESS Filter
Bail arm and front panel stowage c over

Switchable 600 Ω balanced. AF input and output. Switc habl e

20 dB attenuator on AF generator output.




Requires Option 2 to be fitted






Analog Systems Card (Option 2) Required for Options 10 to 16.

High Stability Internal Frequency (OCXO)
Standard (Option 3)

Frequency 10 MHz
Temperature Stability Better than 5 part in 10
Ageing Rate Better than 1 part in 10
Warm-up Time Less than 10 minutes to within 2 parts i n 10

Parallel Interface (Option 4) Allows direct connection of a paral l el pri nter. Additionally

Printer port
Connector 25 way female D-type.
Printers supported 75,100, 150 dots per inch laser printers

Accessory port
Connector 9 way female D-type.

For performance data refer to respective handbook supplement.

8

, 5 to 55°C

7

per year, after 1 month continuous use.

provides 4 software programmable out put lines.

FX80, FX100 Epson format.

7

at 20°C.

1-14 46882-311

OPERATING MANUAL 2945A

Decoding of POCSAG mess ages. Can decode a message as it i s

Outputs 4 independently programmable output lines, each one

GPIB (Option 5) For remote instrument cont rol .

Capability

Memory Card (Option 6) The memory card facility allows the storage of results, set-ups,

SSB Demodulator (Option 8) Provides demodulation of SSB signals (upper and lower

Modulation Meter

Frequency range 400 kHz to 1 GHz
AF demodulation range 10 Hz to 15 kHz
Detection range 2 µV to 150 W
Features Automatic detecti on of USB or LSB.

Demodulation filters (Option 21) Provides a range of high selectivity channel filters in Tx Tes t and

Bandwidths 5 kHz, 12.5 kHz, 25 kHz, 50 kHz and 300 kHz.

POCSAG Decode (Option 22)

Bit Rate

configurable as a logic line or as a relay contact closure.
+5V supply available.

Complies with the following subsets defined by IEEE488:-

SH1, AH1, T6, L4, SR1, RL1, E 1, DC1, DT0

screen dumps and user programs. M eets PCMCIA 2 standard.
Allows the current date and t i m e to be stored with results to the
memory card and/or printed with a screen dump.

sideband.)

BFO can be used for tuning of carri er for AM and FM radios.

Spectrum Analyzer Look and Li sten modes.
Shape factor approximates t o ETSI requirements.

received, or decoding can be triggered from a user-selectable
RIC code or fixed message pattern.

Automatically dec odes any standard bit rate up to 4800 bit /s.
Numeric and Alphanumeric decoding i s provided.
Number of received errors is displayed.

CCITT (Option 23) CCITT weighted filter
C-MESSAGE (Option 24) C-MESSAGE weighted filter
Supplied Accessories AC Supply lead †

Optional Accessories 44991/145 Microphone with PTT

43138/755 DC Supply lead
46882/311 Operating Manual
46882/318 Programming Manual

† The AC supply lead provided with the Service Monitor will
depend on the destination country . See

Power cords

43113/021 Battery Pack
54431/023 20 dB AF attenuator (BNC)

46884/728 Rack Mounting Kit
54421/001 Antenna BNC
46662/571 Ever Ready Case
46880/079 Service Manual

54421/002 Directional Power Head 1 to 50 MHz
54421/003 Directional Power Head 50 to 1000 MHz
54421/016 70 to 1000 MHz Lightweight Directional Power
Head and Adaptor
54421/018 400 to 1000 MHz Lightweight Directional Power
Head and Adaptor
46884/789 Power Head Adaptor
54432/012 Wideband Amplifier

43130/590 1m 7 way DIN lead Assy.
43130/591 3m 7 way DIN lead Assy
59000/189 Memory Card (128 kbyte)

, in chapter 2 of this manual

Power requirements,

contd./...

46882-311 1-15

GENERAL INFORMATION

Optional Accessories (continued) 54442/004 Remote control head kit

Battery Pack

Type 12V Sealed lead-acid
Normal capacity when new ≈30 minutes instrument operation from full charge
Charge time from instrument 16 hrs
Minimum open circuit v ol tage 12 V
Capacity 7 AH
Shelf life:-

0° C to 20° C 12 months
21° C to 30° C 9 months
31° C to 40° C 5 months

Weight 3 kg

46662/616 Soft case for bail arm version
46884/648 Serial cable 9 way female to 25 way male

46884/649 Serial cable 9 way female to 25 way female
46884/650 Serial cable 9 way female to 9 way female

1-16 46882-311

OPERATING MANUAL 2945A

46882-311 1-17

Chapter 2

INSTALLATION

Contents

Introduction.................................................................................................................................... 2-2

Initial visual inspection of new instruments................................................................................... 2-2

Ventilation ..................................................................................................................................... 2-2

‘Ever-ready’ case shoulder strap.................................................................................................... 2-2

Bail arm option....................................................................................................................... 2-3

Power requirements....................................................................................................................... 2-3

Fuses.............................................................................................................................................. 2-3

Class I power cords (3-core)................................................................................................... 2-3

Connecting to a DC supply and fitting batteries ............................................................................ 2-5

RF and AF connections.................................................................................................................. 2-6

Accessory socket connections........................................................................................................ 2-6

Remote control connections........................................................................................................... 2-7

RS232.....................................................................................................................................2-7

GPIB....................................................................................................................................... 2-8

Self tests.................................................................................................................................. 2-9

Using the Service Monitor........................................................................................................... 2-10

Routine maintenance.................................................................................................................... 2-11

Ventilation fan and filter....................................................................................................... 2-11

Routine safety testing and inspection........................................................................................... 2-11

1. Visual inspection ............................................................................................................. 2-11

2. Earth bonding tests.......................................................................................................... 2-12

3. Insulation tests................................................................................................................. 2-12

4. Rectification..................................................................................................................... 2-12

Cleaning................................................................................................................................ 2-13

List of tables

Table 2-1 Accessory socket pin numbering, location and functions............................................. 2-6

Table 2-2 Accessory socket logic and applications ...................................................................... 2-7

List of figures

Fig. 2-1 Preventing strap buckle from slipping............................................................................. 2-2

Fig. 2-2 Accessory in/out socket pin numbers .............................................................................. 2-7

Fig. 2-3 RS232 serial port connections.........................................................................................2-8

Fig. 2-4 Null modem connections................................................................................................. 2-8

Fig. 2-5 IEEE488 parallel port connections.................................................................................. 2-9

46882-311 2-1

INSTALLATION

Introduction

This chapter deals with preparing the Service Monitor for use for the first time and with the checks
to be made when the Service Monito r may have been used under unknown conditions.

The latter situation could well apply where the Service Monitor is used by several users for
differing tasks.

Initial visual inspection of new instruments

After unpacking the Service Monitor and before making any connections to a power source, inspect
for any signs of mechanical damage. Refer to the questionnaire at the front of this manual.

Ventilation

The Service Monitor is force cooled by a fan located in the rear panel. The cooling air is drawn
into the Service Monitor through the fan and expelled through ventilator grills loca t e d on the right
and on the underside. An air filter over the fan inlet prevents the ingress of dust and other
particles.

The Service Monitor requires an unrestricted airflow to ensure that its performance meets
the specification. Before switching the Service Monitor on, check that the air inlet on the
rear panel is not restricted and that there is no loose material close by which could be
sucked into the fan. Refer to Routine Maintenance later in this chapter for details of
cleaning and replacing the air filter.

The optional ‘Ever-ready’ case has ventilation apertures which align with those of the
Service Monitor. Ensure that these are not obstructed.

‘Ever-ready’ case shoulder strap

The shoulder strap supplied with the ‘Ever-ready’ case should be attached to the front handles of
the Service Monitor. When fitting the strap, always loop the tails of the strap through the buckles
in the reverse direction. This will prevent the strap from slipping through the buckle. See Fig. 2-1,
Preventing strap buckle from slipping.

STRAP

BUCKLE

HANDLE

C2509

Fig. 2-1 Preventing strap buckle from slipping.

2-2 46882-311

OPERATING MANUAL 2945A

Bail arm option

If the bail arm carrying handle is fitted, the Service Monitor will not fit into the optional Ever
Ready Case, 46662/571. Do not attempt to attach the shoulder strap supplied with this Ever Ready
Case to a Service Monitor fitted with a bail arm carrying handle.

Power requirements

The Service Monitor can be powered from a wide range of power sources, both AC and DC.
AC supplies must be within the range 90 V to 265 V, at a frequency of between 45 Hz and 67 Hz;

or within the range 90 V to 132 V, at a frequency of between 45 Hz and 440 Hz
The maximum power consumption is 190 VA
Voltage selection is not necessary as the AC power supply module within the Service Monitor is

designed to handle this wide spread of input variations.
For DC operation, the Service Monitor requires a supply within the range 11 V to 32 V. A range

switch adjusts the input circuits of the DC supply module for either 11 V to 20 V or 18 V to 32 V.
The maximum DC power requirement is 100 W.

Fuses

The AC input circuit is fed through a single fuse fitted to the rear panel of the Service Monitor,
within the AC input connector. This should be a 2 A anti-surge, 5 × 20 mm glass cartridge fuse.

The DC input circuit is also fed through a single fuse. This is fitted within the fuseholder adjacent
to the DC input connector. This should be a 10 A anti-surge, 5 × 20 mm glass cartridge fuse.

Class I power cords (3-core)

General

When the equipment has t o be plugged into a Class II (ungrounded) 2-terminal socket outlet, t he
cable should either be fitted with a 3-pin Class I plug and used in conjunction with an adapter
incorporating a ground wire, or be fitted with a Class II plug with an integral ground wire. The
ground wire must be securely fastened to ground. Grounding one terminal on a 2-terminal socket
will not provide adequate protection.

In the event that a moulded plug has to be removed from a lead, it must be disposed of
immediately. A plug with bare flexible cords is hazardous if engaged in a live socket outlet.

Power cords with the following terminations are available from IFR Ltd. Please check with your
local sales office for availability.

This equipment is provided with a 3-wire (grounded) cordset which includes a moulded IEC 320
connector for connection to the equipment. The cable must be fitted with an approved plug which,
when plugged into an appropriate 3-terminal socket outlet, grounds t he case of the equi pment.
Failure to ground the equipment may expose the operator to hazardous voltage levels. Depending
upon the destination country, the colour coding of the wires will differ:-

Wire ended

Country IEC 320 plug type IFR part number

Universal Straight through 23424-158
Universal Right angled 23424-159

North America Harmonised

Line (Live) Black Brown
Neutral White Blue
Ground (Earth) Green Green/Yellow

GREEN/YELLOW
EARTH

BROWN
LIVE

HARMONISED-WIRE ENDED

BLUE
NEUTRAL

C3509

46882-311 2-3

INSTALLATION

British

Country IEC 320 plug type IFR part number

United Kingdom Straight through 23422-001
United Kingdom Right angled 23422-002

The UK lead is fitted with an ASTA approved moulded plug to BS

1363.
A replaceable 13 A fuse to BS 1362 is contained within the plug. This

fuse is only designed to protect the lead assembly. Never use the plug
with the detachable fuse cover omitted or if the cover is damaged.

The fuse(s) or circuit breaker to protect the equipment is fitted at the back of the equipment.

North American

Country IEC 320 plug type IFR part number

North American Straight through 23422-004
North American Right angled 23422-005

The North American lead is fitted with a NEMA 5-15P (Canadian
CS22.2 No 42) plug and carries approvals from UL and CSA for use in
the USA and Canada.

Continental Europe

EARTH

NEUTRAL

LIVE

UNITED KINGDOM

NEUTRAL

U.S./CANADA/KOREA

C3510

EARTH

LIVE

C3511

Country IEC 320 plug type IFR part number

Europe Straight through 23422-006
Europe Right angled 23422-007

The Continental European lead is fitted with a right angle IEC83
standard C4 plug (CEE 7/7) which allows it to be used in sockets with
either a male earth pin (standard C 3b) or side earth clips (standard

EARTH

CONTINENTAL

C 2b) the latter is commonly called the German ‘Schuko’ plug. In
common with other Schuko style plugs, t he plug is not polarized when
fitted into a Schuko socket. The lead carries approvals for use in Austria, Belgium, Finland,
France, Germany, Holland, Italy, Norway and Sweden. Note that this plug will not fit Italian
standard CEI 23-16 outlets. The lead should not be used in Denmark given that the earth
connection will not be made.

Français

Le câble d'alimentation d'Europe Continentale est muni d'un connecteur mâle à angle droit type
CEI83, standard C4 (CEE 7/7), qui peut être utilisé dans une prise femelle à ergot de terre
(standard C 3b) ou à clips latéraux (standard C 2b), cette dernière étant communément appelée
prise “Schuko” allemande. De la même faç on que les autre s connecteurs de type Schuko, celui-ci
n'est pas polar i s é lorsqu'il s'adap te à une prise femelle Schuko. Ce câble d'alimentation est
homologué en Allemagne, Autriche, Belgique, Finlande, France, Hollande, Italie, Norvège et
Suède. A noter que ce connecteur n'est pas compatible avec les prises de courant italiennes au
standard CEI 23-16. Ce câble ne doit pas être utilisé au Danemark à cause du défaut de connexion
de masse.

Deutsch

Das kontinentaleuropäische Netzkabel ist mit einem rechtwinkeligen Stecker nach IEC83 C4
(CEE7/7) Standard versehen, welcher sowohl in Steckdosen mit Erde-Stift (Standard C 3b) oder
seitlichen Erdeklemmen, im allgemeinen “Schukosteckdose ” genannt, paßt. Üblic herweise ist der
Schukostecker be i Verwendung in Schukosteckdosen nicht gepolt. Dieses Netzkabe l besitzt
Zulassung für Österre i ch, Belgien, Finnla nd, Frankreich, Deutschland, Ho l land, Italien, Norwegen
und Schweden.

EARTH

NEUTRAL

EUROPE

LIVE

C3512

2-4 46882-311

OPERATING MANUAL 2945A

Hinweis: Dieser Schukostecker paßt nicht in die i talienischen Standardsteckdosen nac h CEI 23-16
Norm. Dieses Netzkabel sollte nicht in Dänemark verwendet werden, da hier keine
Erdeverbindung he rgestellt wird.

Español

El cable de alimentación tipo Europeo Continental dispone de una clavija C4 normalizada IEC83
(CEE 7/7) que permite su utilización tanto en bases de enchufe con toma de tierra macho (tipo C
3b) o con toma de tierra mediante contactos laterales (tipo C 2b) que, en este último caso, suele
denominarse “Schuko”. Al igual que cualquier otra c l avija tipo Schuko, las conexiones a red no
están polarizadas cuando se conectan a una base tipo Schuko. El cable lleva autorización para su
uso en Austria, Bélgica, Finlandia, Francia, Alemania, Holanda, Italia, Noruega y Suecia. Observe
que este cable no se adapta a la norma italiana CEI 23-16. El cable no debe utilizarse en
Dinamarca en el caso de no efectuarse conexión a tierra.

Italiano

I cavi d'alimentazione per l'Europa continentale vengono forniti terminati con una spina ad angolo
retto del tipo C4 secondo lo standard IEC83 (CEE 7/7) che può essere usato in prese in cui la terra
può essere fornita o tramite connettore maschio (C 3b) o tramite clips laterali (C 2b), quest'ultima
comunemente detta di tipo tedesca “Schuko”. Questa spina, quando collegata a d una presa
Schuko, non è polarizzata.

Il cavo può essere usato in Austria, Belgio, Finlandia, Francia, Germania, Olanda, Norvegia,
Svezia ed Italia. E' da notare che per l'Italia questo non risponde allo standard CEI 23-16.

Questa spina non dovrebbe invece essere usata in Danimarca in quanto non realizza il
collegamento di terra.

Connecting to a DC supply and fitting batteries

If the Service Monitor is to be used from a DC voltage source it should be connected using the
supplied DC connecting lead, part no. 43138-755 The polarity of the connections must be correct,
RED to POSITIVE, BLACK to NEGATIVE, and the DC input voltage selector set to the
appropriate range for the supply.

The negative connection of the DC supply is directly connected to the chassis of the Service
Monitor and therefore to all screen connections of input and output connectors. Note however, that
the AF ports are isolated under some operating conditions.

The Service Monitor will function from any supply with a voltage within the range given under

Power requirements above, but must be capable of delivering a current in the order of 9 amps at

the lowest voltage.
Ensure that the supply lead connections are sound and cannot short together.
The accessory battery pack has an output lead fitted with a connector for direct connection to the

DC input connector.
The accessory battery pack should be fitted into the battery pocket of the ‘Ever-ready’ case. The

battery lead can be left connected to the Service Monitor.
When fitting a battery pack or reconnecting the battery to the Service Monitor for any reason,

ensure that all surplus battery connecting lead is contained within the Service Monitor
compartment of the ‘Ever-ready’ case. Do not leave a loop of cable which could become snagged
when the Service Monitor is being carried.

