Ameritec AM5eXT, AM5XT User Manual

MODELS AM5XT AND AM5eXT

VOICE/DATA TRANSMISSION TEST SET

INSTRUCTION MANUAL

MODELS AM5XT and AM5eXT

Voice/Data Transmission Test Set

Instruction Manual

October 17, 2000

Technical Data Subject to

Change without Notice

760 Arrow Grand Circle

Covina, CA 91722 USA

TEL [phone]
FAX [phone]

www.ameritec.com

For extra copies of this
manual, order Part
No. 18-0022

© 2000 Ameritec Corporation

Record of Revisions

A January 1991 Change from Revision Date to Revision Letter & Date.
B September 5,

1995

C June 1992 Added Change -200 Option Addenda 18-0128 and 18-0129, Caution on

D July 1992 Added Record of Revision Page.

E July 1996 Corrections throughout manual.
F May 1997 Added Calibration Procedure Appendix

F1 May 21, 1999 Page 8-7, Section 8.06 third paragraph: changed Psophometric to C-

G October 17, 2000 Generated Electronic Copy and Reformatted Manual.

Changes to Page 8-3 and 9-3

480062 cables, and Note on 135Ω Noise Measurements.

Message.

This manual was produced on a Power Macintosh using MS Word 6.0, Canvas 3.5 (pict),
Adobe Photoshop 3.0.5 (eps), Adobe Illustrator 6.0 (eps), and Macromedia Freehand 5.0
(eps).

AM5XT/eXT Voice/Data Transmission (18-0022) Table of Contents

Table of Contents

1. INTRODUCTION....................................................................................................1-1

1.1 Overview......................................................................................................... 1-1

1.2 Unpacking........................................................................................................ 1-1

1.3 AM5XT/eXT Basic Units...................................................................................... 1-2

1.4 AM5eXT-200 (ce).............................................................................................. 1-2

2. POWER CONSIDERATIONS ................................................................................... 2-1

2.1 Commercial Power ............................................................................................2-1

2.2 Optional Battery Pack.........................................................................................2-1

3. PHYSICAL AND FUNCTIONAL DESCRIPTION...........................................................3-1

3.1 Introduction...................................................................................................... 3-1

3.2 General........................................................................................................... 3-1

3.3 Front Panel Notes.............................................................................................. 3-2

3.4 Front Panel Components .................................................................................... 3-4

3.5 Rear Panel Components...................................................................................3-11

3.6 Optional Equipment .........................................................................................3-15

3.7 AM-47XT Hand-Held Printer (Optional)................................................................3-16

3.8 Accessories....................................................................................................3-23

3.9 Mask Feature (Optional) ...................................................................................3-26

4. SELF-TEST AND OPERATION TECHNIQUES............................................................4-1

4.1 Introduction...................................................................................................... 4-1

4.2 Self-Test Setup................................................................................................. 4-1

4.3 Switch Setup.................................................................................................... 4-1

4.4 Quiet Send Mode .............................................................................................. 4-1

4.5 Send 1004 Hz...................................................................................................4-2

4.6 Send PAR........................................................................................................4-2

4.7 Send Envelope Delay (ENV DLY).........................................................................4-3

4.8 Send IMD ........................................................................................................4-3

4.9 Auto Calibrate (Up to version 7* only)....................................................................4-3

4.10 Calibration Check (Up to version 7* only)..............................................................4-4

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4.11 Calibration (Version 8* and up)........................................................................... 4-4

4.12 Parameter Set.................................................................................................4-5

4.13 Data Displays.................................................................................................. 4-6

5. CONNECTION AND CONFIGURATION INSTRUCTIONS.............................................. 5-1

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

5.2 General........................................................................................................... 5-1

5.3 Connectors and Cables ...................................................................................... 5-2

5.4 Line Termination Impedances..............................................................................5-5

5.5 Configurations ..................................................................................................5-5

6. LINE FUNCTIONS.................................................................................................. 6-1

6.1 Introduction...................................................................................................... 6-1

6.2 General Line Function Notes................................................................................6-2

6.3 Generator Source Impedances............................................................................. 6-6

6.4 OFF HK (Send Pair Off-Hook/On-Hook)................................................................. 6-6

6.5 Termination Impedances (Receive Pair).................................................................6-7

6.6 OFF HK (Receive Pair Off-Hook/On-Hook).............................................................6-7

6.7 BRDG (Receive Pair Bridged/Terminated).............................................................. 6-7

6.8 2W (2-Wire)...................................................................................................... 6-8

6.9 4W (4-Wire)...................................................................................................... 6-8

6.10 REV (Reversed)..............................................................................................6-8

7. SEND FUNCTIONS................................................................................................ 7-1

7.1 Introduction...................................................................................................... 7-1

7.2 Quiet............................................................................................................... 7-2

7.3 1004 Hz........................................................................................................... 7-3

7.4 VAR HZ (Variable Tone).....................................................................................7-4

7.5 Slope.............................................................................................................. 7-4

7.6 Sweep............................................................................................................. 7-5

7.7 PAR (Peak-to-Average Ratio) .............................................................................. 7-7

7.8 RET LOSS (Return Loss)....................................................................................7-7

7.9 ENV DLY (Envelope Delay) (AM5XT ONLY)...........................................................7-9

7.10 GROUP DLY (Group Delay) (AM5eXT ONLY).....................................................7-12

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AM5XT/eXT Voice/Data Transmission (18-0022) Table of Contents

7.11 IMD (Intermodulation Distortion) .......................................................................7-14

7.12 OPEN..........................................................................................................7-16

7.13 SF SKIP (Signaling Frequency Skip)..................................................................7-16

7.14 TALK...........................................................................................................7-16

7.15 LOOP BACK.................................................................................................7-17

8. MEASURE FUNCTIONS ......................................................................................... 8-1

8.1 Introduction...................................................................................................... 8-1

8.2 LVL/FREQ (Level/Frequency)..............................................................................8-2

8.3 General Noise Measurement Notes....................................................................... 8-6

8.4 NOISE (Idle Channel Noise)................................................................................8-9

8.5 NOTCH NOISE (Noise-with-Tone)........................................................................8-9

8.6 NTG (Noise-to-Ground) ....................................................................................8-10

8.7 S/N (Signal-to-Noise Ratio)................................................................................8-11

8.8 PAR (Peak-to-Average Ratio) ............................................................................8-12

8.9 RET LOSS (Return Loss)..................................................................................8-15

8.10 ENV DLY (Envelope Delay) (AM5XT ONLY) ....................................................... 8-17

8.11 GROUP DLY (Group Delay) (AM5eXT ONLY).....................................................8-27

8.12 IMD (Intermodulation Distortion) .......................................................................8-32

8.13 PHASE JTR (Phase Jitter)...............................................................................8-34

8.14 AMP JTR (Amplitude Jitter)..............................................................................8-35

8.15 IMP NOISE (Impulse Noise without Tone)...........................................................8-35

8.16 TRAN (Transients).........................................................................................8-37

8.17 MICRO INTR (Micro-interruptions).....................................................................8-39

9. AUXILIARY FUNCTIONS........................................................................................9-1

9.1 Introduction...................................................................................................... 9-1

9.2 Filter for Narrow-Band Level/Frequency.................................................................9-2

9.3 Noise Weighting Filters.......................................................................................9-3

9.4 QUASI PK (Quasi-Peak Detector Enable) (AM5eXT ONLY)....................................... 9-4

9.5 Print Enable .....................................................................................................9-4

9.6 Jitter Bandwidth Select.......................................................................................9-6

9.7 START STOP (Timed Study Start/Stop)................................................................. 9-6

9.8 60 Hz Filter ......................................................................................................9-7

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9.9 REL SET (Relative Measure Zero Set)................................................................... 9-7

9.10 DAMP (Display Update Select)........................................................................... 9-9

10. DIALING........................................................................................................... 10-1

10.1 Introduction ..................................................................................................10-1

10.2 Manual Dialing..............................................................................................10-1

10.3 Storage of Dialed Number ...............................................................................10-3

10.4 Automatic Speed Dialing................................................................................. 10-4

10.5 Dual-Tone Dialing Frequencies.........................................................................10-5

10.6 Dial Pulse (DP) Requirements..........................................................................10-5

10.7 Dial Pulse (DP) Requirements..........................................................................10-6

10.8 Remote Control Using TT Commands................................................................10-7

10.9 Remote Control Using TT Commands................................................................10-8

11. MEMORY CONSIDERATIONS (STORE & RECALL) ................................................11-1

11.1 Introduction ..................................................................................................11-1

11.2 Factory Set Defaults.......................................................................................11-1

11.3 User Entered Memories ..................................................................................11-8

12. RS232 COMMANDS...........................................................................................12-1

12.1 Introduction ..................................................................................................12-1

12.2 Command Protocol ........................................................................................12-2

12.3 Response Protocol.........................................................................................12-6

12.4 Password Security........................................................................................12-10

12.5 Miscellaneous Commands..............................................................................12-10

12.6 RS232 Port Configuration...............................................................................12-11

12.7 Auxiliary RS232 Port .....................................................................................12-11

12.8 Daisy Chaining.............................................................................................12-11

12.9 Conditioning Mask Definition Format.................................................................12-12

13. PRINTING AND PLOTTING .................................................................................13-1

13.1 Introduction ..................................................................................................13-1

13.2 Types of Printouts (up to Version 7)...................................................................13-1

13.3 Types of Printouts (Version 8 and up)................................................................13-2

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AM5XT/eXT Voice/Data Transmission (18-0022) Table of Contents

13.4 XY Plotter Operation.......................................................................................13-3

14. ORDERING INFORMATION.................................................................................14-1

15. WARRANTY, CALIBRATION, AND SERVICE.........................................................15-1

15.1 Warranty......................................................................................................15-1

15.2 Service Policy...............................................................................................15-1

15.3 Calibration Policy...........................................................................................15-1

15.4 Return of Unit................................................................................................15-2

16. TECHNICAL SPECIFICATIONS............................................................................16-1

16.1 Measurements..............................................................................................16-1

16.2 Send Functions (Signal Generator)....................................................................16-1

16.3 Receive Functions .........................................................................................16-5

16.4 General ......................................................................................................16-12

A. APPENDIX A: CALIBRATION ................................................................................A-1

A.1 Scope.............................................................................................................A-1

A.2 Equipment Required..........................................................................................A-1

A.3 Calibration Procedure ........................................................................................A-1

A.4 Validation Procedure..........................................................................................A-3

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AM5XT/eXT Voice/Data Transmission (18-0022) Table of Contents

List of Figures

Figure 3-1. Front Panel Components ............................................................................. 3-2

Figure 3-2. Level and Noise Units of Measurement...........................................................3-8

Figure 3-3. Rear Panel Components............................................................................3-11

Figure 3-4. Hand-Held Printer, Component Location.......................................................3-17

Figure 3-5. Standard Cables Supplied with the AM-47XT Printer .......................................3-18

Figure 3-6. Ribbon and paper Installation for the AM-47XT............................................... 3-20

Figure 3-7. Printer Hookup.........................................................................................3-21

Figure 3-8. Bantam Plug Line Cables...........................................................................3-23

Figure 3-9. RS232 Cables .........................................................................................3-25

Figure 5-1. AM-47XT Hand-Held Printer Connection with AC Power..................................... 5-3

Figure 5-2. AM5XT/eXT Connection Cables....................................................................5-4

Figure 5-3. 4-Wire End-to-End Testing...........................................................................5-6

Figure 5-4. 4-Wire Testing with Responder......................................................................5-7

Figure 5-5. 2-Wire Testing with Responder......................................................................5-8

Figure 6-1. Procedure to Enable Line Functions...............................................................6-1

Figure 6-2. 2-Wire Line Circuit Block Diagram.................................................................. 6-3

Figure 6-3. 4-Wire Line Circuit Block Diagram.................................................................. 6-3

Figure 7-1. Procedure to Enable Send Functions.............................................................. 7-1

Figure 8-1. Procedure to Enable Measure Modes.............................................................8-1

Figure 8-2. Setup to Measure 4-Wire Envelope Delay ..................................................... 8-20

Figure 8-3. Setup to Measure 2-Wire Envelope Delay ..................................................... 8-25

Figure 8-4. Setup to Measure Group Delay...................................................................8-31

Figure 9-1. Procedure to Enable Auxiliary Functions......................................................... 9-1

Figure 9-2. Function Boxes.......................................................................................... 9-2

Figure 9-3. C-Message Weighting Characteristic (AM5XT)................................................. 9-9

Figure 9-4. Program Weighting Characteristic (AM5XT).....................................................9-9

Figure 9-5. 3 kHz Flat Weighting Characteristic (AM5eXT)...............................................9-10

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Figure 9-6. 15 kHz Flat Weighting Characteristic (AM5XT)...............................................9-10

Figure 9-7. 50 Kilobit Weighting Characteristic (AM5XT)..................................................9-11

Figure 9-8. Psophometric Characteristic (AM5eXT).........................................................9-11

Figure 9-9. Sound Weighted Characteristic (AM5eXT)..................................................... 9-12

Figure 9-10. Sound Unweighted Characteristic (AM5eXT)................................................9-12

Figure 9-11. 3 kHz Flat Characteristic (AM5XT)..............................................................9-13

Figure 9-12. 2 kHz Flat Characteristic (AM5eXT)............................................................9-13

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AM5XT/eXT Voice/Data Transmission (18-0022) Table of Contents

List of Tables

Table 3-1. Acceptable Holding Tone Ranges................................................................... 3-9

Table 3-2. RS232 Connector Pin Assignment................................................................3-13

Table 3-3. DIP Switch Settings ...................................................................................3-14

Table 3-4. Auxiliary RS232 Connector Pin Assignment....................................................3-14

Table 3-5. AM-47XT Technical Specifications................................................................3-16

Table 8-1. Noise Weighting Filters.................................................................................8-7

Table 8-2. P/AR Requirements of Telephone Lines......................................................... 8-13

Table 9-1. Noise Weighting Filters.................................................................................9-3

Table 9-2. AM5XT Noise Weighting Filters...................................................................... 9-3

Table 9-3. AM5eXT Noise Weighting Filters.................................................................... 9-4

Table 9-4. Jitter Bandwidth Weighting Filters...................................................................9-6

Table 10-1. MF and TT (DTMF) Tone Pairs...................................................................10-5

Table 11-1. Stored Memories and Purpose...................................................................11-1

Table 12-1. Line Control Commands............................................................................12-2

Table 12-2. Send Control Commands ..........................................................................12-3

Table 12-3. Measure Control Commands......................................................................12-4

Table 12-4. Auxiliary Control Commands......................................................................12-5

Table 12-5. Response Protocols................................................................................. 12-7

Table 12-6. Bandwidth Parameter Limits......................................................................12-13

Table 14-1. Voice/Data Transmission Test Set Ordering..................................................14-1

Table 16-1. ERL Filter Response (Frequency Weighting)................................................16-13

Table 16-2. SRL Low Filter Response (Frequency Weighting)..........................................16-13

Table 16-3. SRL High Filter Response (Frequency Weighting).........................................16-14

Table 16-4. P/AR Line Spectrum................................................................................16-14

Table 16-5. Combination of IEEE and O.91 Specification................................................16-15

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Table 16-6. Amplitude Jitter Frequency Weighting 20 – 300 Hz........................................16-15

Table 16-7. Amplitude Jitter Frequency Weighting 4 – 300 Hz..........................................16-16

October 17, 2000 0022-TOC.G_197xii

AM5XT/eXT Voice/Data Transmission (18-0022) Introduction

1. INTRODUCTION

1.1 OVERVIEW

This instruction manual describes the operation of the Ameritec Model AM5XT and
AM5eXT Voice/Data Transmission Test Sets.

