Aeroflex 2975 Operation Manual

2975

Radio Test Set

Operation Manual

1002-4202-2P0

Issue-3

OPERATION MANUAL

RADIO TEST SET

2975

PUBLISHED BY

Aeroflex

COPYRIGHT © Aeroflex 2006
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or

transmitted in any form or by any means, electronic, mechanical, photocopying, recording or
otherwise without the prior permission of the publisher.

Original Printing Jan 2005
Issue-2 Feb 2006
Issue-3 Aug 2006

10200 West York Street/ Wichita, Kansas 67215 U.S.A. / [phone] / FAX [phone]

ELECTROMAGNETIC COMPATIBILITY

Double shielded and properly terminated external interface cables must be used with this equipment
when interfacing with the RS-232 and IEEE-488.

For continued EMC compliance, all external cables must be shielded and 3 meters or less in length.

NOMENCLATURE STATEMENT

The 2975 Radio Test Set is the official nomenclature for the 2975 Radio Test Set. In this manual,
2975, unit or test set, refers to the 2975 Radio Test Set.

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SAFETY FIRST: TO ALL OPERATIONS PERSONNEL

REFER ALL SERVICI NG OF UNIT TO QUALIFIED TECHNICAL PE RSONNEL. THIS UNIT CONTAINS NO
OPERATOR SERVICEABLE PARTS.

CASE, COVER OR PANEL RE MOVAL

Removing protective c overs, casings or panels from this unit exposes the operator to electric al hazards that
can result in electric al shock or equipment damage. Do not operate thi s unit with the case, cover or panels
removed.

SAFETY IDENTI FICATION IN TECHNICAL MANUAL

This manual uses the foll owing terms to draw attention to possible s afety hazards, that may exi st when
operating or servicing this equipment.

CAUTION: THIS TERM IDENTIFIES CONDITIONS OR ACTIVITIES THAT, IF IGNORED, CAN RESULT IN

WARNING: THIS TE RM IDENTIFIES CONDITIONS OR ACTIVITIES THAT, IF I GNORED, CAN RESULT IN

SAFETY SYMBOLS IN MANUALS AND ON UNITS

EQUIPMENT OR PROPERTY DAMAGE (e.g., FIRE).

PERSONAL INJURY OR DEATH.

CAUTION: Refer to accompany ing documents.

AC TERMINAL: Terminal that may supply or be supplied with ac or alternati ng voltage.

SWITCH OFF: AC line power to the devi ce is OFF.

SWITCH ON: AC line power to the devi ce is ON.

DANGEROUS VOLTAGE: Indicates electrical shock hazard due to high vol tage levels.

EQUIPMENT GROUNDING PRE CAUTION

Improper grounding of equipment can resul t in electrical shock.

USE OF PROBES

Check the specific ations for the maximum voltage, current and power ratings of any connector on the uni t
before connecting it with a probe f rom a terminal device. Be sure the term inal device performs within these
specifications bef ore using it for measurement, to prevent electrical shock or damage to the equipment .

USE RECOMMENDED FUSES ONLY

Use only fuses speci fically recommended for the equipment at the specified current and voltage rati ngs.
CAUTION: SIGNAL GENERATORS CA N BE A SOURCE OF ELECTRO-MAGNETIC I NTERFERENCE (EMI) TO

COMMUNICATION RECEI VERS. SOME TRANSMITT ED SIGNALS CAN CAUSE DISRUPT ION AND
INTERFERENCE TO COMMUNICATION SERVICES OUT TO A DISTANCE OF SEVERAL MILES.
USERS OF THIS EQUIP MENT SHOULD SCRUTINIZE ANY OPERAT ION THAT RESULTS IN
RADIATION OF A SIGNAL (DIRECTLY OR INDIRECTLY) AND SHOULD TAKE NECESSARY
PRECAUTIONS TO AVOID POTENTIAL COMMUNICATION INTERFERENCE PROBLEMS.

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ESD WARNING!

PROTECTING THE 2975 AGAINST ELECTROSTATIC DISCHARGE

I

Electrostatic Discharge (ESD) can cause damage or even destroy circuitry within the 2975.
This damage is often unseen and can occur whenever the 2975 is incorrectly touched or
connected to other equipment.

To help reduce the chances of ESD damage, observe the following:

O Make sure the 2975 and all associated equipment are properly earth-grounded to

prevent build up of static charge.

O All persons using the 2975 should be grounded with a 1 MΩ resistor-isolated wrist

strap before touching any conductor on the 2975, or any equipment connected to
the 2975.

O Before connecting an open coaxial cable to the 2975, short the center conductor of

the coaxial cable to the outer conductor of the coaxial cable to discharge any
potential static that may exist.

O If a “rubber-ducky,” telescopic, or similar antenna is directly connected to the 2975,

DO NOT

O All external antennas must use approved outdoor ESD and/or lightning suppression.

Use extreme caution whenever an external antenna is connected to any device!

O Use the 2975 and associated equipment at static-safe workstations that includes

conductive mats, ionizing blowers, wrist straps and any other necessary items as
appropriate.

O Keep all static-generating materials at least one meter away from the 2975 and

connected equipment.

O Store and transport the 2975 in an approved container.
O Touch and handle all printed circuit assemblies by the edges to reduce the chances

of ESD damage.

For more information about ESD and how to prevent damage, check the Electrostatic
Discharge Association web site at:

touch the antenna unless properly grounded.

http://www.esda.org

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PREFACE

SCOPE

This manual provides operational information for using the 2975 and describes features and functions
implemented with software version 1.9.1.4.

ORGANIZATION

The 2975 Operation Manual is composed of the following sections:

SECTION 1 - DESCRIPTION

Contains the 2975 Functions, Capabilities (Product Specifications) and Connector
Descriptions.

SECTION 2 - OPERATION

Contains a functional description of the Generator, Receiver, Duplex, Function Generator,
Oscilloscope, Spectrum Analyzer and Meters.

SECTION 3 - OPTIONAL FEATURES

Contains description of optional features available for the 2975.

SECTION 4 - APPLICATIONS

Contains step-by-step procedures for operating the 2975.

SECTION 5 - REMOTE COMMANDS

Tool Command Language (TCL) allows creation of automated sequences and remote
operation.

SECTION 6 - SYSTEM SETTINGS

Contains descriptions for network, remote and system features settings.

i

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ii

TABLE OF CONTENTS

Paragraph Title Page

SECTION 1 - DESCRIPTION

1-1 Functions and Capabilities ..................................................................... 1-1

1-2 Specifications....................................................................................... 1-5

1-3 Connectors........................................................................................... 1-22

2975 Front Panel ............................................................................. 1-22

2975 Rear Panel.............................................................................. 1-24

SECTION 2 - OPERATION

2-1 Operational Concepts............................................................................ 2-1

2-2 Monitor and Control Functions ................................................................ 2-2

2-3 Operation............................................................................................. 2-3

2-4 Operation Modes................................................................................... 2-22

Generator Mode............................................................................... 2-22

Receiver Mode ................................................................................ 2-31

Duplex Mode................................................................................... 2-34

Function Generator.......................................................................... 2-35

Oscilloscope ................................................................................... 2-39

Spectrum Analyzer........................................................................... 2-43

SINAD Meter................................................................................... 2-52

Distortion Meter............................................................................... 2-54

Power Meter.................................................................................... 2-56

RSSI Meter ..................................................................................... 2-57

Deviation Meter............................................................................... 2-58

AM Modulation Meter........................................................................ 2-59

Modulation Fidelity Meter ................................................................. 2-60

Digital (AC/DC) Voltmeter ................................................................. 2-61

AF Counter ..................................................................................... 2-63

RF Error Meter ................................................................................ 2-64

BER Meter ...................................................................................... 2-65

Meter Panel .................................................................................... 2-67

i

TABLE OF CONTENTS (cont)

Paragraph Title Page

SECTION 3 - OPTIONAL FEATURES

3-1 Optional Features and Functions ............................................................ 3-1

3-2 Description of Options ........................................................................... 3-3

SmartNet™ / SmartZone™ Testing Opt 3 ............................................ 3-3

Smartnet/Smartzone® 900 MHz Opt 8 ................................................ 3-3

P25 Trunking Opt 4 .......................................................................... 3-4

Control Channel Logger Opt 6 ........................................................... 3-5

P25 Trunking VHF/UHF/700 MHz Opt 14............................................. 3-6

Secondary Control Channel Broadcast (SCCB) Opt 21 ......................... 3-7

Explicit Mode of Operation Opt 22 ..................................................... 3-8

P25 Explicit Unit to Unit and PSTN Emulation Opt 23........................... 3-9

P25 Explicit Adjacent Status Broadcast Channel Message Opt 24 ......... 3-10

CQPSK Generate/Receive and Analysis Opt 29................................... 3-12

AutoTest Opt 9................................................................................ 3-13

AES Opt 10 ..................................................................................... 3-15

KVL Loader Opt 12 .......................................................................... 3-16

KVL ASN Opt 20 .............................................................................. 3-16

Audio Analyzer Opt 15...................................................................... 3-19

Audio Simulcast Align Opt 16 ............................................................ 3-22

Rx BER Opt 17 ................................................................................ 3-23

LTR Trunking Opt 18 ........................................................................ 3-23

PassPort® Opt 19............................................................................ 3-24

SECTION 4 - APPLICATIONS

4-1 Digital Transmitter Testing ..................................................................... 4-1

Digital Receiver Testing ........................................................................ 4-6

Analog Transmitter Testing .................................................................... 4-8

Analog Receiver Testing........................................................................ 4-11

Measuring Cable Fault ........................................................................... 4-13

Measuring Return Loss.......................................................................... 4-15

Measuring Filters .................................................................................. 4-17

Filter Pass Band Adjustments................................................................. 4-19

Notch Filter Adjustment ......................................................................... 4-20

P25 Self Check ..................................................................................... 4-21

ii

TABLE OF CONTENTS (cont)

Paragraph Title Page

SECTION 5 - REMOTE COMMANDS

5-1 Introduction.......................................................................................... 5-1

5-2 TCL Basics .......................................................................................... 5-4

5-3 Controlling the 2975 ............................................................................. 5-6

5-4 Controlling the 2975 Display .................................................................. 5-7

5-5 Recalling Saved Instrument States.......................................................... 5-8

5-6 Using the 2975 TCL Command Verbs ..................................................... 5-10

5-7 Remote Test Recommendations.............................................................. 5-12

5-8 Quick Reference List ............................................................................ 5-16

5-9 2975 Commands .................................................................................. 5-26

SECTION 6 - SYSTEM SETTING S

6-1 General ............................................................................................... 6-1

Configuration .................................................................................. 6-1

IP Parameter Setup.......................................................................... 6-2

IEEE-488 (GPIB) Setup .................................................................... 6-2

System Parameter Setup .................................................................. 6-2

RS-232 (Serial) Setup ...................................................................... 6-3

Factory Default (F2)......................................................................... 6-3

Time / Date ..................................................................................... 6-3

Version........................................................................................... 6-4

Reload............................................................................................ 6-4

Calibrations .................................................................................... 6-5

Save / Recall .................................................................................. 6-5

iii

TABLE OF CONTENTS (cont)

Paragraph Title Page

APPENDIX A - I/O CONNECTOR PIN-OUT TABLES

Table of I/O Connectors (Front Panel) ..................................................... A-1

Table of I/O Connectors (Rear Panel)...................................................... A-1

Pin-Out Table for MIC Connector............................................................ A-2

Pin-Out Table for AUDIO I/O Connector................................................... A-2

Pin-Out Table for GPIB Connector .......................................................... A-3

Pin-Out Table for RS-232 Connector ....................................................... A-4

Pin-Out Table for PRINTER Connector .................................................... A-5

Pin-Out Table for TEST PORT Connector................................................. A-6

Pin-Out Table for VGA Connector ........................................................... A-6

Pin-Out Table for MOUSE Connector ....................................................... A-7

Pin-Out Table for KEYBOARD Connector................................................. A-7

Pin-Out Table for USB Connector ........................................................... A-8

Pin-Out Table for ETHERNET Connector ................................................. A-8

APPENDIX B - REPACKING FOR SHIPMENT

Shipping Information ............................................................................. B-1

Authorization........................................................................................ B-1

Tagging Test Sets ................................................................................. B-1

Shipping Containers.............................................................................. B-1

Freight Costs........................................................................................ B-1

Repacking Procedure ............................................................................ B-1

Repacking Diagram ............................................................................... B-2

APPENDIX C - P25 TERMINOLOGY

iv

SERVICE UPON RECEIPT

Unpacking

Special-design packing material inside this shipping carton provides maximum protection for the

2975. Avoid damaging the carton and packing material during equipment unpacking. Use the
following steps for unpacking the 2975.

O Cut and remove the sealing tape on the carton top and open the carton.
O Grasp the 2975 firmly, while restraining the shipping carton, and lift the equipment and

packing material vertically.

O Place the 2975 and end cap packing on a suitable flat, clean and dry surface.
O Remove the protective plastic bag from the 2975.
O Place protective plastic bag and end cap packing material inside shipping carton.
O Store the shipping carton for future use should the 2975 need to be returned.

Checking Unpacked Equipment

O Inspect the equipment for damage incurred during shipment. If the equipment has been

damaged, report the damage to Aeroflex.

O Check the equipment against the packing slip to see if the shipment is complete. Report all

discrepancies to Aeroflex.

DESCRIPTION PART NUMBER QTY

2975 7003-4248-500 1
COVER 1414-4452-900 1
806 MHz ANTENNA, BNC JOINT 1201-7616-000 1
150 MHz ANTENNA, BNC JOINT 1201-7616-800 1
450 MHz ANTENNA, BNC JOINT 1201-7616-900 1
CONN,ADAPT BNC JACK/ N PLUG 2113-0000-004 1
CONN,ADAPT BNC JACK - TNC P LUG 2200-0410-700 2
FUSE,3 AMP,FAST, 5MMX20MM,250 V 5106-0000-055 2
CORD,AC,NEMA5-15,IEC320-C13,RA 6041-0001-200 1
OPERATION MANUAL (CD-ROM) 1002-4202-2C0 1
OPERATION MANUAL (PAPER) (OPTIONAL)

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SECTION 1 - DESCRIPTION

1-1 FUNCTIONS AND CAPABILITIES

The 2975 Radio Test Set is a multi-purpose test solution with all the tools necessary for advanced
testing of conventional two-way and Project 25 Compliant Radios. These tools have been integrated
into a single platform offering over 20 discrete instruments which are presented in a comprehensive,
user-friendly style.