A fully charged battery pack will power the Service Monitor for approximately 30 minutes between
charges. The Service Monitor will recharge the battery in approximately 16 hours if connected to a
mains supply and the mains power switch put to the ‘CHARGE’ position.

When the DC supply powering the Service Monitor falls to a level indicative of battery pack
discharge, a ‘Battery Low’ warning is displayed on the screen.

46882-311 2-5

INSTALLATION

RF and AF connections

All RF and AF connections should made using good quality connectors correctly fitted to
appropriate cable. All connectors should be locked to the Service Monitor using the bayonet or
threaded locking rings. Do not use leads that have damaged connectors or cable as this can cause
poor performance and might damage the Service Monitor.

RF leakage levels in a test set-up can be aggravated by the use of poor quality connector leads. A
double screened lead, 1 metre in length and terminated with male BNC connectors, IFR Part No
43137-052 and a 1 metre, ’N type’ male to ’N type’ male, connector lead 54311-095 are both
available from IFR sales offices.

WARNING

Hot Surfaces

Take care when touching the RF Input Type N connector after the application of high levels of
continuous power. If 50 W is exceeded for a prolonged period, the temperature of the connector
can become excessive.

Accessory socket connections

The accessory socket located on the front panel, is of the 7 pin DIN, 45° configuration.
The function of each of the pins on this socket is shown in the following table. The pin numbering
is shown in Fig. 2-2 Accessory in/out socket pin numbers, and is as viewed from the front of the
Service Monitor.

Table 2-1 Accessory socket pin numbering, location and functions.

Din pin No Function

6 Logic
1 Mic input/PTT-logic
4 Forward power
2 12 V DC at approx 100 mA
5 Reverse power
3 Logic
7 Loudspeaker output

The pin numbering of the Accessory socket, as seen from the front of the Service Monitor, is
shown in Fig. 2-2 Accessory in/out socket pin numbers.

2-6 46882-311

OPERATING MANUAL 2945A

2

45

13

6

EARTH SHIELD

Fig. 2-2 Accessory in/out socket pin numbers

The socket is used for connecting dedicated accessories such as directional power heads and
microphones with press to talk switching capabilities.

Selection logic [or data signals] on pins 1,3 and 6 enables the Service Monitor to recognise the
connections of an external accessory. The appropriate pins are at TTL levels and are active low
(L) as shown below:

Table 2-2 Accessory socket logic and applications

Accessory Pin 1 Pin 3 Pin 6

Nothing connected High High High
Microphone (press to talk) Low High High
External power: Auto zero High Low Low

7

C1785

External power: Peak power High High Low
External power: CW power High Low High

Refer to chapter 3, Operation, for details of using the socket.,
A 3.0 metre lead assembly (part No. 43130/591) is available as an optional accessory.

Remote control connections

RS232

The serial port connection requires a 9 way female ‘D’ Type connector. This should be correctly
fitted to appropriate cable and the locking screws should be used to prevent undue strain from
being applied to the connector housing.

46882-311 2-7

INSTALLATION

The pin connections are listed below and the pin locations shown in Fig. 2-3 RS232 serial port
connections (as seen facing panel).

Contact Function Contact Function

1 Not connected 6 DSR
2 Rx data in 7 RTS
3 Tx data out 8 CTS
4 DTR 9 Not connected
5 Ground

1

5

C0783

9

6

Fig. 2-3 RS232 serial port connections (as seen facing panel)

The use of a NULL MODEM cable assembly is required for connecting to control equipment such
as PCs.

The connections for 9 way to 9 way and 9 way to 25 way versions is shown in Fig. 2-4.

SERVICE

MONITOR

SG

RXD

TXD

CONNECTED

NOT

DSR

PC

9-WAY 9-WAY

5

2

3

4

1

6

5

2

3

4

1

6

SG

RXD

TXD

DTRDTR

DCD

DSR

CONNECTED

SERVICE

MONITOR

9-WAY 25-WAY

5

SG

2

RXD

3

TXD

4

NOT

1

6

DSR

PC

7

3

2

8

6

SG

RXD

TXD

DTRDTR 20

DCD

DSR

RTS

CTS

CONNECTED

NOT

7

8

99

RTS

7

CTS

8

CONNECTED

RTS

CTS

NOT

7

8

4

RTS

5

CTS

C3383

Fig. 2-4 Null modem connections

GPIB

When the optional GPIB interface unit has been fitted, connections are made to it using a 24-way
IEEE 488 male connector. If a stackable connector is used in order to interconnect more than two
pieces of equipment, ensure that no physical damage to the Service Monitor connector will result.

The pin connections are listed below and the pin locations shown in Fig. 2-5 IEEE488 parallel
port connections (as seen facing panel).

2-8 46882-311

OPERATING MANUAL 2945A

Contact Function Contact Function

1 Data I/O 1 13 Data I/O 5
2 Data I/O 2 14 Data I/O 6
3 Data I/O 3 15 Data I/O 7
4 Data I/O 4 16 Data I/O 8
5 EOI 17 REN
6 DAV 18 Pair with 6
7 NRFD 19 Pair with 7
8 NDAC 20 Pair with 8

9 IFC 21 Pair with 9
10 SRQ 22 Pair with 10
11 ATN 23 Pair with 11
12 Ground shield 24 Logic ground

12 1

Fig. 2-5 IEEE488 parallel port connections (as seen facing panel)

Self tests and acceptance tests

The service monitor incorporates a self test program which allows users to verify its condition at
any time. This program is described below.

When it is necessary to prove that the performance of the Service Monitor meets the published
performance data, the Acceptance tests, described in Chapter 5, should be carried out.

Self tests

The built in Self Test program measures the output parameters of the RF generator using the
transmitter test functions. The RF generator output is coupled internally and no external
connections are required.

The self test program is accessed through the help/set-up menu and comprises 17 tests, which are
listed on the display when the [Self Test] key is pressed.

Before running the program, the Service Monitor should be reset t o the factory preset state. This is
done by pressing the [MEM] key, to display the STORE/RECALL screen and menu. The message
’Recall Store No ’is shown. key in and enter the digits ’01’. The Service Monitor will now be ready
to run the self test program.

To run the program the [GO] key is pressed and the tests are carried out consecutively. The legend

‘ACTIVE’ is displayed against each test as it is carried out, which changes to ‘PASS’ or ‘FAIL’ as
each test is completed. If a particular test fails, the reason is given alongside the ‘FAIL’ legend,
together with the measurement.

The tests carried out, the related set-ups and the functions verified are listed below.

24 13

C0683

Test No 1
Test No 2
Test No 3
Test No 4
Test No 5

Broadband power. 500 MHz
Transmitter Frequency. 500 MHz
Broadband power. 1 GHz
Transmitter Frequency. 1 GHz
Broadband power. 10 MHz

46882-311 2-9

INSTALLATION

Test No 6

The above tests compare the generated power and frequency against the broadband power meter
and the frequency meter at each of the frequencies specified.

Related set-up. Manual tune
The functions verified by the above tests are:­Signal generator frequency and level accuracy.
Power meter accuracy.

Test No 7 to 14

Narrow band power meter. Power level +10 dBm. (Test No 7) to -60 dBm. (Test No 14)
These tests compare the generated power levels against the narrowband power meter readings.
Related set-ups. Frequency, 10 MHz, IF Bandwidth, 30 kHz.
The functions verified by the above tests are:­Signal generator level accuracy.
Signal generator attenuators.
Spectrum analyzer level accuracy.
Receiver attenuators.

Test No 15

This test checks the signal generator FM deviation against the modulation meter reading.
Related set-ups. Frequency 10 MHz, level -26 dBm, IF bandwidth 300 kHz, audio bandwidth 0.3 -

3.4 kHz, FM demodulation.
The functions verified by the above tests are:­Signal generator FM accuracy, modulation meter FM accuracy, modulation generator (audio

generator) level accuracy

Transmitter Frequency. 10 MHz

FM deviation. 50 kHz

Test No 16

This test checks the modulation generator output frequency against the audio counter reading.
Related set-ups. Related set-ups. Frequency 10 MHz, level -26 dBm, IF bandwidth 300 kHz, audio

bandwidth 0.3 - 3.4 kHz, FM demodulation.
The functions verified by the above tests are:­modulation generator (audio generator) frequency accuracy

Test No 17

This test checks the signal generator AM against the modulation meter reading.
Related set-ups. Frequency 10 MHz, level -26 dBm, IF bandwidth 0.3 - 3.4 kHz, AM

demodulation.
The functions verified by the above tests are:­Signal generator AM accuracy, modulation meter AM accuracy, audio generator frequency

accuracy, audio generator level accuracy, audio filters, audio counter.

Modulation frequency. 1 kHz.

AM Depth. 50%

Using the Service Monitor

The monitor can be used as a bench instrument, either flat standing or inclined using the elevating
front feet. The monitor can also be used as a field service instrument while left in the ‘Ever-ready’

case. It can be operated in any position convenient to the operator. See the
Ventilation, earlier in this chapter.

Caution under

2-10 46882-311

OPERATING MANUAL 2945A

Routine maintenance

Ventilation fan and filter

The ventilator fan on the rear of the Service Monitor is fitted with a filter to prevent the ingress of
foreign matter into it. This should be inspected and cleaned at regular intervals. The procedure for
this is as follows:-

Disconnect the Service Monitor from the mains supply and from any DC supply.
Remove any other connections to the Service Monitor.

WARNING

Failing to disconnect the power source before removing the filter could result in the fan
becoming switched on accidentally.

Stand the Service Monitor face down on a firm, non-scratch flat surface so that it is supported on
the front handles.† The rear of the Service Monitor, with the fan housing, should be at a safe and
accessible working height.

Remove the two M4 screws holding the fan filter to the rear of the Service Monitor and lift the
filter away.

Take the filter to a suitably ventilated location and remove as much dust and other foreign matter as
is practical. Do not wet or wash the filter.

Refit the filter to the Service Monitor, using the reverse procedure as appropriate.
If the filter is damaged or blocked, a replacement is available as IFR part No. 35907/675.

If the bail arm carrying handle has been fitted, this should be positioned over

†

the top of the Service Monitor before standing the instrument face down,
supported on the front bumpers.

Routine safety testing and inspection

In the UK the ‘Electricity at Work Regulations’ (1989) section 4(2) places a requirement on the
users of equipment to maintain it in a safe condition. The explanatory notes call for regular
inspections and tests together with a need to keep records.

The following electrical tests and inspection information is provided for guidance purposes and
involves the use of voltages and currents that can cause injury. It is important that these tests are
only performed by competent personnel.

Prior to carrying out any inspection and tests the Service Monitor must be disconnected from the
mains supply and all external signal connections removed. All tests should include the Service
Monitor’s own supply lead, all covers must be fitted and the supply switch must be in the ‘ON’
position.

The recommended inspection and tests fall into three categories and should be carried out in the
following sequence:

1. Visual inspection

2. Earth Bonding Test (Class I equipment only)

3. Insulation Resistance test.

1. Visual inspection

A visual inspection should be carried out on a periodic basis. This interval is dependent on the
operating environment, maintenance and use, and should be assessed in accordance with guidelines
issued by the Health and Safety Executive (HSE). As a guide, this Service Monitor, when used
indoors in a relatively clean environment, would be classified as ‘low risk’ equipment and hence
should be subject to safety inspect ions on an annual basis. If the use of the equi pment is contrary
to the conditions specified, you should review the safety re-test interval.

As a guide, the visual inspection should include the following where appropriate:

46882-311 2-11

INSTALLATION

Check that the equipment has been installed in accordance with the instructions provided (e.g. that
ventilation is adequate, supply isolators are accessible, supply wiring is adequate and properly
routed).

The condition of the mains supply lead and supply connector(s).
Check that the mains supply switch isolates the Service Monitor from the supply.
The correct rating and type of supply fuses.
Security and condition of covers and handles.
Check the supply indicator functions (if fitted).
Check the presence and condition of all warning labels and markings and supplied safety

information.
Check the wiring in re-wireable plugs and appliance connectors.
If any defect is noted this should be rectified before proceeding with the following electrical tests.

2. Earth bonding tests

Earth bonding tests should be carried out using a 25A (12V maximum open circuit voltage) DC
source. Tests should be limited to a maximum duration of 5 seconds and have a pass limit of 0.1 Ω
after allowing for the resistance of the supply lead. Exceeding the test duration can cause damage
to the equipment. The tests should be carried out between the supply earth and exposed case
metalwork, no attempt should be made to perform the tests on functional earths (e.g. signal
carrying connector shells or screen connections) as this will result in damage to the equipment.

3. Insulation tests

A 500 V DC test should be applied between the protective earth connection and combined live and
neutral supply connections with the equipment supply switch in the ‘on’ position. It is advisable to

make the live/neutral link on the appliance tester or its connector to avoid the possibility of
returning the Service Monitor to the user with the live and neutral poles linked with an ad-hoc
strap. The test voltage should be applied for 5 seconds before taking the measurement.

IFR Ltd employs reinforced insulation in the construction of its products and hence a minimum
pass limit of 7 MΩ should be achieved during this test.

Where a DC power adapter is provided with the Service Monitor the adapter must pass the 7 MΩ
test limit.

We do not recommend dielectric flash testing during routine safety tests. Most portable appliance
testers use AC for the dielectric strength test which can cause damage to the supply input filter
capacitors.

4. Rectification

It is recommended that the results from the above tests are recorded and checked during each
repeat test. Significant differences between the previous readings and measured values should be
investigated.

If any failure is detected during the above visual inspection or tests, the Service Monitor should be
disabled and the fault should be rectified by an experienced Service Engineer who is familiar with
the hazards involved in carrying out such repairs.

Safety critical components should only be replaced with equivalent parts, using techniques and
procedures recommended by IFR Ltd.

The above information is provided for guidance only. IFR Ltd designs and constructs its products
in accordance with International Safety Standards such that in normal use they represent no hazard
to the operator. IFR Ltd reserves the right to amend the above information in the course of
continuing its commitment to product safety.

2-12 46882-311

OPERATING MANUAL 2945A

Cleaning

Before commencing any cleaning, switch off the Service Monitor and disconnect it from the
supply. The exterior surface of the case may be cleaned using a soft cloth moistened in water. Do
not use aerosol or liquid solvent cleaners.

46882-311 2-13

Chapter 3

LOCAL OPERATION

Contents

About this chapter.......................................................................................................................... 3-4

Front panel layout.......................................................................................................................... 3-4

Rear panel controls and connectors............................................................................................... 3-8

Getting started................................................................................................................................ 3-9

(Applying power and selecting test modes)............................................................................3-9

Test mode screens and menus........................................................................................................ 3-9

HELP/SETUP....................................................................................................................... 3-10

Bar charts..................................................................................................................................... 3-13

Spectrum analyzer........................................................................................................................ 3-14

Oscilloscope................................................................................................................................. 3-14

Using the test modes...................................................................................................................3-15

Brief descriptions......................................................................................................................... 3-15

Tx test (transmitter testing).......................................................................................................... 3-17

Overview .............................................................................................................................. 3-17

Connections.......................................................................................................................... 3-18

Setting up.............................................................................................................................. 3-19

Making measurements.......................................................................................................... 3-25

External attenuators..............................................................................................................3-31

Rx test (receiver testing).............................................................................................................. 3-36

Overview .............................................................................................................................. 3-36

Connections.......................................................................................................................... 3-37

Setting up.............................................................................................................................. 3-38

AF input level measurement................................................................................................. 3-41

Making measurements.......................................................................................................... 3-43

Dx test (duplex testing)................................................................................................................ 3-50

Overview .............................................................................................................................. 3-50

Systems........................................................................................................................................ 3-51

Spectrum analyzer........................................................................................................................ 3-52

Overview .............................................................................................................................. 3-52

Setting up.............................................................................................................................. 3-53

AF test (audio frequency testing)................................................................................................. 3-59

Overview .............................................................................................................................. 3-59

Setting up.............................................................................................................................. 3-60

Input level measurement....................................................................................................... 3-60

Input filtering........................................................................................................................ 3-61

Distortion measurement........................................................................................................ 3-61

Incremental adjustment keys........................................................................................................ 3-62

General ................................................................................................................................. 3-62

Assigning.............................................................................................................................. 3-63

Use within spectrum analyzer mode.....................................................................................3-64

Tones ........................................................................................................................................... 3-64

Tones sub-mode.................................................................................................................... 3-64

Observing tones signals in other test modes......................................................................... 3-65

Signal routeing...................................................................................................................... 3-65

RF input attenuators.............................................................................................................. 3-65

Sequential tones........................................................................................................................... 3-66

Overview .............................................................................................................................. 3-66

Testing sequential tone receivers.......................................................................................... 3-66

Testing sequential tone transmitters...................................................................................... 3-69

CTCSS......................................................................................................................................... 3-70

Output level.......................................................................................................................... 3-71

contd./...