The AM5XT and AM5eXT are microprocessor based test instruments used to
measure transmission impairments on 2- and 4-wire telephone lines. The AM5XT
measures transmission impairments in accordance with IEEE Standard 743-1984
(Bell Standard 41009). The AM5eXT complies with CCITT recommendations for
export.

The instrument also contains a separate full function signal generator able to
generate the test tones normally used with the tests.

The instrument contains 4 impedance selections per line, separate DC hold
circuits, pulse, MF, and DTMF signaling, built-in speaker monitor and talk
microphone. Optional features include RS232 remote control port, batteries for
cordless portable operation, and rack mounting kit for permanent installations.

1.2 UNPACKING

The unit was thoroughly tested and carefully packed before shipment, and was in
good condition when turned over to the carrier for shipment.

Upon receipt, thoroughly inspect the outside of the shipping container for
damage, and if damage is noted, immediately contact the carrier. The name of
the carrier will be noted on the packing slip which is attached to the outside of
the shipping container.

Open the container carefully and compare the contents with the packing slip.
Note any damage or shortages. Notify the carrier in the event of damage. Notify
Ameritec in the event of shortage.

Save the shipping container for future use in the event that the unit may be
returned to the factory.

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Introduction (18-0022) AM5XT/eXT Voice/Data Transmission

1.3 AM5XT/eXT BASIC UNITS

The Digital Signal Processor (DSP) board is not installed in the AM5XT-BASIC,
AM5XT-200 BASIC, AM5eXT-BASIC, and AM5eXT-200 BASIC, as indicated in the last

QUIET Mode PARAMETER DISPLAY (see Display 6 in ¶7.2).
Because of the absence of the DSP board, all BASIC units are NOT equipped with

the measurements listed below, even though these functions are included on the
front panel. The absence of these functions is evident because their function
LEDs will not light when the respective Function Enable Keys are pressed.

The functions listed below can be added by contacting Ameritec to order a
“factory upgrade” of an AM5XT-BASIC, AM5XT-200 BASIC, AM5eXT-BASIC, and
AM5eXT-200 BASIC to the standard AM5XT or eXT version (P/N 25-0036).
Functions of the AM5XT or eXT which are not included in the BASIC versions are:

• Envelope Delay

• Intermodulation Distortion

• Phase Jitter

• Micro-Interruptions

• Transient Tests:

• Gain Hits

• Phase Hits

• Dropouts

• X-Y Plotter (Option)

1.4 AM5eXT-200 (ce)

CAUTION: If the equipment is used in a manner not specified by Ameritec

!

1. All AM5eXT-200(ce) units come equipped with an Ameritec P/N 70009200
Desktop Transformer (230 VAC In, 14 VAC Out), equipped with a U.S. standard
power cord. Use only this provided Desktop Transformer. The user may
change the AC power cord so long as the selected power cord has <HAR>
markings.

October 17, 2000 0022-S01.G_ 208

Corporation, the protection provided by the equipment may be
impaired.

1-2

AM5XT/eXT Voice/Data Transmission (18-0022) Introduction

2. All AM5eXT-200(ce) units come equipped with the following options:

• 24-0017 Sealed Lead Acid Batteries and Integral Charger

• 25-0019 RS232 Remote Control Port with AUX RS232 Output Port

• 25-0045 X-Y Plotter Option

CE Mark certification is based solely on the above configuration. Use of any
other AM5 options, such as LIDs, will negate the certification.

3. The AM5eXT-200(ce) is not equipped with the T/R/T1/R1/Gnd Terminal Block
(see ¶3.5).

4. The AM5eXT-200(ce) is not equipped with the AC Power Selector Switch,
Step-Down Transformer, Fuse Holder, and Power Plug (items 1, 2, 4, and 6)
as shown in ¶3.5. These items are replaced by a Power Connector Mounting
Adapter and the Desktop Transformer.

5. The AM5eXT-200(ce) contains both sealed lead acid batteries and lithium
batteries. The lithium batteries are built into an Integrated Circuit. All

batteries are clearly marked with the

!

warning symbol. Be sure to dispose

of these batteries in accordance with local regulations.

0022-S01.G_ 208 October 17, 2000

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Introduction (18-0022) AM5XT/eXT Voice/Data Transmission

October 17, 2000 0022-S01.G_ 208

1-4

AM5XT/eXT Voice/Data Transmission (18-0022) Power Considerations

2. POWER CONSIDERATIONS

2.1 COMMERCIAL POWER

The AM5XT and AM5eXT are powered from commercial 115 VAC or 230 VAC 50/60
Hz power. A rear panel selector switch allows user selection of 115 VAC or 230
VAC.

A detachable 3-wire cord is furnished, which mates with a rear panel mounted
CCE standard V-type connector. A rear panel mounted fuse, rated at 1/2A, is
provided.

The AM5XT and AM5eXT are equipped with a non-volatile memory. Loss of
power will cause operation of the unit to cease. However, any front panel
configurations previously stored in memory will not be lost.

2.2 OPTIONAL BATTERY PACK

The AM5XT and AM5eXT may be equipped with an optional internal battery pack
to allow full cordless (no commercial power) operation.

The power pack consists of two sealed lead acid batteries and associated charging
circuitry. The batteries, when fully charged, will power the unit for
approximately 5 to 8 hours.

A low battery indicator is provided in the form of blinking decimal points in the
front panel display. Blinking decimal points indicate approximately 1/2 hour of
remaining battery operation before recharging is required.

The unit may be operated while the batteries are recharging. Recharging will
automatically occur whenever the unit is plugged into commercial AC power,
regardless of whether the unit is on or off. Charging will be accomplished faster
when the unit power switch is “OFF”.

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Power Considerations (18-0022) AM5XT/eXT Voice/Data Transmission

October 17, 2000 0022-S02.G_ 210

2-2

AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

3. PHYSICAL AND FUNCTIONAL DESCRIPTION

3.1 INTRODUCTION

This section illustrates and explains the components of the AM5XT/eXT. Also
described are optional equipment and accessories, including the Ameritec
AM-47XT Hand-Held Printer, designed to be used with the AM5XT/eXT. The
paragraphs in this section are listed below:

3.2 General

3.3 Front Panel Notes

3.4 Front Panel Components

3.5 Rear Panel Components

3.6 Optional Equipment

3.7 AM-47XT Hand-Held Printer

3.8 Accessories

3.2 GENERAL

Weight. The AM5XT/eXT weighs 5 pounds without the optional battery pack, and

10 pounds with the battery pack.

Dimensions.

Portable: 8.3”W x 3.5”H x 12.1”D (210mm x 89mm x 307mm)
Rack Mount: 19.0”W x 3.5”H x 12. 1”D (83mm x 89mm x 307mm)

Construction. Electronic components are mounted on four (4) plug-in printed

circuit boards, interconnected with harness connectors and housed
in a sturdy metal case. If the optional canvas Padded Carrying
Case is not ordered, a removable snap-on cover is supplied to
protect the front panel during transport. There are no user
serviceable parts inside the case.

Mounting. A portable unit has a carrying handle and can be stood on any of three

(3) possible sides, each of which has rubber feet.
When placed on a table, the unit can be set in a tilted position for

easier viewing of the front panel. This is done by extending supports
located behind the front feet on the front panel side. The 19” Rack
Mount Kit (85-(X)76) can be ordered for fixed installations.

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Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

3.3 FRONT PANEL NOTES

The Front Panel of the AM5XT is illustrated in Figure 3-1. See ¶3.4 for
descriptions of the components called out.

Figure 3-1. Front Panel Components

Front Panel Layout. The AM5XT front panel is a surface approximately 3” (7.5cm)

high by 8” (20.5cm) wide. It contains switches, keys, LEDs, and displays for
controlling the unit and indicating its operational status.

Color Coding and Marking. The front panel functions are color coded to tie
together associated functions:

GRAY Store and Recall Keys, normal 2-wire or 4-wire interface

select, dialing mode select

BLACK Pair reversal
GREEN Send (Transmit, TX) functions
BLUE Measure (Receive, RX) functions
VIOLET Auxiliary functions, associated with measure functions

Some of the measure (blue) functions that always work together with certain
auxiliary (violet) functions are enclosed with a black border; these are referred to
as Function Boxes. See ¶9.1 and Figure 9-2.

October 17, 2000 0022-S03.G_ 231

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AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

Unit Status. After setting up a test, Function LEDs remain on to indicate the

function is enabled. The status of the unit can thus be determined at a glance.
The Send and Measure functions have prompt-driven DATA and PARAMETER
DISPLAYS which are scrolled through to make readings and set parameters.

Keys. All push-button keys are discrete switches, non-membrane type, and offer
good visual, tactile and audible feedback. All indicators, including the display,
are LEDs and should never need replacement. The unit is controlled by pressing
keys arranged along the left and bottom edges of an X-Y matrix of function LEDs.

Along the left edge of the front panel, there are five (5) Keys, which are used to
select one (1) of the five (5) horizontal rows of operating functions, LINE, SEND,
MEASure, AUXiliary, or Dialing (DP, TT, or MF).

Note: Because of space limitation, most of the keys along the left edge are not

located directly next to the function rows they control. Carefully follow
the color coding which associates a key with the horizontal function row
that it enables.

Along the bottom edge of the front panel, there are 16 Function Enable Keys
referred to as [1], [2], [3], [4], [5], [6], [7], [8], [9], [0], [*], [#], [A], [B], [C], [D].
A Function Enable Key is used to enable the function that is located vertically
above it, within the function row that is enabled at the time the key is pressed.

• For example, press [SEND] key (item 11 in Figure 3-1); SEND LED lights.
Then press [7]. Return Loss send function is enabled (RET LOSS LED lights).
Then, repeatedly press [7] to step through the three (3) Return Loss send
DATA DISPLAYS.

• When [D] is pressed with either SEND or MEAS row enabled, the PARAM SET
LED (green) lights, and the PARAMETER DISPLAY(S) appear, if present. If
thee is no PARAMETER DISPLAY for the function enabled, the PARAM SET
LED does not light. When a PARAM SET LED is on, the 16 keys along the

bottom edge are used to set parameter values.

• When Dialing Mode (DP, TT, MF) is enabled (using item 8 in Figure 3-1),
pressing a key along the bottom edge causes the respective digit to be dialed
(outpulsed).

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Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

See Section 4 for a full explanation of key operation.

3.4 FRONT PANEL COMPONENTS

The numbering of the descriptions below corresponds to the numbering of the
components in Figure 3-1.

1. Power On/Off Push Button

Note: When using AC power, observe CAUTION in ¶3.5 before turning on

power.

Push button IN to turn power ON. Push button again (button will pop OUT) to
turn power OFF.

Button in

= Power ON

Button out

= Power OFF

See Section 2 for power considerations.

2. TX/2W Bantam Jack

For 2-wire circuits (2W LED on): Connect the 2-wire pair to this jack.
Signals are both transmitted and received over this same pair of contacts.

For 4-wire circuits (4W LED on): Connect the send (transmit, TX) pair, over
which the AM5XT/eXT sends signals.

For reverse (REV LED on): This pair becomes the receive pair, RX, over
which the AM5XT/eXT receives signals.

See Figure 3-6 for mating cables.
The connections of this jack are the same as screw terminals T and R on the

Rear Panel, item 10 in Figure 3-3.

3. RX Bantam Jack

For 4-wire circuits (4W LED on): Connect the receive pair, RX, over which
the AM5XT/eXT receives signals. For 4-wire reversed (REV LED on): this pair
becomes the send (transmit, TX) pair, over which the AM5XT/eXT sends
signals.

October 17, 2000 0022-S03.G_ 229

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AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

For 2-wire reversed (REV LED on), signals are both transmitted and received
over this pair of contacts.

See Figure 3-6 for mating cables.
The connections of this jack are the same as screw terminals T1 and R1 on the

Rear Panel, item 9 in Figure 3-3.

4. Monitor Switch

Three-position switch used to select the point to which the internal
amplifier/speaker is connected.

TX (Transmit): Connects the internal amplifier/speaker to the output of
the signal generator.

MEAS (Measure): Connects the internal amplifier/speaker to the output of
the receive circuit auto ranging amplifier and associated filters. This
considerably increases the volume of the speaker and is useful to monitor
low level signals. The signal is always in an 18 dB range for input
signals ranging from -65 to +10 dBm. This setting is particularly useful
for audibly monitoring the residual noise in notched noise and S/N ratio
measurements.

RX (Receive): Connects the internal amplifier/speaker to the signal being
measured. The possibilities are:

• RX (receive) pair of the 4-wire circuit under test.

• 2-wire circuit under test.

• if measuring 2-wire Return Loss, the receive pair of the Internal

Hybrid.

• if measuring Noise-to-Ground, the Noise-to-Ground circuit.

5. Carrying Handle

Thick, soft, flexible plastic handle on right panel. Extends for use, retracts
against case when not in use. The Carrying handle is not installed when the
19” Rack Mounting Kit is installed.

6. 16 Function Enable Keys

See explanation in ¶3.3 under “Keys”.

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3-5

Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

7. Rubber Feet (portable version only)

Set of four (4) Rubber Feet on the bottom panel. Behind the front pair of feet
are hinged plastic supports that can be swung forward (snap into place) to
raise the front and tilt the unit for easier viewing of the Front Panel. In
addition, there is a set of four (4) rubber feet on the left panel on which the
unit can be conveniently set after transporting with the Carrying Handle
(item 5).

8. Dialing Mode Enable Key

Repeatedly press as necessary to enable desire Dialing Mode, indicated by
lighting of respective LED.

DP = Dial Pulse
TT = Touch Tone
MF = Multi-Frequency

See Section 10 concerning Dialing.

9. Auxiliary Function Row Enable Key

This is referred to as the [AUX] key. Press to enable the Auxiliary Function
Row. AUX LED is on when this row is enabled. The Display MEAS LED (item

16) also lights. See Section 9 concerning Auxiliary Functions.

10. Measure Function Row Enable Key

This is referred to as the [MEAS] key. Press to enable the Measure Function
Row. MEAS LED is on when this row is enabled. The Display MEAS LED
(item 16) also lights. See Section 8 concerning Measure Functions.