A closer look at the 2975 reveals these capabilities:

O Operation from front panel, keyboard, mouse or remote connection
O Protected RF Inputs
O RF Receive/Generate with full Duplex Operation to 2.7 GHz
O AM, FM and C4FM Modulation
O RF Power/Frequency/Frequency Error/Distortion/SINAD/AF Level/Voltage Meters
O Full Function Spectrum Analyzer/Oscilloscope/DVM
O IP Addressable
O Supports Network Connectivity
O Portable at 33 lbs.; ideal for the field technician

Standard

functions and features of the 2975 include:

O Spectrum Analyzer functions:

O Eight (8) Markers with frequency / level readout, with marker-to-marker readouts, plus

horizontal or vertical placement

O Sweep speeds and zero span operation
O Cable Fault measurement calculator
O "Quick Span" using mouse for simultaneous frequency and span settings

O Digital Coded Squelch (DCS), Dual-Tone, Multiple Frequency (DTMF) and Continuous Tone

Coded Squelch System (CTCSS) decoding

O Volume and Squelch controls are accessible using the mouse
O RF Generator ON / OFF control is accessible on the Receiver screen
O An internal hard drive and 3.5 inch floppy drive for simplified program installation.
O User definable screen permits customized screen construction
O Screen capture function allows to capture spectrum displays and oscilloscope displays
O SETUP RECALL accessible from any screen providing easier access to stored information
O Receiver "Find Frequency" function which automatically tunes to the frequency of a

transmitter

1-1

Standard

functions and features of the 2975 (cont)

O Internal Web Server. The 2975 features an internal web server that:

O Permits upload and download of files to and from the 2975
O Permits viewing the 2975 settings and meters on the PC browser
O Permits browsing the internal 2975 HELP files
O Provides access to the 2975 Operation Manuals and Technical Application Notes
O Permits downloading the 2975 LabWindows® CVI driver zip file for the user to develop

user specific LabWindows® applications

O The 2975 supports DHCP, permitting easy connection onto a computer network. For easy

remote display connection, the 2975 display can be redirected to a PC's X Windowing System
client from the 2975 Internal Web Server.

O P25 functionality which includes:

O Wider frequency error capture range for P25 radios (more forgiving for radios that are off-

frequency)

O C4FM Modulation Fidelity Meter displays frequency error and deviation at symbol time in

addition to the modulation fidelity reading

O Rx BER function permits stimulus / response of P25 radios with support for four standard

test patterns

O LCO #7 (telephone number dialing) support

O Op-codes "03" and "06" have continuous delivery
O Function Generator has Arbitrary and SINC waveform capability
O RF Generator microphone press-to-talk (PTT) control
O Audio Route controls for the MODULATOR loopback
O Demod Audio filter selection for APCO-25
O Deviation Meter and AM% Meter have added functionality for Peak, Average, Positive Peak

and Negative Peak

O Scope markers for the integral dual channel oscilloscope

Optional

functions and features available on the 2975 include:

P25 Options

O Control Channel Logger (2975OPT6) for capturing P25 trunking protocol messages.
O P25 Trunking VHF/UHF/700 MHz (2975OPT14) for testing P25 systems in various frequency

bands of operation.

O Rx BER Option (2975OPT17) extends the BER function within the 2975 by adding external

data input through the front panel Test Connector (data from radio under test).
2975 SmartNet™ /SmartZone™ Option
O SmartNet™ /SmartZone™ 900 MHz (2975OPT8) for testing radios in the 900 MHz band using

this trunking protocol.

1-2

Encryption Options
O AES (2975OPT10) Advanced Encryption System to permit testing radios using this powerful

encryption scheme.
O KVL Keyloader (2975OPT12) to permit loading and management of encryption keys within the

2975.

O KVL ASN Option (2975OPT20) is a proprietary key transfer protocol used by Motorola KVL-

3000 and older keyloaders. This protocol is proprietary to Motorola and Aeroflex is under

license by Motorola to distribute this technology.
AutoTest Option

O Autotest 1 (2975OPT9) provides user defined tests and limits for transmit, receive and audio

systems.
Audio Analyzer Option

O Audio Analyzer Option (2975OPT15) provides a frequency domain spectrum display of the

audio band.
O Analog Simulcast Align Option (2975OPT16) extends the test capability of the Audio

Analyzer Option for test and alignment of Motorola base stations.
LTR Trunking Option

O LTR Trunking Option (2975OPT18) for testing radios utilizing the LTR trunking protocol.
Passport Trunking

O Passport© Option (2975OPT19) is a proprietary analog trunking protocol developed by

Trident Microsystems, Inc., Two Trident Drive - Arden, NC 28704. Aeroflex is under license

by Trident Microsystems, Inc. to distribute this technology.
P25 Secondary Control Channel Broadcast Message

O P25 Secondary Control Channel Broadcast Message (2975OPT21) for verifying how P25

radios switch over to secondary control channels.
P25 Explicit Mode Operation

O P25 Explicit Mode Operation (2975OPT22) for testing trunked VHF/UHF radios systems that

use explicit message format for the latest P25 trunking systems.
O P25 Explicit Unit to Unit and PSTN Emulation (2975OPT23) for verifying that a radio can

generate and receive Unit to Unit and PSTN calls.
O P25 Explicit Adjacent Status Broadcast Channel Message (2975OPT24) for verifying how

P25 radios switch over to adjacent control channels when roaming.
CQPSK Generate/Receive and Analysis

O CQPSK Generate/Receive and Analysis (2975OPT29) allows the user to generate and

receive CQPSK modulation as defined in the TIA/EIA-102 Standard. Typical applications for

this modulation include the 6.25 kHz implementation for narrowband P25 operation as

specified in the standard, as well as analysis of Linear Simulcast Modulation (LSM) systems

deployed by manufacturers of P25 equipment.

1-3

AVAILABLE 2975 OPTIONS

Option

Number

2975OPT3
2975OPT4 P25 Trunking Radio Test P25_trunk - OK
2975OPT6 Control Channel Logger P25_CTRL_LOG 2975OPT4

2975OPT8

2975OPT9 Autotest 2 Auto_Test - OK
2975OPT10 AES AES - OK
2975OPT12 KVL Keyloader KEY_MGT - OK
2975OPT14 P25 Trunking VHF/UHF/700MHz P25_OBT - OK
2975OPT15 Audio Analyzer Audio_Analyzer - OK
2975OPT16 Analog Simulcast Align Analog_Simulcast 2975OPT15 OK
2975OPT17 RX BER RX_BER - OK
2975OPT18 LTR Trunking LTR - OK
2975OPT19 Passport PASSPORT - OK
2975OPT20 KVL ASN Mode MOTOROLA_ASN 2975OPT12 OK
2975OPT21 P25 Secondary Control Channel

2975OPT22 P25 Explicit Mode Operation P25_trunk OK
2975OPT23 P25 Explicit Unit to Unit and PSTN

2975OPT24 P25 Explicit Adjacent Status

2975OPT29 CQPSK Generate/Receive and

SmartNet™ /SmartZone™ Testing

SmartNet™ /SmartZone™ 900 MHz

Broadcast Message

Emulation

Broadcast Channel Message

Analysis

Option Name Screen Name Requires

Option

SzSnet - OK

OR

2975OPT14

SzSnet_900 2975OPT3 OK

P25_trunk OK

P25_trunk 2975OPT22 OK

P25_trunk 2975OPT22 OK

P25_LSM OK

Export?

OK

1-4

1-2 SPECIFICATIONS

A warm-up time of 5 minutes is required for the following performance requirements.
RF measurements are referenced to 50 Ω.
Accuracy and Resolution stated in percent are referenced to measured or selected value unless

otherwise stated.
Receive IF Bandwidth set to the narrowest setting that does not limit input signal bandwidth.
Where resolution exceeds accuracy, resolution takes precedence.
Specifications and features are subject to change without notice.

GENERATE FUNCTIONS

GEN PORT

Protection

10 W for 30 sec.
Threshold 100 mW input (nominal)

GEN PORT VSWR

2.05:1 max

FREQUENCY

Range

1 MHz to 2.7 GHz

Resolution

1 Hz

Accuracy

Same as Time Base

AMPLITUDE - GEN PORT

Range

+10 to -110 dBm

Resolution

0.1 dB

Accuracy

±1.5 dB (≤1.3 GHz)
±2.5 dB (>1.3 GHz)

1-5

AMPLITUDE - T/R PORT

Range

-30 to -137 dBm

Resolution

0.1 dB

Accuracy

±1 dB (≤1.3 GHz, >-120 dBm)
±1.5 dB (>1.3 GHz, >-110 dBm)

SPECTRAL PURITY

Harmonic Spurious

-20 dBc max ≤50 MHz

-25 dBc max >50 MHz

Non-Harmonic Spurious

-40 dBc max ≤1.5 GHz

-30 dBc max >1.5 GHz and <2.7 GHz

Residual Spurious

-95 dBm max <-50 dBm

Residual FM

<15 Hz rms (Post Detection BW = 300 Hz to 3 kHz)

SSB Phase Noise (20 kHz offset)

-100 dBc/Hz typical

-92 dBc/Hz max (≤1 GHz)

-90 dBc/Hz max (>1 GHz)

Residual AM

0.1% (Post Detection BW = 300 Hz to 3 kHz)

FREQUENCY AGILITY

10 mS <100 MHz step to <1 kHz frequency error

MODULATION - FM

Deviation Accuracy

3%, + residual, ± LSD (1 kHz through 20 kHz deviation, 1 through 10 kHz rate)
5%, + residual, ± LSD (>20 kHz deviation, 1 through 20 kHz rate)

Deviation Range

Off, 10 Hz to 40 kHz deviation

Deviation Resolution

10 Hz

1-6

MODULATION - FM (cont)

Modulation Rate Bandwidth

50 to 20 kHz (MOD 1, MOD 2, and Audio In [SINAD] unbalanced)
50 Hz to 20 kHz (Audio In [SINAD] balanced and Mic In)

Modulation Distortion (THD)

1% (1 kHz rate, 6 kHz deviation, 50 Hz to 15 kHz bandwidth)

External Modulation Sensitivity (Audio 1 Input)

1 Vpp = 4 kHz deviation ±15% (50 Hz to 10 kHz unbalanced)
1 Vpp = 4 kHz deviation ±15% (1 kHz balanced)

External Modulation Sensitivity (MIC Input)

1 Vpp = 40 kHz deviation ±15% (300 Hz to 3 kHz)

MODULATION - AM

Depth Range

30% to 90% (Usable 0% to 100%)

Depth Accuracy

±2% of full scale at 1 kHz rate Typical (Generate level <dBm T/R Port and <dBm Gen Port)

Depth Resolution

1%

Modulation Rate Bandwidth

100 Hz to 3 kHz

Modulation Distortion (THD)

4% typical

External AM Sensitivity (Audio 1 Input)

1 Vpp = 8% modulation (balanced and unbalanced)

External AM Sensitivity (MIC 1)

0.1 Vpp = 8% modulation

DIGITAL MODULATION FORMAT

C4FM

9600 bits/sec, 4800 symbols/sec

FSK Error

<1% typical, <2% max

P25 User Defined Signals

1011 Hz Tone
5% BER Calibration tone
Speech (repeated test phrases)
Silence
Voice from audio inputs

1-7

DIGITAL MODULATION FORMAT (cont)

P25 Standard Signals

STD 1011 STD IDLE STD SYMRATE
STD CAL STD LDU1TRG STD LOWDEV
STD SILENCE STD NOTRIG STD FIDPAT
STD INTFRNC STD LDU2TRG STD FIDSPECT
STD BUSY STD 511

RECEIVE FUNCTIONS

ANT PORT

Protection

10 W for 30 sec.
Threshold 100 mW input (nominal)

ANT PORT VSWR

2.15:1 max

LO EMISSIONS

T/R Port: ≤ -110 dBm
ANT Port: ≤-70 dBm

10.7 MHZ IF OUTPUT

-10 dBm (50 Ω nominal) typical

FILTERS

IF Filters

12.5 kHz, 25 kHz, 60 kHz, 200 kHz

POWER METER

VSWR - T/R Port

<1.2:1 to 1 GHz, <1.25:1 (typical) >1 GHz to 2.7 GHz, 1.3:1 max

Frequency Range

1 MHz to 2.7 GHz

Accuracy

10% ±LSD

Meter Range

100 mW to 200 W in a 1,2,5 sequence

Dynamic Range

100 mW to 125 W

Resolution

3 digits

1-8

POWER METER (cont)

Alarm

Alert sounds at 100°C Pad Temp or 135 W

Maximum Power

50 W continuous, 125 W 1 min ON / 4 min OFF

FREQUENCY COUNTER/FREQUENCY ERROR METER

RF Frequency Range

1 MHz to 2.7 GHz

Accuracy

Same as timebase ± 1 Hz

In-Band Frequency Range

½ selected receive bandwidth, nominal

Resolution

1 Hz

Frequency Error Ranges

AUTO, ±100 Hz, ±200 Hz, ±500 Hz, ±1 kHz, ±5 kHz, ±10 kHz, ±20 kHz, ±50 kHz, ±100 kHz

Input Level Sensitivity

T/R Port: Input Level >-10 dBm, 0 dB attenuation
ANT Port: Input Level >-40 dBm, 0 dB attenuation

Input Level Range (T/R Port)

T/R Port: Input Level >-10 dBm, 0 dB attenuation, not to exceed +50 dBm
ANT Port: Input Level >-60 dBm, 0 dB attenuation

FM DEVIATION METER

Frequency Range

1 MHz to 2.7 GHz

Resolution

10 Hz

Accuracy

±5%, ±2 LSD + residual (12.5 kHz IF, 1 kHz rate, deviation >1 kHz and ≤5 kHz)
±5%, ±2 LSD + residual (25 kHz IF, 1 kHz rate, deviation >1 kHz and ≤10 kHz)
±5%, ±2 LSD + residual (60 kHz IF, 1 kHz rate, deviation >1 kHz and ≤25 kHz)
±7%, ±2 LSD + residual (200 kHz IF, 50 to 20 kHz rate, deviation >5 kHz and ≤40 kHz)

Meter Ranges

AUTO, 5 kHz, 10 kHz, 20 kHz, 50 kHz, 100 kHz

1-9

FM DEVIATION METER (cont)

Input Level Sensitivity

T/R Port: Input Level >-10 dBm, 0 dB attenuation
ANT Port: Input Level -40 to -20 dBm, 0 dB attenuation

Input Level Range

T/R Port: Input Level -20 to +30 dBm, 0 dB attenuation, not to exceed +50 dBm
ANT Port: Input Level -60 to -10 dBm, 0 dB attenuation, not to exceed +10 dBm

AF Bandwidth

DC to 20 kHz

Demod Output Sensitivity

1 Vpp = 5 kHz deviation typical

AM MODULATION METER

Frequency Range

1 MHz to 2.7 GHz

Accuracy
(antenna input -40 dBm to -30 dBm)

±5% of Full Scale + residual (6 kHz IF, 1 kHz rate, 10% to 90% depth)

Resolution

1%

Meter Ranges

5%, 10%, 20%, 50%, 100%, AUTO

Input Level Sensitivity

T/R Port: Input Level >-10 dBm, 0 dB attenuation
ANT Port: Input Level -40 to -20 dBm, 0 dB attenuation

Input Level Range

T/R Port: Input Level -20 to +30 dBm, 0 dB attenuation, not to exceed +50 dBm
ANT Port: Input Level -60 to -10 dBm, 0 dB attenuation, not to exceed +10 dBm