46882-311 3-1

LOCAL OPERATION

Contents

(continued)

Tone selection....................................................................................................................... 3-71

Tone frequency shift............................................................................................................. 3-71

DCS..............................................................................................................................................3-71

Overview...............................................................................................................................3-71

DCS receiver decoder testing................................................................................................3-72

DCS transmitter encoder testing...........................................................................................3-73

DTMF..........................................................................................................................................3-73

Overview...............................................................................................................................3-73

Tx test DTMF tones function................................................................................................3-74

Rx test DTMF tones function................................................................................................3-74

Dx test DTMF tones function...............................................................................................3-76

AF test DTMF tones function............................................................................................... 3-76

POCSAG...................................................................................................................................... 3-76

Overview...............................................................................................................................3-76

Testing a radio pager ............................................................................................................ 3-78

Decoding POCSAG type signals .......................................................................................... 3-79

Oscilloscope................................................................................................................................. 3-80

Setting up.............................................................................................................................. 3-80

Expanded display.................................................................................................................. 3-81

Stores, settings/results.................................................................................................................. 3-82

Overview...............................................................................................................................3-82

STORE/RECALL................................................................................................................. 3-82

Storing .................................................................................................................................. 3-83

DISPLAY HOLD STORE.................................................................................................... 3-83

Other memory functions ....................................................................................................... 3-83

Titling store locations ........................................................................................................... 3-84

Memory card................................................................................................................................ 3-84

Formatting memory cards.....................................................................................................3-84

Accessing the memory cards................................................................................................. 3-85

Write-protecting cards..........................................................................................................3-85

Coded store protection ..........................................................................................................3-86

Storing on memory cards...................................................................................................... 3-87

Printing from memory cards.................................................................................................3-87

Error messages...................................................................................................................... 3-88

Real time clock. Date and time stamping............................................................................. 3-88

Printer .......................................................................................................................................... 3-89

Parallel printer port option....................................................................................................3-90

List of tables

Table 3-1 Parallel printer port connections................................................................................. 3-90

Table 3-2 Rear accessory port connections.................................................................................3-91

List of figures

Fig. 3-1 Front panel....................................................................................................................3-4

Fig. 3-2 Typical displays............................................................................................................3-5

Fig. 3-3 Rear panel layout, (with optional GPIB fitted)............................................................. 3-8

Fig. 3-4 Transmitter test connections.......................................................................................3-18

Fig. 3-5 Tx power, harmonic analysis screen........................................................................... 3-26

Fig. 3-6 Power Transient Analysis screen................................................................................ 3-27

Fig. 3-7 Transient Analysis displays........................................................................................3-30

Fig. 3-8 Distortion level and signal to noise level measurements. ........................................... 3-33

Fig. 3-9 Receiver test connections ........................................................................................... 3-37

Fig. 3-10 Selectivity test setup...................................................................................................3-47

Fig. 3-11 Spurious response ‘Image Frequency’ location.......................................................... 3-48

Fig. 3-12 One port duplex test setup..........................................................................................3-50

3-2 46882-311

OPERATING MANUAL 2945A

Fig. 3-13 Alternative two port duplex setups.............................................................................. 3-51

Fig. 3-14 Spectrum analyzer test setup....................................................................................... 3-52

Fig. 3-15 Spectrum analyzer test setup using the tracking generator.......................................... 3-52

Fig. 3-16 Spectrum Analyzer setup, Look and Listen function................................................... 3-57

Fig. 3-17 Audio test setup........................................................................................................... 3-59

Fig. 3-18 Tones selection screen and Tones mode receiver input level setting........................... 3-64

Fig. 3-19 RF Sequential tones encoder display, main menu....................................................... 3-67

Fig. 3-20 RF Sequential tones standard selection menu..............................................................3-67

Fig. 3-21 RF Sequential tones decoder screen............................................................................ 3-69

Fig. 3-22 RF CTCSS encoder screen and menu.......................................................................... 3-70

Fig. 3-23 RF DCS ENCODER screen and menu........................................................................ 3-72

Fig. 3-24 RF DTMF DECODER screen and menu..................................................................... 3-74

Fig. 3-25 POCSAG radio pager test screen and menu................................................................ 3-77

Fig. 3-26 Alternative address/warning messages........................................................................ 3-78

Fig. 3-27 Parallel printer port socket contacts............................................................................ 3-90

Fig. 3-28 Rear accessory port socket connections ...................................................................... 3-90

Fig. 3-29 Simplified diagram of rear accessory port switching................................................... 3-91

46882-311 3-3

LOCAL OPERATION

About this chapter

This chapter deals with using the Communications Service Monitor as a ‘stand alone’ instrument.

The front panel layout is described and a brief explanation of all controls and connections is
given.

The connectors and occasional controls on the rear panel are identified.
An introduction to each of the test modes explains the principles behind tests that can be

carried out and suggests some applic ations for the use o f the monitor.
The power up and setup procedure is explained.
The operating sequences for each of the test modes is explained and the relevant menus

outlined.
The internal setup and results memories are described and their use explained.
The use of the optional memory card facility is explained.
Producing hard copy of results on an external printer is described.

Before using the instrument, familiarise yourself with the power requirements and powering up
procedure described in Chapter 2, Installation.

Front panel layout

Fig. 3-1 Front panel

(1) Display. The dominant feature of the front panel is the display screen, used to give information as

to the operation of the instrument.
Information relating to the state of the instrument, the mode of operation and results of

measurements and tests are all given visually on the display screen. See Fig. 3-2, Typical displays.
The screen is divided into four main areas. They are:-

3-4 46882-311

OPERATING MANUAL 2945A

The information display area, which shows the parameters relating to the test, together with
settings and results, including bar charts. When the oscilloscope function is called up, all bar
charts are removed from the display and the standard or expanded oscilloscope screen displayed.

When the SPEC ANA test mode is selected, the display changes to the
screen.

The test title area, where the current test description is displayed. LED indicators adjacent to
each RF connector show the assignment of the connectors. This information is also shown in the
test title area of the display when in Dx TEST mode.

Soft key menus, left and right. These areas each have menus of soft key labels designated to the
adjacent soft keys. Some modes of operation only require one menu area of six selections. For
example, the Tx TEST mode and the AF TEST mode both display and use only the right hand soft
keys, the Rx TEST mode only the left hand soft keys. The Dx TEST mode uses the right hand soft
keys for transmitter test functions and the left hand soft keys for receiver functions.

SPECTRUM ANALYZER

Fig. 3-2 Typical displays

The various keys on the front panel are grouped according to their use or located adjacent to
associated items.

(2) Soft keys. To each side of the display screen are six unmarked keys. These are the ‘Soft’ keys

referred to in the display description above. The specific function of each of these keys is defined
by the instrument software and is indicated by the legend on the label immediately adjacent to it on
the display screen.

(3) Data Input keys. The right hand area of the front panel contains the ‘Data Input’ keys. These

keys are used to key in data for the various test parameters. They are arranged in three groups:-
Function keys on the left of the group are coloured orange. They are used to define the parameter

to be addressed; frequency, level, increment change or memory store location; before any digits are
entered. The [ON/OFF] function key acts directly on the selected function.

Digit keys are in the centre of the group and include the minus sign and decimal point. These two
keys have alternative symbols printed beneath them on the front panel which can be entered as data
where appropriate. No action other than a normal keypress is required, as only one of the three
options for each of these keys is relevant to the entry at any one time. The 'Delete' key back-spaces
over figures entered on the display to correct any errors. Corrections cannot be made to an entry
after a terminator key has been pressed for that entry. The original setting will be retained if an
entry is not completed. The incomplete entry will be replaced on the display by the original setting
when a keypress is made that confirms to the program that the setting being made has been aborted.

Terminator keys used to conclude a parameter value are on the right of the group. They are
coloured orange.

46882-311 3-5

LOCAL OPERATION

When setting a modulation level, the entry is completed using the Hz, kHz, MHz or % key. The
appropriate modulation type, FM or AM, is automatically selected.

(4), (5) & (6) RF input and output connectors.

The three sockets at the right hand edge of the front panel are the RF input/output connectors.
Refer to the Performance data section in Chapter 1 for measurement accuracy, maximum power
input levels and reverse power limits. The nominal impedance of all RF input and output circuits is
50 W.

(4) ANTENNA connection. This is a female BNC connector, for ’Off Air’ measurements and

monitoring, using a suitable antenna. This connector can also be used for direct input of low level
signals.

(5) BNC RF output connector. This provides output from the RF signal generator.
(6) N type RF connector. This is dual function, input and/or output. A 20 dB Delta attenuator is

incorporated within the Service Monitor. This inter-connects the ’N type’ connector with the RF
generator output and the measuring receiver input, through the input/output selector switching.

WARNING

Hot surfaces

Take care when touching the RF Input N Type connector after the application of high levels of
continuous power. If 50 W is exceeded for a prolonged period, the temperature of the connector
can become excessive.

(7) RF input select key. The [SELECT ] key switches through all the RF co nnector combinations

available. The current selection is indicated by LEDs. The  symbol shows the RF output
connector and the  symbol shows the RF input connector.

(8) Increment adjustment keys. Under the variable control are the two pairs of increment adjustment

keys, FREQ (frequency): [Ö] and [×], and LEVEL: [Ö] and [×].
These enable the frequency and level of the RF generator or a selected AF generator to be adjusted

in pre-defined steps. The assignment and the value of the steps is shown on the display.
The FREQ [Ö] and [×] keys can be assigned to the Tx frequency value or either of the audio

generators when in the Tx TEST mode, the RF generator or either of the modulation generators
when in the Rx TEST mode, or either of the AF generators when the AF TEST mode is active.

The LEVEL [Ö] and [×] keys have the same options. The frequency keys and the level keys do
not have to be assigned to the same generator.

The FREQ [Ö] and [×] keys can be assigned to the RF generator frequency or transmitter
frequency as channel increments.

When operating in Dx TEST mode the increment keys are disabled.
The SPEC ANA mode uses the FREQ [Ö] and [×] keys for span range and centre frequency

adjustment. The LEVEL [Ö] and [×] keys are used for reference level adjustment. See page 3-64.
The span is ranged up or down in a 1, 2, 5 sequence, from 1.0 kHz to 1.0 GHz.
Adjustment to the span by these keys is linear about the centre frequency and will not adjust below

zero or above the top frequency limit.
The LEVEL [Ö] and [×] keys adjust the reference level range of the spectrum analyzer in either

2 dB or 10 dB steps depending on the setting of the reference level vertical range.

(9) Variable control. The large rotary control under the data input keys is used to make adjustments

to frequencies and levels that require a finite change such as when matching a test signal to an
undefined signal, or assessing the squelch operating level of a receiver. It has no mechanical stops.
This control is also used to select items or digits from displayed lists, in conjunction with TONES
and SYSTEM modes.

3-6 46882-311

OPERATING MANUAL 2945A

(10) Audio connections.

AF GEN OUT socket. The signal available at this BNC socket is the combined output from both

or either of the AF generators and/or the tones generator.
AF INPUT socket. Signals fed into this BNC socket can be measured using the AF counter, the

AF voltmeter and the distortion measuring circuits. It is also the input for the digital oscilloscope.
ACCESSORY socket. Used for connecting Directional Power Heads and other accessories. The

presence of these is automatically detected. The socket is also used for direct connection of a
headset, allowing modulation of the signal generator by a microphone and audio signal monitoring
through headp hones.

When using the accessory microphone with PTT switch, automatic switching between Tx and Rx
modes using the PTT switch is possible.

DISPLAY HOLD key. To the left of the variable control is the [DISPLAY HOLD] key. Pressing this

key at any time will freeze the display and prevent any adjustment to parameters displayed on the
screen. The soft key menu changes to show two keys, [Store] and [Print].

The [Store] key, gives access to the

STORE/RECALL screen and menu. The use of this feature is

explained on page 3-82
The [Print] key is used to start the Screen Print function. This causes a hard copy of the held

screen to be printed onto a suitable printer. If the memory card option is fitted, the current time
and date, as held in the Real Time Clock, are printed on the hard copy.

The use of the Screen Print feature is explained under the heading ’Printer’ on page 3-89.

AC/DC. AF input coupling option key Located above the AF input socket, this key toggles the AF

input circuit between direct and capacitive coupling. The option selected is displayed on the
screen.

(11) Memory card slot. Instruments with the optional memory card interface fitted, can make use of

memory cards for the storage and retrieval of results and settings.
Details of the use of memory cards is given under later in this chapter under Stores, settings and

results on page 3-82 and Memory Card on page 3-84.

(12) Volume. This control varies the level of the AF signal fed to the loudspeaker.
(13) RF receiver squelch level control. W hen monitoring the demodulated out put through the

loudspeaker or headphones, the RF level below which signals are isolated from the AF circuits can
be controlled. Clockwise rotation of the squelch control raises this level and anti-clockwise
rotation decreases it.

(14) Scope trace vertical position. This adjusts the vertical position of the trace within the graticule.
(15) Oscilloscope sweep mode keys. The [SINGLE] and [REP] keys, located above the scope vertical

position control, select the oscilloscope sweep mode.

(16) Test mode select keys. On the left of the front panel are six blue keys. These are the ‘Test Mode

Select’ keys, used to put the instrument into one of the basic test modes. They are active whenever
the instrument is powered up and under local control.

(17) HELP/SETUP key. Above the test mode select keys is the ‘HELP/SETUP’ key.

Pressing this key will cause the HELP/SETUP access screen to be displayed if the instrument is
under local control. This does not interrupt any on-going function of the Service Monitor. See
HELP/SETUP on page 3-10

When the instrument is under remote control, pressing this key will return control to LOCAL
unless an instruction to prevent local operation has been sent from the remote control device.

46882-311 3-7

LOCAL OPERATION

Rear panel controls and connectors

21

CHARGE - OFF (o) - ON (I)

11-20V 18-32V

252322 24

DC SUPPLY

-

+

100W MAX

10 A-T

AC SUPPLY

100-240V

50-60Hz
108-118V
50-400Hz

190VA 2A-T

Fig. 3-3 Rear panel layout, (with optional GPIB fitted)

SERIAL

PORT

EXT MOD

IN

DEMOD

OUT

29303120

EXT. STD

1/2/5/10MHz

28

26

C4744

27

On the rear panel of the instrument are:-

(20) AC power supply input connector. One range for all mains voltages. See the Performance data

section in Chapter 1. The AC supply fuse is contained within this connector.

(21) DC input voltage selector. Switches the power supply DC input circuits to match the available

supply voltage. Ranges are 11-20 V and 18-32 V.

(22) Power sw itch. The power switch has three positions ON, OFF, CHARGE. The ON position

connects the power source to the instrument, the CHARGE position allows the Service Monitor
power supply to recharge the accessory battery pack (if connected) from the AC mains supply. See
Getting started; on Page 3-9.

(23) DC supply input voltage connector. For direct connection of optional accessory battery pack and

for powering the instrument from other DC supplies. See Performance data, in Chapter 1.

(24) DC supply pin connection diagram. Shows the polarity of the DC power connector
(25) DC supply fuse.
(26) GPIB interface connector. This connector is only present when the GPIB interface option is

fitted. Connection details are given in Chapter 2, under Remote control connections, GPIB.
(27) GPIB interface unit. Optional. See (26) above.
(28) External frequency standard input. This can be 1, 2 5 or 10 MHz; the Service Monitor will

identify the applied frequency. In the event of external standard failure, control will revert to the

internal standard.
(29) Demodulated signal output. The demodulated signal removed from the input RF signal is

brought to this connector for feeding to external eq uipment.
(30) EXT MOD IN (External modulation input). A signal applied to this connector can be used as a

modulation source for the receiver test signal. The input level of the applied signal should be

1.00 V (RMS sinewave) in order to maintain the correlation with the modulation level calibration.

The frequency of the signal should be within the range of the internal modulation source of 20 Hz

to 20 kHz (AM), DC to 100 kHz (FM).

3-8 46882-311

OPERATING MANUAL 2945A

(31) Serial port. The SERIAL PORT connector provides RS232 interface facilities for remote control.

It is also used for the serial output to a printer. Connection details are given in Chapter 2, under
Remote control connections, RS232.

Getting started

(Applying power and selecting test modes)

The power ON/OFF switch, located on the rear of the instrument, has three positions.
Pressing the inside toggle will power up the instrument, from either AC or DC supply.
If both AC and DC supplies are connected, the AC supply will take precedence. A small trickle

charge is also supplied to the DC supply.
Pressing the toggle nearest the edge of the instrument will supply a charging current of up to 7 A

peak to the accessory battery pack from the AC mains supply.
The centre position is OFF.
With a power source connected, switching on the instrument will cause the cooling fan to operate

and one of the test mode menus to be displayed. Which screen is displayed will depend on which
store is selected as the ’Power Up From’ store on setup page 2.