11. Send Function Row Enable Key

This is referred to as the [SEND] key. Press to enable the SEND Function
Row. SEND LED is on when this row is enabled. The Display SEND LED
(item 16) also lights. See Section 7 concerning Send Functions.

12. Line Function Row Enable Key

This is referred to as the [LINE] key. Press to enable the Line Function Row.
LINE LED is on when this row is enabled. See Section 7 concerning Send

Functions.

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3-6

AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

13. Microphone

Three holes labeled TALK. The Microphone is located behind the Front
Panel. Speak into the Microphone when in one of the TALK modes. See
¶7.14 for details.

14. Recall Key [RCL]

This key is used to recall and execute commands stored in non-volatile
memory, either front panel setups or dialed numbers. Up to 40 front panel
setups can be recalled. See Section 11 for details. Up to 10 dialed numbers
can be recalled, each with up to 48 digits. Also, the last dialed number can
always be recalled and redialed using this key. See ¶10.2 and 10.3 for
details.

15. Store Key [STO]

This key is used to store commands in non-volatile memory, either front
panel setups or dialed numbers. Up to 40 front panel setups can be stored.
See Section 11 for details. Up to 10 dialed numbers can be stored, each with
up to 48 digits. See ¶10.2 for details.

16. Display LEDs, SEND and MEASure

These LEDs indicate what function is being viewed on the Display. One of
these LEDs is always on.

SEND on = enabled SEND function being viewed on the Display.
MEAS on = enabled Measure function being viewed on the Display.

The SEND Display LED automatically lights when the [SEND] key (item 11) is
pressed. The MEAS Display LED automatically lights when either the [MEAS]
key (item 10) or [AUX] key (item 9) is pressed.

17. Left LED Display

This is a red LED display with four (4) 7-segmented characters with floating
decimal points. The type of reading (Send Function or Measure Function) is
indicated by the LEDs to the left of this display; see item 16. The unit of
measurement is indicated by LEDs located to the right of this display. See
item 18.

0022-S03.G_ 229 October 17, 2000

3-7

Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

18. Units of Measurement LEDs

Each of these LEDs is labeled with a unit(s) of measurement. One of these
LEDs is lit, as appropriate, to indicate the unit of measurement for a
numerical value displayed in the left display (item 17).

relative zero reference

can be established

at any point

-90 -80 -70 -60 -50 -40 -30 -20 -10 0 +10 dBm

0 +10 +20 +30 +40 +50 +60 +70 +80 +90 +100 dBrn

arbitrary zero reference
for noise measurement

intensity of

1 milliWatt

of power

Figure 3-2. Level and Noise Units of Measurement

The possible units of measurement are explained as follows:

dB

The deciBel (dB) is a logarithmic (base 10) electrical unit used to
compare or indicate changes in level. The dB unit is only a relative unit
however, and does not have a meaning unless a point of reference is
established. Thus the systems of dBm and dBrn were established as
described below.

dBm
To establish a point of reference in making comparisons in level (and
noise for CCITT standard) measurements in transmission testing, the

system of dBm was adopted.

00.0 dBm is defined as the level of one (1) milliWatt of power, hence the

abbreviation “m” after the dB. Levels of less power than this reference
point are negative, -dBm values; and levels of greater power are positive,

+dBm values. See Figure 3-2.

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3-8

AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

It turns out that 00.0 dBm is a strong level for a telephone line, so most of
the level measurements in units of dBm are negative, i.e., less power than
the 00.0 dBm reference. For example, -10.0 dBm is a typical level at
which dialing tones are sent.

dBrn (AM5XT only)
The dBrn unit is used in noise level measurements, “rn” meaning relative
noise. Note in Figure 3-2 that the zero reference for noise measurement
has been established at -90 dBrn, an extremely low level for a telephone
line. Thus, noise measurements will always be positive (higher level)
with respect to the 00.0 dBrn reference.

Absolute and Relative Measurements. An absolute level measurement is
made in units of dBm, as described above. A relative measurement is in
units of dB. A zero point of reference is established at any level, and
subsequent level measurements are made relative to that level. See ¶9.9
for an explanation of how relative measurements are used.

mSEC

milli-seconds. One mSEC = one thousandth of a second. Unit of
measure in Envelope Delay.

HOLD TONE. This LED lights when a valid Holding Tone is present at the
receive port. A valid Holding Tone is required for Notched Noise, S/N Ratio,
Phase Jitter, Amplitude Jitter, and Transient Tests. This LED must be on for
these tests to be valid. A Holding Tone is nominally 1004 Hz. See Table
3-1 for Holding Tone range specifications, which depend on the type of
measurement.

Table 3-1. Acceptable Holding Tone Ranges

Acceptable Range Type of Measurement

990 Hz to 1030 Hz Phase Jitter and Amplitude Jitter
995 Hz to 1025 Hz All other Holding Tone tests

0022-S03.G_ 229 October 17, 2000

3-9

Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

19. Metal Case

This is a sturdy aluminum case, painted blue. with a steel rear panel. For
portable units, if the optional canvas Padded Carrying Case is not ordered, a
removable snap-on cover is supplied to protect the front panel during
transport. For fixed installations, an optional 19" Rack Mounting Kit
(installed at the factory) can be ordered.

20. Right LED Display

This is a red LED display with four (4) 7-segmented characters with floating
decimal points. The type of reading (Send Function or Measure Function) is
indicated by the LEDs on the far left of the display area; see item 16. The unit
of measurement is indicated by LEDs located to the right of this display. See
item 21.

21. Units of Measurement LEDs

Each of these LEDs is labeled with a unit(s) of measurement. One of these
LEDs will light as appropriate to indicate the unit of measurement for a

numerical value displayed in the right display (item 20). The possible units
of measurement are explained below.

kHz = Kilo-Hertz = 1000 Hertz = 1000 cycles per second.

Note: All frequencies are expressed in kHz, not Hz. A common mistake is

to try to set a frequency value and enter it as if it were expressed in
Hz instead of kHz. For example, enter 1004 Hz as 1.004 kHz (be sure
to enter the decimal point between the 1 and the 0). If an attempt
were made to enter this as 1004 without the decimal point, the
display would default to 200 kHz, the maximum possible value for a
frequency. Thus, if the display “mysteriously” shows 200 kHz
instead of the value entered, the frequency was entered as if it were
in units of Hz. Reenter the correct value in units of kHz, with a
decimal point in the appropriate place.

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AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

SEC = Seconds (time).
PAR = (Peak-to-Average Ratio) units. See ¶8.8.
MIN = Minutes.
% = Percent.
CNT = Counts.
DEG = Degrees.

22. Volume Control Knob

This controls the volume of the speaker, item 23. Turn clockwise to increase
speaker volume and turn counter-clockwise to decrease speaker volume.

23. Speaker

This is located on the top of the unit near the front. The speaker is connected
to a monitor point determined by the position of the Speaker Monitor Switch,
item 4. Speaker volume is controlled by the Volume Control Knob, item 22.

3.5 REAR PANEL COMPONENTS

The numbering of the descriptions below corresponds to the numbering of the
components in Figure 3-3.

10

9

0022-S03.G_ 229 October 17, 2000

87 6

11

5

Figure 3-3. Rear Panel Components

3-11

1312

123

4

Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

1. AC Power Selector Switch

115V/230V. Red slide switch. Before plugging in the power cord, set this
switch to match the power source to which the power cord is to be connected,
either 115 VAC or 230 VAC.

CAUTION: Observe the CAUTION printed on the back of the unit. When

!

2. Step-Down Transformer

Part of the power supply.

3. Foot/Guard

Two places. The unit can be stood on end, resting on these rubber-coated
supports. They protrude to allow clearance for rear panel components and
rear-mounted cables.

connected to a 230 VAC source, be sure to set this switch to
the 230V position before turning on the power. Damage to the
unit will result if 230 VAC is applied with this switch set to
115V.

4. Fuse Holder

With slotted cover. Unscrew with common blade screwdriver to
inspect/replace the fuse. The fuse is 1/2 amp, 250V.

5. Power Plug

Three pronged male, for 115 or 230 VAC. Mating power cord is supplied. Be
sure AC Power Selector Switch (item 1) is in correct position.

6. Recorder Outputs (optional)
These Bantam Jacks, labeled “A” and “B”, are the outputs of the X-Y Plotter,

Option 25-0045. See ¶3.6 and Section 13 for details concerning the plotter
function. In general, these contacts are used as follows:

“A” Bantam Jack: Sleeve = ground

Tip = not used
Ring = auxiliary logic output

“B” Bantam Jack: Sleeve = ground

Tip = Plot X or auxiliary logic output
Ring = Plot Y or auxiliary logic output

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AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

7. Screw Terminal, Ground

This is the same connection as the Sleeve contacts on the front-panel Bantam
Jacks (items 2 and 3 in Figure 3-1). Use this ground as the reference ground
in the Noise-to-Ground test (¶8.6).

8. Screw Terminals, T1, R1

These are the same connections as the Tip and Ring of the right front-panel
Bantam Jack (item 3 in Figure 3-1. See ¶3.4,3).

9. Screw Terminals, T, R

These are the same connections as the Tip and Ring of the left front-panel
Bantam Jack (item 2 in Figure 3-1. See ¶3.4,2).

10. RS232 Connector (optional)
25-pin male DB25, only with units equipped with Option 25-0019. Connector

pin assignments are listed in Table 3-2.

Table 3-2. RS232 Connector Pin Assignment

PIN FUNCTION DIRECTION

2 TD Transmit Data From AM5XT/eXT
3 RD Received Data To AM5XT/eXT
4 RTS Request to Send Not Used
5 CTD Clear to Send Not Used
7 GNF Common ---­9 +V +Power (+12 Vdc) From AM5XT/eXT
10 -V -Power (-12 Vdc) From AM5XT/eXT
20 DTR Data Terminal Ready Not Used
22 RI Ring Indicator Not Used

A printer or terminal can be connected here. This connector is also used to
connect the unit in a chain if this is other than the first unit in the chain. See
Section 12 concerning RS232 port operation.

Note: This area is filled with a plastic cover if the unit is not equipped with

the RS232 option.

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3-13

Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

11. 8-Switch DIP Switch

Table 3-3 lists the switch functions and positions. An abbreviated list, item
13, is given on the rear panel.

Table 3-3. DIP Switch Settings

DIP SWITCH FUNCTION CODE

1 & 2 Set Baud Rate 1 OFF, 2 OFF = 300 BAUD

3 Parity Enable ON = PARITY, OFF = NO PARITY
4 Parity Select ON = EVEN PARITY, OFF = ODD PARITY
5 Not Used ---­6 Not Used ---­7 Setup Protect ON = PROTECT, OFF = UNPROTECTED
8 Password Enable ON = Password needed, OFF = No Password needed

1 ON, 2 OFF = 1200 BAUD
1 OFF, 2 ON = 2400 BAUD
1 ON, 2 ON = 9600 BAUD

Switches 1 thru 4 control the operating characteristics of the RS232 port. See
Section 12 concerning RS232 port operation.

Switches 5 and 6 are not used.
Switch 7 protects/unprotects the front panel setups stored in non-volatile

memory. Note that Switch 7 does not protect Dialed Numbers stored in
non-volatile memory per ¶10.2.

Switch 8 controls the remote control password enable.

12. Auxiliary (AUX) RS232 Connector

9-pin female D-type miniature. This is used to connect to the RS232 port of
an auxiliary unit (printer, test access switch, etc.), installed near the
AM5XT/eXT. Use cable 48-0083 for this function. See ¶12.1 for details.
Available pins are listed in Table 3-4.

Table 3-4. Auxiliary RS232 Connector Pin Assignment

Pin Function Direction

2 RD Received Data To AM5XT/eXT
3 TD Transmit Data From AM5XT/eXT
7 GND Common ----

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3-14

AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

Baud Rate and Parity are the same as those of the main RS232 port (set with
Switches 1 thru 4 of the DIP switch, item 11).

13. List of DIP Switch Settings

See Table 3-3 for detailed information on settings.

3.6 OPTIONAL EQUIPMENT

This paragraph describes features that can be made a part of the AM5XT/eXT when
specially ordered. See ¶3.7 and 3.8 for accessories that can be specially ordered
to use with the AM5XT/eXT.

Sealed Lead Acid Batteries and Integral Charger, Option 24-0017

When fully charged, these batteries allow 5 to 8 hours of cordless (no
commercial power) operation. See ¶2.2 for details.

RS232 Port, Option 25-0019

The RS232 port is required for printouts and external control of the AM5XT/eXT
from a terminal or computer. The RS232 port makes possible additional
functions and capabilities that cannot be done with the front panel controls alone.
A unit equipped with this option has an RS232 connector (item 10 in Figure 3-3)
on the rear panel. See Section 12 concerning RS232 port operation.

19” Rack Mounting Kit, Option 85-0076

Order this option if the unit is to be mounted in a 19” relay rack. The Carrying
Handle and Rubber Feet are not included when this option is ordered.

X-Y Plotter Outputs, Option 25-0045

Voltages are delivered to rear panel Bantam Jacks, which are connected to an
external plotter for hard copy graph of test results. A unit equipped with this
option has two (2) Bantam Jacks (item 6 in Figure 3-3) on the rear panel. See
¶13.1 for details. This option is not available for an AM5XT-BASIC.

Delete Front Panel, Option 25-0020

RS232 Port, Option 25-0019, must also be ordered. The Front Panel is deleted for
exclusive remote control of the unit through the RS232 Port when front panel
manual control will never be needed.

0022-S03.G_ 229 October 17, 2000

3-15

Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

Siemens Adapter, Option 25-0041 (AM5eXT only)

This brings the line connections to two (2) 3-socket connectors, designed to mate
with lines that are connected with a 3-pronged Siemens-type Banana connector, a
standard in some European countries. These connectors are mounted on the
bottom of the AM5eXT, flush with the front panel.

3.7 AM-47XT HAND-HELD PRINTER (Optional)

The AM-47XT Hand-Held Printer is designed to be used with an AM5XT or AM5eXT
to provide a hard copy of the measurements and setups.

Operating Instructions

See ¶13.1.

Technical Specifications

Table 3-5. AM-47XT Technical Specifications

CHARACTERISTICS SPECIFICATIONS

Input Signal Serial ASCII RS232 (modified for plot function)
Input Connector 4-Wide Modular Jack
Input Speed 300, 1200, 0r 9600 Baud with 1500 Character FIFO Buffer
Print Type 6 x 8 Impact Dot Matrix
Paper 2.25”w x 1.8” Dia. Adding Machine Paper (Part No. 26-0014)
Ink Supply Replaceable Inked Ribbon Cartridge (Part No. 26-0015)
Characters per Line 40
Print Speed 0.4 Lines per Second
Power Internal NiCad Battery Pack with Built-in Charger
Battery Life Approximately 7,000 Lines
Charge Time 8 to 14 hours
Size 7.6”L x 3.4”W x 1.9”D
Weight 1.5 lbs.
Cables Printer Cable (48-0095) and AC Adapter (70-0029), supplied

October 17, 2000 0022-S03.G_ 229

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AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

Component Locations

See illustration in Figure 3-4.