AF Bandwidth

100 Hz to 3 kHz

Demod Output Sensitivity

1 Vpp = 8% modulation depth typical

1-10

AUDIO FREQUENCY COUNTER

Frequency Range

1 MHz to 2.7 GHz

Accuracy

Same as timebase ± 1 Hz

Resolution

0.1 or 1 Hz

Frequency Range (FM)

50 Hz to 10 kHz
10 kHz to 20 kHz (Modulation level >1 kHz deviation)

Input Level Sensitivity

T/R Port: Input Level >-10 dBm, 0 dB attenuation
ANT Port: Input Level -40 to -20 dBm, 0 dB attenuation

Input Level Range (T/R Port)

T/R Port: Input Level -20 to +30 dBm, 0 dB attenuation, not to exceed +- dBm
ANT Port: Input Level -60 to -10 dBm, 0 dB attenuation, not to exceed +10 dBm

Audio Filters

None, 300 Hz LP, 4 kHz LP, 4 kHz LP (Butterworth), 4 kHz HP, 15 kHz LP, 20 kHz LP,
300 Hz HP, 300 Hz to 4 kHz BP

RECEIVE SIGNAL STRENGTH INDICATION (RSSI) METER

Frequency Range

1 MHz to 2.7 GHz

Accuracy

±1.5 dB (typical)

Resolution

0.1 dB

Input Level Sensitivity

T/R Port: Input Level -30 to +20 dBm, 0 dB attenuation
ANT Port: Input Level -70 to -20 dBm, 0 dB attenuation

Input Level Range (T/R Port)

T/R Port: Input Level -40 to +30 dBm, 0 dB attenuation
ANT Port: Input Level -80 to -10 dBm, 0 dB attenuation

1-11

SINAD METER

Frequency Range

1 MHz to 2.7 GHz

Accuracy

±1 dB ±1 LSD at 1 kHz rate and 12 dB SINAD

Resolution

0.1 dB

Modulation Level Range (FM)

500 Hz to 60 kHz deviation

Test Frequency

1 kHz nominal

Meter Range

20 and 40 dB full scale

Input Level Sensitivity

T/R Port: Input Level >-10 dBm, 0 dB attenuation
ANT Port: Input Level -40 to -20 dBm, 0 dB attenuation

Input Level Range

T/R Port: Input Level -20 to +30 dBm, 0 dB attenuation, not to exceed +50 dBm
ANT Port: Input Level -60 to -10 dBm, 0 dB attenuation, not to exceed +10 dBm

Audio Filters

None, C-Weighted

DISTORTION METER

Frequency Range

1 MHz to 2.7 GHz

Accuracy

±1.5% ±1 LSD at 1 kHz rate at 5% distortion

Resolution

0.1%

Modulation Level Range (FM)

500 Hz to 40 kHz deviation

Test Frequency

1 kHz

Meter Ranges

5%, 10%, 20%, 50%, 100% Full Scale

Input Level Sensitivity

T/R Port: Input Level >-10 dBm, 0 dB attenuation
ANT Port: Input Level -40 to -20 dBm, 0 dB attenuation

1-12

DISTORTION METER (cont)

Input Level Range

T/R Port: Input Level -20 to +30 dBm, 0 dB attenuation
ANT Port: Input Level -60 to -10 dBm, 0 dB attenuation

Audio Filters

None, C-Weighted

DIGITAL DEMODULATION METERS (C4FM)

Input Level Range

T/R Port: Input Level -20 to +30 dBm, 0 dB attenuation
ANT Port: Input Level -60 to -10 dBm, 0 dB attenuation

FSK Error
(Antenna input -40 dBm to _30 dBm)

<2% + residual, 3% to 10% reading, 400 symbols

Meter Ranges

5%, 10%, 20%, 50%, 100% Full Scale

SPECTRUM ANALYZER FUNCTIONS

SWEEP (HORIZONTAL) ACCURACY

Frequency Range

1 MHz to 2.7 GHz

Frequency Resolution

1 Hz

Frequency Span Width Range

Analyzer Screen: Zero Span, 1 kHz to 2 GHz in a 1/2/5 sequence, 3 GHz
Gen / Rec Screens: Zero Span, 1 kHz to 5 MHz in a 1/2/5 sequence

Span Accuracy

±1% of (total) Span Width

Frequency Display

Span Accuracy + Frequency Standard Accuracy + 50% of RBW

Sweep Rate Range

200 ms, 500 ms, 750 ms, 1 sec, 2 sec, 3 sec, 4 sec, 5 sec, 6 sec, 7 sec

Sweep Rate Accuracy

1%

1 dB COMPRESSION

>-10 dBm (Antenna Port, 10 dB attenuation)
>-20 dBm (Antenna Port, no attenuation)

1-13

3RD ORDER INTERMOD

-60 dBc (1 MHz to 2.7 GHz),(-30 dBm input), (Antenna Port, No input attenuation)

HARMONIC SPURIOUS

-55 dBc at -40 dBm (Antenna Port, no attenuation)

NON-HARMONIC SPURIOUS

-60 dBc at -40 dBm (10 MHz to 2.7 GHz) (Antenna Port, no attenuation)

RESIDUAL SPURIOUS

≤−80 dBm (Input terminated, Antenna Port, no input attenuation)

AMPLITUDE (VERTICAL)

Level Accuracy

±2 dB (-30 dBm input, Antenna Port, 0 dB attenuation, -20 dB reference level, normalized)

Scales

2 dB/div, 5 dB/div, 10 dB/div

LOG Linearity

±2 dB

Reference Level Resolution

0.1 dB

Attenuator Range

0 to 40 dB, 10 dB steps (Auto coupled to reference level)
0 to 10 dB (ANT Port) (Auto coupled to reference level)

Attenuator Accuracy

±0.5 dB/step, ±1 dB maximum at 100 MHz

Dynamic Range

ANT Port: -100 to -20 dBm, no attenuation
≤-10 dBm, 10 dB attenuation

T/R Port: -30 to +30 dBm, no attenuation

Typical Noise Floor Performance

-110 dBm, 10 MHz to 2.7 GHz
(300 Hz Resolution Bandwidth selected)

Residual Phase Noise

-92 dBc/Hz at 20 kHz offset

1-14

RESOLUTION BANDWIDTH

Analyzer Screen

300 Hz, 3 kHz, 30 kHz, 60 kHz, 300 kHz, 6 MHz

Generate and Receive Screens

300 Hz, 3 kHz, 60 kHz

Selectivity

60 dB/3 dB ratio <15:1

Bandwidth Switching Error

±1 dB typical

VIDEO BANDWIDTHS

None, 10 Hz to 3 MHz in 1-3-10 steps

SPECIAL FUNCTIONS

Display Modes

Live, Average, Peak, Compare, Tracking Generator
Manual / Auto coupling for Span, Sweep, VBW, RBW

SPECTRUM ANALYZER VIDEO OUTPUT

Reference Level

= -5 V

Bottom-of-Screen

= +5 V

TRACKING GENERATOR

Frequency Range

10 MHz to 2.7 GHz

Output Level Range

GEN Port, +10 to -110 dBm

Output Level Resolution

0.1 dBm

Output Flatness

±2 dB, ≤500 MHz Span, up to 1.25 GHz Center Frequency

Harmonic Spurious

-20 dBc max ≤50 MHz

-25 dBc max >50 MHz

Non-Harmonic Spurious

-40 dBc max ≤1.5 GHz

-30 dBc max >1.5 GHz

Input Ports

Reference appropriate Receive function for Antenna and T/R Port specifications.

1-15

TIME BASE

ACCURACY

I/O Frequency

10 MHz nominal

Temperature Stability

±0.01 ppm

Time Base Aging

±0.1 ppm per year

OUTPUT LEVEL

1 to 5 Vpp into 10 kΩ

WARM-UP

<5 min.

INPUT LEVEL

1 to 5 Vpp input (sine or square wave)

OSCILLOSCOPE FUNCTIONS

Vertical Inputs

2 input channels (CH1 and CH2), MIC Input, Audio I/O Input, Internal Demod

Input Impedance

1 MΩ , 80 pF nominal

External Coupling

AC, DC, GND

Range

20 mV to 50 V/div in a 1, 2, 5 sequence

Accuracy

10% of full scale (DC to 50 kHz, Vertical position set on CENTER graticule))

Bandwidth

500 kHz usable

HORIZONTAL SWEEP

Range

10 µs to 1 sec per division (selectable to 1 µs/div)

Accuracy

1% of Full Scale sweep

TRIGGER SOURCE

Channel 1, Channel 2, Internal or External Trigger
External Trigger: TTL input level (nominal 2 V - trigger level)

1-16

SPECIAL FUNCTIONS

Modes

Live, Triggered Mode (Auto, Normal, Single)

AF Filters on Demod Input

None, 300 Hz LP, 4 kHz LP (Butterworth), 4 kHz LP (Bessel), 4 kHz LP, 15 kHz LP, 20 kHz LP,
300 Hz HP 300 Hz to 4 kHz BP

AUDIO FREQUENCY GENERATOR

WAVE SHAPE FORMATS

Wave Shapes

Sine, Square, Triangle, Ramp

AMPLITUDE

Level

The combination of FGEN 1 and FGEN 2 cannot exceed the following:
Unbalanced: 0 to 20 Vpp into 10 kΩ (Audio Out 1 [FGEN] and Audio Out 2 [DEMOD])
Balanced - High Range: 0 to 6 Vrms into 10 kΩ (Audio Out 1 [FGEN] only)
Balanced - Low Range: 0 to 600 mVrms into 10 kΩ (Audio Out 1 [FGEN] only)

RESOLUTION

High Range

1 mV (Audio Out 1 [FGEN] and Audio Out 2 [DEMOD])

Low Range

0.1 mV (Audio Out 1 [FGEN] only)

ACCURACY (SINE WAVE)

Unbalanced (Audio 1 or 2, Level >0.5 Vpp)

3% (20 Hz through 3 kHz)
5% (3 through 5 kHz)
15% (5 through 10 kHz)

Balanced

High Range: 10% (frequency at 1 kHz, level >0.5 Vpp)
Low Range: 10% (frequency at 1 kHz, level >0.05 Vpp)

Distortion (THD, sinewave)

<0.5% (1 kHz, 3 Vpp)
<2% (20 Hz to 20 kHz, 1 through 15 Vpp)

1-17

FREQUENCY

Range

Unbalanced: DC to 20 kHz (Audio Out 1 [FGEN] and Audio Out 2 [DEMOD])
Balanced: 50 Hz to 20 kHz (Audio Out 1 [FGEN[ only)

Resolution

0.1 Hz

Accuracy

±1 Hz

SIGNALING ENCODER

DTMF ENCODE
(Generation DTMF Tones)

Modes: Continuous, One-Shot, Key
Digits: (0-9, *, A, B, C, D)

CTCSS Encode

Generation of Standard Tone frequencies selected from a menu.
Decoding of received frequency displayed.

DCS Encode

Generation of digitally coded squelch.

Tones Remote Encoding Functions

Standard tone remote signaling and user defined tone signaling.
Fully programmable from the Remote Command Interface.

Tone Signaling Encoding Functions

Fully programmable from the Remote Command Interface.

BASE-BAND AUDIO FUNCTIONS

Input Level Range

Audio In: 200 mVpp to 20 Vpp
MIC: 10 mVpp to 1 Vpp

Frequency Range

Audio In (SINAD): 50 Hz to 20 kHz (unbalanced)
Audio In (SINAD) 50 Hz to 20 kHz (balanced)
Mic In (MIC) 50 Hz to 20 kHz (unbalanced)

1-18

INPUT IMPEDANCE

Audio In (SINAD)

Low Impedance Input: 600 Ω (balanced) nominal
High Impedance Input: 10 kΩ (unbalanced) nominal

MIC In (MIC)

High Impedance Input: 10 kΩ nominal
Phantom Power (Electret): +5 V through 5 kΩ nominal

AUDIO FREQUENCY COUNTER

Input Sources

Demodulated Audio, MIC Input, Audio I/O Input

Ranges

200, 500, 1 k, 2 k, 5 k, 10 k, 20 k

Accuracy

±1 Hz

Resolution

0.1 Hz

Audio Filters (Demod only)

None, 300 Hz LP, 4 kHz LP, 4 kHz LP (Butterworth), 4 kHz HP, 15 kHz LP, 20 kHz LP, 300 Hz HP,
300 Hz to 4 kHz BP

MICROPHONE AUDIO INPUT

Modes

Electret: +5 V through 5 kΩ nominal
Dynamic

DVM FUNCTIONS

AC

Input Impedance

1 MΩ : ±15% (Range >0.4 V)
600 Ω : ±10%
150 Ω : ±10%

Range

400 mV to 100 V in a 1,2,4 sequence

Resolution

0.1 mV: 0.4 V scale
1 mV: 1 V, 2 V and 4 V scales
10 mV: 10 V, 20 V and 40 V scales
100 mV: 100 V scale

1-19

AC (cont)

Accuracy

6% of Full Scale (50 Hz to 10 kHz) ±1 LSD
6% of Full Scale (10 kHz to 20 kHz) ±1 LSD input <60 Vac
9% of Full Scale (10 kHz to 20 kHz) ±1 LSD input >60 Vac

DC

Range

400 mV to 100 V in a 1,2,4 sequence

Resolution

0.1 mV: 0.4 V scale
1 mV: 1 V, 2 V and 4 V scales
10 mV: 10 V, 20 V and 40 V scales
100 mV: 100 V scale

Accuracy

2% of full scale ± 1 LSD

Input Impedance

10 MΩ nominal

DIGITAL I/O

GPIB (IEEE-488-2)
Parallel Printer Port
Serial Port (RS-232)
Video Monitor Port (VGA)
Mouse Port (PS2 compatible)

AC POWER

Input Range

100 to 120 VAC, 60 Hz
220 to 240 VAC, 50 Hz

Fuse Requirements

3 A, 250 V, Type F

Maximum Power Consumption

200 W

Main Supply Fluctuations

≤10% of nominal voltage

Transient Over-Voltage Installation

Installation Category II

Keyboard Port
Ethernet Port (10T/100T)
Front Panel Test Port

3.5 inch Floppy Drive
USB Port

1-20

ENVIRONMENTAL/MECHANICAL

Weight

33 Ibs. (15 kg)

Volume

7.75 in. (H) x 14 in. (W) x 19in. (D)

19.7 cm (H) x 35.6 cm (W) x 48.3 cm (D)

Operating Temp Range

32° to 104°F (0° to 40°C)

Storage Temp Range

-13° to 158°C (-25° to 70°C)

Humidity

80% up to 31°C, decreasing linearly to 50% at 40°C

Pollution

Pollution Degree 2

Shock

MIL-PRF-28800F Class 3 (30g)

Vibration

MIL-PRF-28800F Class 3

Altitude

9,843 feet (3000 meters)

Bench Handling

MIL-PRF-28800F Class 3

WARRANTY

2 years
Extended warranty available upon request

COMPLIANCE

The 2975 shall be modified in the future to be complaint with the following standards:

Electromagnetic Compliance

EMC Directive 89/336/EEC
EN 61326: 1997+A1 1998

Safety

EN 61010-1
UL 3111-1
CSA C22.2 No. 1010-1

1-21

1-3 CONNECTORS

CONNECTORS

(Front Panel)

10

21 2 3 4

TEST PORT

1

2

3

This port is used for the purpose of programming radios through a data connection.
The port consists of 4 digital input and 4 digital output (open collector) lines. The
port also provides a 0 to 12 V, 50 mA programmable source. Software to support
specific radios is planned for future software releases.