The low battery warning is activated when the voltage at the DC terminals falls to approximately
11 volts. The user selectable ’Po wer Up From’ settings will be found useful when using the
instrument from a battery pack. This will ensures that after replacing a battery pack, the instrument
returns to the settings best suited to the tests being performed. See Setup page 2 on page 3-11.

If you are unfamiliar with the instrument a few minutes spent exploring the setup menus and test
modes is helpful.

The following explanation of keys and menus will assist in this.

Test mode screens and menus

The six test modes are selected by pressing the appropriate MODE key. These are light blue, with
dark blue lettering. (Item 16 in Fig. 3-1, Front panel). Select each in turn and observe the display
presented.

Each area of six soft key labels forms a menu. Various menus are called up as a result of selecting
a change of test mode or by pressing a soft key within a test mode.

Fold out diagrams will be found at the end of this chapter, which show the screens displayed when
each of the mode keys is pressed. These also show branching to the second or third level screens
and menus. A diagram of the screens accessed from the HELP/SETUP key is also included.

These fold out diagrams are numbered to correlate with the associated key position as follows:­(1.0) HELP/SETUP

(2.0) Tx TEST
(3.0) Rx TEST
(4.0) Dx TEST
(5.0) SYSTEM
(6.0) SPEC ANA
(7.0) AF TEST

References in the manual to specific screens on the fold out diagrams is given as in the following
example:-

Fold out diagram (2-2-3). This is the screen shown after pressing the [Tx TEST] mode key, then
the [Tx Power] key (second key down), followed by the [Harmonic analysis] key (third key
down). Where there are keys on both sides of a screen, keys 1 to 6 are on the left, keys 7 to 12 on
the right.

To move to the top level menu of any test mode, including the currently active mode, press the

relevant ‘MODE’ key.
For detailed use of specific TEST MODES see the section later in this chapter relating to that test

mode.

46882-311 3-9

LOCAL OPERATION

HELP/SETUP

Pressing the [HELP/SETUP] key, at any time, will display the screen shown in fold out diagram

(1-0), or a variation of it. Displaying the HELP/SETUP screen does not interrupt any ongoing

operation or test.

The centre panel of the screen lists the following information:-

Serial number of the Service Monitor.

Software fitted, with the version codes and IFR part numbers.

Options fitted to the Service Monitor (except Option 3).

Help

The help facility is accessed by using the [HELP] key. Each soft key in the help menu displays ‘On

Screen Help’ relating to the blue system key to the left of it. The [Return] key removes the on

screen help and displays the top level screen of the mode from where HELP/SETUP was selected.

Self Test

Pressing this key gives access to the SELF TEST function of the Service Monitor. Refer to Self

tests and acceptance tests in Chapter 2, for details.

Diagnostic

The DIAGNOSTIC screen can only be accessed by entering a protection code. When accessed, it

allows a low level of software fault diagnosis to be undertaken. Certain areas of memory can also

be reset from this screen. Details of access are given in the maintenance manual relating to this

instrument.

Calibrate

Access to the CALIBRATION screen is also code-protected. Details relating to access and use are

given in the maintenance manual relating to this instrument.

Brightness

Pressing this key will shift the selected brightness level up by one. If the present level is ‘4’ the

next press will extinguish the screen, the next will set the level to ‘1’. Note that with the screen

blanked, all keys remain in the same state of acti vi t y as before the screen was extinguished.

Contrast

Selecting this key allows the contrast of the display to be varied using the variable control. The

contrast may also be adjusted by the entry of a number between 0 & 255 using the data input keys.

Setup

The setup facilities allow selection of options of user preference and system compatibility. There

are two setup pages.

Page 1, shown in fold out diagram (1-10), allows option selection of RF generator facilities.

Page 2, shown in fold out diagram (1-10-6), allows selection of AF level measurement units, GPIB

address setting, remote control option selection and serial port setup.

The [Setup] key displays setup page 1, and give access to setup page 2.

Setup page 1

This page allows the following optional settings to be selected.

3-10 46882-311

OPERATING MANUAL 2945A

RF Counter Resolution 1 Hz/10 Hz

The RF counter resolution can be set to 1 Hz or 10 Hz. Selecting 1 Hz will slow the screen update
rate by a factor of 10:1. The choice is made by toggling between the two options using the soft key
adjacent to the text.

RF Level Measured in Watts/Volts/dBm

The RF level from the transmitter being tested can be displayed in terms of Watts into a 50 ohm
load, voltage across the 50 ohm load or dBm into 50 ohms. The choice would normally be made
so as to match the specification parameter of the transmitter under test. The selection is made by
pressing the soft key adjacent to the text. This will toggle through the three op tions.

AF Distn/SINAD Averages

When distortion or SINAD tests are made to receivers using the Rx TEST mode or AF TEST
mode, the results displayed are obtained by averaging the results of a number of measurements.
This allows the user to balance the speed of testing against greater repeatability of measurement.
The number of measurements made can be set within the range 1 to 20 by entering the required
figure using the dat a input keys.

RF Level In: EMF/PD

With the EMF option selected, the displayed RF output level shows the open circuit voltage
available at the RF output connector.

With the PD option selected the displayed RF output level shows the voltage that would be present
across a 50 Ω load.

The selection is made by toggle action of the soft key.

RF Power Ext Atten: dB

The value of any attenuator entered here is considered as part of the instrument and all power
measurements will be as from the input to the attenuator, not to the instrument input. Similarly
power output levels will be adjusted to take account of the external attenuator value entered.

To enter a value of attenuation, which must be in dB, press the adjacent soft key, key in the digits
of the value using the data entry keys and then press the dB terminator key.

The entered value will be applicable to all RF connectors into and out of the monitor. When
changing test setups or test modes this must be taken into account to prevent erroneous readings.

The indicator  is shown against any signal level which has been calculated to include the external
attenuator.

Rx=Tx Offset Freq: Hz

A setup option within the Tx TEST mode (Rx=Tx) will set the signal generator used for receiver
testing to the measured frequency of a transmitter being tested. An Rx=Tx offset frequency entered
here will cause the signal generator frequency to differ from the measured transmitter frequency by
the offset frequency. To enter an offset frequency, press the adjacent soft key, key in the
appropriate digits, using the minus key and the decimal point key if necessary, then use the relevant
terminator key, (MHz, kHz or Hz). A positive figure will set the signal generator frequency above
the measured transmitter frequency, while a negative figure will set the signal generator to a lower
frequency than the transmitter.

Return

Returns to the Help/Setup Menu.

Setup page 2

This page allows the following optional settings to be selected.

46882-311 3-11

LOCAL OPERATION

Audio Level Measured in:

Repeated presses of the adjacent soft key will toggle through

highlight the selecti on in inverse vide o.

The level of a signal applied to the AF input socket is measured in terms of the selected option.

This will then apply to all subsequent measurements.

The indicated output level from the AF generators is not affected by this selection.

Audio Input Impedance:

This key is only active if the 600 Ω interface option is fitted. Pressing it will toggle between the

600 Ω balanced input impedance or the standard high impedance. The AF input connector on the

front panel is used in either case.

Audio Output Impedance:

This key is also only active if the 600 Ω interface option is fitted. Pressing it will toggle between

the 600 Ω balanced output impedance or the standard low impedance. The AF generator output

connector on the front panel is used in either case.

20 dB audio attenuator:

This key is also only active if the 600 Ω interface option is fitted. Repeated presses of it will insert

or remove a 20 dB attenuator from the output circuit of the audio amplifiers. With the attenuator in

circuit the maximum output is limited to 400 mV. The adjustment resolution is increased to

0.01 mV below 40 mV and to 0.1 mV from 40 mV to 400 mV.

Volts, dBm, dBV or Watts and

GPIB Address

Pressing the [GPIB Addr] key allows a new GPIB address to be entered by using the data input

keys to enter the digits, followed by the ENTER terminator key. It may have a value between 1

and 30.

Remote Control

The Service Monitor can be operated by remote control using either the RS232 (serial) port or the

optional GPIB (IEEE 488) interface. The [Remote Control] key toggles between the two options

The active function is highlighted in inverse vide o.

Serial Setup

The[Serial Setup] key gives access to the serial port setup menu. The parameters that must be set

for compatibility with other equipment connected to the port are:-

Baud Rate; Parity Bit; Character Length; Stop Bit; and Handshaking.

Setting up of the serial port is described in the Chapter 4 of the Programming manual (46882-318)

under Preparing the Service Monitor for remote operation.

Printer Setup

A menu of printer type options and printer port selection is accessed through this key. The options

are:-

Epson FX80 or FX100.

Laser Printer 75 dpi, 100 dpi, 150 dpi.

RS232 serial port or ‘Centronics’ parallel port. The selected port is highlighted in inverse video.

If the parallel port option is not fitted, it is not shown on the menu, and the [Printer Port] key

enables or disables the RS232 serial port as a printer port.

Power Up From

Successive presses of this key will toggle through the options available for configuration of the

Service Monitor at ‘Power Up’.

3-12 46882-311

OPERATING MANUAL 2945A

Last Used Store 0
Store 0 is loaded with the current settings each time power is removed from the instrument. With

this selection made, the instrument will power up to the same settings as when power was removed,
whether this was by user action or through po wer failure.

Preset Store 1
Store 1 contains the factory preset settings. With this selection made, the instrument will power up

to the Rx TEST mode with all settings, for every mode, to the factory preset settings and options.

User Store 2
Store 2 is the first user accessible store, which is loaded through the user memory function. With

this selection made, the instrument will power up to the settings stored in user memory store 2
without having to access the memory as a separate function.

Access to the user memory is by pressing the orange [MEM] key. See Stores, settings/results, later
in this chapter, starting on page 3-82.

Return

Returns to the last screen displayed prior to the pressing of the Help/Setup mode key.

Card Setup

A section giving a detailed explanation of memory cards and their use will be found later in this
chapter starting on page 3-84. This key displays the MEMORY CARD FORMAT screen and
menu. The real time clock is also set from this screen.

Return (on the HELP/SETUP screen)

Bar charts

Returns to the last used main mode.

The bar charts used to indicate signal levels can be set to autorange or to user selected ranges. The
current state of each bar chart is shown by either an

A (for Autoranging) or H (for Held range) at

the left of it. The top level screen of Tx TEST, Rx TEST, Dx TEST and AF TEST, all have a
[Scope/Bar] key.

Pressing this key will change the soft keys to those shown below. The function of each key is
explained.

[Barchart Select]

[Auto range]

[  ]

[

 ]

[Scope/Bar]

[Return]

This key will select each visible bar chart in turn. The selected bar chart is
indicated by a highlighted A or H at the left of it.

This key will set the s elected bar chart to autorange. If it is currently set to
autorange, the key will have no effect.

Each press will change the bar chart to the next
bar chart is set to autorange, the first press will remov e autoranging and hold
the current range. The next press will change the range. When the highest
range is set, subsequent presses will have no effect.

Each press will change the bar chart to the next
bar chart is set to autorange, the first press will remov e autoranging and hold
the current range. The next press will c hange the range. When the lowest
range is set, subsequent presses will have no effect.

Pressing this key once, will remove the bar charts from the display and cause
the normal oscilloscope to be displayed. Subsequent presses will display the
expanded oscilloscope, then the bar charts again.

This key will display the top level screen of the selected test mode.

highest

range. If the selected

lowest

range. If the selected

46882-311 3-13

LOCAL OPERATION

Spectrum analyzer

The spectrum analyzer (SPEC ANA) mode presents a graphical display of Radio Frequency against

RF level over a selected sweep of the RF spectrum.

Data relating to the setup and to measurements of the signals being analyzed is presented on the

periphery of the display.

As well as the basic spectrum analyzer function, the monitor has a ‘Look and Listen’ function

which allows the operator to listen to the demodulated signal extracted from the RF signal being

examined.

Oscilloscope

The digital oscilloscope function, available from the Tx, Rx and AF test modes, displays signal

waveforms on part of the display screen. The operation of the oscilloscope function is described in

detail later in this chapter under Oscilloscope, starting on page 3-80.

When reference to the oscilloscope facility is necessary when describing other functions, this is

indicated by heading the reference, *

EXPANDED OSCILLOSCOP E * as appropriate.

*

OSCILLOSCOPE*, *STANDARD OSCILLOSCOPE* or

3-14 46882-311

OPERATING MANUAL 2945A

Using the test modes

Brief descriptions

As the Service Monitor 2945A is a duplex instrument, the RF signal generator and the receiver
circuits are able to operate simultaneously. This allows mobile transceivers to be tested under their
normal operating conditions, with both their receiver section and transmitter section functioning.
By selecting a particular test mode on the Service Monitor, one or both sections of the transceiver
can be studied. A brief description of the function of each test mode is given below. Detailed user
instructions follow under the relevant headings.

Tx TEST

With Tx TEST selected, the
TEST mode features is available. See fold out diagram (2-0) at the end of this chapter.

The AF voltmeter makes measurements to the signals from the Service Monitor demodulator and
displays the results.

The RF signal generator is active, producing an RF signal at the frequency and level set in the
Rx TEST mode. This signal will be modulated at the level and frequency set, if the modulation
generator selection does not conflict with the requirements of the Rx TEST mode.

Rx TEST

With Rx TEST mode selected, the
TEST mode features is available. See fold out diagram (3-0) at the end of this chapter.

The AF voltmeter makes measurements to the signal obtained from the demodulated output of the
mobile transceiver and fed into the AF input socket on the front panel of the Service Monitor. The
AF generators are active at the frequencies and levels set in the Tx TEST mode and their output
routed to the AF GEN OUT socket, if theAF generator selection does not conflict with the
requirements of the Tx TEST mode.

Dx TEST

With Dx TEST selected, the
receiver test features is available. See fold out diagram (4-0) at the end of this chapter. These
features are not as comprehensive as those available from the

RECEIVER TEST

Service Monitor has two AF generators, either or both of which can be used to modulate the
transmitter being tested or the RF generator. However, each generator can only serve one function
at the same time. There is only one AF measurement path, which is switched by the software
between receiver test and transmitter test functions.

screens, but do allow measurements to be made to the major parameters. The

TRANSMITTER TEST

RECEIVER TEST

DUPLEX TEST

screen is displayed and access to transmitter and

screen is displayed and access to all Tx

screen is displayed and access to all Rx

TRANSMITTER TEST

or

SPEC ANA

With SPEC ANA selected, the
spectrum analyzer features is available. See fold out diagram (6-0) at the end of this chapter. The
RF signal generator is active, producing an RF signal at the frequency and level set in the Rx TEST
mode, if the tracking generator feature is not selected. The spectrum analyzer tracking generator
signal is provided by the RF generator.

The modulation generators will modulate the RF signal generator, with the same provisos as in Rx
TEST mode. If the
sweep signal, therefore it is not available to provide modulation.

46882-311 3-15

LOOK AND LISTEN

SPECTRUM ANALYZER screen is displayed and access to the

screen is displayed, AF Gen 2 is used to provide the

LOCAL OPERATION

AF TEST

With AF TEST selected, the

AUDIO TEST

screen is displayed and access to the AF TEST
features is available. See fold out diagram (7-0) at the end of this chapter. The RF generator is
disabled.

SYSTEMS

The SYSTEM key gives access to the SYSTEM TEST mode. If any of the system test options
have been provided on the particular Service Monitor, the user is able to carry out automatic and/or
manual tests to pertinent equipment. The use of the SYSTEM TEST mode is described in the
supplementary operating manuals, supplied when any of these options are fitted. Fold out diagram
(5-0) at the end of this chapter shows typical SYSTEM TEST mode displays. The displays from
all keys are not shown, as there are many similarities to the various systems.

Press To Talk facility

A mode switching capability is provided by the ‘Microphone with PTT switch’ optional accessory.

Performance data, optional accessories, in Chapter 1.

See
With ‘microphone’ selected as the external modulation source and the instrument operating in the

Tx TEST mode, pressing the PTT switch will cause the instrument to switch to the Rx TEST mode.
With the instrument set to the Rx TEST mode or Dx TEST mode, pressing the PTT switch will

allow voice modulation of the RF signal from the Service Monitor, but mode switching will not
happen.

Tones

A soft key designated [Tones] is included in the top level menus of the Tx TEST mode, Rx TEST
mode, Dx TEST mode, and AF TEST mode.

Pressing this key will display the menu shown in fold out diagram (2-5), (3-5), (4-5) or (7-5), and
give access to the ‘TONES’ test facility. This facility is used to provide modulation generators and
demodulation decoders to simulate the various coded calling signals used on mobile radio systems
for automatic selective calling of mobile transceivers.

General

The instructions for transmitter testing assumes that the Tx TEST mode has been selected, and for
receiver testing assumes that the Rx TEST mode has been selected. However, these instructions
apply equally to the Dx TEST mode. References are made to Dx TEST mode to clarify this, or to
identify a difference in presentation. These references are headed *DUPLEX*.