PUSH UP HERE

TO REMOVE COVER

PAPER ROLL

COMPARTMENT

PAPER CUTTER

BATTERY CHARGE/

PAPER FEED

BUTTON

POWER LED

Ameritec

HAND-HELD PRINTER • Model AM-47XT

PAPER

ADVANCE

POWER

OFF ON

DATA RECEIVE LED

POWER

9VDCINSIGNAL

IN

BAUD RATE

ADJUST

SIGNAL

BAUD

300
1200
9600

TOP VIEW

POWER SWITCH

AC ADAPTER PLUG BAUD RATE DIP SWITCH

END VIEW

Figure 3-4. Hand-Held Printer, Component Location

0022-S03.G_ 229 October 17, 2000

3-17

Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

Connectors, Cables

The connectors are used with the AC Adapter (70-0029) and the Printer Cable
(48-0095), shown in Figure 3-5. Both of these cables are supplied with the
AM-47XT.

25-PIN D
FEMALE

2.5mm JACK

4-WIDE
MODULAR

PRINTER CABLE 48-0095, 3 FT.

110 VAC ADAPTER 70-0029, 6 FT.

Figure 3-5. Standard Cables Supplied with the AM-47XT Printer

Power

Power is supplied by an internal NiCad battery pack. There is an internal
charging circuit in the printer that operates when the AC Adapter is plugged in.

Power Switch

See charging instructions in ¶13.1 concerning the position of this switch during
charging and operation.

2-Position DIP Switch

This is used to set the BAUD Rate (300, 1200, or 9600). Settings are indicated in a
table on the label above the switches.

Note: Printer Power Switch must be OFF when changing Baud Rate on the

AM-47XT. Moving DIP switches with the Printer Power Switch ON does

not change the Baud Rate until the Printer is switched OFF and then
switched ON again.

LEDs

The LEDs light as described below:

1. The POWER LED lights continuously when the AC Adapter is connected

and the battery pack is charging (starts charge cycle each time power is
turned ON).

October 17, 2000 0022-S03.G_ 229

3-18

AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

2. The POWER LED blinks when power is ON and the battery pack has been

charged.

3. The SIGNAL LED lights when data is being received from the AM5XT/eXT.

Printing Mechanism

Printing mechanism is dot matrix impact type with replaceable ribbon cartridge.
Standard-width adding machine paper is used. The ribbon cartridge and paper
roll are housed within the case. The printout is in 40-column format, at a speed
of 0.4 lines per second.

Ribbon Cartridge Replacement

Refer to Figure 3-6. For replacement ribbon cartridges, order Part No. 26-0015.

1. Push up on end of housing to remove paper roll compartment cover.

2. Observe how ribbon is routed on the old cartridge.

3. Push on end or cartridge as indicated in Figure 3-6 to eject old cartridge.

4. Snap in new cartridge, being careful to insert ribbon correctly.

5. Rotate manual ribbon take-up to apply tension to the ribbon.

6. Re-install compartment cover.

Paper Roll Installation

Refer to Figure 3-6. For additional rolls of paper, order Part No. 26-0014.

1. Push up on end of housing to remove paper roll compartment cover.

2. Install paper roll in cradle and feed paper into slot.

3. Push [PAPER ADVANCE] button to route paper through printer.

4. Re-install compartment cover.

0022-S03.G_ 229 October 17, 2000

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Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

PAPER ROLL

RIBBON

MANUAL

RIBBON

TAKE-UP

RIBBON CARTRIDGE

PAPER CUTTER

PUSH DOWN

HERE TO

EJECT RIBBON

CARTRIDGE

PAPER ROLL COMPARTMENT

PUSH (PAPER ADVANCE)

BUTTON TO ROUTE

PAPER THROUGH

3

FEED PAPER

INTO SLOT

2

1

INSTALL

PAPER

ROLL

PAPER ROLL INSTALLATION

Figure 3-6. Ribbon and Paper Installation for AM-47XT

Self Test

For a printout of all possible characters, hold down the [PAPER ADVANCE] button
and set the POWER switch to ON. Self test printouts will continue to output until
the [PAPER ADVANCE] button is released.

Charging Considerations

The AM-47XT NiCad battery pack is charged through the AC Adapter (70-0029).
See Figure 3-7 for connection.

October 17, 2000 0022-S03.G_ 229

3-20

AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

115 VAC
WALL JACK

AM-47XT
HAND-HELD PRINTER

AC ADAPTER
(70-0029) 6 FT

PRINTER CABLE
(48-0095) 3 FT

NOTE: LINE CONNECTION CABLES NOT SHOWN

OFF ON

Ameritec

H

A

N

D

-H
ELD

PR

PAPER

ADVANCE

POWER

POWER

9VDC

IN

SIGNAL
IN

PAPER CUTTER

IN

TER

• M

odel A

M

-47

SIGNAL

RS232

AM5XT
(REAR VIEW)

Figure 3-7. Printer Hookup

0022-S03.G_ 229 October 17, 2000

3-21

Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

Charging is controlled by a microprocessor that is programmed to run the
charging circuitry without sensing the actual charged or discharged state of the
battery pack.

With the AC Adapter connected, each time the power is turned ON, the
microprocessor assumes the worst case and goes into a full 14-hour charge cycle.

With the AC Adapter connected and the power OFF, the AM-47XT is charged with
a very low trickle current which takes several days to charge the battery pack.

Note: The AM-47XT is normally charged with the power ON even though many

other devices are typically charged with the power OFF.

The AC Adapter can be left continuously connected to the AM-47XT. There is no
danger of “overcharging” the battery pack.

After the charging cycle, the POWER LED will blink. Also after the charging
cycle, a timer is set which will start the charge cycle again after it is decremented
to zero. Each time a line is printed, the timer is decremented a certain amount. If
the POWER switch is left ON, the AM-47XT can print about 7,000 lines before the
timer is decremented to zero and a new charge cycle is initiated.

There are two (2) charging procedures:

1. A normal procedure.

2. A procedure if the battery pack is completely discharged.

Normal Charging Procedure

Connect AC Adapter (70-0029) as shown in Figure 5-2. Turn POWER switch ON
and note POWER LED. If LED lights, unit is charging. If LED does not light,
battery pack is completely discharged; go to next charging procedure.

When charging cycle is complete (after about 14 hours), POWER LED will blink.

Note: Each time power is turned ON with the AC Adapter connected, the

AM-47XT will go through a complete charging cycle, regardless of the

charge of the battery pack..

October 17, 2000 0022-S03.G_ 229

3-22

AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

Charging Procedure When Battery Pack is Completely Discharged

Connect AC Adapter (70-0029) as shown in Figure 5-2. Turn POWER switch ON
to verify POWER LED does not light. Turn POWER switch OFF. This will initiate
a trickle charge that will charge the battery pack enough to operate the
microprocessor-controlled charging circuitry. Leave the POWER switch OFF for
about one (1) hour.

Turn the POWER switch ON. The POWER LED will now light continuously,
indicating that the full charge cycle has begun. After about 14 hours, the POWER
LED will start to blink, indicating that charging is complete.

3.8 ACCESSORIES

The items described in this paragraph are not automatically supplied with the
AM5XT/eXT; they must be added to the order per customer request. See ¶3.7
concerning the AM-47XT Hand-Held Printer.

Line Cables

Bantam Plug Line Cables are illustrated in Figure 3-8, along with their lengths
and part numbers.

BANTAM PLUG

BANTAM PLUG

BANTAM PLUG

CABLE 48-0047, 6 FT.

CABLE 48-0048, 6 FT.

CABLE 48-0062, 6 FT.

310 PLUG

GREEN R

RED T

BLACK S

Figure 3-8. Bantam Plug Line Cables

Each of these cables can be used for a front-panel line connection, mating to the
Bantam Jacks (items 2 and 3, Figure 3-1) in the upper right-hand corner of the
unit.

0022-S03.G_ 229 October 17, 2000

3-23

Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

Padded Carrying Case, Model No. 87-0070B

This case is ideal to protect and carry the AM5XT/eXT and AM-47XT Printer while
field testing. The AM5XT/eXT could be operated without removing it from the
case. This case is constructed of green/gray heavy canvas, filled with foam
padding. Other features are listed below:

• Case dimensions: approximately 11”L x 5”W x 13”H (28cmL x 13cmW

x 33cmH).

• Side pocket with individual Velcro fastened cover flap, designed to carry
AM-47XT Hand-Held Printer.

• Hand-carrying strap and padded shoulder carrying strap.

RS232 Cables

Cables that can be used with the RS232 Port are illustrated in Figure 3-9, along
with their lengths and part numbers.

October 17, 2000 0022-S03.G_ 229

3-24

AM5XT/eXT Voice/Data Transmission (18-0022) Physical and Functional Description

5
6
7
8
9
10
15
20
22
25
2
3
7

RED
GREEN

BLACK

AM5XT/eXT
STRAPPING

2
3
5
6
7
8
9
10
15
20
22
25

TO INPUT OF DEVICE
FROM OUTPUT OF DEVICE

TO GROUND OF DEVICE

DB 25 PIN FEMALE

RS232 UNIVERSAL CABLE 48-0012

DB 25 PIN

FEMALE

PRINTER/TERMINAL/CRT CABLE 48-0084

7 FEET

INTERCONNECTIONS

7 FEET

DB 25 PIN

MALE

SPADE LUGS

PRINTER
STRAPPING

RED (TX —>)

GREEN (RX <—)

BLACK (Signal GND)

4
5
6
7
8
9
10
15
20
22
3
2
7

4 FEET

DB 25 PIN

2
3
7

FEMALE

INTERCONNECTIONS

CHAINING CABLE 48-0083

DB 9 PIN

MALE

2
3
7

Figure 3-9. RS232 Cables

Each of these cables mates to the RS232 port connector (item 10, Figure 3-3).
See Section 12 for applications that use these cables.

0022-S03.G_ 229 October 17, 2000

3-25

Physical and Functional Description (18-0022) AM5XT/eXT Voice/Data Transmission

3.9 MASK FEATURE (Optional)

This feature provides eight sets of performance limits (masks) that are applied to
Level/Freq and Delay sweep results to determine whether a line is measuring
according to its specifications. When the measurement results are within limits,
the printer/plotter output is normal. When a measurement result is outside the
mask, an indication of the error is recorded on the printer plot.

There are eight different performance masks to select from, each with eight
different limit specifications. A mask is selected using the “Cond” parameter for
Level/Frequency or Group Delay measurements. Stored memory recalls 81 to 88
are also reserved for this purpose. Masks are recalled independently from LINE
parameters or MEASUREMENT setups.

A printer plot output of a mask specification allows a graphic display of the
mask. This plot uses the same scaling parameter as a normal printer plot, so it
can be compared with an actual plot of the line under test.

October 17, 2000 0022-S03.G_ 229

3-26

AM5XT/eXT Voice/Data Transmission (18-0022) Self-Test and Operation Techniques

4. SELF-TEST AND OPERATION TECHNIQUES

4.1 INTRODUCTION

This section describes procedures to verify that the AM5XT/eXT is working
properly. Refer to Figure 3-1 for front panel details. Some important operation
techniques are discussed in this section.

4.2 SELF-TEST SETUP

These tests are done with the AM5XT/eXT looped back on itself, not connected to
any external equipment. The signals sent (generated) through the Transmit (TX)
port are routed directly back to the Receive (RX) port through a Bantam cable
plugged into the front panel jacks or through a pair of wires attached to the rear
panel screw terminals (T to T1 and R to R1).

When the AM5XT/eXT is turned on, all LEDs and displays are lit for approximately
three (3) seconds. TEST PASS is then displayed. The unit then assumes its
default configuration.

4.3 SWITCH SETUP

Place Monitor Switch in the TX (Transmit) mode.
Press the LINE key. Turn off the BRDG LED by pressing [#]. Verify that the unit

is set for 600Ω TX, 600Ω RX, and 4W.
Verify that CMSG (PSHO for AM5eXT) is lit on the AUX line.

4.4 QUIET SEND MODE

Press the SEND key. The SEND LED lights. Press key [1] to activate QT (Quiet)
mode.

Press the MEAS key. The MEAS LED lights. Verify that the LVL/FREQ LED is lit.
The display should read “undr” with units “dBm”.

Press key [2] for NOISE. The display should read “undr” with units “dBrn”
(“dBm” for AM5eXT).

0022-S04.G_ 212 October 17, 2000

4-1

Self-Test and Operation Techniques (18-0022) AM5XT/eXT Voice/Data Transmission

4.5 SEND 1004 Hz

Press the SEND key. The SEND LED lights. Press key [2] to send 1004 Hz (at 00.0
dBm).

Note: Turn volume control up or down as desired to increase or decrease

volume of the speaker sound. The speaker is monitoring the 1004 Hz
tone being sent.

Press the MEAS key. The MEAS LED lights. Press key [1] for LVL/FREQ. The
display should read 00.0 ±1.0 dBm, 1.004 ±.002 kHz.

Press key [2] for NOISE. The display should read 90.0 ±1 dBrn (01.0 ±1.0 dBm for
AM5eXT).

Press key [3] for NOTCH NOISE. Note that the HOLD TONE LED is on (signal
being received). The reading on the display must be less than 40.0 dBrn and at

1.004 kHz (-50 dBm for AM5eXT). If the left display reads undr, the right display is
blank.

Press key [5] for S/N (signal-to-noise ratio). Note that the HOLD TONE LED is still
on. The display should read greater than 50.0 dB ( or should read over) and at

1.004 ±.002 kHz.
Verify that the JTR 20-300 LED is on in the AUX line.
Press key [0] for PHASE JTR. The display should read PJTr and 00.0 ±0.2 with the

DEG LED lit.
Press key [*] for AMP JTR. The display should read AJTr and 00.0 ±.2 with the %

LED lit.

4.6 SEND PAR

Press the SEND key. Press key [6] for PAR. The display should read 0.00 dBm
and PAr. Press the MEAS key. Press key [6] for PAR. The display should read

00.0 ±1.0 dBm and 100 ±2 PAR.

October 17, 2000 0022-S04.G_ 212

4-2

AM5XT/eXT Voice/Data Transmission (18-0022) Self-Test and Operation Techniques

4.7 SEND ENVELOPE DELAY (ENV DLY)

Press the SEND key. Press key [8] for ENV DLY. Press key [8] again to display

00.0 dBm and rEF.
Press the MEAS key. The display should read 3.965 ±.010 mSEC and 1.800 ±.002

kHz.

4.8 SEND IMD

Press the SEND key. Press key [9] for IMD. Press the MEAS key. The display
should read 00.0 ±.5 dBm and 4T. Press key [9]. The display should change to
OVER dB and 2 4T. Press key [9] again. The display should change to OVER dB
and 3 4T.