Refer to Appendix A for Connector Pin-Out Table.

SCOPE CH1 and CH2

The 2975 includes a dual channel oscilloscope suitable for trouble shooting audio
paths.

100 V maximum input!

Use caution when probing live circuits! DO NOT connect to AC line!

DVM (Input)

AC/DC Voltmeter

100 V maximum input!

5 876

9

Use caution when probing live circuits! DO NOT connect to AC line!

1-22

4

5

MIC (Input)

Electret (+5 V through 5 kΩ ) or Dynamic
Microphone Connection

PIN SIGNAL
1 GND

2 GND
3 MIC+
4 PTT
5 DEMOD+
6 GND

AUDIO I/O

SINAD Meter Input
600Ω Balanced / Unbalanced Audio Output
600Ω Balanced / Unbalanced Audio Input

PIN SIGNAL
1 SINAD+ (Audio Input)

2 SINAD- (Audio Input)
3 FGEN+ (Audio Output 1)
4 FGEN- (Audio Output 1)
5 DEMOD+ (Audio Output 2)
6 GND (Audio Output 2)

PIN 1

MIC

MIC

AUDIO I/O

AUDIO I/ O

PIN 1

6

7

8

9

10

GEN

RF Generator output
Protected to 10 W in case of accidental connection to transmit power
Used for Signal Generator high output level and Tracking Generator output
LED indicates port selected for generator output

DO NOT transmit RF into this connector!

T/R

Transmit / Receive
Used for direct connection to transmitter output
LED indicates port selected for generator output

DO NOT exceed 50 W continuous RF power!

Use caution when connecting high power transmitters!

ANT

Protected to 10 W in case of accidental connection to transmit power
Used for off-the-air monitoring

DO NOT transmit RF into this connector!

FLOPPY DISK DRIVE

3½” floppy disk drive for copying data and program files to/from the 2975 system

LCD

Liquid Crystal Display

1-23

CONNECTORS

(Rear Panel)

1
2
3

17

18

14

1

3

6

10 11 12

2

4

MAIN POWER SWITCH

System AC Input

BATTERY SENSE

Future Use

PARALLEL PORT

Future Use
Refer to Appendix A for Connector Pin-Out Table.

5

7

9

8

16

15

S/N 598002639 and on

13

4
5
6

7

8

RS-232

Serial I/O Connection with the 2975
Refer to Appendix A for Connector Pin-Out Table.

VIDEO PORT

External VGA Monitor Port
Refer to Appendix A for Connector Pin-Out Table.

MOUSE

Control connection designed for PS-2 compatible mouse. Mouse controls cursor for
point and click control of screen items in addition to front panel keyboard operation.

Refer to Appendix A for Connector Pin-Out Table.

KEYBOARD

Control connection designed for PS-2 compatible keyboard. Keyboard controls
function of unit in addition to front panel keyboard operation.

Refer to Appendix A for Connector Pin-Out Table.

USB

Future use: Universal Serial Bus connection with the 2975
Refer to Appendix A for Connector Pin-Out Table.

1-24

9

10

11
12
13

14
15
16

ETHERNET

The Ethernet connection allows the 2975 to be configured as a computer on the
network. The display and front panel keyboard can be routed to any other computer
on that network allowing for complete remote control.

Refer to Appendix A for Connector Pin-Out Table.

SYNC

Future Use

EXT TRIG

External Oscilloscope Trigger

EXTERNAL RF I/O

10 MHz Timebase In and Out

GPIB

IEEE-488 Remote Control Interface
Refer to Appendix A for Connector Pin-Out Table.

A

Future Use

B

Future Use

TYPE I INTERFACE (Units prior to S/N 598002639)

Not Used
Refer to Appendix A for Connector Pin-Out Table.

SPECTRUM ANALYZER IF

17
18

Intermediate Frequency Output (10.7 MHz)

SPECTRUM ANALYZER VIDEO

Video Output (LOG Detector)

1-25

THIS PAGE INTENTIONALLY LEFT BLANK.

1-26

SECTION 2 - OPERATION

2-1 OPERATIONAL CONCEPTS

The 2975 is equipped with all of the tools required for the maintenance and calibration of FM, AM and
Project 25 Radio Systems. These tools work together in harmony to easily accomplish routine tasks.

The 2975 is equipped with an IQ modulator and demodulator to handle the demands of digital
communications systems. Digital IF and audio processing allow the 2975 to be configured as
required through software changes for future upgrades. Hard drives and floppy drives provide vast
storage capabilities for test setups and configurations.

Primary modes of operation for transceiver testing include:
Generate (Receiver Test)
Receive (Transmitter Test)
Duplex (Transmitter / Receiver Test)
Function Generator
Scope
Spectrum Analyzer
NOTE: Examples may reference optional modes of operation. Examples may also include screens

containing tiles for optional modes of operation.

The 2975 operates continuously in Duplex mode with
both the Generator and Receiver active. The Duplex,
Generate and Receive modes offer a control panel for
the Generator, the Receiver or both, along with empty
screen space where additional monitor or control
functions can be enabled.

Empty screen segments can be filled with any monitor
or control function that is available for the actively
displayed screen mode. Both Generate and Receive
modes offer up to 6 free screen segments and Duplex
mode offers 4. All monitor and control features require
at least 1 segment each. The Scope and Spectrum
Analyzer functions each require 2 screen segments.
The Audio Analyzer option and some Trunking options
functions also require 2 screen segments.

Monitor and control functions may be expanded into
larger windows that allow access to all features of that
function. The Scope and Spectrum Analyzer occupy
the full screen when expanded.

1 2 3 4

1 2

2-1

3 4 5 6

2-2 MONITOR AND CONTROL FUNCTIONS

The following monitor and control functions are available in various screen displays and can be
placed in the numbered locations on the previous page.

Scope

Spectrum Analyzer

FM

Deviation

Distortion

RF Frequency

Error

SINAD

RF Power

AM

Modulation

RF Level

Mod

Fidelity

Generate Control Panel

Receiver

Control Panel

AF Counter

P25 Downlink

(Encode Data)

DVM

BER Meter

P25 Uplink

(Decode Data)

Meter Panel

Function

Generators

2-2

2-3 2975 OPERATION

USER SCREEN

The 2975 has a user configurable screen, allowing for the creation of customized test scenarios.
Unlike other screens, such as Generator or Receiver, the User screen does not have preset tiles.
The User screen can be set up to resemble other screens, or it may simply be set up for a single
measurement.

The screen (to the right) shows the 2975 Mode
selection menu.

All instrument selections are available for use on the
User screen using the Options selector located at
the top of the screen.

The screen (to the right) shows one example of how
the User screen may be configured. This screen
shows nine (9) meters, the Spectrum Analyzer, the
Oscilloscope, the C4FM Eye Modulation plot and the
EVM function, all running simultaneously. The RF
Generator and Receiver systems are operating, but
are not visible, permitting all the instruments to be
displayed together.

NOTE: The C4FM Eye Diagram is a standard

feature; the QPSK Constellation is an
optional feature.

2-3

SELECTING OPERATION MODE

Pressing the [MODE] Key activates a pull down menu to allow access to available operating modes.
Screen or mode selection can be made by pressing the associated menu selection number.

The 2975 offers the modes of operation displayed below:

NOTE: Audio Analyzer is an optional mode.
The following key sequence could be used to select the GENERATE mode of operation:

[MODE]
[1]

Mouse Click

If a mouse is connected to the 2975, click on the
screen identifier label to access the pull down menu.
Selection can be made by clicking on the desired mode
of operation.

2-4

SELECTING OPTIONS

After an operational mode has been selected, the operator
interface allows for screen reconfiguration. There are 6
definable segments available in the Generate mode. A bar
graph meter takes up 1 segment. The Scope or Spectrum
Analyzer requires 2 segments. There are more functions
available than segments, so the operator has the ability to
choose the functions that are to be displayed.

The Options menu is accessed by pressing [SHIFT] [MODE] or
by clicking on the screen “options” tab. Pressing [0] [1] [2] [3]
enables the first four items on the list. Pressing the [RETURN]
key or selecting Accept Options configures the selected items
onto the screen.

All other options should be turned OFF. An item is selected
when the adjacent square is checked with a red square.

5 6

1 2 3 4

2-5

ZOOMING

The 2975 interface allows function tiles to be expanded to a larger scale, which also provides more
controls for that function. A function can be expanded by positioning the cursor to a function label
and pressing the [ENTER] Key. Some examples of this are shown in the Duplex mode below. The
expanded function can be exited by pressing the [RETURN] Key.

2-6

TONE SIGNALING DECODE

The 2975 has the ability to decode and display DCS,
DTMF and CTCSS from a radio (off-air or direct RF

connection).
The Tone Signal Decode is accessible from the

Receiver or Duplex screen Options menu.

Tone Signal Decode 15 (number may vary)

DCS (Digital Coded Squelch)
The DCS Decode is selected in the Tone Signaling

Decode tile using the button in the upper right corner.

The RECEIVED code field indicates the 3-digit octal
code decoded. This code may be an alternate (ALT)
image to a valid DCS CODE.

The DCS CODE field is the 3-digit octal squelch code.
This code is the value to reference as the DCS value.

The INVERTED field is the logical inversion of the DCS
CODE value. This is provided as a convenience as
some systems deviation is reversed in polarity,
yielding the inverted code.

The STATUS field indicates the most recently received
code is:

OK means the DCS code was received without
errors.

FIXED means the DCS code had an error, but the error was correctable. This occurs if the
receive signal level is close to the noise floor or at higher receive signal levels if the UUT has
a faulty encoder.

COULD NOT FIX means the DCS code had too many errors for correction (noise, no code or
bad code).

The CLEAR button resets the DCS decoder and display fields to start a new set of readings.
The DEV Field indicates the deviation of the DCS signal.

2-7

DTMF (Dual-Tone, Multiple Frequency)
The DTMF Decode is selected from the Tone Signaling

Decode tile using the button in the upper right corner.

The DIGITS field indicates the particular DTMF digit
decoded. Digits range from 0 through 9, A, B, C, D, E,
F, # or *.

The STATUS field indicates whether the most recently
received DTMF digits are:

VALID means the DTMF digits are recognized.
INVALID means the DTMF could not be detected

(noise, wrong frequencies, etc.).
The DEV field indicates the deviation of the DTMF

signal.
The CLEAR button resets the DTMF decoder and display

fields to start a new set of readings.

CTCSS (Continuous Tone Coded Squelch System)
The CTCSS Decode is selected from the Tone Signaling

Decode tile using the button in the upper right corner.

The FREQUENCY field indicates the frequency of the
received CTCSS code.

The REED CODE is the code designator assigned to the
frequency of the CTCSS code.

The TARGET FREQ field indicates the nearest standard
tone.

The ERROR field indicates the difference between the
TARGET FREQUENCY and the FREQUENCY.

The DEV field indicates the deviation of the CTCSS
signal.

2-8

VOLUME AND SQUELCH CONTROLS

The 2975 has the ability to control the Volume and
Squelch functions using the mouse, with the added
benefit of observing the relative position of the knob
settings.

When the VOL/SQL button (upper right corner of the
screen) is pressed, using the mouse, or if either the
VOLUME or SQUELCH control is turned, the Volume /
Squelch sliders are displayed.

The 2975 also provides the user with the ability to turn
the Volume Display Box ON/OFF. The ON/OFF button is
accessed via the System Configuration Screen (MODE, 7,

1).
The Volume / Squelch sliders show a relative position

number and sliding scale slider buttons. The left side is
minimum volume and minimum squelch setting. The right
side is maximum volume and maximum squelch setting.

The numbers indicate the relative value for the current
position.

Volume range of values is 0 to 100 (left to right).
Squelch range of values is 821 to -140 (left to right).
As the corresponding knob is rotated, the value and slider

moves to indicate the setting. Also, the volume or
squelch setting can be altered using the mouse to click
and drag the slider to the desired setting. Release
mouse button at the desired setting.

After the knob motion or mouse movement stops for
5 seconds, the Volume / Squelch display pop-up
disappears (hides).

RF GENERATOR ON/OFF CONTROL

The 2975 allows the user to control the RF Generator
output (ON, OFF or PTT) from the Receiver tile.

This control allows users to turn the 2975 Generator ON
and OFF while testing simplex radio systems, alleviating
the need to switch between the Generator and Receiver
screens.

2-9

SETUP / RECALL

Fast Setup / Recall

The 2975 has a Fast Setup Recall function which
allows users to quickly select and restore setups from
any screen.

The Setup field is located on the top line of all
screens. The number field shows the recall item
number; the name assigned to the recall item is shown
next to the number under the LABEL heading.

The Save/Recall screen example (to the right)
(MODE, 7, 6) includes a FILE name, descriptive
LABEL, DATE and DIRECTORY. The Save/Recall
screen combines a directory listing of the setups and
permits RECALL, SAVE, BACKUP and DELETE for
stored items. The SAVE / RECALL may also be
selected by pressing the SETUP button for quick
access.

To recall a Setup, the mouse or keyboard may be
used.

O Mouse recall requires clicking on the recall

number field to select the field for numeric
edit, and then pressing ENTER to recall. If
the desired number is displayed, double­clicking the number recalls the setup.

O Keyboard recall is similar to Mouse recall.

Move the cursor (RED BOX) to the Setup
number field, enter the desired setup
number and press ENTER.

When the RECALL SETUP softkey is pressed, the
highlighted directory list item is restored and
activated. If mouse operation is being used, simply
double-click the desired directory list item to restore.

The SAVE SETUP softkey invokes a screen (to the
right) to allow selection, naming and storage of
Setups. A dropdown menu offers the user the option
to save the Setups on an INTERNAL disk or FLOPPY
or to store them in a subdirectory. The feature also
allows Setups to be labeled with a descriptive title.

The BACKUP function allows users to save existing Setups to a floppy or restore backup Setups from
a floppy.

NOTE: Standard Setups are embedded in the 2975 and may not be modified by the user.

2-10

AUDIO ROUTE

The AUDIO ROUTE function is common to Function Generator Mode,
Receiver Mode, Duplex Mode and Generator Mode. This function
provides the ability to route the DEMOD audio or a SQUELCH demod
audio to the 2975 modulator.