The Dx TEST mode, the Oscilloscope function, and the TONES facility, each have a section of this
chapter dedicated to their operation.

3-16 46882-311

OPERATING MANUAL 2945A

Tx test (transmitter testing)

Overview

The Communications Service Monitor 2945A has been designed to test the performance of mobile
communication equipment. This section explains the use of the Tx TEST mode. Typical uses are:-

• Performance checking following manufacture

• Routine quality assurance testing

• Workshop or field fault diagnosis etc.

The tests which need to be carried out will depend on the specification of the transmitter and the
reason for testing, however a generalised list would be:-

Transmitter power
Transmitter frequency
RF distortion
Spurious outputs
Modulation characteristics
Modulation frequency response
Companding/limiting
Modulation distortion

This Service Monitor will perform all of the above tests.
With the Tx TEST mode selected, the screen and menu shown in fold out diagram (2-0) is

displayed.
Using this screen and menu, the Service Monitor is set up for transmitter testing, and the test results

displayed.
The sections of the monitor available for transmitter testing are:-

The AF generators, used to provide a modulating signal for the transmitter.
The audio tones generator. Used to provide sequential tones for P OCSAG and DCS

systems.
The RF power meter.
The RF counter.
The modulation meter, to measure the depth of amplitude modulation or the deviation of

frequency modulation and to recover the modulating signal for other tests. The demodulated
output is fed to the audio amplifier, and can therefore be monitored on the loudspeaker or on
a headset connected to the accessory socket. The SSB option allows Single Side Band
modulation to be demodulated.

The oscilloscope, to examine the wave form of the demodulated signal.

As well as setting up the major sections of the Service Monitor, the following parameters are
selected from the

The

TRANSMITTER TEST screen allows setting of the following;

IF filter bandwidth.
AF filter pass-band.
De-emphasis filtering.
Distortion measurement methods.

TRANSMITTER TEST screen:-

46882-311 3-17

LOCAL OPERATION

Connections

AF

VOLTMETER

AF

GEN

1

AF

GEN

2

TONES

GEN

SERVICE

MONITOR

AF
GEN
OUT

20dB

ATTENUATOR

MODULATION

RF IN

ALTERNATIVE

CONNECTIONS

RF

POWER-

METER

METER

RF

COUNTER

DISTORTION

METER

AF

FILTERS

AF

COUNTER

AF

OSCILLOSCOPE

AUDIO

AMPLIFIER

ANTENNA'N'

Tx UNDER TEST

C3373

Fig. 3-4 Transmitter test connections

The transmitter and the Service Monitor are connected as shown in Fig. 3-4, Transmitter test
connections. The block diagram of the Service Monitor shows the signal routeing within it.

3-18 46882-311

OPERATING MANUAL 2945A

The Audio frequency input connection to the transmitter must be to the audio input, in place of the
usual microphone input. This connection will vary for differing types of equipment. Points to note
are:-

• The microphone must be disconnected, as any input from it would affect the performance of

the test.

• The microphone and its cable may complete the ‘keying’ circuit of the transmitter using a

‘press to talk’ switch, in which case an alternative arrangement must be provided.

• The RF output connection from the transmitter should be made using good quality RF cable

with correctly fitted connectors. Worn connectors and damaged or kinked cable can give rise
to high levels of reflected power. This can cause misleading results and possible damage to
the transmitter.

• Consider the power output of the transmitter and connect to the appropriate input connector on

the monitor. The maximum power to the BNC (Antenna) socket is 1 W and to the ‘N-Type’
connector 150 W. If the transmitter output power exceeds this level then a suitable power
attenuator should be connected between the transmitter and the monitor or a calibrated
‘sniffer’ used to take a sample of the output, using a dummy load if necessary.

• The power source for the transmitter should be reliable and stable. The battery of a vehicle

may discharge if supplying a transmitter during prolonged testing or the ‘earth’ common return
connection may become open circuit if the transmitter is removed from its normal location.

The procedure for making each of the tests listed above follows. Some of the tests may require
separate operations and others will only require a reading to be made.

WARNING

Hot surfaces

Take care when touching the RF Input Type N connector after the application of high levels of
continuous power. If 50 W is exceeded for a prolonged period, the temperature of the connector
can become excessive.

Setting up

When all the required connections have been made, select the Tx TEST mode to display the screen
and menu show in fold out diagram (2-0).

Set the parameters or options to suit the test requirements, from the
The complete setup can be stored by making use of the internal setup/results memories or the

optional memory card facility. Both of these features are described under Stores, settings/results,
later in this chapter, starting on page 3-82.

RF generator state

This Service Monitor is a duplex instrument as mentioned earlier. (See Using the test modes, on
page 3-15.) The state of the RF generator is shown on the TX TEST display by the legend
0$ %#, -, or 0$ %#, -$$. The state of the RF generator can be switched by pressing the top
left soft key.

Tx frequency

Press the [Tx Freq] key.
The soft key options change to those shown in fold out diagram (2-1)
The receiver circuits of the Service Monitor must be set to the RF output frequency of the

transmitter under test. This can be set manually using the data input keys, or automatically by
pressing the [Auto Tune] key.

TRANSMITTER TEST menus.

Manual frequency setting

Range; 100 kHz to 1.05 GHz

46882-311 3-19

LOCAL OPERATION

With the 2$0#/ legend highlighted, data can be entered from the keyboard to the Tx FREQ
parameter. As the entry can only be a frequency setting, it is not necessary to select the orange
[FREQ] key. Ente r the require d frequency by using the digit keys and the decimal point key if
relevant. The resolution of the RF FREQ entry is 1 Hz, but it is not necessary to enter every digit

down to the least significant place if a ‘multiplier’ terminator key is used.
The entry is completed by pressing a terminator key. Using the [MHz], [kHz] or [Hz] key causes

the entered frequency to be displayed according to normal convention. The following examples
explain further.

Pressing:-

[1] [2] [5] [MHz] will display 125.000000 MHz
[1] [2] [5] [kHz] ” “ 125.000 kHz

[1] [2] [5] [0] [kHz] ” “ 1.250000 MHz
[1] [.] [2] [5] [MHz] ” “ 1.250000 MHz
[1] [2] [5] [0] [0] [0] [1] [Hz] ” “ 1.250001 MHz

Variable control

With the
variable control.

2$0#/ legend highlighted, the Tx FREQ parameter can be adjusted by using the

Frequency increment

The FREQ [Ö] and [×] keys can be assigned to transmitter frequency adjustment. Refer to the
section on incremental adjustments which starts on page 3-62.

Automatic frequency setting

Pressing the [Auto Tune] key causes the Service Monitor to sweep over the RF input range and
lock onto the strongest signal present on the selected RF input socket. The mean frequency of the
signal is displayed against the

SSB (if fitted). The autotune function may not operate when attempting to tune to an SSB
transmitter unless a steady tone is being used as a modulation source. The frequency to
which the Service Monitor w ill t une will be the true RF frequency of the sideband and not
that of the channel frequency.

Pressing the [Rx=Tx] key causes the RF generator used for the Rx TEST mode to be set to the
same frequency as the measured RF from the transmitter under test. A frequency offset facility can
be set up which gives a set difference between the frequency of the measured transmitter RF and
the set frequency of the receiver test generator. (Rx=Tx ± offset). See the option selections within
setup page 1, for more information.

After setting the Tx FREQ and any associated adjustments, use the [Return] key to revert to the
original TX TEST menu.

Tx power

The [Tx Power] key gives access to RF power measurement functions or associated functions.

Tx FREQ

legend, with

Auto tune

replacing

OFFSET.

Broad Band or Narrow Band power

The [Broad/Narrow] key selects which of the RF power measurement methods is operative. The
selected method is indicated on the display by the letters BB or NB to the right of the digital power
reading. The use of this facility is explained under Making measurements later in this chapter,
starting on page 3-25.

3-20 46882-311

OPERATING MANUAL 2945A

Directional Power

The [Dir Power] key displays the screen required for using the optional directional power and
VSWR accessories. The use of the Directional Power Head accessory is described in Appendix A
of this manual, and of the Light-weight Directional Power Head accessory, in Appendix B.

To leave this screen, press any of the blue MODE keys. The top level screen of that mode will be
displayed.

RF harmonic Analysis

The [Harmonc Analys] key activates the RF harmonic Analysis function. The right-hand side of
the screen shows five horizontal bar charts. The upper bar chart shows the power meter reading
and is the same as that shown on the other Tx TEST screens.

The four

HARMONICS bar charts display the level of the 2nd, 3rd, 4th and 5th harmonics of the

carrier. The frequency ra nge of the instrument gover ns the number of harmonics of which readings
can be made.

The use of this facility is explained under Making measurements later in this chapter, starting on
page 3-25. Pressing the [Return] key will display the previously used Tx TEST screen with the Tx
power menu.

RF transient power Analysis

The [Trans Analys] key selects the RF Power

TRANSIENT ANALYSIS mode.

This mode displays a captured RF power profile of a transmitter against time. Triggering is
activated by the RF level passing a preset value. The signal is captured using a continually
updated, first in/first out, storage device. This allows the Service Monitor to show the power
profile both before and after the trigger point.

The use of this facility is explained under Making measurements later in this chapter, starting on
page 3-25.

Pressing the [Return] key will display the previously used Tx TEST screen with the top level
Tx TEST menu.

Modulation meter, demodulation options setup

Set up the demodulation options to be compatible with the transmission from the unit under test.
Press the [Mod Meter] key. The so ft keys change to the demod soft keys shown in fold out

diagram (2-3).

Modulation Type

The Service Monitor can demodulate AM and FM signals. The demodulated signal is made

available at the ‘DEMOD OUT’ connector on the rear of the instrument. SSB signals can be
demodulated if the SSB option is fitted.

The [AM/FM] key, or [AM/FM/SSB] key, is used to select the appropriate modulation type by
sequential key presses. The

% for AM; and by MHz or kHz for FM. When SSB has been selected, no modulation level is

MOD LEVEL indication within the main display becomes suffixed by

shown, either digitally or as a bar chart.
Selecting the modulation type for Tx TEST does not change the current modulation type set on the

Service Monitor RF generator.

SSB Input sensitivity

No RF carrier signal is produced by SSB transmitters. Therefore the automatic gain control
circuits of the Service Monitor cannot respond to these signals.

46882-311 3-21

LOCAL OPERATION

When ‘SSB’ demodulation has been selected, the RF sensitivity of the Service Monitor can be
controlled manually. Three sensitivity settings are given as soft key choices; high, medium and
low. The approximate sensitivities of these are shown in the following table:-

WARNING

Hot surfaces

Take care when touching the RF Input Type N connector after the application of high levels of
continuous power. If 50 W is applied for a prolonged period, the temperature of the connector can
become excessive.

IF bandwidth

The IF bandwidth of the Service Monitor receiver circuits can be selected from the following
options:-

[High Sens]

[Med Sens]

[Low Sens]

90 dBm to −30 dBm at ‘N type’

−

110 dBm to −50 dBm at ‘Antenna’

−

30 dBm to +20 dBm at ‘N Type’

−

50 dBm to 0 dBm at ‘Antenna’

−

20 dBm to +50 dBm at ‘N Type’

+

0 dBm to +30 dBm at ‘Antenna’

300 Hz 3.0 kHz 30 kHz 300 kHz

Press the [IF Filter] key. The right hand soft keys change, to allow selection of IF bandwidth
filters as shown above.

The selected filter is shown on the display. Press the [Return] key after selecting the required
filter.

Audio frequency filtering

The demodulated signal can be filtered using the following audio filters:-

0.3 - 3.4 kHz
band pass

†

Only if option 23 (CCITT filter) is fitted.

‡

Only if option 24 (C-MESS filter) is fitted.

Press the [AF Filter] key. The right hand soft keys change, to allow selection of AF filters as
shown above. Press the [Return] key after selecting the required filter.

*OSCILLOSCOPE*

The input to the oscillosc ope is taken from the demodulator s through any selected AF filters.
Therefore modulation measurements made using the oscilloscope will include the characteristics of
the selected AF filter.

50 kHz
low pass

15 kHz
low pass

300 Hz
low pass

†

CCITT

C-MESS

or

‡

3-22 46882-311

OPERATING MANUAL 2945A

Audio distortion measurement

The Service Monitor is able to measure signal noise and distortion against the following
parameters:-

Signal to noise
ratio

SINAD
level

Percentage
distortion

Press the [Dist S/N] key. The right hand soft keys change, t o allow selection of S/N, SINAD and
distortion measurements.

Off

Disables any active distortion measuring function.

Hint.
By disabling this function, the time taken to measure the remainder of the measurement functions

is shortened thereby reducing the update time.

S/N

Selects signal to noise ratio as the measurement method. The Signal to Noise bar chart ranges
available are 0 to 30 dB and 0 to 100 dB. The signal to noise ratio is displayed as a digital
read-out above the bar chart. The TX TEST mode menu is recalled automatically after pressing
this key.

SINAD

Selects SINAD as the measurement method.

The AF1 generator will be set to 1 kHz by this ac t ion, regardless of any previous setting.

The distortion bar chart ranges available are 0 to 18 dB and 0 to 50 dB. The SINAD level is
displayed as a digital readout above the bar chart. The TX TEST mode menu is recalled
automatically after pressing this key.

Dist’n

Selects distortion percentage as the measurement method.

The AF1 generator will be set to 1 kHz by this ac t ion, regardless of any previous setting.

The distortion bar chart ranges available are 0 to 10%, 0 to 30% and 0 to 100%. The distortion
percentage level is displayed as a digital readout above the bar chart. The TX TEST mode menu is
recalled automatically after pressing this key.

With all the required parameters set, power up the transmitter.
The power output of the transmitter is shown on the POWER LEVEL bar chart, with the power

level given in digital form above it.
The level of modulation is displayed on the modulation level bar chart, with the FM DEVN or the

AM DEPTH shown digitally. When the SSB demodulation function has been selected, no

modulation bar chart is displayed. The legend ‘SSB Trans’ and the selected sensitivity is shown.
The FREQ OFFSET will indicate the difference between the mean (measured) frequency of the

transmission and that entered as transmitter frequency.

46882-311 3-23

LOCAL OPERATION

More (de-emphasis, FM deviation pk/rms, modul at i on dBr)

Press the [More] key. T he right hand soft keys cha nge, to allow selection of de-emphasis mode,
and FM deviation and modulation measurement modes.

De-emph

De-emphasis filtering, ON/OFF, is toggled by alternate presses of the [Deemph] key. The
de-emphasis filtering uses a 750 µs time constant to give a 6 dB/octave roll-off.

De-emph ON appears on the main display when appropriate. No indication is given to show that

de-emphasis is not on.
Press [More] to return to the previous menu or [Return] to display the main Tx TEST menu.

FM Dev Pk/rms

Toggles between measuring FM modulation with RMS or with peak detectors. The measurement
mode –

Press [More] to return to the previous menu or [Return] to display the main Tx TEST menu.

Mod dBr

Toggles between measuring the absolute AM or FM modulation or the AM or FM modulation
relative to the value registered at the moment the key is pressed. The modulation level is shown in
units of dBr when appropriate.

Press [More] to return to the previous menu or [Return] to display the main Tx TEST menu.

Pk or rms – appears to the left of the FM deviation bar chart.

Audio generator setup

Freq. range 10 Hz to 20 kHz
Level range 0.1 mV to 4 V rms
Shape option Sine or square

To set up the audio generators in order to modulate the transmitter, press the [Audio Gen] key.
This will display the audio setup menu shown in fold out diagram (2-4).

Set up the audio generator(s) for the required frequency and output level by using the soft keys and
data input keys:-

[Gen 1/Gen 2] to select AF1, then, [FREQ][n]....[n][kHz/Hz]

[LEVEL][n]...[n][V/mV/dBm]

then [Gen 1/Gen 2] to select AF2 if required, ....[.../dBm]

The FREQ [Ö] and [×] and the LEVEL [Ö] and [×] keys can be assigned to AF ge nerator
frequency and level. See Incremental adjustments which starts on page 3-62.

Either or both generators can be switched off to suit the test requirement. To disable a generator
select it using the [Gen 1/Gen 2] key to toggle between them. When the title of the generator is
highlighted on the di splay, press the or ange[ON/OFF] function key. Repeated p resses of this key
will toggle the ON/OFF action.

The shape of each audio generator output waveform can be either sine or square wave. This is
controlled by first selecting the audio generator as for [ON/OFF] control above, then pressing the

[Shape] key to toggle between the options.

Note that the audio generators are also used as modulation generators for the

receiver test signal generator. If both generators are set up as a modulation
source in the Tx test mode, switching to Rx TEST mode will show both
modulation generators in the OFF condition. Either or both generators can be
set up and turned on within the Rx TEST mode. The frequency, level and shape
settings of their last use in the Rx TEST mode will be retained within the

3-24 46882-311

OPERATING MANUAL 2945A

Rx TEST mode setup. These settings will be effective when the generators are
switched to the ‘ON’ condition in receiver test mode. Their use as audio

generators in the Tx TEST mode will then be disabled.