Press the SEND key. Press key [9]. The display should read 00.0 dBm and TEST.
Press the MEAS key. The display should read 30.0 ±.5 dBm and 3 4T. Press key
[9]. The display should read 00.0 ±.5 dBm and 4T. Press key [9] again. The
display should read 20.0 ±.5 dB and 2 4T. Press key [9] again. The display should
read 30.0 ±.5 dB and 3 4T.

4.9 AUTO CALIBRATE (Up to version 7* only)

Note: See ¶7.2, Display 5 to determine the software installed in the AM5XT/eXT

being used.

The AM5XT/eXT was calibrated at the factory for proper measurement accuracy by
loading certain values into internal RAM. RAM is maintained by a small internal
“super cap” (1 farad capacitor) with 30-day life. As long as the AM5XT/eXT is
connected to commercial power at least once each 30 days or if equipped with
the internal battery option, the RAM “super cap” will retain its charge indefinitely.

If the unit is not equipped with the internal battery option and is not connected to
commercial power for 30 days or more, the unit will require recalibration. This
is easily accomplished in the field. As part of the power-on self-test, the unit
automatically diagnoses itself and informs the operator of the need for
recalibration.

0022-S04.G_ 212 October 17, 2000

4-3

Self-Test and Operation Techniques (18-0022) AM5XT/eXT Voice/Data Transmission

If during the power-on self-test, the display indicates AUTO CAL?, proceed as
follows:

1. Remove all input leads.

2. Press the [AUX] key to enter AUX mode.

3. Press the [#] key.

4. Press the [D] key.

The unit will go through an auto-calibration process wherein the send/receive
pairs are internally looped. The internal signal generator sends 6 different levels
at 1004 Hz plus 1 level at PAR while the measurement circuitry calibrates itself.
This process takes approximately 30 seconds, following which the unit reverts to
normal operation.

4.10 CALIBRATION CHECK (Up to version 7* only)

When desired, the AM5XT/eXT can be forced into auto-calibration any time by
entering AUX mode and pressing the [#] key and the [ENTER] or [D] key. Make
certain that all input leads are disconnected during auto-calibration or erroneous
calibration will result.

4.11 CALIBRATION (Version 8* and up)

AM5XT/eXTs with version 8 and up software allow for complete field calibration
using only a high accuracy digital voltmeter. The voltmeter must read out in AC
Volts RMS and be accurate at 1000 Hz within .4%. Minimum input impedance
should be 200 kΩ.

CAUTION: Do not enable the FULL CAL unless you have a high accuracy digital

!

1. Disconnect all input leads from the AM5XT/eXT.

2. Connect the leads of the voltmeter to T1 and R1 either on the front right

3. Press the [AUX] key to enter the AUX mode.

4. Press the [#] key. The display reads AUTO CAL?

5. Press the [#] key again. The display reads FULL CAL?

October 17, 2000 0022-S04.G_ 212

voltmeter available. Corruption of calibration will result.

Bantam jack or rear terminal screws.

4-4

AM5XT/eXT Voice/Data Transmission (18-0022) Self-Test and Operation Techniques

6. Press any key (other than [D]) to abort the FULL CAL?

7. Toggle DIP Switch 5 to enable the FULL CAL?

8. Press the [D, ENTER] key. The display reads V1 on the left and four
dashes on the right. The PARAM SET LED is lit.

9. Enter the voltage shown on the voltmeter, with the decimal. The PARAM

SET LED blinks. The voltage should be larger than 1.200 and smaller than

2.600. Larger or smaller readings cannot be entered. If the reading is

outside this range, the unit must be repaired. Press the [D, ENTER] key to
enter the reading. The PARAM SET LED remains lit.

10. Press the [D, ENTER] key. The display reads V2 on the left and four
dashes on the right.

11. Enter the voltage shown on the voltmeter, with the decimal. The PARAM

SET LED blinks. The voltage should be larger than 0.250 and smaller than

0.450. Larger or smaller readings cannot be entered. If the reading is

outside this range, the unit must be repaired. Press the [D, ENTER] key to
enter the reading. The PARAM SET LED remains lit.

12. Press the [D, ENTER] key. The display is blank on the left and reads CAL?
on the right. The PARAM SET LED goes out.

13. Disconnect the voltmeter from the AM5XT/eXT.

14. Press the [D, ENTER] key. The unit begins to calibrate itself. This
process takes approximately 4 minutes. After calibration is completed,
the unit goes into operating mode and is ready for use.

4.12 PARAMETER SET

The Parameter Set mode is used with Send and Measure functions to
change/adjust the signal level, variable frequency, and sweep parameters. To
enter Parameter Set mode:

1. Press the [SEND] or [MEAS] key to enable the Send or Measure function
row.

2. Press [D].

0022-S04.G_ 212 October 17, 2000

4-5

Self-Test and Operation Techniques (18-0022) AM5XT/eXT Voice/Data Transmission

3. The PARAM SET LED lights. Press [D] to step to the next parameter.
Press [C] to step to the previous parameter.

It is important to note that the PARAM SET LED indicates the state of the values
entered/changed:

• If the PARAM SET LED is ON, the value displayed is entered into the
AM5XT/eXT. The value can be changed with the number keys, or in

increments with the up and down arrow keys.

• If the PARAM SET LED is BLINKING, the value displayed has been changed
but not entered. Press [D] to enter or press [C] to cancel the value and
revert to the previous value.

• If the PARAM SET LED is OFF, all values have been entered and the user
is able to begin testing

To exit Parameter Set mode, press the [SEND] or [MEAS] key again.

4.13 DATA DISPLAYS

Data Displays are accessed by pressing the same key that is used to enable the
function. For example, RETURN LOSS has three types of white-noise test tones.
Refer to ¶7.8, Displays 1, 2, and 3.

1. Press the [SEND] key.

2. Press [7] to select Echo Return Loss (ErL).

3. Press [7] again to select Singing Return Loss-Lo (SrLL).

4. Press [7] again to select Singing Return Loss-Hi (SrLH).

5. Press [7] again to return to Echo Return Loss (ErL).

October 17, 2000 0022-S04.G_ 212

4-6

AM5XT/eXT Voice/Data Transmission (18-0022) Connection & Configuration

5. CONNECTION AND CONFIGURATION INSTRUCTIONS

5.1 INTRODUCTION

This section describes the AM5XT/eXT connections and configurations made in
preparation for testing. It is divided into the following paragraphs:

5.2 General

5.3 Connectors and Cables

5.4 Line Termination Impedances

5.5 Configurations

In ¶5.5, basic operating instructions are given for testing with the Western
Electric 829 loopback device, and also with Ameritec Responders.

5.2 GENERAL

Low-Level Measurements

Power the AM5XT/eXT with batteries when making a low-level noise
measurement. Do not use AC power for this test because interference from the
AC source can affect the measurement.

Independent Send and Measure Modes

The Send, Measure, and Filter modes of the AM5XT/eXT operate independently.
Almost any combination of Send, Measure, or Filter can be selected. However,
depending on the setup, the resulting measurements may or may not be valid.

For example, a 1004 Hz holding tone must be sent for various measure modes,
and a PAR waveform must be sent when PAR is measured. If the 1004 Hz tone or
PAR waveform were not present in the corresponding measurement, the
measurement would not be valid. The AM5XT/eXT configuration (see ¶5.5)
determines in what part of the system the signals need to be sent and measured.

The correct Send, Measure, and Filter modes are indicated for each test described
in the operating instructions of Sections 7 and 8.

0022-S05.G_ 218 October 17, 2000

5-1

Connection & Configuration (18-0022) AM5XT/eXT Voice/Data Transmission

5.3 CONNECTORS AND CABLES

See Figures 3-2 and 3-3 for illustrations of the AM5XT/eXT connectors and cables.
Note that some cables are standard and others are optional. Connect the
appropriate cable(s) described in this paragraph according to the desired
application.

AC Operation

Connect the power cord (supplied) to the three-pronged connector on the rear
panel of the unit. Connect the other end into a standard 115 or 230 VAC wall
socket. Note that positioning of the red 115/230 switch near the AC connector on
the unit for proper setting.

CAUTION: Severe damage will occur to the unit if set for 115 VAC and connected

!

Printer Cables

There are two (2) types of cables used with printers. The 48-0095 is used with the
AM-47XT Hand-Held Printer. The 48-0078 is used to connect to most other 25-pin

female serial EIA printers. There is also a 48-0083 cable used to connect an EIA
Serial ASCII type device to the AUX port of the AM5XT/eXT.

to the 230 VAC power.

Figure 5-1 shows the connections for the AM-47XT Hand-Held Printer.

October 17, 2000 0022-S05.G_ 218

5-2

AM5XT/eXT Voice/Data Transmission (18-0022) Connection & Configuration

115 VAC
WALL JACK

AM-47XT
HAND-HELD PRINTER

AC ADAPTER
(70-0029) 6 FT

PRINTER CABLE
(48-0095) 3 FT

NOTE: LINE CONNECTION CABLES NOT SHOWN

OFF ON

Ameritec

H

A

N

D

-H
ELD

PR

PAPER

ADVANCE

POWER

POWER

9VDC

IN

SIGNAL
IN

PAPER CUTTER

IN

TER

• M

odel A

M

-47

SIGNAL

RS232

AM5XT
(REAR VIEW)

Figure 5-1. AM-47XT Hand-Held Printer Connection with AC Power

See ¶13.1 for operating instructions for printing.

0022-S05.G_ 218 October 17, 2000

5-3

Connection & Configuration (18-0022) AM5XT/eXT Voice/Data Transmission

Line Connection Cables

There are three (3) Bantam cables illustrated in Figure 5-2 that are used for line
connections. Use these cables as required to connect the AM5XT/eXT to 2-wire or
4-wire lines.

BANTAM PLUG

BANTAM PLUG

BANTAM PLUG

CABLE 48-0047, 6 FT.

CABLE 48-0048, 6 FT.

CABLE 48-0062, 6 FT.

310 PLUG

GREEN R

RED T

BLACK S

Figure 5-2. AM5XT/eXT Connection Cables

Note: The rear panel screw terminals and Bantam jacks are wired in parallel,

resulting in the identical connection by using either type.

AM5XT/eXT Interface with Line Connections

The state of the Line Reverse LED determines the connection of the AM5XT/eXT
internal circuitry to the 2-Wire or 4-Wire lines. The connections for the different
settings are listed below:

2W Connects together the internal measurement circuitry and signal

generator across the 2-Wire line at the TX jack. The signal generator
source impedance of 135Ω, 600Ω, 900Ω, or 1200Ω (determined by
the line selections) terminates the line in all signal generator modes
except OPEN.

4W Connects the internal measurement circuitry to the RX pair and the

internal signal generator to the TX pair.

REV Send and receive pairs (as defined above) are reversed.

AM5XT/eXT is Polarity Sensitive

It does not matter which way the Send pair or the Receive pair of contacts are
connected. The Send T and R can be interchanged without affecting the
measurement. Also, the Receive T1 and R1 could be switched without changing
the measurement.

October 17, 2000 0022-S05.G_ 218

5-4

AM5XT/eXT Voice/Data Transmission (18-0022) Connection & Configuration

5.4 LINE TERMINATION IMPEDANCES

It is important that the line(s) be properly terminated with a matching impedance.
This paragraph gives instructions for terminating lines with 135Ω, 600Ω, 900Ω,
or 1200Ω impedance.

To terminate the line(s) correctly:

1. Choose either terminate or bridge mode:
A. Select terminate mode or
B. Select bridge mode and terminate the line with some other device

(such as a modem) of proper impedance.

2. Set the transmit and receive impedances to match those of the circuit
under test.

5.5 CONFIGURATIONS

There are three basic AM5XT/eXT configurations to test 2-Wire and 4-Wire
telephone and data communication lines:

1. End-to-end – requiring two AM5XT/eXTs

2. Loopback

3. Testing with responders

This paragraph describes the different configurations, explains how they are
used, and discusses the advantages and disadvantages.

Note: End-to-End and responder testing applies to either 2-Wire or 4-Wire.

Loopback testing only applies to 4-Wire.

End-to-End Testing

Measurements on telephone transmission lines are usually made by applying an
appropriate signal at one end of the transmission line and then measuring the
results at the other end of the line. This configuration requires a test set at each
end of the line and is called “end-to-end” testing. Figure 5-3 shows a 4-Wire
end-to-end configuration, making measurements over a telephone network that
normally connects two modems.

0022-S05.G_ 218 October 17, 2000

5-5

Connection & Configuration (18-0022) AM5XT/eXT Voice/Data Transmission

CPU

MODEM

RCV

AM-5XT

Telephone

Network
<RCV> <SND>
<SND>

<RCV>

AM-5XT

XMIT
RCVXMIT

MODEM

DTE

Figure 5-3. 4-Wire End-to-End Testing

Each AM5XT/eXT both sends and receives signals, sending a signal over the TX
pair of lines, and measuring the signal received over the RX pair of lines.

End-to-End testing can also be done over 2-Wire lines. The AM5XT/eXT on one
end sends a signal and the AM5XT/eXT on the other end measures the received
signal. End-to-End testing is necessary to perform Envelope Delay
measurements.

End-to-End testing is the most reliable for characterizing the near-to-far
impairments, but it has the disadvantage of requiring two test sets and an operator
at each test site.

Loopback Testing

The distant end of a 4-wire transmission line can be looped back (1) manually or
(2) with a commandable loopback device such as the Western Electric Model

829. The AM5XT/eXT at the near end sends a signal which travels to the distant
end where it makes a U-turn and travels back to the AM5XT/eXT which measures
the received signal.

The advantage of this configuration is that it requires only one (1) operator and a
test set at a central site. Although this method is more convenient and less costly
than end-to-end testing, it is also less reliable. The disadvantage is that it does
not characterize transmission impairments in each direction. Instead of detecting
impairments, a loopback measurement could actually cover them up. An
apparently satisfactory loopback measurement may contain impairments in each
direction which cancel each other. This method of testing may be useful
however, providing its limitations are recognized.

Note: A loopback test can not be done on 2-wire because signals can not be

sent and measured simultaneously on the same pair of lines.

October 17, 2000 0022-S05.G_ 218

5-6

AM5XT/eXT Voice/Data Transmission (18-0022) Connection & Configuration

To do a loopback test with a Western Electric Model 829:

1. Connect the AM5XT/eXT at the near end of the 4-wire line under test.

2. Momentarily press “Loop Back” (Send/C) to send a 2713 Hz (or whatever
is the necessary loopback tone) tone over the TX line. This trips the
distant Model 829 into loopback.