The Modulator routing may be set to either of these sources.
Selecting DEMOD or SQUELCH permits the demodulated audio to be
looped back to the generate modulator in a repeater-type action.
This configuration is indicated in the Rx field on the Receiver Tile.
This function, available on the Audio Output ports, also allows for
special tone conditioning.

DEMOD AUDIO, FGEN 1, FGEN 2, MIC In, and AUDIO IN functions allow for various signal routing
configurations. The Output Filter and Output Level functions allow special signal conditioning to be
performed. DEMOD AUDIO also allows the 2975’s Receiver demod audio to be routed to AUDIO OUT
1, AUDIO OUT 2 or to the internal speaker.

MIC/Audio Adapter

MIC Connector

PIN SIGNAL
1 GND

2 GND
3 MIC+
4 PTT
5 DEMOD+
6 GND

AC25007

MIC

PIN 1

AUDIO I/O

AUDIO I/O Connector

PIN SIGNAL
1 SINAD+ (Audio Input)

2 SINAD- (Audio Input)
3 FGEN+ (Audio Output 1)
4 FGEN- (Audio Output 1)
5 DEMOD+ (Audio Output 2)
6 GND (Audio Output 2)

2-11

NETWORK CONNECTIVITY

Network connectivity features of the 2975 extend use and functionality. Network Connectivity options
can be accessed through the CONFIGURATION screen (MODE, 7, 1). The CONFIGURATION screen
allows the network items to be viewed and changed.

IP PARAMETER SETUP

The IP Address (ADDRESS field) is selectable
between FIXED and DHCP (Dynamic Host
Configuration Protocol) easing network installation.
Whenever DHCP is selected, the 2975 negotiates an
IP address with the network resource server and
receives a valid address.

WEB SERVER SETUP

The 2975 has the ability to be accessed as a web
server whenever installed onto a network. The
WEB SERVER SETUP ENABLE/DISABLE set to
ENABLE provides server functions; DISABLE halts
the server functions.

VOL/SQL WINDOW CONTROL

Selecting ON/OFF allows the user to display the VOLUME/SQUELCH Slider.

WEB SERVER USAGE

The screen below shows the 2975 web server page
using a PC web browser. The URL (web address)
shown is the IP address for the 2975, or the DNS name
of the unit if your network administrator has assigned
one. When the 2975 web server is accessed, this page
is returned and updated at approximately 5 sec
intervals.

2-12

The various links provide access to the following information:

O Help Pages. This link accesses the HELP

system within the 2975 for online
descriptions for each screen and for various
functions.

O Application Notes. This link provides

access to the Application Notes and
technical information stored within the 2975
for explaining how to use the 2975.

O Installed Options. This link displays the

Option Status page within the 2975.

O Firmware Versions. This link displays the

Firmware Status page within the 2975.

2-13

O User Files. This link provides access to

User file storage areas within the 2975.
The directories listed may be used to store
information or provide access to system
files, such as frequency lists and setups.

The two error log files (errorLog and
errorLog.old) contain useful debug information
in the event of error conditions. Files may be
uploaded to and downloaded from a computer.

O Other Files. This link provides access to

the 2975 Operation Manual and to the 2975
LabWindows® CVI driver. The Operation
Manual is in Adobe® Acrobat format and the
driver is in ZIP format.

O Remote Display. This link provides a

convenient means to run a remote 2975
display on a PC. The remote PC must run
an X Windowing System and must grant the
2975 permission to use the X server. If the
PC does not support X Windowing System,
links to several X Windowing programs are
included for reference and consideration.

When the Remote Display link is selected from
the web browser screen the 2975 displays a
small window indicating the remote display is
being generated. When the remote display is
acquired this window opens into the 2975
remote display screen.

2-14

RECEIVER FIND FREQUENCY

The FIND command searches for an RF signal by starting at 0 MHz and
progressively looks at the selected RF input for signals. If no signals are
found, the original starting frequency is restored. If a signal is found, the
2975 stops at the new frequency.

The FIND NEXT command searches for an RF signal beginning at the
currently selected frequency and looks for the signals higher in frequency
from this point. This is useful for finding harmonics of a transmitter.

The FINE TUNE command searches for an RF signal "near" the currently
selected frequency (within the selected IF bandwidth) and adjusts the
receiver frequency for the lowest measured RF error. This is useful after
finding a signal and the FIND result is slightly off-frequency.

Important considerations for FIND functions:

O If the RF signal is too low for an accurate frequency count, the receiver frequency is not

changed.

O If the RF signal is being modulated, there is some residual frequency error after the fine

tune operation; a modulated signal is a moving target.

O The transmitter should be directly connected to the 2975; off-the-air reception may be

confused by other RF signals being received.

O The signal to be found should be at least 30 dB above the noise floor of the 2975.

Depending upon input selection (ANT or T/R) and attenuation settings, this can range from
about -50 dBm (Antenna, 0 dB attenuation) to +10 dBm (T/R, 40 dB attenuation). In
general, the signal should be 30 dB above the noise floor of the spectrum analyzer in
5 MHz span mode.

DEMOD FILTER

The DEMOD FILTER within the 2975 Receiver tile has been
enhanced to add APCO-25 filter as a selection.

This filter is the same as used by APCO-25 radios utilizing
C4FM modulation. The plot display (to the right) shows the
APCO-25 filter response while using the Audio Analyzer
Option.

2-15

P25 UPLINK DATA TILE

The 2975 P25 Uplink Data feature allows users to
monitor P25 Uplink Data. The fields displayed on the
Uplink Data tile are display only fields and can not be
edited by user.

The P25 Uplink Data tile can be enabled when the 2975
is operating in Duplex Mode (as shown in the following
examples), Receiver (Tx Test) Mode or when the User
Screen is selected.

The P25 Uplink Data Tile updates automatically to
display the current data sent by the radio. When
individual messages are sent this tile periodically
switches to display individual messages, before
reverting back to the radio’s continuous mode of
operation. For example, LCO’s 00, 03 and 06 are
continuously sent LCO’s which designate call types.
Occasionally control messages are sent interspersed
within the voice data messages. The control messages
are only visible for a moment before the LCO decode
reverts back to the voice data messages.

The following field definitions are for a Group voice
channel user. Refer to TIA/EIA-102.BAAA, “Link Control
Word Formats and Messages” for more information about
LCO configurations.

FIELD DEFINITIONS

UPLINK

The UPLINK button expands the Uplink Data tile to
provide more detail of the received P25 data.

FRAME #

This field displays the frame number of the P25 Uplink
Data stream.

NAC

This field displays the Network Access Code of the P25
Uplink Data stream.

DUID

This field displays the Data Unit ID in the P25 Uplink Data stream.

LDU

This field displays the Logic Link Data Unit in the P25 Uplink data stream.

LCO

This field displays the Link Control Opcode in the P25 Uplink Data stream.

P

This field displays the Protected flag value in the P25 Uplink Data stream.

SF

This field displays the State Flag value in the P25 Uplink Data stream.

2-16

MFID

This field displays the Manufacturer Identifier in the header of the P25 Uplink data stream.

EMG

This field displays the Emergency value in the P25 Uplink data stream.

TGID

This field displays the Talk Group Identifier value in the header of the P25 Uplink data stream.

SID

This field displays the Source Address Identifier in the P25 Uplink data stream.

STATUS

This field displays the current P25 Uplink status message. A text description of the status value is
displayed to the right of this field.

EXPANDED UPLINK DATA TILE

MFID

This field displays the Manufacturer Identifier in the
header of the P25 Uplink data stream.

ALGID

This field displays the Algorithm Identifier in the
header of the P25 Uplink data stream.

TGID

This field displays the Talk Group Identifier in the
header of the P25 Uplink data stream.

KEY ID

This field displays the Key Identifier in the header of
the P25 Uplink data stream.

MI

This displays the Message Identifier in the header of the P25 Uplink
data stream.

VOICE FRAMES

NAC

This field displays the Network Access Code in the P25 Uplink data
stream.

DATA UNIT ID

This field displays the Data Unit Identifier in the P25 Uplink data
stream.

LDU

This field indicates the Logical Link Data Unit value in the P25
Uplink data stream.

2-17

LINK CONTROL

RAW

This field displays the raw hexadecimal values in the P25 Uplink data stream.

LCO

This field displays the Link Control Opcode in the P25 Uplink data stream.

P

This field displays the Protected flag value in the P25 Uplink data stream.

SF

This field displays the SF value in the P25 Uplink data stream.

MFID

This field displays the Manufacturer Identifier in the P25 Uplink data stream.

EMG

This field displays the Emergency value in the P25 Uplink data stream.

TGID

This field displays the Talk Group Identifier in the P25 Uplink data
stream.

SID

This field displays the System Identifier in the P25 Uplink data
stream.

ES DATA (Encryption Synchronization)

KID

This field displays the Key Identifier in the Encryption
Synchronization Data of the P25 Uplink data stream.

ALGID

This field displays the Algorithm Identifier in the Encryption
Synchronization Data of the P25 Uplink data stream.

MI

This field displays the Message Identifier in the Encryption Synchronization Data of the P25 Uplink
data stream.

LSD

This field displays the Low Speed Data value in the P25 Uplink data stream.

STATUS SYM

This value displays the P25 Uplink status message. A text description of the status value is
displayed to the right of this field.

2-18

P25 DOWNLINK DATA

The P25 Downlink Data tile provided users with the
ability to configure P25 Downlink Data.

The P25 Downlink Data tile can be enabled when the
2975 is operating in Duplex Mode (as shown in the
following examples) or in Generate (Rx Test) Mode, or
when User Screen is selected.

FIELD DEFINITIONS

DOWNLINK DATA

The DOWNLINK button expands the Downlink Data tile
to provide more detail of the received P25 data.

SEND HEADER

Selecting this toggle button stops the current P25
downlink data stream and sends a new data stream
with a header containing displayed information.

KEY / LOAD KEYS

Selecting this button displays the Key Management
Dialogue screen. This button is only enabled when
P25 KEYLOADER (2975OPT12) is installed.

NAC

This field displays the Network Access Code in the P25
Downlink Data stream.

ALGID

This field displays the Algorithmic Identifier in the header of the P25 Downlink data stream. User
may edit field to define this ALGID value.

AES / DES / CLEAR

Advanced Encryption is available only when AES (2975OPT10) is installed in the 2975. User may
select AES, however, data encryption does not occur if the AES option is not installed. Data is
transmitted as CLEAR (not encrypted).

LCO

This field displays the Link Control Opcode present in the P25 Downlink Data stream. User may edit
field to define this value. A text description of the LCO message is displayed below this field.

P

This field displays the Protected Flag value present in the P25 Downlink data stream. User may edit
field to define this value.

SF

This field displays the State Flag value present in the P25 Downlink data stream. This is a read only
field defined by the LCO value.

2-19

SEND

Selecting this button sends the currently displayed LCO message. After this message is sent the
data stream defaults to sending either Group (LCO 00), Unit to Unit (LCO 03) or Telephone Voice
(LCO 06) messages according to how the call was configured prior to being sent. LCO’s 00, 03 and
06 are sent continuously unless the SEND button sends a particular message or changes the call
type.

MFID

This field displays the Manufacturer Identifier in the P25 Downlink data stream. User may edit field
to define this value.

EMG

This field displays the Emergency value present in the
P25 Downlink data stream. User may edit field to
define this value.

TGID

This field displays the Targeted Group Identifier in the
P25 Downlink data stream. User may edit field to
define this value.

SID

This field displays the Source Address Identifier
present in the P25 Downlink data stream. User may
edit field to define this value.

STATUS

This field displays the current P25 Downlink status message. User
may select this field to set the status. A text description of the
status value is displayed to the right of this field.

EXPANDED DOWNLINK DATA TILE

MFID

This field displays the Manufacturer Identifier in the header of the
P25 Downlink data stream. User may edit field to define this value.

ALGID

This field displays the Algorithmic Identifier in the header of the P25
Downlink data stream. User may edit field to define this value.

AES / DES / CLEAR

Advanced Encryption is available only when AES (2975OPT10) is
installed in the 2975. User may select AES, however, data
encryption does not occur unless the AES option is not installed.
Data is transmitted as CLEAR (not encrypted). Reference 2975
Operation Manual for description regarding use of this option.

TGID

This field displays the Targeted Group Identifier in the header of the
P25 Downlink data stream. User may edit field to define this value.

KEY ID

This field displays the Key Identifier in the header of the P25 Downlink data stream. User may edit
field to define this value.

2-20

VOICE FRAMES

NAC

This field displays the Network Access Code in the P25 Downlink Data stream.

LINK CONTROL

RAW

This field displays the raw hexadecimal values present in the P25 Downlink data stream.

LCO

This field displays the Link Control Opcode present in the P25
Downlink Data stream. User may edit field to define this value. A
text description of the LCO message is displayed below this field.

P

This field displays the Protected Flag value present in the P25
Downlink data stream. User may edit field to define this value.

SF

This field displays the State Flag value present in the P25 Downlink
data stream. This is a read only field defined by the LCO value.

SEND

Selecting this button sends the currently displayed LCO message.
After this message is sent the data stream defaults to sending “LCO
00” messages.

MFID

This field displays the Manufacturer Identifier in the P25 Downlink data stream. User may edit field
to define this value.

EMG

This field displays the Emergency value present in the P25 Downlink data stream. User may edit
field to define this value.

TGID

This field displays the Targeted Group Identifier in the P25 Downlink data stream. User may edit
field to define this value.

SID

This field displays the Source Address Identifier present in the P25 Downlink data stream. User
may edit field to define this value.

LSD

The LSD field on the left displays the upper 16 bits of Low Speed Data. The LSD field on the right
displays the lower 16 bits of Low Speed Data. User may edit both of these fields to define these
values.

STATUS SYM

This field displays the current P25 Downlink status message. User may select this field to set the
status. A text description of the status value is displayed to the right of this field.

2-21

2-4 OPERATION MODES

GENERATOR MODE

The Generate (RX Test) mode allows testing of Analog FM, AM or Digital P25 Receivers. To access
the Generate mode, use the following key sequence:

[MODE] Key
[1] Key

FIELD DEFINITIONS

FREQUENCY ENTRY

Allows entry of the receiver channel frequency in MHz.
Using the rotary knob, position the cursor on the
frequency field. A new frequency can be entered
directly through the numeric keypad and terminated by
pressing the [ENTER] Key. To edit an existing
frequency, press the [ENTER] Key to highlight the
existing frequency, then use the left or right arrow
keys to position a cursor to the digit to edit. Using the
up or down arrow keys or the rotary knob increments/
decrements the current value. Frequency values
ranging from 0 to 2800 MHz can be made with 1 Hz
resolution.

FREQUENCY LABEL

INCR
Allows entry of a frequency increment value.

When in Generator mode of operation, the
frequency can be set with the frequency field and
then adjusted by the defined increment value
through the use of the side function keys.

2-22

SWEEP
Allows entry of a start and stop frequency with

increment for swept RF measurements. Select
SETUP to configure the sweep parameters. To
begin the sweep, press function key labeled
START SWEEP.