Pressing the [Lock] key locks the output level of the two audio generators to the same level. The
unselected generator locks to the level of the selected generator.

When the audio generators are set to the required settings press the [Return] key to restore the Tx
TEST menu.

Making measurements

This section describes the actions needed to make measurements of each parameter associated with
transmitter testing. All tests are describe d individually as ‘one off’ tests, but in practice, once set
up, all active parameters will be measured simultaneously with continuous updating and the results
displayed using the selected measurement units.

The results obtained from tests can be stored for later analysis or transfer to hard copy by making
use of the internal setup/results memories or the optional memory card facility. Test mode screen
settings can similarly be stored for future use.

All of these features are described under

Stores, Settings/results,

Transmitter power

Broad Band and Narrow Band power measurements

The monitor has both Broad Band and Narrow Band power measurement facilities. The Broad
Band power meter measures the total average power of all signals present at either RF input, while
the Narrow Band power meter measures only the average power of the signal contained within the
IF pass band selected for the Tx TEST mode.

The facilities of the Service Monitor allow the RF signal generator to remain active in the Tx TEST
mode. Therefore the signal from this will be present at common points within the RF input/output
circuits of the instrument and will contribute to measurements made by the power meters. When
making measurements where this will make any significant difference to the measurement, disable
the RF generator by selecting the
mode.

Narrow band power measurements cannot be made when the frequency of a transmitter has been
set using the [Auto Tune] key.

The maximum continuous power rating of the ‘N-Type’ connector is 50 W with a minimum
indication of 5 mW. Lower levels of input signal are indicated as voltage levels, the first bar chart
graduation being at 20 µV. The maximum continuous power rating of the antenna BNC connector
is 5 W.

A power overload condition is indicat e d by an audible and visual warning. Should this
condition be indicated, immediately reduce the level of RF power from the transmitter into
the Service Monitor.

Do not stop the warning by switching off the Service Monitor, as this will silence the warning
but will leave the excessive RF power connected to t he internal load.

Do not attempt to stop the warning by disconnecting the RF connector, as this can damage
the transmitter and may cause electric shock or skin burns.

RF Gen OFF condition from the Rx TEST mode or the Dx TEST

or

Printer,

later in the chapter.

46882-311 3-25

LOCAL OPERATION

WARNING

Hot surfaces

Take care when touching the RF Input Type N connector after the application of high levels of
continuous power. If 50 W is applied for a prolonged period, the temperature of the connector can
become excessive.

With the monitor in the Tx TEST mode, and the transmitter connected to the monitor as described
above, key up the transmitter.

The RF power bar chart gives an analogue representation of the active power meter reading. A
digital read-out of the power is displayed above the bar chart.

The options available for the digital read-out from the power meter are dBm, Watts or Volts.
The bar chart can be auto-ranging or manually selected. See
External attenuators can be included in the input path to the Service Monitor. The value of any

such attenuators can be entered into Setup Page 1 of the Service Monitor, which will cause the
power measurement software to calculate the power at the attenuator input. The result of this
calculation is shown on the RF power bar chart and as the digital power reading.

Power read i ngs which i nclude an attenua tion factor ha ve an inverse vide o ’A’ adjacent to them.
The full-scale ranges of the RF power bar chart, are:-

Directional power measurements

Directional power and VSWR measurements can be made using the optional Directional Power
Head accessory or Light-weight Directional Power Head accessory. The

METER

the
TEST] key. See Appendices A and B.

Bar charts on page 3-13.

10 mW to 100 kW in 15 steps of 1-3-10 sequence.
100 mV to 3 kV in 16 steps of 1-3-10 sequence.

DIRECTIONAL POWER

screen, accessed by pressing the [Dir Power] key, is used with these accessories. To leave

DIRECTIONAL POWER METER display and return to the Tx test mode display, press the [Tx

RF harmonic analysis

The harmonic content of a transmitter output can be analysed using the harmonic analyzer function.

B3197

Fig. 3-5 Tx power, harmonic analysis screen

To obtain an analysis of a signal, proceed as for making a power level reading. With the power
level of the signal to be analysed displayed, press the [Harmonc Analys] key. The screen shown in
Fig. 3-5, Tx power, harmonic analysis screen, is displayed. The power level bar chart shows the
power output of the transmitter as before. The harmonic content of the signal is shown on the

HARMONICS bar charts. These four bar charts are each given to progressive harmonics of the

fundamental frequency of the signal. They are graduated in dB relative to the carrier level (dBc),
from 0 to -80 dBc.

3-26 46882-311

OPERATING MANUAL 2945A

The harmonic number and frequency is shown over each active bar chart, with the level, in dBc,
given as a digita l read-out.

The level of a harmonic which has a frequency above the RF range of the monitor cannot be
measured and bar charts which would be given to these frequencies remain inactive.

IF passband filters

When making harmonic analysis readings, the IF passband of the Service Monitor can be set
independently to that set in the main

Tx TEST mode. Pressing the [IF Filter] key when the

harmonic analysis function is displayed, allows selection of the following IF passband filters.

300 Hz 3 kHz 30 kHz 300 kHz

The filter selection is retained within the harmonic analysis setup. The IF filter selected in the main

Tx TEST mode will be unchanged.

For accurate results, the noise floor over the measurement range should be as low as possible, but
the passband should not clip the sidebands of the fundamental signal. Select the filter that will best
suit these requirements.

As the Spectrum Analyzer uses the same IF filters, the optimum filtering can be selected by
examining the signal using the Spectrum Analyzer.

Pressing the [Return] key will display the top level Tx TEST mode screen.
If the operating mode of the Service Monitor is changed from Tx TEST mode with the harmonic

analysis function selected, the harmonic analysis screen will be displayed again when Tx TEST
mode is next selected.

RF transient power analysis

This facility is used to capture, display and record changes to power levels of RF signals. The

TRANSIENT ANALYSIS screen, used to control and display this function, is accessed from the

Tx TEST mode by the key sequence [Tx Power], [Trans Analys]. See Fig. 3-6, Power Transient
Analysis screen.

1 Ref Level 5 Display Centre-line
2 Trigger Level 6 Marker Datum
3 Trigger Datum 7 Marker Point
4 Trigger Point 8 Time/Div Adjustment

Fig. 3-6 Power Transient Analysis screen

46882-311 3-27

LOCAL OPERATION

To observe the power level profile of an RF signal during a level transition, the signal is applied to
the RF input of the monitor and the instrument armed to trigger when a specific RF level is passed
through.

The instrument then displays an RF Power Level vs Time graph, showing the transition.

Bandwidth

The IF filter selected on the Tx TEST screen remains selected when the
function is selected.

Ref level

The graticule of the transient analysis screen is calibrated in 10 dB/division vertically with the top
of the display as the reference level.

To set the reference level, press the [Ref Level] key to highlight the
reference level can then be set, either by entering a new value using the data entry keys, or by
adjusting the variable control. The reference level should be set so that the expected maximum and
minimum levels will be visible on the display.

The reference level setting is common with the SPEC ANA mode reference level; a value set
on one, will be found set on the other, when next accessed.

Marker

A variable marker can be displayed, indicated by a fine dotted vertical line, with a read-out of the
marker values displayed at the bottom of the screen. The marker reading provides two values.

TRANSIENT ANALYSIS

Ref Level legend. The requir ed

The absolute RF power level at the marker position. (Not the level relative to the

Level

).

Ref

A time difference of the position of the marker relative to the trigger point.

If the marker, the
They will appear at the bottom of the screen with the

Mkr legend and the relevant readings are not displayed, press the [Marker] key.

Mkr legend highlighted. The position of the

marker along the time axis of the display can be adjusted using the variable control.

When the marker is displayed and the

Mkr legend highlighted, pressing either t he

[Ref Level] key or the [Trig Level] key will highlight the appropriate legend and transfer
the variable control operation from the marker to the highlighted function.

When the marker is displayed and the

Mkr legend highlighted, pressing the [Marker] key

will remove the marker and its readings from the display.
When the marker is displayed but the

key will transfer the variable control operation to the marker, and highlight the

Mkr legend is not highlighted, pressing the [ Marker]

Mkr legend.

Trigger level

The transient c apture operation is started by the signal level passing through the set Trigger Level.
The set Trigger Level is relative to the Ref Level (top of display). This is set by pressing the [Trig
Level] key to highlight the Trigger Level legend, then either entering a new value using the da ta
input keys or by using the variable control. The Trigger Level can be set to any point within the
dynamic range of the current display.

Positive or negative triggering

The transient capture operation can be initiated by either a rising or falling signal. Repeated
presses of the [+/- Trig] key alternates the selection. The state of the current setting is shown as
either +ve edge or -ve edge.

Pre-trigger display

The user can select the proportion of the display given to pre-trigger activity. Repeated presses of
the [Pre Trig] key will step through
display to commence (on the left of the screen) at the time of trigger,

0 %, 25 %, 50 %, 75 %

100 % values. 0 % will cause the

and

50 % will place the trigger

point centre screen with pre-trigger levels shown to the left and post-trigger levels shown to the
right while

100 % will cause the display to finish (on the right of the screen) at the time of trigger.

3-28 46882-311

OPERATING MANUAL 2945A

25 % and 75 % will produce displays with these proportions of pre-trigger visible. The trigger

point is indicated on the display by a medium pecked line.

Transmitter frequency

The frequency of the transmission to be analysed can either be set manually or transferred from the
previous test mode used.

When the transient analysis function is accessed, the transmitter frequency set in the Tx TEST
mode is taken as the transmitter frequency for analysis.

If the SPEC ANA mode is accessed and the span changed to use a new centre frequency, this will
become the new transmitter frequency for the Tx TEST mode and therefore the transmitter
frequency for the transient analysis function.

Time scale

The time scale of the display is adjustable from 50 µs/division (500 µs full scale), to 5 s/divisio n
(50 s full scale). Repeated presses of the [  ] key will progressively increase the time/division in
a 1, 2, 5 sequence. Using the [  ] key will similarly cause the time/division to decrease.

Arming, triggering and storing

The transient capture operation has three phases. The current phase is shown in inverse video at
the bottom right of the display.

The  phase is active when the transient analysis function is accessed. The level of any signal
entering the selected RF input connector at the set transmitter frequency is displayed on the screen,
if it is within the dynamic range currently being displayed.

Samples of the level of the signal displayed are stored in a circular buffer, configured to be filled
within the time of one display scan.

While in the  phase, the display is re-initialised if a setting is changed which could otherwise
result in an erroneous display being produced. The settings which cause re-initialising when
changed are:-

Reference level
Transmitter frequency
Display time scale
Pre-trigger.

The 2 phase is activated by the RF level passing through the tri gger level in the selected
direction.

Writing to the circular buffer is stopped after the elapse of the post-trigger time to be displayed.
When the display is complete, it will show the profile of the transmitter level transient. This starts

the 1 phase. Fig. 3-7, shows transient records of the same signal transient at Time/div settings
of 50 ms, 500 µs and 50 µs.

46882-311 3-29

LOCAL OPERATION

Fig. 3-7 Transient Analysis displays

From this condition a permanent record can be made on a suitable printer by using the [DISPLAY
HOLD], [Print], key sequence or stored to a memory card using the [DISPLAY HOLD], [Store],
[Store Screen], key sequence.

When the current display is no longer required, the

 phase can be reset by pressing the [arm]

key.

3-30 46882-311

OPERATING MANUAL 2945A

External attenuators

Compensation for an external attenuator or test fixture included in the RF input path of the monitor
can be programmed. The value, in dBs, of the attenuator should be entered in the

RF Power Ext Atten: field of setup page 1. The value of the attenuator will then be included in power

calculations and the power indicated by the power meter will be that at the input to the external
attenuator.

This feature makes use of the extended ranges of the power meter.
The value of the attenuator will also be included in RF level calculations and readouts when in the

Rx TEST mode and in Dx TEST mode.

‘’ is shown against any signal level which has been calculated to include the external attenuator.

*OSCILLOSCOPE*

With the oscilloscope facility selected, the POWER bar chart is removed from the display but the
digital read-out of the power level is retained.

*DUPLEX*

With the monitor in the Dx TEST mode the POWER bar chart and digital display remain in the
same location and the indications are identical to those given in the Tx TEST mode.

Transmitter frequency

The digits adjacent to the Tx Freq legend on the Tx TEST display refer to the frequency to which
the Service Monitor receiver circuits are tuned.

If the frequency of the transmitter is known, this figure can be entered manually. This is done by
firstly pressing the [Tx Freq] key in the Tx TEST mode menu and then ent ering the figure using
the data input keys. Complete the entry by use of the appropriate terminator key.

The receiver circuits of the monitor will then be tuned to that frequency and any signal within the
IF pass band will be examined. The frequency difference between the set frequency and the true
frequency will be displayed as ‘offset’.

Hint
When testing a transmitter using sequential tones, it may be necessary to pre-tune the S e rvice

Monitor receiver circuits in this way in order to successfully decode the initial tones.

If the transmitter frequency is unknown, or it is to be measured, key up the transmitter and use the
key sequence [Tx Freq], [Autotune].

The receiver circuits of the monitor will then carry out a sweep to locate the signal and tune to it.
The frequency of the signal is displayed against the

Tx FREQ legend.

*DUPLEX*

The same frequency measurement procedures are applicable when in the Dx TEST mode.

RF distortion, and
Spurious outputs

Distortion of the transmission RF output may be deliberate (modulation is a form of deliberate
distortion), it may be due to a fault or because of design limitations. Whatever the reason the
distortion produces harmonics or other spurious outputs.

These can be located using the SPEC ANA mode of operation.
By viewing the output signals from the transmitter on a voltage vs frequency plot, any

transmissions outside the transmitter's specified bandwidth can be identified.
The use of the SPEC ANA mode is explained fully under that heading.

46882-311 3-31

LOCAL OPERATION

Modulation characteristics
Modulation frequency response and
Companding/limiting

The requirements of individual users will vary but the principle of the tests will be the same.
A signal having a known level and frequency is applied to the AF input of the transmitter and the

level of modulation produced is measured.
To test the modulation characteristics of a transmitter with any degree of accuracy requires that the

signal used to provide the modulation is accurately defined.
The Service Monitor has two AF generators for this purpose. The setting up instructions for

frequency, level and shape options of these is given under ‘Setting Up, AF Generators’ above.
The output from the AF generators is available at the AF output connector on the front panel. This

signal should be used to modulate the transmitter, by direct connection to the AF input of the
transmitter under test.

With the modulation meter options set to correspond with the modulation characteristics of the
transmitter, the signal can be examined.

Modulation measurement with the Service Monitor is made using a method which evaluates the
positive value and negative value as separate readings. This allows the results of both to be given
on the display. The bar chart is a dual display indicating the positive value on the top bar and the
negative value on the lower bar. The digital read-out is given in three parts. The normal size
legend displays the P-P/2 modulation level, while the individual levels are given in half size
numerals.

By making changes to the level of the applied AF signal, the linearity of the modulating circuits can
be checked, limiting circuits, companders and voice activated switching circuits can be tested and
adjusted.

The dual - positive and negative - readings are particularly useful when checking and adjusting the
symmetry of transmitters.

Similarly, by repeating the tests at differing frequencies, the frequency response of the modulating
circuits and filters can be plotted and adjusted.

By using both AF generators at different frequencies, or by using squarewave output,
intermodulation distortion levels can be explored and transient response examined.

*STANDARD OSCILLOSCOPE*

The digital oscilloscope facility can be used for modulation testing. When this facility is active
within the Tx TEST mode, the Service Monitor demodulator output is applied to the input of the
oscilloscope.

The input to the oscillosc ope is taken from the demodulator s through any selected AF filters.
Therefore modulation measurements made using the oscilloscope will include the characteristics of
the selected AF filter.

The Y ranges of the oscilloscope are directly calibrated in deviation frequency when FM
demodulation is selected and in percent modulation when AM demodulation is selected. The
ranges are from 200 Hz/ Div. to 10 kHz/Div. in a 1, 2, 5, sequence and 25 kHz/ Div. FM and 5%,
10% and 20%/ Div. AM.

The X ranges are from 50 µs/Div to 5 s/Div. in a 1, 2, 5, sequence.
When the oscilloscope facility is selected, the modulation level bar chart is removed from the

display. The digital read-out of modulation level, including the positive and negative readings, is
retained. The Modulation frequency digital readout is also retained.

*EXPANDED OSCILLOSCOPE*

When the expanded oscilloscope is selected, all of the above relating to the standard oscilloscope
apply except that the positive and negative modulation readings are not displayed.