3. Send the desired test signal with the AM5XT/eXT and make the desired
measurement of the looped-back signal.

4. After testing is finished, momentarily press “Loop Back” to restore the
Model 829 to its normal, transparent state.

Testing with Responders

Using multifunction responders has most of the advantages of end-to-end testing
with the added advantage of not requiring an AM5XT/eXT at the far end of the
system. This configuration is similar to loopback testing except that the
responder can generate signals in addition to looping back. Unlike a dedicated
loopback device, responders can be used in 2-wire far-to-near testing.

On 4-wire circuits, a DTMF commandable responder, such as the Ameritec Model
AM3-4, may be placed permanently at the distant modem, where it remains
transparent until commanded by DTMF signals sent from the AM5XT/eXT at the
central site. In addition to performing loopback, the responder can send various
tones. This allows far-to-near tests as well as loopback tests.

Example: 4-wire far-to-near and loopback tests for level and frequency with an
Ameritec AM3-4A or AM3-4B Responder:

1. Connect an AM5XT/eXT to the near end of a 4-wire facility, and an
Ameritec AM3-4A or AM3-4B Responder at the far end. A typical
configuration is illustrated in Figure 5-4.

Loopback, Quiet,

Send Tones,

Amputate

AM3-4A

Responder

XMIT
RCVXMIT

MODEM

DTE

CPU

MODEM

RCV

AM-5XT

<RCV>
<SND>

Telephone

Network

Figure 5-4. 4-Wire Testing with Responder

0022-S05.G_ 218 October 17, 2000

5-7

Connection & Configuration (18-0022) AM5XT/eXT Voice/Data Transmission

2. Use AM5XT/eXT “TT” digits to send the appropriate DTMF command
sequence to command the responder into milliwatt mode (responder
generates 1004 Hz, 0 dBm signal). Measure received signal and note level
and frequency.

3. Use AM5XT/eXT “TT” digits to send the appropriate DTMF command
sequence to command the responder into loopback.

4. Use AM5XT/eXT to send 1004 Hz tone at 0 dBm. Measure loopback
received level and frequency.

5. Use AM5XT/eXT “TT” digits to send DTMF command sequence to restore
responder to normal.

On a 2-wire network, dial access responders are very useful in measuring far-to­near characteristics. An Ameritec AM3-2C Responder (automatic milliwatt) or

AM3-2A Responder can be dialed up over the network path under test using the
AM5XT/eXT keypad. It can then be commanded with touch tone from the
AM5XT/eXT to make level measurements or send tones. The AM3-2C can perform

far-to-near level and frequency, idle channel noise, and noise with tone. In
addition to the AM3-2C functions, the AM3-2A can also perform far-to-near gain
slope and near-to-far level. A typical configuration is illustrated in Figure 5-5.

MW

AM-5XT

<SND>

AM3-2

2W RESPONDER

PBX

MW

CO

FX

DISTANT

LOCAL

CO

TIE

TELEPHONE NETWORK

CO

AM3-2

2W RESPONDER

PBX

AM-5XT

<SND>

Figure 5-5. 2-Wire Testing with Responder

October 17, 2000 0022-S05.G_ 218

5-8

AM5XT/eXT Voice/Data Transmission (18-0022) Line Functions

6. LINE FUNCTIONS

6.1 INTRODUCTION

LINE Functions determine the condition of the interface of the AM5XT/eXT with
the 2- or 4-wire telephone line connected for test.

Some Line Functions are color-coded per the line pair to which the function is
applied:

GREEN (TX/2W) = 2-wire pair, or 4-wire transmit pair: T, R
BLUE (RX) = 4-wire receive pair: T1, R1

Other Line Functions are color-coded to match the type of connection enabled:

GRAY = 2-wire or 4-wire normal connection
BLACK = 2-wire or 4-wire with connections reversed (T, R becomes T1, R1

and vice versa)

Note: The color coding of the Line Functions matches the color coding of the

labels of the Line Bantam Jacks (see items 2 and 3 in Figure 3-1).

See Figure 6-1 for instructions to select the desired Line Function.

Figure 6-1. Procedure to Enable Line Functions

Unlike the Send and Measure Functions, there are no displays associated with
Line Functions. The status of the Line Functions is completely determined by
the condition of the Line Function LEDs. Also, unlike the Send and Measure
Functions, more than one Line Function LED will be on at the same time.

0022-S06.G_ 233 October 17, 2000

6-1

Line Functions (18-0022) AM5XT/eXT Voice/Data Transmission

In this section, the Function enable Key for each Line Function is shown
enclosed in a square

. For example,

8

600Ω indicates that key [8] is pressed
to connect 600Ω to the receive pair, RX (T1, R1), when the line is terminated
(BRDG LED off).

Paragraphs in this section are listed below:

6.2 General Line Function Notes

6.3 Generator Source Impedances

6.4 OFF HK (Send Pair Off-Hook/On Hook)

6.5 Termination Impedances

6.6 OFF HK (Receive Pair Off-Hook/On Hook)

6.7 BRDG (Receive Pair Bridged/Terminated)

6.8 2W (2-Wire)

6.9 4W (4-Wire)

6.10 REV (Reversed

6.2 GENERAL LINE FUNCTION NOTES

Note: Line functions enabled are stored/recalled separate from other front panel

functions. See ¶11.2.

Line Circuits Block Diagrams

See Figures 6-2 and 6-3. For reverse (REV), note that the RX (T1, R1) and TX (T,
R) pair are reversed, as indicated in the black-background labeling under the front

panel Bantam jacks.

October 17, 2000 0022-S06.G_ 231

6-2

AM5XT/eXT Voice/Data Transmission (18-0022) Line Functions

RCV

200KΩ200KΩ

*STANDARD
FOR AM5XT

T

TX/2W

R

ELECTRONIC

LINE HOLD

CIRCUIT

ON / OFF

HOOK

SWITCH

RING

DETECTOR

300Ω

450Ω

600Ω

300Ω

450Ω

600Ω

67.5*

67.5*

QUIET
OPEN

IMPEDANCE SELECT

SIGNAL

GENERATOR

NTG

Figure 6-2. 2-Wire Line Circuit Block Diagram

T1

RCV

ELECTRONIC

LINE HOLD

CIRCUIT

RX

135* 600Ω 1200900Ω

ON / OFF

HOOK

SWITCH

R1

67.5*

300Ω

ELECTRONIC

LINE HOLD

CIRCUIT

ON / OFF

HOOK

SWITCH

RING

DETECTOR

TX

450Ω

600

67.5*

300Ω

450Ω

600Ω

Ω

TERMINATE

IMPEDANCE
SELECT

*STANDARD
FOR AM5XT

BRIDGE

200KΩ 200KΩ

QUIET
OPEN

IMPEDANCE SELECT

NTG

SIGNAL

GENERATOR

Figure 6-3. 4-Wire Line Circuit Block Diagram

0022-S06.G_ 231 October 17, 2000

6-3

Line Functions (18-0022) AM5XT/eXT Voice/Data Transmission

Line Impedances

The Transmit Pair, TX (T, R), and Receive Pair, RX (T1, R1), each have four (4)
impedances from which to select:

135Ω (150Ω for AM5eXT)
600Ω
900Ω
1200Ω

Line Function Enable Keys [1] thru [4] and [7] thru [0] are used to select the line
impedances. The LEDs of the selected line impedances will be on.

Note: The dBm and dBrn readings are always calculated based on the

AM5XT/eXT RX line impedance selected, even when the RX pair is

bridged. The internal microprocessor takes the internal voltage and
calculates the reading using the formula:

dBm = 10 log (E x 1000)

2

R

Where: R = selected RX line impedance

E = measured voltage

The receive pair, RX (T1, R1), of a 4-wire circuit under test is terminated with the
selected RX impedance only when the line is terminated (BRDG LED off) – see
below and ¶6.7 concerning the Bridge/Terminate Line Function.

When sending a test tone, the transmit line TX/2W (T, R), is always terminated
because the selected source impedance for the signal generator terminates the
line. The transmit line is bridged only when the SEND function is OPEN (signal
generator is disconnected). Likewise, a 2-wire line is bridged only when the
SEND function is OPEN.

DC Line Hold (On-Hook/Off-Hook)

The TX/2W (T, R) and RX (T1, R1) lines have separate DC hold circuits. The hold
circuits are electronic equivalents of a line hold coil. Key [5] is used to
connect/disconnect the TX/2W (T, R) line hold circuit, while key [*] is used to
connect/disconnect the RX (T1, R1) line hold circuit. With DC hold on (OFF HK
LED on), the circuit connects a 200Ω DC path across T and R (or T1 and R1) which
presents a high impedance path (>50 kΩ) to AC signals.

October 17, 2000 0022-S06.G_ 231

6-4

AM5XT/eXT Voice/Data Transmission (18-0022) Line Functions

Bridge/Terminate

The RX (T1, R1) line pair can be either bridged or terminated, using key [#].
For 4-wire circuits, “terminated” means that the RX (T1, R1) line is terminated by

the selected AM5XT/eXT RX impedance. “Bridged” (not terminated) means that
the AM5XT/eXT presents a high impedance (>50 kΩ) to the RX (T1, R1) line under
test. When in bridged mode, the RX (T1, R1) line must be terminated by a device
external to the AM5XT/eXT. The TX (T1, R1) line is always terminated unless the
SEND function is OPEN.

In 2-wire mode, (2W LED on), the line will only be bridged when the OPEN send
mode is enabled, in which case the signal generator is disconnected.

Note: A line under test is terminated be either an external impedance or the

AM5XT/eXT. Do not terminate the line both externally and with the
AM5XT/eXT.

2W, 4W, REV (2-Wire, 4-Wire, Reversed)

Keys [B] and [C] are used to select the type of line (2-wire or 4-wire) connected
to the AM5XT/eXT. Key [D] is used to conveniently reverse the connections.
When Reversed, TX/2W (T, R) becomes RX (T1, R1) and vice versa.

Line Connections (for normal non-reversed operation)

4-Wire Circuits

Front Panel Connection:

• Connect the receive pair (over which the AM5XT/eXT receives
signals) to the RX Bantam jack.

• Connect the send (transmit) pair (over which the AM5XT/eXT
sends signals) to the TX/2W Bantam jack.

Rear Panel Connection:

• Connect the receive pair (over which the AM5XT/eXT receives
signals) to the T1 and R1 screw terminals.

• Connect the send (transmit) pair (over which the AM5XT/eXT
sends signals) to the T and R screw terminals.

0022-S06.G_ 231 October 17, 2000

6-5

Line Functions (18-0022) AM5XT/eXT Voice/Data Transmission

2-Wire Circuits

Front Panel Connection:

• Connect the pair to the TX/2W Bantam jack.

Rear Panel Connection:

• Connect the pair to the T and R screw terminals.

6.3 GENERATOR SOURCE IMPEDANCES (Transmit Pair)

The front panel labels are color-coded green for each of the possible generator
source impedances. The choices are listed below, along with their Function
Enable Keys:

1

135Ω (150Ω for AM5eXT)

2

600Ω

3

900Ω

4

1200Ω

One of the associated LEDs will be on to indicate which of these impedances has
been selected for AM5XT/eXT signal generator. The selected source impedance is
connected to the transmit pair, TX (T, R), as indicated in Figures 6-2 and 6-3.
Note that half of the impedance is connected to each side of the line.

When the Send Function is set to QUIET, the signal generator is disconnected and
the Transmit pair, TX (T, R), is terminated with the selected source impedance.
When the Send Function is set to OPEN, both the signal generator and the
selected generator source impedance are disconnected from the TX (T, R) pair.

6.4

5

OFF HK (Send Pair Off-Hook/On-Hook)

OFF HK LED ON

Off-hook condition with DC path (>50 kΩ AC path) across transmit pair, TX (T, R),
equivalent to 200Ω holding coil.

OFF HK LED OFF

On-hook condition with holding coil disconnected.

October 17, 2000 0022-S06.G_ 231

6-6

AM5XT/eXT Voice/Data Transmission (18-0022) Line Functions

6.5 TERMINATION IMPEDANCES (Receive Pair)

The front panel labels are color-coded blue for each of the possible termination
impedances. The choices are listed below, along with their Function Enable
Keys:

7

135Ω (150Ω for AM5eXT)

8

600Ω

9

900Ω

0

1200Ω

One of the associated LEDs will be on to indicate which of these impedances has
been selected for the receive pair, RX (T1, R1).

With the BRDG LED off (RX terminated), the selection termination impedance is
connected across the receive pair, RX (T1, R1), as indicated in Figures 6-2 and
6-3. With the BRDG LED on, RX becomes high impedance (no termination).

With the BRDG LED on (RX bridged), set the RX impedance to the same value as
the external termination impedance on the receive pair, RX (T1, R1). This setting
is used to tell the AM5XT/eXT microprocessor the value of the external termination
impedance so that it can calculate the proper measure reading. The formula is
given in ¶6.2 under “Line Impedances”.

6.6

*

OFF HK (Receive Pair Off-Hook/On-Hook)

OFF HK LED ON

Off-hook condition with DC path (>50 kΩ AC path) across receive pair, RX (T1,
R1), equivalent to 200Ω holding coil.

OFF HK LED OFF

On-hook condition with holding coil disconnected.

6.7

#

BRDG (Receive Pair Bridged/Terminated)

BRDG LED ON

High impedance bridge (>50 kΩ) across receive pair, RX (T1, R1).

0022-S06.G_ 231 October 17, 2000

6-7

Line Functions (18-0022) AM5XT/eXT Voice/Data Transmission

BRDG LED OFF

Receive pair, RX (T1, R1), terminated by impedance selected per ¶6.5.

6.8

6.9

B

2W (2-Wire)

This function is color-coded gray on the front panel.
2W LED ON

Transmit pair TX (T, R), is connected to both the signal generator (send) and the
measure (receive) circuits, as shown in Figure 6-2.

C

4W (4-Wire)

This function is color-coded gray on the front panel.
4W LED ON

Transmit pair TX (T, R), is connected to the signal generator and receive pair, RX
(T1, R1), is connected to the measure (receive) circuitry.

Tone Ringer, Incoming Ring

With this feature enabled, a ringback tone will be heard from the AM5XT/eXT
speaker when a ringing voltage appears across the transmit pair, TX (T, R).

To enable the tone ringer, press the appropriate keys on the front panel to enable
4W and OPEN:

1. With LINE LED on, press [C]. 4W LED will light.

2. With SEND LED on, press [0]. OPEN LED will light.

6.10

October 17, 2000 0022-S06.G_ 231

D

REV (Reversed)

This function is color-coded black on the front panel.
REV LED ON

Transmit pair TX (T, R), and receive pair, RX (T1, R1), connections reversed
compared to the connections listed in ¶6.8 and ¶6.9. Note labeling with black
background under front panel Bantam jacks, which indicates this connection
reversal.

6-8

AM5XT/eXT Voice/Data Transmission (18-0022) Send Functions

7. SEND FUNCTIONS

7.1 INTRODUCTION

The AM5XT/eXT contains a highly flexible signal generator capable of generating
a variety of test tones which are applied to the Transmit (TX) pair.