The frequency sweep begins with the START
frequency and increments by the value defined
in the INCR field value, after delayi ng the
number of seconds that have been specified in
the RATE field. The sweep continues until the
STOP frequency is reached and the sweep
starts over. Once the sweep has started,
function keys allow for STOP SWEEP or PAUSE
SWEEP.

LIST
Allows frequencies to be selected from a pre-

programmed list. The frequency list box allows
entry of up to 300 generate and receive
frequencies. Frequencies are selected by entry
of the list index value associated with the
frequencies in the list. The list can be auto­filled by entering a base frequency in the REC
FREQ field and an increment value. The list is
filled automatically by activating the FILL LIST
function which is accessed from the SETUP key.
Each frequency pair has a default label that may
be changed to better identify the frequency pair.

LEVEL

This field changes the RF Output level of the T/R or
GEN Port. Units can be selected to be dBm, mV or
µV. Output level range varies with output port
selection.

GEN Port: +10 to -110 dBm
TR Port: -30 to -137 dBm

RF GENERATOR ON/OFF CONTROL

The 2975 has the capability to control the RF
Generator output (ON, OFF or PTT) from the
Receiver tile and from the PTT.

This control allows users to turn the 2975 Generator
ON and OFF while testing simplex radio systems,
alleviating the need to switch between the Generator
and Receiver screens.

NOTE: This may need to be turned OFF if working

with simplex systems prior to entering the
Receive mode of operation. The 2975 can
monitor it’s own output signal if both input
and output ports are selected to be the TR
Port.

2-23

MOD TYPE

Select FM or AM mode for testing radios in the Analog
mode. Select one of the optional P25 modes for testing
Project 25 radios in the Digital mode.

NOTE: To test P25 Digital radio’s the TGID, SID and NAC

settings must be configured in the Project 25
Downlink window available from the Options Menu.

P25 LSM and P25 P2 are optional modes that are

available when the CQPSK Generate/Receive and

Analysis option (2975OPT29) is installed in unit.
OFF
Allows CW signal generator operation when no

modulation source is desired.
P 25
Configures Project 25 modulation type without

encryption. With P25 selected, a PATTERN field
becomes available to allow selection of the P25
waveform.

1011 - A defined bit pattern, which when decoded,

sounds like the traditional 1 kHz (1011 Hz) tone.

This pattern is normally used to perform BER tests

on a receiver. This pattern may have the NAC,

TGID and SID modified to accommodate the system

under test.

CALIBRATION - A defined bit pattern representing

the 1011 tone as above, but with a 5% BER added.

A P25 receiver should be able to decode this

pattern successfully with a strong receive RF level.

This pattern may have the NAC, TGID and SID

modified to accommodate the system under test.

SILENCE - A defined bit pattern, which when

decoded, produces no sound (silence) on the

receiver audio. This pattern may have the NAC,

TGID and SID modified to accommodate the system

under test.

SPEECH - Embedded Speech patterns that repeat

the following phrases:

“These shoes were black and brown”

“They took the cross town bus”

“Don’t throw trash on the street”

The SPEECH pattern is used for testing repeater

sensitivity without the use of other external

equipment. This pattern may be encrypted. This

pattern may have the NAC, TGID and SID modified

to accommodate the system under test.

2-24

VOICE - Internal or external audio source for

modulating P25. Includes the following audio

sources:

M1 Function Generator (internal)
M2 Function Generator (internal)
MIC Input (external)
Audio In (external)
Demod

This pattern may be encrypted. This pattern may

have the NAC, TGID and SID modified to

accommodate the system under test.

STANDARD - Pre-defined patterns waveforms, as per

the TIA/EIA 102.CAAA P25 standard. The screen (to

the right) shows the STANDARD available patterns.

Refer to the TIA/EIA 102.CAAA for details for each of

these standard patterns. These patterns may be

used to stimulate a P25 receiver under test for test

and analysis purposes. These patterns are fixed

format, and cannot have the NAC, TGID and SID

modified to accommodate the system under test.

TGID = 1, SID = 1 and NAC = 293 (per the Standard).

These patterns cannot be encrypted.

2-25

FM
Configures FM modulation type. Enables tones

menu to select various FM modulation modes.

M1 AND M2

Selecting a MOD TYPE of FM or AM allows control of
internal modulation sources 1 and 2. Selecting M1 or
M2 allows access to a tone signaling selection list.

OFF
Disable internal modulation source.
TONE
Configures M1 or M2 for Function Generator

operation and allows entry of FM Deviation or AM
modulation level, audio frequency rate and wave
shape. Sinewave, Squarewave, Triangle or Ramp
wave shapes may be selected.

TREM
Select Tone Remote operation. The Tone Remote

function provides default settings for frequency,
level and duration. These values may be altered
for specific requirements by selecting the CONFIG
function. Selecting the tone format and pressing
the SEND button activates the selected tone
sequence.

2-26

DTMF
Select DTMF operation. Values are entered and

sent after pressing the ENTER key. Mode
selections for Continuous, Burst or Keypad are
available. The CONFIG button allows changes to
the Mark, Space and End timing in ms.

CTCSS
Select CTCSS operation. In this mode, CTCSS

entries may be made by code value. If the code
value is unknown, use the TONE selection. The
CONFIG button allows configuration of the
deviation level to be used.

DCS
Select DCS operation. In this mode, DCS entries

may be made by code value. The CONFIG button
allows configuration of the deviation level to be
used as well as the code type of Normal or
Inverted.

2-27

TSIG

(

Tone Signaling operation provides several pre­configured setups for paging formats. The
User_TS selection allows configuration of a
unique tone sequence. Frequency, Mark and
Space timing can be configured. 13 separate
tones can be configured.

SINC CONFIG

The SINC waveform is used for audio spectrum
analysis, somewhat similar to a tracking generator for
RF spectrum analysis. However, since the audio
analyzer uses digital signal processing techniques
rather than a swept-mixer approach, a different
method of generating the stimulus signal is needed.

The SINC waveform defined as:

sin(ϖ t)
SINC(t) =

Like all signals in the 2975, this signal is generated
digitally at a specified number of samples per second.

RATE
This is the equivalent sample rate of the signal, in samples per second. The faster this number,

the more frequently the pattern repeats, the higher the maximum frequency of the signal, and the
greater the resolution bandwidth of the signal.

OMEGA
This sets how wide the signal is in frequency. Higher omegas give a signal with a narrower

frequency band, lower omegas give a signal with a wider frequency band (for a given sample
rate). However, as the signal gets wider, it also "droops," so that wider signals are not as flat as
narrower signals.

ϖ t)

2-28

ARB

The ARB function is a simple arbitrary waveform
generator that provides up to 16384 samples per
waveform. The samples repeat.

RATE
This is the sample rate at which to play back the

waveform. For example, a waveform derived from a
CD must be played back at 44100 Hz to sound
correct.

SHAPE (Testing or Noise)
This selects the shape file from the hard disk. User

generated files may be uploaded (via the web server
interface) to /usr/waveforms and are automatically
added to the waveform menu. (It may be necessary
to create the /usr/waveforms directory first).

TESTING

Generates arbitrary voice waveform that continuously repeats sentence “Testing 1, 2, 3.”
NOISE

Generates random pre-programmed noise used to create audio interference.
SHAPE FILE LAYOUT
A waveform file is a text file that resembles the following:

NAME noise

DESCRIPTION "Band limited AGN to (0.3 * Fs/2)"

data {

-0.178018803083987

-0.314125720479411

-0.385662785219341

...

0.005406993939079

}
NAME
This field indicates the name of the waveform that appears in the menu
DESCRIPTION
This field provides a more detailed description of the waveform as it appears when selected. This

value MUST BE IN QUOTATION MARKS (or CURVED BRACKETS {}).data: This is the waveform
data, as 16384 floating-point values from -1.0 to 1.0. This data MUST BE IN CURVED
BRACKETS. The data can be one value per line, or multiple values per line.

MIC

The MIC routes the Microphone input jack to the modulator to allow voice modulation. When the
function is enabled, the microphone bias type may be selected (Dynamic or Electret). The MIC/Audio
Adapter (AC25007) combination is of the Electret type.

2-29

OUTPUT

Allows selection of the 2975’s RF Output Port. Use the T/R Port for single connection transmit and
receive operations or GEN for output only operation.

AUDIO

Routes external audio input to the modulator to allow for external modulation.
NOTE: If the MIC/Audio Adapter (AC25007) is used, ensure that AUD is turned OFF when making

SINAD measurements.

AUDIO ROUTE

Refer to para 2-3 for information on AUDIO ROUTE capabilities.

2-30

RECEIVER MODE

The Receiver (TX Test) mode is used to test a digital P25 or analog transmitter. To access the
Receiver mode, use the following key sequence:

[MODE] Key
[2] Key

FIELD DEFINITIONS

FREQ

This field allows entry of the transmitter channel
frequency in MHz. Using the rotary knob,
position the cursor on the frequency field. A new
frequency can be entered directly through the
numeric keypad and terminated by pressing the
[ENTER] Key. To edit an existing frequency,
press the [ENTER] Key to highlight the existing
frequency, then use the left or right arrow keys to
position a cursor to the digit to edit. Using the
up or down arrow keys or the rotary knob
increments or decrements the current value.
Frequency values ranging from 0 to 2700 MHz
can be made with 1 Hz resolution.

FREQ Label

INCR
Allows entry of a frequency increment value.

When in this mode of operation, the
frequency can be set with the frequency field
and then adjusted by the defined increment
value through use of the side function keys.

SCAN
Allows entry of a start and stop frequency

with increment for swept RF measurements.
Select SETUP to configure the sweep
parameters. To begin the sweep, press
function key labeled START SWEEP.

2-31

LIST
Allows frequencies to be selected from a pre-

programmed list. The frequency list box allows
entry of up to 300 generate and receive
frequencies. Frequencies are selected by entry
of the list index value associated with the
frequencies in the list. The list can be auto­filled by entering a base frequency in the REC
FREQ field and an increment value. The list is
filled automatically by activating the FILL LIST
function. Each frequency pair has a default
label that may be changed to better identify the
frequency pair.

REC’D

This is a display only field that indicates the frequency received by the 2975. The received
frequency must be within the selected IF Bandwidth.

INPUT

This field allows selection of the input port where the signal is injected into the 2975. Use the ANT
Port for low level off-the-air measurements where signal strengths are <-10 dBm. Use the T/R Port
for direct connection to a transmitter where power levels may reach 50 W continuous or up to 125 W
for 1 minute ON, 4 minutes OFF.

ATTEN

0 (ANT) (T/R)
10 (ANT) (T/R)
20 (T/R)
30 (T/R)
Select an appropriate amount of attenuation to achieve the maximum signal strength as viewed on the

Spectrum Analyzer. The signal level should not exceed the top reference line on the Spectrum
Analyzer, as this would cause compression in the 2975 Receiver.

DEMOD

Select the demodulator type:
P25 (Project 25 FDMA Digital Modulation)
FM (Analog Frequency Modulation)
AM (Analog Amplitude Modulation)
P25 LSM (P25 CQPSK Data as used in Motorola Simulcast) (Optional feature)
P25 P2 (P25 Phase II CQPSK per APCO 25 Standards) (Optional feature)

2-32

IF

Select the IF Bandwidth:
6 kHz (AM)

12.5 kHz (AM, FM, P25)
25 kHz (AM, FM, P25)
60 kHz (AM, FM)
200 kHz (AM, FM)
NOTE: When DEMOD has been set to AM, the IF is automatically set to 6 kHz and cannot be

changed.

FILTER

Audio Filters are available during Receiver (TX Test)
when DEMOD is set to AM or FM. Selecting a Filter
setting filters the Audio Bandwidth to the Oscilloscope,
Deviation Meter, Frequency Counter and Speaker.

NOTE: The Audio Filters are not available with

P25 selected.

AUDIO ROUTE

Refer to para 2-3 for information on AUDIO ROUTE capabilities.

2-33

DUPLEX MODE

The Duplex Mode allows simultaneous control of the RF signal generator and the RF Receiver. To
access the Duplex Mode, use the following key sequence:

[MODE] Key
[3] Key

The two RF systems are completely independent of
each other allowing any frequency offset or modulation
type. This feature is required to test VHF to UHF
Cross-Band Duplex Systems.

The upper left quadrant allows configuration and
control of the RF Receiver. The upper right quadrant
allows configuration and control of the RF Generator.
The features displayed in the upper left and right
quadrants are fixed and can not be changed by the
Options menu.

The Options Menu may be used to configure the lower
left and right quadrants on the display.

All functions for the Generator and Receiver in the
Duplex Screen are the same as the stand-alone
Generate and Receive Screens.

2-34

FUNCTION GENERATOR

The FUNCTION GENERATOR within the 2975 has SINC
[sin (x)/x] and ARB (arbitrary) waveform capabilities.

To access the Function Generator, use the following key
sequence:

[MODE] Key
[4] Key

These Function Generators are configurable as Audio
Sources routed to the Front Panel.

The Option menu allows user to select various meters
and the Audio Analyzer for display if needed.

NOTE: The Oscilloscope is always displayed on the

Function Generator [MODE], [4] screen.

In the second example screen, FGEN1 is set to SINC
mode, and the oscilloscope is set up to monitor the
resulting waveform. The sin (x)/x sample rate, omega
(width) and level may be varied as desired.

In the last example the ARB function is shown on
FGEN2. The oscilloscope shows a sin (x)/x pulse,
followed later by the arbitrary burst.

The level and rate may be set as desired; the SHAPE is
bandwidth limited NOISE (AGN) or TESTING.

The Field Definitions are the same for Function
Generator #1 and Function Generator #2.

2-35

FIELD DEFINITIONS

OFF

Disables internal modulation source.

TONE

Allows entry of audio frequency, level and wave shape. Sinewave,
Squarewave, Triangle or Ramp wave shapes are the available
selections.

TREM

Select Tone Remote operation. The Tone Remote
function provides default settings for frequency, level
and duration. These values may be altered for specific
requirements by selecting the CONFIG function.
Selecting the tone format and pressing the SEND button
activates the selected tone sequence.

DTMF

Select DTMF operation. Values are entered and sent
after pressing the ENTER key. Mode selections for
Continuous, Burst or Keypad are available. The CONFIG
button allows changes to the Mark, Space and End
timing in ms.

2-36

CTCSS

Select CTCSS operation. In this mode, CTCSS entries may
be made by code value. If the code value is unknown, use
the TONE selection.

DCS

Select DCS operation. In this mode, DCS entries may
be made by code value.

The CODE button opens a menu that selects the DCS
code used to un-Squelch the radio.

2-37

TSIG

Tone Signaling operation provides several pre-configured
setups for paging formats. The User_TS selection allows
configuration of a unique tone sequence for 13 separate
tones. Frequency, Mark and Space timing can also be
configured.

AUDIO ROUTE

Refer to para 2-3 for information on AUDIO ROUTE capabilities.