3-32 46882-311

OPERATING MANUAL 2945A

*DUPLEX*

All of the above information relating to modulation characteristics and frequency response testing
also applies to tests made using the Dx TEST mode. The oscilloscope facility is not available
when in Dx TEST mode.

Modulation distortion

dBdB

Signal

a

dB dB

Filter Response

cd

1 1

Distortion Products

Noise

b

Distortion Products

Noise Noise

Frequency Frequency

kHz kHz

11

Filter Response

FrequencyFrequency

kHzkHz

C1640

Fig. 3-8 Distortion level and signal to noise level measurements.

The signal containing the information being communicated will become distorted during its
progress through the system. This distortion may be very slight and almost unnoticeable to the ear
or it may be so severe as to cause the information to become unintelligible.

The reasons for this distortion to the signal are the non-linearity of the amplifiers and modulators in
the system, and noise within the circuits becoming attached to the signal.

By applying a sinewave signal of known purity to the input of the system and measuring the
distortion and noise levels of the demodulated signal obtained at the output of the system,
evaluation of the quality of the transmitter is possible.

The three measurements used for this evaluation are SINAD level; distortion percentage; and signal
to noise ratio.

The procedures described below are carried out repeatedly under the instruction of the instrument
software and the displayed results are continually updated.

To obtain the SINAD level of a signal at the output of a transmitter the output level is measured
and noted.

The signal measured comprises the value of the fundamental signal, the values of any distortion
products generated and the value of any noise present.

A notch filter tuned to the frequency of the input signal is then placed in the output signal path and
the level again measured and noted. The second measurement comprises only the values of any
distortion products generated and the value of any noise present. See page 3-33, Fig. 3-8 a, b, & c,
Distortion level and signal to noise level measurements.

46882-311 3-33

LOCAL OPERATION

The SINAD level is then calculated according to the formula:-

SINAD

To obtain the distortion factor of a signal at the output of a transmitter the output level is measured
and noted as for SINAD level measurement.

A notch filter as used for SINAD measurement is used to make a second reading which comprises
the same values as for the second SINAD measurement.

The distortion factor is then calculated according to the formula:-

Distortion

= 20

=

V

1

log

dB

V

2

++

()

20log

SND

+

()

ND

V

=100

V

=

100

()

dB

2

%

1

+

()

ND

++

SND

%

For signal to noise level measurements a reading is taken of the output level as for SINAD level
and distortion factor measurements. The AF input signal is then disabled and a second level
reading taken. A notch filter is not included in the signal output path. The second measurement
only comprises the value of any noise present on the demodulated signal. See page 3-33, Fig. 3-8
a, & d, Distortion level and signal to noise level measurements.

The signal to noise level is then calculated according to the formula:-

V

S/N

= 20

log

1

dB

V

2

20log

()SND

N

dB

=

++

The distortion measuring system within the Service Monitor has the capability to make all three
measurements. Pressing the [Mod Dist] key accesses the distortion measurement menu shown in
fold out diagram (3-4).

The action of selecting a measurement system returns the

TRANSMITTER TEST main (top level)

menu to the display.
The result of the selected measurement will be displayed on a bar chart within the transmitter test

screen and a digital read-out given above it. When no distortion measurement system is selected,
by pressing the [Off] key within the distortion measuring menu, the distortion bar chart and digital
read-out are removed from the screen.

Hint
By disabling this function, the time taken to measure the remainder of the measurement functions

is shortened thereby reducing the update time.

Measurements of SINAD and distortion percentage carried out by the monitor use a frequency of
1 kHz for the tests. When either of these test methods is selected, the system software sets the
frequency of the modulation generator to this frequency to avoid erroneous results.

The input signal level influences the readings obtained by the distortion measuring system and is
usually specified as part of the test specification.

3-34 46882-311

OPERATING MANUAL 2945A

*OSCILLOSCOPE*

With the oscilloscope facility selected, the distortion level bar chart is removed from the display
but the digital read-out is retained.

*DUPLEX*

When in the Dx TEST mode, modulation distortion tests are not displayed.

46882-311 3-35

LOCAL OPERATION

Rx test (receiver testing)

Overview

The Communications Service Monitor 2945A has been designed to test the performance of mobile
communication equipment. This section explains the use of the Rx TEST mode. Typical uses
are:-

• Performance checking following manufacture

• Routine quality assurance testing

• Workshop or field fault diagnosis etc.

The tests which need to be carried out will depend on the specification of the receiver and the
reason for testing, however a generalised list would be:-

Sensitivity
AF Bandwidth
AF Distortion
Selectivity

Blocking (or desensitisation)
Spurious response
AGC response

With the Rx TEST mode selected, the screen and menu shown in fold out diagram (3-0) is
displayed.

From this screen and menu, the setting up of the inbuilt devices for receiver testing, and the read
out of results is carried out.

The sections of the monitor available for receiver testing are:-

RF signal generator .
Audio modulation generators. Used to provide modulation of the RF generator.
Audio tone generator. Provides tones for CTCSS, Sequential, DTMF systems.
Audio distortion meter
Digital oscilloscope

As well as setting up the major sections of the Service Monitor, the selection of the following
parameters are selected from the

RECEIVER TEST screen:-

Audio filters
Pre-emphasis filtering
Selection of distortion measuring methods.

3-36 46882-311

OPERATING MANUAL 2945A

Connections

MOD

GEN

1

MOD

GEN

2

TONES

GEN

SERVICE

MONITOR

BNC

RF

GENERATOR

ATTENUATOR

RF OUT

ALTERNATIVE

CONNECTIONS

20dB

FILTERS

'N' AF

AF

VOLTMETER

AF

DISTORTION

METER

AF

COUNTER

AF

OSCILLOSCOPE

IN

RF

IN

AF

OUT

Rx UNDER TEST

C3374

Fig. 3-9 Receiver test connections

Before making any connections between the Service Monitor and the receiver ensure that the RF
generator of the Service Monitor is
highlight the
of the RF generator.

%#,$0#/F legend. Pressing the orange [ON/OFF] function key will change the state

-$$ is shown adjacent to the indicated generator frequency when the RF

OFF. With the Rx TEST mode selected, press [RF Gen] key to

generator is disabled.
The RF generator settings can be changed with the generator

ON or OFF.

46882-311 3-37

LOCAL OPERATION

When testing the receiver section of a transceiver, ensure that the power output of the transmitter
section will not exceed the power handling capability of the connector on the Service Monitor.

Also ensure that the transceiver cannot be switched to ‘
The receiver and the Service Monitor should be connected as shown in Fig. 3-9 Receiver test

connections. The block diagram of the Service Monitor shows the signal routeing within it.
Points to note are:-

Setting up

When all the required connections have been made, select the Rx TEST mode to display the screen
shown in fold out diagram (3-0).

Set the parameters or options to suit the test requirements from the

TRANSMIT’ inadvertently.

The power source for the receiver should be reliable and stable. The battery of a vehicle
may discharge if supplying a mobile transceiver during prolonged testing or the earth
connection may become open circuit if the transceiver is removed from its normal
location.

When testing the receiver section of transceivers take precautions to prevent the
inadvertent ‘keying’ of the transmitter.

The RF input connection to the receiver should be made using good quality RF cable with
correctly fitted connectors. Worn connectors and damaged or kinked cable can produce
reflections and losses in the system which will give misleading results.

RECEIVER TEST menus.

Rx frequency

Range 400 kHz to 1.05 GHz

Press the [RF Gen] key.
The

%#,$0#/ legend is highlighted as shown in fold out diagram (3-1).

If the Rx=Tx function has been set from the Tx TEST mode, the
receiver frequency relevant to that test. If this is correct for the receiver under test, there is no need
to re-enter the frequency.

Manual frequency setting

With

%#,$0#/ legend highlighted, data may be entered from the keyboard to the GEN FREQ

parameter. Enter the required frequency by using the digit keys and the decimal point key if
relevant. The resolution of the RF generator frequency entry is 1 Hz, but it is not necessary to
enter every digit down to the least significant place.

The entry is completed by pressing a terminator key. Using the [MHz], [kHz] or [Hz] key causes
the entered frequency to be displayed according to normal convention. The following examples
explain further.

Pressing:-

[1] [2] [5] [MHz] will display 125.000000 MHz
[1] [2] [5] [kHz] ” “ 125.000 kHz

[1] [2] [5] [0] [kHz] ” “ 1.250000 MHz
[1] [.] [2] [5] [MHz] ” “ 1.250000 MHz
[1] [2] [5] [0] [0] [0] [1] [Hz] ” “ 1.250001 MHz

GEN FREQ will be set to the

Variable control

With the

%#,$0#/ legend highlighted, the GEN FREQ parameter can be adjusted by using the

variable control.

3-38 46882-311

OPERATING MANUAL 2945A

Frequency increment

The FREQ [Ö] and [ ×] keys can be assigned to RF genera t or frequency adjustment. See
Incremental adjustments which starts on page 3-62.

Output level setting

Range

N-Type connector, -135 dBm to -15 dBm; 0.04 mV to 40 mV pd
BNC connector, -115 dBm to +5 dBm; 0.4 mV to 400 mV pd

(with uncalibrated overrange to +7 dBm)

WARNING

Hot surfaces

Take care when touching the RF Input Type N connector after the application of high levels of
continuous power. If 50 W is applied for a prolonged period, the temperature of the connector can
become excessive.

The signal generator output level is set using the data keys. It can be defined in dBm with the
[dBm] terminator key or by voltage level with the [V], [mV] or [µV] terminator key.

Voltage levels will be shown as PD or EMF, depending on the selection made on setup page 1.
The output range from each connector is given in the Performance data section of chapter 1.

The signal generator output level from the BNC connector is calibrated up to +5 dBm. The output
level can be increased to approximately +7 dBm, uncalibrated.

To enter an output value press the [RF Gen] key, followed by the or ange [LEVEL] funct ion key.
The

Enter the required value using the data entry numeric keys and the relevant terminator key. The
level will be displayed in correct engineering convention.

Note that any external attenuator values entered on setup page 1 will reflect in the level of
indicated output. If an external attenuator value is currently set, output levels which have
been modified to take account of the additional attenuation will be indicated on the
display by  against them. See RF Power Ext Atten : dB, on page 3-11.

%#, and +#4#+ legends will be highlighted.

Variable control

With the
the variable control.

Level increment

The LEVEL [Ö] and [×] keys can be assigned to RF generator l evel adjustment. See Incremental
adjustments

%#, and +#4#+ legends highlighted, the GEN LEVEL parameter can be adjusted by using

which starts on page 3-62.

Modulation

The RF signal generated for receiver testing can be modulated using either or both of the AF
generators or by an external source.

Modulation type

The modulation type is automatically set, to be appropriate to the level terminator key used (FM
for Hz, kHz or MHz; AM for %).

46882-311 3-39

LOCAL OPERATION

Modulation generators

Set up one or both of the modulation generators for the required frequency, level and shape by
using the soft keys and data input keys. When these and the de-emphasis filter are set to the
required settings press the [Return] key to restore the

Modulation frequency and level

The frequency range and level must not exceed the following limits:-

To enable or set up the modulation generators press the [Mod Gen] key. The screen and menu
shown in fold out diagram (4-2) will be displayed.

Set up the modulation generator(s) for the required frequency and output level by using the soft
keys and data input keys:-

RECEIVER TEST menu.

Modulating freq. range 20 Hz to 20 kHz.
AM depth range 0 to 99% total sum of

active modulation sources.

FM deviation range 0 to 75 kHz total sum of

active modulation sources.

[Gen 1/Gen 2] to select MOD1, then, [FREQ][n]....[n][kHz/Hz]

[LEVEL][n]...[n][kHz/Hz]

then [Gen 1/Gen 2] to select MOD2 if required,....[.../Hz]

Frequency and level increment

The FREQ [Ö] and [×] and the LEVEL [Ö] and [×] keys can be assigned to the modulation
generator frequency and level . See Incremental adjustments which starts on page 3-62.

Modulation generator state

Either or both generators can be switched off to suit the test requirement. To disable a generator,
first select it using the [Gen 1/Gen 2] key. Repeated presses of the orange [ON / OFF] function key
will disable or enable the selected generator.

Note that the modulation generators are also used as AF generators to provide a
modulation source in the Tx TEST mode.

If both AF generators are set to
TEST mode will show both modulation generators to be

ON in the Tx TEST mode, switching to Rx

OFF.

Either or both generators can be set up and turned on within the Rx TEST mode.

The frequency, level and shape settings of their last use in the Rx TEST mode will be retained
within the Rx TEST mode setup. These settings will be effective when the generators are switched
to ON in the Rx TEST mode. Their use as audio generators in the Tx TEST mode will then be
disabled.

Modulation generator shape

The shape of the output waveform from each modulation generator can be set to either sine or
square wave. To change the output waveform from a generat or, first select it using the
[Gen 1/Gen 2] key. Repeated presses of the [Shape] key will toggle between sine or square wave.

Modulation generator level locking

Pressing the [Lock] key locks the output level of the two modulation generators to the same level.
The unselected generator locks to the level of the selected generator.

Pre-emphasis filter

The pre-emphasis filter can be switched in or out of circuit after pressing the [Mod Gen] key.

3-40 46882-311

OPERATING MANUAL 2945A

Pressing the [Pre-emph] key will toggle the pre-emphasis filter into and out of circuit. The time
constant of the filter is 750 µs, giving an increase with frequency of 6 dB/octave.

The legend

Pre-emph ON is displayed when the filtering is in circuit. No indication is given when

the filtering is out of circuit.

External Modulation

An external modulation source may be used to modulate the RF generator signal. Pressing the [Ext
Mod] key will display the external modulation input selection menu.

The options available are:-

[DC Ext] Selects the ‘EXT MOD IN’ connector on the rear of the

instrument, with DC coupling.

[AC Ext] Selects the ‘EXT MOD IN’ connector on the rear of the

instrument, with AC coupling .

[Mic

]

Selects Microphone (connected to the ACCESSORY socket on
the front panel) as the external modulation source.

The selection is shown on the display next to the

Ext Level Source legend. The frequency range for

each input option is specified in the Performance data section of Chapter 1.
The level of the external modulation signal should be 1.0 V rms. This retains correlation of the

modulation level indicated on the display with that applied to the RF signal.

Setting external modulation level

Press the [Ext Mod] key, which as well as displaying the menu mentioned above, will highlight the

#62+#4#+F legend. Use the data input keys to set the required level, followed by the appropriate

[Hz], [kHz] or [%] key.

Hint
The modulation source level can be measured using the AF INPUT connector on the front panel

and AF LEVEL bar chart, or by monitoring the modulation level of the RF generator using the Dx
TEST mode.

Microphone input

A microphone suitable for connecting to the accessory socket, is available as an optional accessory.
See Options and accessories, in the Performance data section of Chapter 1.

The microphone input circuit contains a limiter to prevent over-modulation, and the external
modulation level setting remains effective when the microphone option is selected. This gives
versatility of test options to suit the user's requirements.

The microphone input must be selected to make use of the PTT switching facility available in the
Tx TEST mode.

The level of the modulation from the external source will add to the level of any internal
modulation and will therefore be included in the total sum of modulation sources.

The state of the external modulation source can be changed by pressing the orange [ON/OFF]
function key when the

#62+#4#+ legend is highlighted. Off is displayed next to the external

modulation parameters when the external modulation is disabled.

Note that only one type of modulation can be applied to the RF signal. For example:­If the [%] terminator key is used to complete a modulation setting when an FM deviation

level is already set from another source, the latest selection will cause the previous setting
to be cancelled.

AF input level measurement

The measured level of signals applied to the AF INPUT connector can be displayed in volts, dBm,
dBV or mW. The selection is made from setup page 2, as described under Audio Level Measured

46882-311 3-41

LOCAL OPERATION

in: on page 3-12. When the input level is displayed in dBm or mW, the signal is assumed to be
measured across 600 Ω.

The 600 Ω interface unit allows the Service Monitor to provide a 600 Ω termination. (See Audio
Input Impedance on page 3-12.) With the input impedance set at 600 Ω, the indicated level is that
of the input to the Service Monitor. With the input impedance set at High, the indicated level is
that of the input to the Service Monitor with an assumed 600 Ω load.

AF filters

The AF signal to the AF INPUT connector on the front panel can be filtered using the following
audio filters:-

0.3 - 3.4 kHz
band pass

†

Only if option 23 (CCITT filter) is fitted.

‡

Only if option 24 (C-MESS filter) is fitted.

Press the [AF Filter] key. The left hand soft keys change, to allow selection of AF filters shown
above. Press the [Return] key after selecting the required filter.

*OSCILLOSCOPE*

The input to the oscilloscope is taken directly from the AF input connector on the front panel, not
through any of the AF filters. Therefore measurements obtained on the AF vo ltmeter will show the
effects of filtering, whereas those made using the oscilloscope will not.

Audio distortion

The Service Monitor is able to measure signal noise and distortion against the following
parameters:-

Distortion levels introduced into the audio signal path can be measured using the distortion
measuring module.