SEND refers to the signal generator condition applied to the TX pair of the line
under test. See Figure 7-1 for instructions to select the desired Send Function.
Note that SEND Functions are color-coded GREEN.

Figure 7-1. Procedure to Enable Send Functions

In this section, the paragraph heading for each Send Function shows its Function
Enable Key enclosed in a square

. For example,

1

QUIET indicates that key
[1] is pressed to select QUIET Send mode. DATA and PARAMETER DISPLAY
information is also provided. Section 4 explains how the DATA and PARAMETER
DISPLAYs are accessed and used.

To access the level display:

1. Press the [SEND] key.

2. Press any Send Function Enable key.

3. Press [D] to access Set Level Display (first PARAMETER DISPLAY).

0022-S07.G_ 250 October 17, 2000

7-1

Send Functions (18-0022) AM5XT/eXT Voice/Data Transmission

Remember that when the level value is changed, it changes the level for all SEND
signals, except for dialed tones (see Display 4, ¶7.2, for PARAMETER DISPLAY to
set Touch Tone level). When power is turned off, the send level always defaults
to 00.0 dBm. The level for dialed tones, however, is stored in non-volatile
memory.

7.2

1

QUIET

The signal generator is disconnected from the TX line and the line is quiet
terminated with a passive resistance equal to the TX line impedance selected per
¶6.3.

Miscellaneous PARAMETER DISPLAYs

Parameters are set and information is displayed here that is of a general nature or
can not be conveniently implemented elsewhere. Note that these displays are not
related to the QUIET mode.

Display 2

Set Level

(for other send functions)

-50 dBm to 10.0 dBm
(Default = 00.0 dBm)

Set Level for send functions. Note that Level does not have meaning for

QUIET mode.
Display 3

Set loopback frequency

(Momentary auxiliary tone)

0.020 kHz to 200 kHz

(Factory Setting = 2.713 kHz)

Set frequency for Loop Back Tone, sent by pressing [C]. See ¶7.15.

October 17, 2000 0022-S07.G_ 249

7-2

AM5XT/eXT Voice/Data Transmission (18-0022) Send Functions

Display 4

7.3

Set Touch Tone

(and MF) Level

-50 dBm to 7.0 dBm
(Default = 0.0 dBm)

Set level for DTMF (Touch Tone) or MF tones dialed. See ¶10.1 concerning
dialing.

Displays 5 & 6

Software Version

of the Main Unit

Software Version of

the Digital Signal

Processor (DSP)

Information Only

Display

Information Only Display

255 = DSP not included

These displays indicate the present software installed.

2

1004 Hz

The signal generator outputs a continuous 1004 Hz sine wave to the TX pair.

DATA DISPLAY

Level/1.004 kHz being sent

PARAMETER DISPLAY

Set Level -50 dBm to 10.0 dBm

(Default = 00.0 dBm)

Level is adjustable with the PARAMETER DISPLAY.

0022-S07.G_ 249 October 17, 2000

7-3

Send Functions (18-0022) AM5XT/eXT Voice/Data Transmission

7.4

7.5

3

VAR HZ (Variable Tone)

The signal generator outputs a sine wave tone to the TX pair.

DATA DISPLAY

Level/Frequency being sent

PARAMETER DISPLAYS

Set Level -50 dBm to 10.0 dBm

Set Frequency 0.020 kHz to 200 kHz

(Default = 00.0 dBm)

(Default = 1.004 kHz)

Level and Frequency are adjustable with the PARAMETER DISPLAYS.

4

SLOPE

The signal generator outputs:

1. AM5eXT Four tones: 1004 Hz, 2003 Hz, 3004 Hz, and 304 Hz in a

repetitive cycle.

This sequence of tones is used for multiple-point gain/slope measurements, i.e., a
plot of transmission loss vs. frequency at four points.

October 17, 2000 0022-S07.G_ 249

7-4

AM5XT/eXT Voice/Data Transmission (18-0022) Send Functions

DATA DISPLAY

7.6

Level/Frequency steps

through tones as set

by parameters

PARAMETER DISPLAYS

Set Level -50 dBm to 10.0 dBm

Set Duration of each tone 00.2 sec to 999.9 sec

Press [4] to restart

sequence at 1.004 kHz

(Default = 00.0 dBm)

(Default = 5.0 sec)

Level and Rate (duration of each tone) are adjustable with the PARAMETER
DISPLAYS.

5

SWEEP

The signal generator sweeps through a series of frequencies. With factory
default parameter settings, the sweep starts at 0.204 kHz and increases in 0.100 kHz
steps every one second, until 5.004 kHz is reached, at which time the sweep starts
again at 0.204 kHz.

0022-S07.G_ 249 October 17, 2000

7-5

Send Functions (18-0022) AM5XT/eXT Voice/Data Transmission

DATA DISPLAY

Level/Frequency steps

through tones as set

by parameters

PARAMETER DISPLAYS

Set Level -50 dBm to 10.0 dBm

Set start frequency

(Start of sweep)

Set stop frequency

(End of sweep)

Set step size 0.020 kHz to 200 kHz

Press [5] to restart

sweep sequence

(Default = 00.0 dBm)

0.20 kHz to 200.0 kHz
(Default = 0.204 kHz)

0.20 kHz to 200.0 kHz
(Default = 5.004 kHz)

(Default = 0.100 kHz)

Set Duration of each tone 00.1 sec to 999.9 sec

Set additional dwell
inserted before and

after sweep sequence

(Default = 1.0 sec)

00.1 sec to 999.9 sec

(Default = 1.0 sec)

All parameters are adjustable with the PARAMETER DISPLAYS, including the
Level and Delay Time (inserted before and after the sweep sequence).

October 17, 2000 0022-S07.G_ 249

7-6

AM5XT/eXT Voice/Data Transmission (18-0022) Send Functions

7.7

7.8

6

PAR (Peak-to-Average Ratio)

The signal generator outputs 16 specific frequencies simultaneously per Bell
41009 specification. This composite test tone is used for a P/AR (peak-to-

average) measurement.

DATA DISPLAY

P/AR being sent level

PARAMETER DISPLAY

Set Level -50 dBm to 00.0 dBm

The composite Level is adjustable with the PARAMETER DISPLAY.

7

RET LOSS (Return Loss)

The signal generator outputs shaped, white-noise test tones, used in the Return
Loss measurement mode (¶8.9). Three (3) measurements are made using these

tones, each with its characteristic test tone band.

(Default = 00.0 dBm)

0022-S07.G_ 249 October 17, 2000

7-7

Send Functions (18-0022) AM5XT/eXT Voice/Data Transmission

DATA DISPLAYS

Level/ERL

Level/SRL-Low

Level/SRL-High

PARAMETER DISPLAY

Set Level -10.0 dBm to -02.0 dBm

(Default = -02.0 dBm)

1. Echo Return Loss (ERL), with white noise test tone band-limited (3 dB
points at 560 Hz and 1965 Hz).

2. Singing Return Loss LO (SRLL), white noise test tone band-limited to
exclude high frequency components (3 dB points at 260 Hz and 500 Hz).

3. Singing Return Loss HI (SRLH), white noise test tone band-limited to
exclude low frequency components (3 dB points at 2200 Hz and 3400 Hz).

Enable the appropriate DATA DISPLAY to send the respective Return Loss test
tone.

Level is adjustable with the PARAMETER DISPLAY.

October 17, 2000 0022-S07.G_ 249

7-8

AM5XT/eXT Voice/Data Transmission (18-0022) Send Functions

7.9

8

ENV DLY (Envelope Delay) (AM5XT ONLY)

An Envelope Delay test measures the non-linearities in the phase response of a
line. A transmission test set is required at each end of the circuit to be measured.

There are two (2) types of send signals generated with an Envelope Delay test:

1. A Sweep series of carrier frequencies, usually from 200 Hz to 4000 Hz,
modulated by 83-1/3 Hz.

2. A constant carrier Reference Frequency, usually 1800 Hz, also
modulated by 83-1/3 Hz.

One or the other of these signals is generated from both the near-end and far-end
test set.

The displays listed are identified by number for ease of reference.

0022-S07.G_ 249 October 17, 2000

7-9

Send Functions (18-0022) AM5XT/eXT Voice/Data Transmission

DATA DISPLAYS

Sweep Mode. Test signal

level/frequency

Reference Frequency.

Level being sent

PARAMETER DISPLAYS

Set Level -40.0 dBm to 10.0 dBm

Normal Mode

Press [0] to enable.

1

Press [8] twice to restart

sweep sequence

2

3

(Default = 0.0 dBm)

4A

4B

Repeat Mode

Press [1] to enable.

4C

Hold Mode

Press [2] to enable.

Displays 4A, 4B, and 4C can also be accessed from the Measure Display
PARAMETER DISPLAY LIST (see ¶8-10).

Note: Displays 4A, 4B, and 4C show the three possible selections for the mode

parameter. These displays are enabled by pressing keys [0], [1], and [2],
respectively, or by using the up or down arrow key.

October 17, 2000 0022-S07.G_ 249

7-10

AM5XT/eXT Voice/Data Transmission (18-0022) Send Functions

PARAMETER DISPLAYS

Set reference frequency 0.200 kHz to 4.000 kHz

Set start frequency

of test signals

Set stop frequency

of test signals

Set step size .000 kHz to 4.000 kHz

(Default = 1.800 kHz)

0.200 kHz to 4.000 kHz
(Default = 0.200 kHz)

0.200 kHz to 4.000 kHz
(Default = 4.000 kHz)

(Default = 0.100 kHz)

5

6

7

8

9

Set Duration of each tone 0.1 sec to 999.9 sec

(Default = 3.0 sec)

10

Set dwell inserted before

and after sweep sequence

0 to 999.9 sec

(Default = 0.0 sec)

See ¶8.10 for Setup and Test Procedures, including both Send and Measure
functions.

0022-S07.G_ 249 October 17, 2000

7-11

Send Functions (18-0022) AM5XT/eXT Voice/Data Transmission

7.10

8

GROUP DLY (Group Delay) (AM5eXT ONLY)

A Group Delay test measures the non-linearities in the phase response of a line.
A transmission test set is required at each end of the circuit to be measured. Test
signals are generated over a 2-wire circuit from the test set on one end, and the
Group Delay is measured on the other end. See ¶8.11 for Measure functions and
Test Procedure.

With a Group Delay test, there are two (2) types of send signals which are
alternately generated for 120ms:

• A constant carrier Reference Frequency, usually 1800 Hz, modulated by
41-2/3 Hz.

• A Sweep series of carrier frequencies, usually from 200 Hz to 20 kHz, also
modulated by 41-2/3 Hz.

The displays listed are identified by number for ease of reference. Display 1
indicates the level and frequency of the Sweep carrier frequency being set at the
time. With factory default parameter settings, the Sweep starts at 0.200 kHz and
increases in 0.100 kHz steps every 3 seconds until 20.00 kHz is reached, at which
time the Sweep starts again at 0.200 kHz.

DATA DISPLAY

1

Sweep test signal

Level/Frequency

Press [8] to restart

sweep sequence

All parameters are adjustable with the PARAMETER DISPLAYS, including the
Level, Reference Frequency, and Delay Time (inserted before and after the
sweep sequence.

October 17, 2000 0022-S07.G_ 249

7-12

AM5XT/eXT Voice/Data Transmission (18-0022) Send Functions

PARAMETER DISPLAYS

Set Level -50 dBm to 10.0 dBm

Set reference frequency 0.200 kHz to 20.00 kHz

Set start frequency

of test signals

Set stop frequency

of test signals

(Default = 00.0 dBm)

(Default = 1.800 kHz)

0.200 kHz to 20.00 kHz
(Default = 0.200 kHz)

0.200 kHz to 20.00 kHz
(Default = 20.00 kHz)

2

3

4

5

6

Set step size 0.000 kHz to 20.00 kHz

(Default = 0.100 kHz)

7

Set Duration of each tone 0.1 sec to 999.9 sec

(Default = 3.0 sec)

8

Set dwell, inserted before

and after sweep sequence

0022-S07.G_ 249 October 17, 2000

7-13

0.0 to 999.9 sec

(Default = 0.0 sec)

Send Functions (18-0022) AM5XT/eXT Voice/Data Transmission

7.11

9

IMD (Intermodulation Distortion*)

* Licensed under U.S. Patent #3,862,380.

Definition. Intermodulation Distortion is also known as “Non-Linear Distortion”
or “4-Tone Test”. Intermodulation Distortion is signal component generation
that is produced from the transmitted signal and adds to the transmitted signal.
These additional signal components are usually undesirable.

Send Signals. Three (3) types of signals are used with the Intermodulation
Distortion test. See ¶8.12 for the Test Procedure that explains how these signals
are used.

The Intermodulation Distortion send displays are numbered for ease of reference.

DATA DISPLAYS

4-tone "IMD" signal level

Test signal level (for calibration)

1

2

3

2-tone signal/noise check signal level

The send signals are described below:

1. 4-Tone Signal. This test signal is composed of four (4) tones, all at the

same level, as described below:

• Two (2) tones are 6 Hz apart, centered at 860 Hz.

• Two (2) tones are 16 Hz apart, centered at 1380 Hz.

The 4-Tone Signal is sent when Display 1 is enabled.

October 17, 2000 0022-S07.G_ 249

7-14

AM5XT/eXT Voice/Data Transmission (18-0022) Send Functions

2. Calibration Test Signal. This is a special signal used to self-test the
calibration of the AM5XT/eXT when the unit is looped back on itself (send,
TX, connected directly to receive, RX). This signal is composed of the 4
tones listed above, plus additional tones which represent second and third
order intermodulation products. The Calibration Test Signal is sent
when Display 2 is enabled.

3. 2-Tone Signal. This signal is composed of two (2) of the tones listed
under 4-Tone Signal (those centered at 860 Hz). The 2-Tone Signal is sent
when Display 3 is enabled.

PARAMETER DISPLAY

Set Level -40.0 dBm to 0.0 dBm

(Default = 0.0 dBm)

0022-S07.G_ 249 October 17, 2000

7-15

Send Functions (18-0022) AM5XT/eXT Voice/Data Transmission

7.12

7.13

0

OPEN

Similar to QUIET (¶7.2) mode, but completely disconnects the signal generator
from the transmit line. For this mode, the transmit line is not terminated by the
generator impedance.

DATA DISPLAY

"Open"

PARAMETER DISPLAY

Set Level -50.0 dBm to 10.0 dBm

A

SF SKIP (Signaling Frequency Skip)

SF SKIP is used to avoid sending tones in the “signaling frequency” band to avoid

knocking down a long distance dialed circuit. SF SKIP is an ON/OFF toggle used
in connection with the VAR HZ, SWEEP, and ENVELOPE (or GROUP) DELAY
modes.