2-38

OSCILLOSCOPE

Available Signal

Input

Sweep
Rates

Markers Setup

Trigger Mode
Control

Trigger Level
Control

Trigger Rise / Fall

Vertical

Position

Vertical

Scale

Persistence

Control

The Oscilloscope (Scope) provides users with the
ability to perform time dependent measurement
analysis. The Scope Screen can be expanded from
any function screen that lists Scope in the Options
Menu. The Scope Options Menu permits selection
of various Scope Inputs.

The screen to the right shows an example of the
Scope Screen with two active markers. User can
configure Markers by selecting the MARKERS soft
key.

Horizontal
Trigger Offset

2-39

SCOPE INPUT OPTIONS

CH1 and CH2 route the front panel Scope input
connectors to the Scope trace functions.

Selecting CH1 and CH2 Scope inputs activates
additional soft keys on the Scope Screen which are
not available with other Scope input selections.

NOTE: CH1 or CH2 cannot be used with any

CH 1

CH 2

other input sources.
MIC (Dynamic)
Routes the MIC Input (MIC/Audio Adapter)

(AC25007) to the Scope Input through the MIC and
AUDIO I/O Connectors (switches to Dynamic MIC
Type).

MIC (Electret)
Routes the MIC Input (MIC/Audio Adapter)

(AC25007) to the Scope Input through the MIC and
AUDIO I/O Connectors (switches to Electret MIC
Type).

AUDIO
Routes the Audio Input (MIC/Audio Adapter)

(AC25007) to the Scope Input through the MIC and
AUDIO I/O Connectors on the Front Panel
(switches to unbalanced input).

AUDIO BAL
Routes the Audio Input (MIC/Audio Adapter)

(AC25007) to the Scope Input through the MIC and
AUDIO I/O Connectors on the Front Panel
(switches to balanced input).

DEMOD
Routes the 2975’s Receiver Demod to the Scope Input.
SQUELCH
Routes the 2975’s Receive Demod to the Scope Input, stopping the Scope when SQUELCH is

closed.

MIC

AUDIO

FIELD DEFINITIONS

SWEEP

The SWEEP field sets the sweep rate of the Scope. The sweep rate is the sample time per horizontal
division on the Scope. The range of Sweep times vary according to the selected input.

TRIGGR (TRIGGER)

TRIGGR sets the triggering mode control of the Scope. TRIGGER mode selections are:

AUTO Scope is free-running and is always triggered
NORM Scope is triggered each time signal crosses the defined trigger level
ONE Scope is triggered the first time the signal crosses the defined trigger level.

2-40

ARM

This button re-arms the Scope when it is set to ONE shot mode.

SOURCE

The SOURCE button selects the triggering source of the Scope. Available selections are:

CH1 Trigger from the Scope Channel 1 input when Scope Channel 1 or 2 is selected
as the Scope Input.
CH2 Trigger from the Scope Channel 2 input when Scope Channel 1 or 2 is selected
as the Scope Input.
EXT Trigger from the external trigger input on the rear panel when Scope Channel 1
or 2 is selected as the Scope Input.
MIC DYN When MIC DYN (Dynamic) is selected as the Scope Input, MIC Dynamic is the
only available triggering source.
MIC ELEC When MIC ELEC (Electret) is selected as the Scope Input, MIC Electret is the
only available triggering source.
AUDIO When AUDIO is selected as the Scope Input, Audio is the only available
triggering source.
AUD BAL When AUD BAL is selected as the Scope Input, Audio Balance is the only
available triggering source.
DEMOD When DEMOD is selected as the Scope Input, Demod is the only available
triggering source.
SQUELCH When SQUELCH is selected as the Scope Input, SQUELCH is the only available
triggering source.

LVL V / LVL kHz

This field sets the triggering level of the Scope. The trigger level is indicated in volts below the LVL
field and by an arrow on the left side of the user screen.

CH1, CH2, MIC, AUDIO Units are in Volt s
DEMOD FM Units are in kHz Deviation
DEMOD AM Units are in % AM
DEMOD P25 Units are in % Maximum Audio Level

SLOPE

This field indicates the direction the signal must cross
the TRIGGER level in order to trigger the Scope. User
may select from:

RISE triggers as the signal crosses the trigger level
going up (positive).

FALL triggers as the signal crosses the trigger level
going down (negative).

HPOS

This field set the horizontal position of the trigger on
user screen. An HPOS of 0 indicates the trigger appears
at the left edge of the screen. An HPOS of +1 division
positions the trigger 1 division to the right from the left
edge of the screen. An HPOS of -1 positions the trigger
off of the screen to the left. User may edit field to
define this value.

LVL Indicator

2-41

PERSIST

Persistence Control permits successive traces to remain on the screen until the screen is turned OFF
or cleared.

ON prevents scope trace from being erased on each sweep.
OFF causes sweep trace to be erased on each sweep.
CL clears the sweep trace.

AC / DC / GND (Coupling)

Scope channels 1 and 2 may be set to DC Coupling or AC Coupling. AC Coupling removes any DC
offset from the signal, allowing small AC signals on top of large DC offsets to be seen. Coupling for
any of the other signals is always DC. User may select from drop-down menu to define field.

V/div

This button selects the vertical scale for the channel. User can select from drop-down menu to
define this value.

VPOS

This field allows the vertical trace to be moved up or down on the display.
Selecting VPOS to change button text to BLACK on a WHITE background engages use of spinner

knob to move Scope trace up and down on user screen.
Selecting VPOS to change button text to WHITE on a GRAY background disables use of spinner knob

to move vertical position of Scope trace.

2-42

SPECTRUM ANALYZER

The Spectrum Analyzer permits viewing off-air or directly connected RF signals in an RF-level versus
frequency display format.

The 2975 Spectrum Analyzer has two basic modes of operation: Channel Mode or Stand-Alone Mode.

CHANNEL MODE

The Channel Mode is available when zoomed in from any of the other functional test screens (i.e.,
Receive, Generate, Duplex, etc.). When in Channel Mode, spans of up to 5 MHz can be selected to
view the channel under test. The Tracking Generator is not available in Channel Mode.

STAND-ALONE MODE

To access window spans of up to 3 GHz, the Stand-Alone Spectrum Analyzer must be selected from
the Mode Selection Menu [MODE] [6].

OPTIONS

The Spectrum Analyzer option selections control the
display mode of operation and the Tracking Generator.
These options are accessible by pressing the [SHIFT]

[MODE] keys.

LIVE

The LIVE mode displays the signals on-screen
immediately upon being received. This mode is the
"standard" operating mode for general use.

Live may be used simultaneously with Average, Peak,
Compare and/or Tracking Generator operation as
desired.

Live selection sets (F5) Soft Key to SAVE TRACE
function to permit storing trace to reference memory
for use with the Compare function.

While in Live operation, the trace line is displayed in WHITE.

AVERAGE

The Average mode displays the signals on-screen as the average of the specified number of traces in
the AVG edit field. The AVG field appears in the area below the lower-right corner of the Spectrum
window. This mode is useful for displaying repetitive signals in the presence of noise.

Average may be used simultaneously with Live, Peak, Compare and/or Tracking Generator operation
as desired.

Average selection sets (F5) Soft Key to SAVE TRACE function to permit storing trace to reference
memory. Average selection sets (F6) Soft Key to CLEAR TRACE function to permit restarting of the
average function by purging previous trace data with new traces received.

While in Average operation, the trace line is displayed in LIGHT GREEN.

2-43

PEAK

The Peak mode displays the signals on-screen as the peak value for each frequency point on the
trace display. This mode is useful for catching spurious, one-time events or monitoring a portion of
the spectrum over a long period of time.

Peak may be used simultaneously with Live, Average, Compare and/or Tracking Generator operation
as desired.

Peak selection sets (F5) Soft Key to SAVE TRACE function to permit storing trace to reference
memory.

Peak selection sets (F6) Soft Key to CLEAR TRACE function to permit restarting of the peak function
by purging previous trace data with new traces received.

While in Peak operation, the Peak line is displayed in LIGHT BLUE.

COMPARE

The Compare mode displays the last SAVE TRACE display line on the Spectrum Analyzer. This mode
is useful for visual comparison of a reference trace (the SAVE TRACE) to the Live, Average or P T
that is displayed simultaneously.

Compare may be used simultaneously with Live, Average, Peak and/or Tracking Generator as
desired. When used independently, if a trace is stored in memory, only the stored trace is displayed.

While in Compare operation, the RECALL TRACE is displayed in YELLOW, and other simultaneously
displayed trace line is displayed in its respective color.

TRACKING GENERATOR

The Tracking Gen mode provides a great tool for RF
analysis by activating a RF source signal (generator)
that is swept in synchronism with the Spectrum
Analyzer RF receiver. This swept RF generator may
be applied to components or systems and the output
monitored to display the frequency response of these
items.

The Tracking Generator mode activates additional
controls when selected.

The TG LVL edit field appears in the area below the
center-right of the Spectrum window. This field
displays and permits changes to the RF level of the
Tracking Generator.

The (F4) Soft Key becomes the TG OUTPUT selection
control, permitting the Tracking Generator to be routed to the GEN or T/R Port on the 2975 Front
Panel.

The Tracking Generator may be used simultaneously with Live, Average, Peak and/or Compare
operation as desired, with the trace lines displayed in their respective colors.

2-44

MARKERS

The Spectrum Analyzer Control Options ([SHIFT] [MODE] and [7])selection screen shows the
Configure Markers addition for:

Configure Markers 7

The Configure Markers menu allows for:

O entry of Marker frequencies for eight

Markers with corresponding level readout;

O difference calculations for level or

frequency between any two Markers;

O a cable fault calculator based on two Marker

positions. This calculation determines the
distance to a fault (a short or open) within a
transmission line from the 2975.

O the ability to orient a Marker either

horizontally or vertically.

The Spectrum Analyzer screen (to the right) shows
three active Markers. The Marker level and frequency
values are displayed next to the respective Marker
line. The Markers may be re-positioned on the screen
in one of two ways:

O If using a mouse, left-click and hold on the

Marker box at the top of a Marker line and
move the Marker to a desired location, then
release the mouse button.

O If using the keyboard / spinner, highlight the

desired Marker box using the spinner or
left/right keys and then press ENTER. Move
the Marker to the desired location, then
press ENTER to set.

2-45

CABLE FAULT MEASUREMENT CALCULATOR

The Spectrum Analyzer Markers have a cable fault
feature, providing a convenient way to find the location
of a problem in a coaxial transmission line.

The technique for measuring a transmission line is
described in Section 4 of this manual. Select the
velocity factor (VF) of the particular coaxial cable and
position two markers at two adjacent null points. The
2975 displays the distance to the fault on the
Configuration Markers screen.

The example screens show the Markers set at the null
points and the accompanying cable fault calculation for
an open-ended 15 ft, RG-58 coaxial cable. Note the
use of the 5 dB/div scale to make positioning of the
markers easier.

2-46

QUICK SPAN

g

The Spectrum Analyzer has additional features
available whenever a mouse is used. The "Quick
Span" feature permits rapid center frequency and span
selection using a drag-and-drop type of mouse action.

The screen (to the right) illustrates how to perform
Quick Span.

Position the mouse cursor at a position just to the left
of Marker 1 (white arrow), then push and hold the right
mouse button. Drag the mouse to the position just to
the right of Marker 2 and release the mouse button.

After release of the mouse button, the SPAN is
changed to the closest fit for the selected range and
the FREQ is adjusted to the mid-point of the mouse­selected span. The result of the above action is
shown.

Remember, the Quick Tune feature remains available,
permitting left button double-click on a Spectrum
Analyzer screen position to tune to center frequency.

SWEEP SPEED AND ZERO SPAN

The example screens (to the right) show the Spectrum
Analyzer 2-5-10 sweep progressions from 5 ms to
10 sec. Zero span (0 SPAN) has 5 and 10 ms minimum
sweep time, while the minimum sweep time for 1 kHz
through 3 GHz is 20 ms. The selected SPAN dictates
allowable sweep speeds appropriate for correct
operation.

The Spectrum Analyzer screen has triggering and
display controls for capturing dynamic signals while in
Zero Span Sweep. The example screen (to the right)
shows a captured AM signal that triggered the trace
when the signal level exceeded -75 dBm with a rising
slope, with a shift of 5 divisions. This shift positions
the trigger point at mid-screen for easy viewing and
analysis.

The TRIGGER field option selections are:

O AUTO for free-running operation.
O NORMAL for repetitive trigger upon trigger

condition occurrence.

O ONE SHOT for a capture and hold display.

The ONE SHOT may be repeated by
pressing the TRACE-RUN soft-key.

Zero Span Sweep

Speeds

Trigger Point

-75 dBm, Risin

1 kHz Span and

above

2-47

FIELD DEFINITIONS

The various control fields permit changes to the
Spectrum Analyzer RF and display systems within the

2975.

FREQ

The FREQ field is the frequency at the center vertical
graticule of the trace display. This frequency is set to
the Receiver frequency when the Spectrum Analyzer is
initially entered and can be edited as desired thereafter.
Frequency changes for the Spectrum Analyzer are
simultaneously made to the Receiver frequency.

The range of Frequency entry is 0 to 2800 MHz. When
displaying trace areas that would be outside this range
of frequencies, the trace line drops to the bottom of the
trace window to indicate the frequency area is invalid.

Resolution of Frequency is 1 Hz (0.000001 MHz).

SPAN

The SPAN field defines the size of the window over
which the Spectrum Analyzer sweeps. This SPAN is the
entire window size left to right, therefore each vertical
graticule line represents 1/10th of this frequency.

The range of Span values is 0 to 3 GHz SPAN in Stand­Alone Mode and 0 to 5 MHz SPAN in Channel Mode.

Changing SPAN while in AUTO mode causes the RBW,
VBW and SWEEP fields to update automatically to the
optimum settings for frequency and level accuracy at the
selected SPAN.

Changing SPAN while in MAN mode may cause the RBW, VBW and/or SWEEP fields to change
background color, and an UNCAL annunciator to appear on the screen. This indicates that one or
more fields may need to be changed to achieve frequency and level accuracy.

RBW

The RBW field defines the Resolution Bandwidth (RBW) that is used by the Spectrum Analyzer. The
RBW is the width of the filter that is used within the receiver as it is swept over the specified SPAN
(the filter located before the log detector).

RBW selections are:
Stand-Alone Mode: 300 Hz, 3 kHz, 30 kHz, 60 kHz,

300 kHz and 6 MHz
Channel Mode: 300 Hz, 3 kHz and 60 kHz
RBW is NOT selectable while in AUTO mode, as RBW is set automatically according to SPAN.
Changing RBW while in MAN mode may cause the RBW, VBW and/or SWEEP fields to change

background color, and an UNCAL annunciator to appear on screen. This indicates that one or more
fields may need to be changed to achieve frequency and level accuracy.

2-48

VBW

The VBW field defines the Video Bandwidth (RBW) that
is used by the Spectrum Analyzer. The VBW is the
width of the filter that is applied to the signal after it
has been processed by the detector, commonly called
Log Video.