Pressing the [Dist/S-N] key will display the screen and menu shown in fold out diagram (3-4). The
function of each soft key on this menu is as follows:-

50 kHz
low pass

Signal to
noise ratio

15 kHz
low pass

SINAD
level

300 Hz
low pass

Percentage
distortion.

†

CCITT
C-MESS

or

‡

Off

Disables any active distortion measuring function and removes the distortion bar chart from the
display.

Hint
By disabling this function, the time taken to measure the remainder of the measurement functions

is shortened thereby reducing the update time.

3-42 46882-311

OPERATING MANUAL 2945A

S/N

Selects Signal to noise ratio as the measurement method. Compares the level of the demodulated
signal together with the system noise, against the level of the system noise only, using the formula:-

V

S/N

= 20

log

1

dB

V

2

20log

()SND

N

dB

=

++

See Fig. 3-8 a, & d, Distortion level and signal to noise level measurements, on page 3-33. The
distortion bar chart is graduated in dB and is also displayed as a digital read-out above the bar
chart. The Rx test menu is recalled automatically after pressing this key.

SINAD

Selects SINAD as the measurement method. The modulation generator is set to 1 kHz. By
filtering the demodulated signal with a 1 kHz notch filter and comparing the result with the
unfiltered signal, the SINAD level is established using the formula:-

V

SINAD

= 20

log

1

dB

V

2

++

()

20log

SND

()

ND

dB

+

=

See Fig. 3-8 a, b, & c. Distortion level and signal to noise level measurements, on page 3-33. The
distortion bar chart is graduated in dB and the SINAD level is displayed as a digital readout above
the bar chart. The Rx test menu is recalled automatically after pressing this key.

Dist’n

Selects distortion percentage as the measurement method. The modulation generator is set to
1 kHz. By filtering the demodulated signal with a 1 kHz notch filter and comparing the result with
the unfiltered signal, the distortion percentage level is established by the formula:-

Distortion

See Fig. 3-8 a, b, & c. Distortion level and signal to noise level measurements, on page 3-33. The
distortion bar chart is graduated in % and the distortion percentage level is displayed as a digital
readout above the bar chart. The RX TEST menu is recalled automatically after pressing this key.

Making measurements

(Examples of receiver tests).
The procedure for making each of the tests listed in the receiver testing overview, above, follows.

Some of the tests may require separate operations and others will only require a reading to be
made.

V

2

=100

=

%

V

1

+

()

ND

100

++

()

SND

%

Sensitivity

Receiver sensitivity is defined as the minimum RF level required at the antenna to produce an
intelligible output of the modulated information.

46882-311 3-43

LOCAL OPERATION

The problem with the above definition is that of defining ‘intelligible output’. As this is a
subjective decision, sensitivity specifications require certain parameters to be set down. The nature
of FM and phase transmissions makes sensitivity measurements less straightforward than with AM
transmissions. A sensitivity test on an AM receiver can be stated as ‘X watts audio output from
Y µV RF input at Z% modulation’.

As there is no direct/linear relationship between RF signal level and audio output with FM
receivers, most manufacturers normally quote receiver sensitivity in one of the following four
ways:-

When defined as part of a specification, the sensitivity will be given in the form:­‘Sensitivity (12 dB SINAD) 0.25 µV’

‘Sensitivity (20 dB SINAD) 1.0 µV EMF’

12 dB SINAD sensitivity.
20 dB weighted SINAD sensitivity.
20 dB signal to noise sensitivity.
20 dB quieting sensitivity.

or

or

‘12 dB (minimum) SINAD for 0.31 µV (pd) signal input (at 60% of maximum system deviation
and 1 kHz modulation).’

The test method for each of the above sensitivity specifications varies, but the common features are
that each requires a signal of accurately defined level, modulation frequency and modulation level
to be injected into the receiver, the AF output level referenced, the modulation or a portion of it, to
be removed and the audio level re-referenced.

To carry out each of these tests using Service Monitor proceed as follows:-

12 dB SINAD sensitivity

This test determines the level of the modulated RF signal at which the SINAD measurement is
12 dB. The level of modulation is given as part of the test specification. The standard modulation
frequency is 1 kHz.

As the RF signal level is reduced, the ‘noise’ component of the AF output will become
proportionally greater. This will result in the SINAD dB reading becoming closer to zero.

To use this Service Monitor to make a 12 dB SINAD sensitivity test, the Service Monitor is set up
to make a SINAD distortion measurement and the RF level progressively reduced until the SINAD
level reads 12 dB. The RF level of the signal generator will equal the 12 dB SINAD sensitivity
level of the receiver.

For a GO/NO GO test the monitor is set up in the same manner as above. The RF level is set to the
specified sensitivity level and the SINAD distortion level observed. A reading higher than 12 dB
would indicate GO, while a reading of less than 12 dB (i.e. closer to zero) would indicate NO GO.

20 dB weighted SINAD sensitivity

This test is very similar to the 12 dB SINAD sensitivity test
The differences are firstly that the SINAD level specified is 20 dB and secondly that a

psophometric weighting filter is included in the test path. This filter imposes a frequency response
characteristic to the signal similar to that of the human ear response.

There are two specifications of filter in common use. One is the European standard CCITT and the
other is the American C-MESS. The specification of the receiver will state the correct filter to
select.

The Service Monitor can have a filter meeting one of these specifications fitted as an option.

3-44 46882-311

OPERATING MANUAL 2945A

The test procedure is identical to that for 12 dB SINAD sensitivity except that the SINAD
distortion pass level is 20 dB.

20 dB signal to noise sensitivity

This test determines the level of RF carrier which, when unmodulated will produce an AF output
level due only to receiver noise, 20 dB below the AF level produced when modulated at the
specified level and at the specified frequency.

As the RF signal level is reduced, the ‘noise’ component of the AF signal will become
proportionally greater. This will result in the Signal to Noise dB reading becoming closer to zero.

To use this Service Monitor to make a 20 dB S/N sensitivity test, it is set up to make signal to noise
measurements through the di st ortion meter menu of the Rx TEST mode. The modulation
frequency and level are set according to the receivers test specification requirements.

The RF level is adjusted until the S/N level indicated on the Service Monitor reads 20 dB. The RF
level will then equal the 20 dB S/N sensitivity level.

For a GO/NO GO test the monitor is set up in the same manner as above. The RF level is set to the
specified sensitivity setting and the S/N level observed. A reading higher than 20 dB would
indicate GO, while a reading of less than 20 dB (i.e. closer to zero) would indicate NO GO.

20 dB quieting sensitivity

This test determines the level of unmodulated RF signal that will produce an AF output from the
receiver that is 20 dB lower than the noise level from the receiver when no carrier is being
received.

The reduction in AF output when a carrier is being received is due to the action of the automatic
gain control circuits in the RF amplifiers of the receiver.

The gain of the receiver will reduce as the level of the RF signal increases. Therefore the noise
level will decrease with an increase in RF signal level.

To use this Service Monitor to make a 20 dB quieting sensitivity test the unmodulated RF signal is
applied to the receiver at the frequency called for in the test specification. If no frequency is
specified, a convenient mid band frequency is selected.

Select [RF Gen] from the soft key options. Turn the RF signal off by use of t he orange [ON/O FF]
function key and note the indicated AF level.

Turn the RF signal

ON and adjust the RF level until the indicated AF level is 20 dB less than the

previously noted level. The indicated RF level is the 20 dB quieting sensitivity level of the
receiver.

For a GO/NO GO test proceed as above until the AF level with no RF input is noted. Then turn the
RF signal on and adjust the RF level to the figure specified as the 20 dB quieting sensitivity level.
Now observe the AF level indication. A reading greater than 20 dB will indicate GO. A reading
lower than 20 dB, (i.e. closer to zero), will indicate NO GO.

Basic sensitivity test

To carry out a basic sensitivity test on an AM receiver:
Set the RF generator frequency to that required by the test program. This setting can be entered

using the data input keys or set using the Rx=Tx facility discussed under Tx mode. The RF
generator can be switched off during the setup operation if required, by pressing the orange [ON
OFF] function key.

Select the ‘Mod Gen’ menu from the

RECEIVER TEST screen.

Set the modulation frequency and level. It is usual to use a single sinewave tone when carrying o ut
sensitivity tests and essential for SINAD tests.

Select the ‘pre-emphasis’ facility if required, by pressing the [Pre-emph] key.
Return to the

RECEIVER TEST screen and select the ‘AF filter’ menu. Select the required AF

filtering.

46882-311 3-45

LOCAL OPERATION

Return to the RECEIVER TEST screen and adjust the RF output level to that required by the test
specification.

Switch the RF generator output
The audio output from the receiver is measured and the level and frequency displayed.
For measuring sensitivity levels, rather than checking against settings, the various parameters on

the monitor can be adjusted in steps using the LEVEL [Ö] and [×] keys, or by precision
adjustment using the var iable control.

AF bandwidth

The audio bandwidth of a receiver should be complementary to that of the transmitter or
transmitters associated with it.

The test for audio band wid t h is made by establis hi ng a reference frequency, usually 1 kHz, and
reference level, then varying the modulating frequency until the measured audio output level
reduces by 3 dB. The 3 dB points above and below the reference frequency will be the limits of
the AF bandwidth.

When carrying out audio bandwidth tests the monitor audio filtering should be set to the widest
possible, i.e. 50 kHz.

Note that most FM transceivers apply pre-emphasis filtering to the transmitter modulation and
de-emphasis filtering to the demodulated signal.

ON by pressing the ora nge [ON OFF] function key.

AF distortion

The two methods used for quoting distortion within radio receivers are Distortion Factor and
SINAD.

SINAD tests are usually made in conjunction with sensitivity testing (see above), while distortion
test results are often quoted within the power output parameter. For example ‘3 Watts output with

better than 10% THD’ (total harmonic distortion).
The signal to noise level is also quoted but is a measure of receiver quality, not a true measure of

distortion.
The AF distortion measuring facility performs continuous reading and display metering using the

selected function, (SINAD or distortion factor). Therefore a distortion test can be carried out by
ensuring that the RF generator is tuned to the correct frequency, select the distortion measuring
function required and set the levels of the RF and AF generators. The distortion factor or SINAD
level is then read from the screen.

To obtain sets of readings relating to differing levels of RF or AF, the levels are reset and the new
reading made.

3-46 46882-311

OPERATING MANUAL 2945A

Selectivity

2041

Signal Generator

'ADJACENT CHANNEL' SIGNAL

Coupler

Service Monitor

'ON CHANNEL' SIGNAL

Rx

DE MODULATED AF TEST SIGNAL

Under

Test

C3375

Fig. 3-10 Selectivity test setup

Selectivity tests are measurements of the capability of a receiver to differentiate between a wanted
signal and an unwanted signal, usually that transmitted on an adjacent channel.

This test is carried using the Service Monitor as for previous tests but with a second RF signal
generator simulating the adjacent channel transmitter. See Fig. 3-10, Selectivity test setup, on
page 3-47.

A specification for receiver selectivity requires parameters to be set down to measure against.
Within the specification of a typical mobile radio a typical adjacent channel selectivity figure might
read:- ‘12 dB adjacent channel selectivity; better than 80 dB’, and the 20 dB weighted SINAD

sensitivity is quoted as ‘better than 1 µV’.
To confirm this selectivity figure proceed as follows:­The equipment is connected as in Fig. 3-10, Selectivity test setup. The level of modulation for the

‘wanted’ signal is set to 60% of the maximum deviation for FM receivers or 30% modulation for
AM receivers. The modulation frequency is 1 kHz unless specified differently.

The generator being used to provide the adjacent channel signal is set to the frequency of the
adjacent channel with a modulation frequency of 400 Hz unless specified differently. The
modulation level is set to 60% of the maximum deviation for FM receivers or 30% modulation for
AM receivers. The carrier is switched off at the commencement of the test.

The level of the Service Monitor providing the ‘wanted’ signal is adjusted until a SINAD reading
of 20 dB is obtained as for sensitivity testing. The RF output level of the generator should be
noted. This should be the same level as that established in the 20 dB sensitivity test (above).

The carrier from the signal generator providing the ‘adjacent channel’ signal is switched on and the
level of its output increased until the SINAD level is reduced to 12 dB. The RF output level should
be noted.

The difference in output level of the two RF generators, expressed in dB, is the ‘12 dB Adjacent
Channel Selectivity’ level.

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LOCAL OPERATION

In the example above, with a ‘wanted’ signal level of −90 dB and a ‘adjacent’ signal level of

−7 dB, the performance of the receiver would be satisfactory. If the ‘adjacent’ signal level was
found to read −13 dB the performance of the receiver would be below specification.

Blocking (or desensitisation)

Blocking (or desensitisation) is an undesirable response by a receiver to a signal whose frequency
is spaced from the wanted signal by a frequency difference greater than the adjacent channel
spacing. The interfering signal will enter the IF pass band of the receiver with sufficient strength to
cause the automatic gain control to operate. This will reduce the gain of the receiver and ‘block
out’ weak signals.

The test setup is the same as for selectivity testing.
The generator being used to provide the ‘wanted’ signal is set as for selectivity testing and the level

adjusted to produce a SINAD level of 20 dB.
The generator providing the ‘interfering’ signal should be unmodulated and set to an RF level of

between 80 and 90 dB above the level of the ‘wanted’ signal
The frequency of the ‘Interfering’ signal should be slowly swept over a range of 1 to 10 MHz either

side of the ‘wanted’ signal frequency and the SINAD level observed for any significant variation.
If any interaction is found, adjust the frequency of the ‘interfer ing’ signal for maximum reaction.
Vary the level of the ‘interfering’ signal until the SINAD level is 14 dB and note the RF level.
This is the blocking level of the receiver for the frequency concerned.

Spurious response

The two types of spurious response measurements normally carried out on a receiver are image
frequency rejection and IF rejection.

For a specific receiver type, the frequency of the image signal of a ‘wanted’ signal is twice the
receiver intermediate frequency above the wanted frequency if the receiver local oscillator runs at a
frequency above the wanted signal, or twice the receiver intermediate frequency below the wanted
frequency if the receiver local oscillator runs at a frequency below the wanted signal. See Fig. 3­11, Spurious response ‘Image Frequency’ location.

Local oscillator running

above

875 MHz

(TUNED FREQUENCY)

For a 10.7 MHz Intermediate Frequency

tuned frequency

885.7 MHz

(LOCAL OSCILLATOR)

Frequency

896.4 MHz

(IMAGE FREQUENCY)

Local oscillator running

below

853.6MHz

(IMAGE FREQUENCY)

tuned frequency

864.3MHz

(LOCAL OSCILLATOR)

Frequency

875 MHz

(TUNED FREQUENCY)

C1614

Fig. 3-11 Spurious response ‘Image Frequency’ location

With the receiver and Service Monitor set up as for sensitivity testing, establish a reference RF
input level. Change the RF output frequency of the Service Monitor to the image frequency of
receiver tuning point, without altering the receiver tuning. Increase the RF output level of the
Service Monitor RF generator until the SINAD level reads 20 dB and note the RF level. The

3-48 46882-311

OPERATING MANUAL 2945A

difference in the level of the RF generator readings for the two frequencies, expressed in dB, is the

‘image frequency re jection ratio’.
The procedure for measuring the IF rejection ratio is similar to that used to measure image

frequency rejection and uses the same setup. The RF reference level is found at the RF frequency
to which the receiver is tuned, then the RF generator is retuned to the IF frequency of the receiver
under test. The RF output level is increased until a 20 dB SINAD level is obtained. The output
level of the RF generator is noted. The difference in level of the RF generator readings, expressed
in dB, is the ‘IF rejection ratio’ of the receiver.

AGC response

Automatic Gain Control is used in AM receivers to stabilise the level of the audio output signal
against changes in the level of RF input. This is necessary as the output voltage from the detector
circuit with a constant % depth of modulation is proportional to the level of the RF signal applied
to the detector.

To plot the AGC response of a receiver, set up the instrument and receiver as described for receiver
audio frequency response tests. The test can be made at one RF frequency only or at various points
throughout the receiver tuning range. This will depend on the reason for making the test and the
specification of the receiver.

Set the RF generator frequency of the Service Monitor to the selected tuning point of the receiver
with the modulation level set to 30% at 1 kHz. Increase the RF output level until an AF output is
registered on the Service Monitor display, either bar chart or oscilloscope.

Reduce the RF output level until the AF output level of the receiver reaches the noise level.
Record the RF signal level and the AF output level.
Increase the RF generator level by suitable increments and record the level of AF output at each

point.
Continue until the RF input to the receiver reaches the maximum allowed by the receiver

specification or until the AF output level no longer increases, whichever occurs at the lowest RF
level.

FM receivers incorporate limiting circuits which reduce the level of the RF signal by clipping the
extremities of the signal rather than by compression which is necessary with AGC circuits for AM
receivers.

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