VBW selections are: 10 Hz, 30 Hz, 100 Hz, 300 Hz,

1 kHz, 3 kHz, 10 kHz, 30 kHz,
100 kHz, 300 kHz, 1 MHz,
3 MHz and NONE (no filter).

VBW is NOT selectable while in AUTO mode, as VBW
is set automatically according to SPAN.

Changing VBW while in MAN mode may cause the
RBW, VBW and/or SWEEP fields to change background
color, and an UNCAL annunciator to appear on screen.
This indicates that one or more fields may need to be
changed to achieve frequency and level accuracy.

SWEEP

The SWEEP field defines the time that the Spectrum
Analyzer takes to display the trace from left to right.

SWEEP selections are: 100 ms, 200 ms, 500 ms,

1 s, 2 s, 5 s and 10 s.

The SWEEP selections vary according to the SPAN
selected.

Changing SWEEP while in MAN mode may cause the
RBW, VBW and/or SWEEP fields to change background
color, and an UNCAL annunciator to appear on screen.
This indicates that one or more fields may need to be
changed to achieve frequency and level accuracy.

AUTO/MAN

The AUTO/MAN field permits selection of automatic (AUTO) SWEEP, RBW and VBW settings
according to SPAN or manual (MAN) selections for SWEEP, RBW and VBW.

During AUTO operation, the 2975 Spectrum Analyzer selects optimum SWEEP, RBW and VBW
settings.

It may be necessary to view spectrum conditions at other settings, so MANUAL selection may be
used. It is possible to set conditions using MANUAL settings that place the Spectrum Analyzer into
an uncalibrated mode of operation, which is indicated by the appearance of the UNCAL annunciator
on the screen. This indicates that one or more fields may need to be changed to achieve frequency
and level accuracy.

TRACE (F2)

Soft Key (F2) controls the TRACE STOP / RUN condition.
The Spectrum Analyzer begins in RUN condition, where repetitive spectral traces occur at current

settings, each new trace eliminating the previous trace.
If a particular condition displayed on-screen needs to be observed in detail, press STOP to halt the

repetitive trace action until RUN is pressed.

2-49

INPUT (F3)

Soft Key (F3) controls the RF input that is currently displayed on the Spectrum Analyzer.
Selections are T/R or ANT (Antenna) Port.
The TOP OF SCALE reference level and ATTEN (attenuation) settings change according to the

selected input.

TG OUTPUT (F4)

Soft Key (F4) is only active if the Tracking Generator is ON.
Soft Key (F4) controls the RF output that is currently active for the Tracking Generator.
Selections are T/R or ANT (Antenna) Port.

SAVE TRACE (F5)

Soft Key (F5) is used to SAVE TRACE. Pressing this key saves the current trace display to reference
memory for recall when COMPARE mode is activated.

CLEAR TRACE (F6)

Soft Key (F6) is visible when Average and/or Peak is selected. Pressing key clears the current
Average and/or Peak Trace and displays a new Average and/or Peak Trace.

Pressing this key recalls and displays the reference trace memory when in COMPARE mode.

NORMAL (F7)

Soft Key (F7) is used to normalize (NORMAL) the Spectrum Analyzer system.
Normalization adjusts internal settings to compensate for differences between the various filters

within the 2975 to give accurate spectrum displays.
When (F7) is pressed, a pop up window displays progress of the internal calibration process.
Perform normalization initially on first use of the Spectrum Analyzer and as desired thereafter.

TOP OF SCALE

The far-left of the display area has eight (8) numbers vertically indicating the level at each major
division. The TOP OF SCALE, or the top-most value is commonly referred to as the Reference Level.

This TOP OF SCALE value may be edited to set the desired reference level depending upon which
INPUT is selected (T/R or ANT) and for the signal level of the desired carrier.

UNITS/DIV

The UNITS/DIV field selects the resolution of the vertical axis.
Each major division vertically may be selected to be in the step size of 10, 5 or 2 dB/div.

ATTEN

The ATTEN field is used to indicate the amount of attenuation that is applied to the selected input to
achieve the desired TOP OF SCREEN value.

AVG

The AVG field is only displayed when the AVERAGE mode is activated.
The AVG field is the number of display sweeps that are averaged for the currently displayed spectrum

trace.

CTR

The CTR field displays the RF level of the signal at the center position of the analyzer display.

2-50

TG LVL

z

The TG LVL field is only displayed when the Tracking Generator mode is activated.
The TG LVL field is the RF level for the Tracking Generator output. The range of TG LVL varies

according to the selected TG OUTPUT, either the T/R or GEN Port.

T/R Port level range is: -30 to -137 dBm
GEN Port level range is: +10 to -110 dBm

RETURN

The RETURN key is active in the Channel Analyzer Mode only. When pressed, the Analyzer
"un-zooms" and return to the previous Generator, Receiver or Duplex mode in minimized format.

QUICK TUNE (Mouse Required)

If a mouse is attached to the 2975, a quick and convenient method called Quick Tune is provided for
tuning the Spectrum Analyzer.

The Spectrum Analyzer display window may be
"double-clicked" on a signal of interest, and the 2975
tunes the center frequency to the selected signal. This
permits easy and quick centering of the desired signal.

As shown in the top screen, the mouse pointer (white
arrow) is positioned over the signal of interest at

102.1 MHz. When the left mouse button is double­clicked, the Spectrum Analyzer re-tunes to this
position of 102.1 MHz, as shown in the lower screen.

Signal at

102.1 MH

Double

click

Re-tuned to

102.1 MHz

2-51

SINAD METER

The SINAD Meter is used for making audio quality measurements on analog receivers and allows
measurement of a receiver’s sensitivity. The audio quality is measured as a ratio of
(Signal + Noise) / Noise.

The SINAD Meter function allows selection of the
input signal source. The Scope and Distortion Meter
input is automatically updated to match any change
to the input field that is made.

FIELD DEFINITIONS

SOURCE INPUT

DEMOD
Allows the demodulated audio from the 2975’s

Receiver to be routed to the SINAD Meter input.
SQUELCH
Allows SINAD Meter input to be controlled by the

Squelch control.
MIC (Dynamic or Electret)
Allows the MIC input to be routed to the SINAD

Meter input. This input selection has greater
sensitivity than other inputs and is better suited
for very low audio levels.

AUD BAL
Allows the input to the SINAD Meter to be 600 Ω

balanced input.
AUDIO
Allows the input to the SINAD Meter to be an unbalanced input.

RANGE

Selects the SINAD Meter range (20, 60 or AR [Auto-Range]) for the bar graph display. When in Auto­Range, the SINAD Meter automatically selects the appropriate range for the bar graph display.

NOTE: The range selection is for display purposes only and has no effect on the reading accuracy.

HIGH LIMIT

Allows setting of a High limit. When the measured level exceeds the High Limit setting, the Bar
Graph changes from GREEN to RED.

LOW LIMIT

Allows setting of a Low limit. When the measured level drops below the Low Limit setting, the Bar
Graph changes from GREEN to BLUE.

PEAK HOLD

With Peak Hold enabled, the highest reading remains on the display.

LIMIT ALARM

When enabled, an audible alarm sounds if the High or Low limit is exceeded.

2-52

AVERAGE

Allows the indicated SINAD Meter reading to be the average of a specified number of readings.
Setting this value to one (1) turns averaging OFF.

C WEIGHT

The C-Weight field turns the C-Weight Bandpass Filter ON or OFF as required. The C-Weight Filter
is specified by many Radio Manufacturers for SINAD measurement.

RF GEN LEVEL

Allows the Generator RF Level to be adjusted within
the “zoomed” SINAD Meter. The Generator Level
range is the same as the Generator screen for the
particular port (T/R or GEN) selected.

ADVANCED

This window allows customization of how the SINAD
is measured. The default values are correct for most
conditions.

WINDOWING
Selects the type of window applied to the data

before computing the FFT. KAISER is the default
and is recommended; however, NONE may be
selected for special conditions.

NOISE LOW FREQ
This is the lowest frequency that is considered

when computing the SINAD. Any signals below
this frequency are ignored. This can be used to
eliminate CTCSS and DCS signals from being
considered.

NOISE HIGH FREQ
This is the highest frequency that is considered

when computing the SINAD.
SIGNAL LOW FREQUENCY
This is the lowest frequency that is considered signal, rather than noise.
SIGNAL HIGH FREQUENCY
This is the highest frequency that is considered signal, rather than noise.

EXAMPLE:
User would like to measure the SINAD of a channel using a 2 kHz tone, in the presence of a

107 Hz PL tone and a 6 kHz supervisor audio tone.

O To eliminate the 107 Hz PL, set the Noise low frequency above the PL

frequency ≤ 150 Hz.

O To eliminate the 6 kHz SAT, set the Noise high frequency below the SAT

frequency ≤ 5 kHz.

O Set the Signal low and Signal high to 1900 and 2100 Hz, respectively, to select

the 2 kHz signal.
RESTORE DEFAULTS
Restores the SINAD Meter to the proper value to measure a 1 kHz tone.

2-53

DISTORTION METER

The Distortion Meter is used for making audio quality measurements on analog receivers and allows
measurement of a receiver’s sensitivity. The audio quality is measured as a percentage where the
RMS level of the 1 kHz test tone is measured and compared to the same signal with the 1 kHz tone
removed.

The 2975 Distortion Meter function allows selection
of the input signal source. The SINAD and Distortion
Meter inputs are automatically updated to match any
change made to the input field.

FIELD DEFINITIONS

SOURCE INPUT

DEMOD
Allows the demodulated audio from the 2975’s

Receiver to be routed to the Distortion Meter
input.

SQUELCH
Allows DISTORTION Meter input to be controlled

by the Squelch control.
MIC (Dynamic or Electret)
Allows the MIC input to be routed to the

Distortion Meter input. This input selection has
greater sensitivity than other inputs and is better
suited for very low audio levels.

AUD BAL
Allows the input to the Distortion Meter to be

600 Ω balanced input.
AUDIO
Allows the input to the Distortion Meter to be an unbalanced input.

RANGE

Selects the Distortion Meter range (5, 10, 20, 50, 100 or AR [Auto-Range]) for the bar graph display.
When in Auto-Range, the Distortion Meter automatically selects the appropriate range for the bar
graph display.

NOTE: The range selection is for display purposes only and has no effect on the reading accuracy.

HIGH LIMIT

Allows setting of a High limit. When the measured level exceeds the High Limit setting, the Bar
Graph changes from GREEN to RED.

LOW LIMIT

Allows setting of a Low limit. When the measured level drops below the Low Limit setting, the Bar
Graph changes from GREEN to BLUE.

PEAK HOLD

With Peak Hold enabled, the highest reading remains on the display.

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LIMIT ALARM

When enabled, an audible alarm sounds if the High or Low limit is exceeded.

AVERAGE

Allows the indicated Distortion Meter reading to be the average of a specified number of readings.
Setting this value to one (1) turns averaging OFF.

C WEIGHT

The C-Weight field turns the C-Weight Bandpass Filter ON or OFF as required. The C-Weight Filter
is specified by many Radio Manufacturers for Distortion measurement.

ADVANCED

This window allows customization of how Distortion is
measured. The default values are correct for most
conditions.

WINDOWING
Selects the type of window applied to the data

before computing the FFT. KAISER is the default
and is recommended; however, NONE may be
selected for special conditions.

NOISE LOW FREQ
This is the lowest frequency that is considered

when computing the Distortion. Any signals below
this frequency are ignored. This can be used to
eliminate CTCSS and DCS signals from being
considered.

NOISE HIGH FREQ
This is the highest frequency that is considered

when computing the Distortion.
SIGNAL LOW FREQUENCY
This is the lowest frequency that is considered

signal, rather than noise.
SIGNAL HIGH FREQUENCY
This is the highest frequency that is considered

signal, rather than noise.

EXAMPLE:
User would like to measure the Distortion of a channel using a 2 kHz tone, in the presence

of a 107 Hz PL tone and a 6 kHz supervisor audio tone.

O To eliminate the 107 Hz PL, set the Noise low frequency above the PL

frequency ≤ 150 Hz.

O To eliminate the 6 kHz SAT, set the Noise high frequency below the SAT

frequency ≤ 5 kHz.

O Set the Signal low and Signal high to 1900 and 2100 Hz, respectively, to select

the 2 kHz signal.
RESTORE DEFAULTS
Restores the Distortion Meter to the proper value to measure a 1 kHz tone.

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POWER METER

The Power Meter is used to measure RF power at the T/R Port. The 2975 has a 50 Ω power
termination pad within the unit that sustains RF transmitter power of 50 W continuously.

FIELD DEFINITIONS

CABLE LOSS

Entering a positive value compensates for external
cable loss, allowing the Power Meter to reflect the
amount of power (in dB) that is at the source output as
opposed to the end of the cable.

RANGE

Selects the Power Meter range for the bar graph
display:

Watts Mode: 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50,
100, 200 or AR (Auto-Range)

dBm Mode: AR, +50 or +30 dBm
When in Auto-Range, the Power Meter automatically

selects the appropriate range for the bar graph display.

HIGH LIMIT

Allows setting of a High limit. When the measured
level exceeds the High Limit setting, the Bar Graph
changes from GREEN to RED.

LOW LIMIT

Allows setting of a Low limit. When the measured level
drops below the Low Limit setting, the Bar Graph
changes from GREEN to BLUE.

PEAK HOLD

With Peak Hold enabled, the highest reading remains
on the display.

LIMIT ALARM

When enabled, an audible alarm sounds if the High or Low limit is exceeded.

METER UNITS

Power can be displayed in Watts or dB.

ZERO METER

For accurate measurements, the Power meter must be zeroed with no power applied.

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RSSI METER

The RSSI (Received Signal Strength Indication) Meter is useful for measuring RF signals at the IF
detector. The RSSI Meter is also useful for monitoring off-air signals using an antenna, or for
measuring amplitude modulated (AM) transmitter power.

FIELD DEFINITIONS

CABLE LOSS

Entering a positive value compensates for external
cable loss, allowing the RSSI Meter to reflect the
amount of power (in dB) that is at the source output as
opposed to the end of the cable.

RANGE

Selects the RSSI Meter range (+53, +10, -30 dBm or
AR [Auto-Range]) for the bar graph display. When in
Auto-Range, the RSSI Meter automatically selects the
appropriate range for the bar graph display.

HIGH LIMIT

Allows setting of a High limit. When the measured
level exceeds the High Limit setting, the Bar Graph
changes to RED.

LOW LIMIT

Allows setting of a Low limit. When the measured level
drops below the Low Limit setting, the Bar Graph
changes from GREEN to BLUE.

PEAK HOLD

With Peak Hold enabled, the highest reading remains
on the display.

LIMIT ALARM

When enabled, an audible alarm sounds if the High or
Low limit is exceeded.

METER UNITS

Power is displayed in dBm. When the RF Level is too low to verify accuracy the Units change to dB
(relative) and the RSSI Meter and Bar changes from GREEN to YELLOW.

CAL METER

Calibrates the RSSI Meter so accurate measurements can be obtained. CAL is required when the
CAL background changes to YELLOW.

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