(Default = 0.0 dBm)

With the SF SKIP LED on, the signal generator cannot be set to send frequencies
in the band 2450 Hz through 2750 Hz (2130 Hz to 2430 Hz for AM5eXT). With the

SF SKIP LED off, the signal generator is fully variable.

7.14

October 17, 2000 0022-S07.G_ 249

B

TALK

Instead of the internal signal generator, the TALK mode connects a front panel
microphone to the transmit line. This allows the operator to talk to a testing
partner at the distant end of the line under test. The TALK function will work on
wet or dry (no DC voltage) 2- or 4-wire lines. Two (2) modes are available: Full
Duplex and Push-to-Talk. Full Duplex in 2-wire mode employs a hybrid to
provide hands-free “speaker phone” operation.

7-16

AM5XT/eXT Voice/Data Transmission (18-0022) Send Functions

Full-Duplex TALK Mode, LED flashes.

1. Press [B] momentarily to disconnect the signal generator and connect the
built-in microphone to the TX line. The microphone is located behind the
three holes labeled TALK in the upper left corner of the front panel.

2. Set the MONITOR switch to RX to enable the speaker.

3. Full Duplex (speaker phone) operation is now enabled. For 2-wire, a
hybrid is used to allow Full Duplex operation.

To exit Full Duplex mode, momentarily press [B]. The LED will go out.
In some cases audible regenerative feedback may result, especially in the 2-wire

mode, where the line under test is not impedance matched to the hybrid, and at
high volume settings. This may be overcome by using the “push-to-talk” mode,
described next.

Half-Duplex TALK Mode (“Push-to-Talk”), LED continually ON.

Press and hold [B] to enable the Push-to-Talk mode. [B] is also used to select the
direction of the conversation:

• To speak, hold down [B] to operate the microphone and mute the
speaker. The microphone (item 13 in Figure 3-1) is located behind the
three holes labeled TALK in the upper left corner of the front panel.

• To listen, release [B] to disconnect the microphone and enable the
speaker (TALK LED remains steady on).

To exit Push-to-Talk mode, momentarily press [B]. The LED will go out.

7.15

0022-S07.G_ 249 October 17, 2000

C

LOOP BACK

LOOP BACK is a Programmable Momentary Auxiliary Tone intended to trip and

restore a 4-wire loopback device such as a Western Electric Model 829.
The frequency and level of this tone is set with a QUIET Send mode PARAMETER

DISPLAY (Display 3), see ¶7.2. To activate a Model 829, program the frequency
for 2713 Hz, the default setting.

7-17

Send Functions (18-0022) AM5XT/eXT Voice/Data Transmission

Momentarily press [C] to disconnect the present Send mode and send the
Auxiliary Tone over the TX pair. The Auxiliary Tone will be applied as long as
the [C] key is held down.

Release [C] to automatically restore the previous Send (signal generator) mode.

October 17, 2000 0022-S07.G_ 249

7-18

AM5XT/eXT Voice/Data Transmission (18-0022) Measure Functions

8. MEASURE FUNCTIONS

8.1 INTRODUCTION

The AM5XT/eXT contains highly versatile detectors and filters which are
connected to the receive line (RX) under test. The term MEASURE refers to the
detection mode being used in order to detect and display the characteristics of the
received signal(s). See Figure 8-1 for instructions to select the desired Measure
Mode. Note that MEASURE Functions are color-coded BLUE.

Figure 8-1. Procedure to Enable Measure Modes

In this section, the paragraph heading for each Measure Function shows its
Function Enable Key enclosed in a square

. For example,

6

PAR indicates

that key [6] is pressed to select PAR Measure mode. DATA and PARAMETER

DISPLAY information is also provided. Section 5 explains how the DATA and
PARAMETER DISPLAYs are accessed and used.

Paragraphs in this section are listed below:

8.2 LVL/FREQ (Level/Frequency)

8.3 General Notes Concerning Noise Measurements

8.4 NOISE (Idle Channel Noise)

8.5 NOTCH NOISE (Noise with Tone)

8.6 NTG (Noise-to-Ground)

8.7 S/N (Signal-to-Noise Ratio)

8.8 PAR (Peak-to-Average Ratio)

8.9 RET LOSS (Return Loss)

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Measure Functions (18-0022) AM5XT/eXT Voice/Data Transmission

8.10 ENV DLY (Envelope Delay) for AM5XT only

8.11 GROUP DLY (Group Delay) for AM5eXT only

8.12 IMD (Intermodulation Distortion)

8.13 PHASE JTR (Phase Jitter)

8.14 AMP JTR (Amplitude Jitter)

8.15 IMP NOISE Impulse Noise without Tone)

8.16 TRAN (Transients)

8.17 MICRO INTR (Micro-Interruptions)

8.2

1

LVL/FREQ (Level/Frequency)

Note: There is a dark box around the LVL/FREQ and 15kHz LEDs for the AM5XT

(LVL/FREQ and UN WTD LEDs for AM5eXT). This “Level Box” indicates
that the 15 kHz (or UN WTD) filter is always associated with the
Level/Frequency Measurement. See ¶9.2 and ¶9.3 for descriptions of 15
kHz (AM5XT) and Sound-Unweighted (AM5eXT) low-pass filters, enabled
in the Auxiliary Function row, AUX.

AM5XT

LVL/FREQ

15 KHz

LEVEL BOX

AM5eXT

LVL/FREQ

UN/WTD

LEVEL BOX

Wide-Band Level/Frequency (AUX filter not used)

An autoranging amplifier, average detector, and frequency counter are connected
to the RX pair. A 200 kHz low-pass filter is used, allowing full bandwidth
operation. The detected average voltage is converted to dBm by the
microprocessor, based upon the impedance selected for the RX line (¶6.2 thru
¶6.5).

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AM5XT/eXT Voice/Data Transmission (18-0022) Measure Functions

To enable this mode:

1. Set LVL/FREQ LED “ON”.

2. Set 15kHz LED “OFF” (AM5XT) or UN WTD LED “OFF” (AM5eXT)

Narrow-Band Level/Frequency (AUX filter used)

This is the same as above, except the AUX Function filter in the “Level Box” is
enabled (LED “ON”). The filter is a low-pass filter connected to the front end,
effectively eliminating high-frequency components. This mode is useful in
making measurements on voice-band circuits where high-frequency components
are of no interest.

To enable this mode:

2. With MEAS LED on, set LVL/FREQ LED "ON".

3. With AUX LED on for AM5XT, set 15 kHz LED "ON" (connecting 15 kHz
low-pass filter), or for AM5eXT, set UN WTD LED "ON" (connecting
Sound-Unweighted low-pass filter).

Setup

For end-to-end testing, the transmitted (Send) test tone is applied to the far-end
transmit (TX) circuit. For 4-wire loopback testing, the transmitted (Send) test
tone is applied to the near-end transmit (TX) circuit.

Enable the appropriate Send Function (Section 7):

• 1004 HZ for single point loss tests

• SLOPE for 3-point (4-point for AM5eXT) gain/slope tests

• VAR HZ or SWEEP for multi-point Frequency response curve tests.

Operation

The AM5XT/eXT measures the resultant signal on the near-and receive pair (RX).
Read the voltage and frequency in the DATA DISPLAY.

DATA DISPLAY

Measured level/frequency -64.9 dBm to 10 dBm

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8-3

0.020 kHz to 200.0 kHz

Measure Functions (18-0022) AM5XT/eXT Voice/Data Transmission

If the received signal has excessive power-line hum or excessive high-frequency
components (in excess of 15 kHz), an erratic display may result.

Connect the appropriate filter(s) to eliminate undesired frequencies and stabilize
the display:

1. To eliminate power-line hum:

• Enable the Auxiliary Functions (AUX LED "ON")

• Press [B] to connect the 60 Hz high pass filter (6O Hz LED will light).

With the 60 Hz filter connected, frequency components below 60 Hz
will be effectively eliminated from the reading. Press [B] again to
disconnect the filter from the measurement (60 Hz LED will go out).

2. To eliminate high frequency, make a Narrow-Band Level/Frequency
measurement (described above), using the AUX filter.

Rapidly fluctuating readings may be captured as follows:

1. Enable the Auxiliary Function (AUX LED “ON”).

2. Press [D] (DAMP LED will light). With DAMP ON, the display will
update at the rate of 2-times per second, half the normal 4-times per
second update rate.

A slight peaking effect at 90 kHz to 120 kHz may occur when making attenuation
measurements when the AM5XT is making loop-back test (AM5XT signal generator
and receiver being used simultaneously) on high loss (>20 dB for this effect to
occur. This effect can be avoided in end to end tests by quiet-terminating the
transmitter when making measurements on the receiving end of the circuit.

Plotting

For plotting a graph of the results through the RS2432 port, use PARAMETER
DISPLAYS to set:

2. Low level limit of the plot

3. High level limit of the plot

4. Rate at which lines are printed

5. Performance limits for line on printer/plotter

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AM5XT/eXT Voice/Data Transmission (18-0022) Measure Functions

PARAMETER DISPLAYS (For Plotting)

Set low level limit of plot -99.9 to 99.9 dB

Set high level limit of plot

Time interval between printouts 0 sec to 255 sec

Line conditioning for

performance limits

(Default = -40.0 dB)

-99.9 to 99.9 dB

(Default = 10.0 dB)

(Default = 0, Autotrack)

Enter a digit 1 to 8 or use up or

down arrows to select mask

2

3

4

5

See ¶13.1 for details concerning plotting.

Automatic Tracking Printing Mode

To deliver a printout each time there is a shift in frequency, set the RATE
parameter to “0”. With RATE = 0, there must be a discrete, stable shift in the
frequency in order for there to be a printout. If the frequency changes at least 8
Hz (approximately), and stabilizes for about 0.5 sec., there will be a printout.
This setting is useful when the Send Function is SLOPE (3 or 4 frequency steps)
or SWEEP (multiple frequency steps).

Note: Do not set RATE to 0 when the Send source is a continuous (not step)

sweep generator. With a continuous sweep, no frequency lasts for 0.5

sec., so there would never be a printout with the RATE set to “0”.

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8-5

Measure Functions (18-0022) AM5XT/eXT Voice/Data Transmission

8.3 GENERAL NOISE MEASUREMENT NOTES

The information discussed here applies to all four (4) types of noise
measurements:

1. (Idle Channel) NOISE

2. NOTCH NOISE

3. NOISE-TO-GROUND (NTG)

4. SIGNAL-TO-NOISE (S/N) RATIO

Note: There is a dark box around the function LEDs that are associated with

noise measurements, enclosing the noise functions in the MEAS row and
the noise filters in the AUX row. This box is referred to as the “Noise
Box”.

NOTCH

NOISE

NOISE

CMSG

PGM 3KHz

AM5XT NOISE BOX

NOTCH

NOISE

NOISE

PSHO

SWTD

NTG

NTG

WTD

S/N

15KHz

UN

3KHz
FLAT

50K

S/N

2KHz

QUASI

FLAT

PK

AM5eXT NOISE BOX

Noise Measurement with Filter

To set up a noise measurement using a filter:

1. In the Measure Functions row (with MEAS LED ON), press the
appropriate key to enable the desired noise test (NOISE, NOTCH NOISE,
NTG, or S/N). The corresponding LED will light.

2. Press the [AUX] key. The AUX LED will light.

3. Press the appropriate key, [2] thru [6], to enable the desired noise
filter. The respective LED will light, indicating that the filter is enabled.
Possible filters are listed in Table 8-1.

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8-6

AM5XT/eXT Voice/Data Transmission (18-0022) Measure Functions

Table 8-1. Noise Weighting Filters

KEY AM5XT AM5eXT

2 C-Message (CMSG) Psophometric (PSHO)
3 Program (PGM) Sound-Weighted (SWTD)
4 3kHz flat Sound-Unweighted (UN WTD)
5 15kHz flat 3kHz flat
6 50kBit 2kHz flat

160kHz-Filter Noise Measurement

To set up a 160kHz-FILTER noise measurement:

1. In the Measure Functions row (with MEAS LED ON), press the
appropriate key to enable the desired noise test (NOISE, NOTCH NOISE,
NTG, or S/N). The corresponding LED will light.

2. In the Auxiliary (AUX) Functions row, check if a filter is enabled
(LED lit). Possible filters are listed in Table 8-1.

3. If a filter is enabled (LED lit), press the same key that was used to
enable the filter (with AUX LED ON). The LED will extinguish, indicating
that the filter is disabled. Note that if the same filter key is pressed
repeatedly, it will toggle (alternate) between enabled and disabled as
evidenced by the LED turning ON and OFF.

4. If none of the filters shown in Table 8-1 are selected, a 160 kHz low-
pass filter will be in the measurement path.

Quasi-Peak Detector (AM5eXT only)

With the AM5eXT there is a choice of devices to measure the voltage on the
receive pair. Select either the RMS Detector or the Quasi-Peak Detector.

With the AM5eXT, follow the steps below to make a noise measurement using
the Quasi-Peak Detector:

1. In the Measure Functions row (with MEAS LED ON), press the
appropriate key to enable the desired noise test (NOISE, NOTCH NOISE,
NTG, or S/N). The corresponding LED will light.

2. Press the [AUX] key. The AUX LED will light.

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8-7

Measure Functions (18-0022) AM5XT/eXT Voice/Data Transmission

3. Press [7]. The QUASI PK LED will light, indicating that the Quasi-
Peak Detector is enabled.

For the AM5eXT, the Quasi-Peak Detector is enabled when the QUASI PK LED is
ON. The RMS Detector is enabled when the QUASI PK LED is OFF.

For the AM5XT, all noise measurements are made with the RMS Detector (there is
no QUASI PK LED).

Test Setup

Enable the appropriate Send signal (QUIET or 1004Hz). For end-to-end testing,
the Send signal is connected to the far-end transmit (TX) circuit. For 4-Wire
Loopback testing, the Send signal is applied to the near-end transmit (TX) circuit.
When using a responder, command the responder into the appropriate send mode.

Units of Measurement for Noise

For noise measurements, the voltage on the receive pair is measured using an
RMS Detector (RMS Detector or Quasi-Peak Detector for the AM5eXT). This
voltage is converted to dBm by the microprocessor, based upon the selected
terminate impedance (¶6.2). In the AM5XT, the microprocessor further converts
the readings to dBrn in accordance with the formula: dBrn = dBm + 90. For
example, -50 dBm = -50 + 90 = 40 dBrn. With the AM5XT therefore, noise
measurements are in units of dBrn and the AM5eXT noise measurements are in
units of dBm.

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8-8

AM5XT/eXT Voice/Data Transmission (18-0022) Measure Functions

8.4

2

NOISE (Idle Channel Noise)

The Idle Channel NOISE test measures the noise, through a selected filter, on a
theoretically “quiet” line, i.e., a QUIET terminated circuit without a test signal.
See notes in ¶8.3 concerning noise measurements.

Send Function

Set the Send Function to QUIET (¶7.2).

DATA DISPLAY

Measured noise level

10 to 99 dBrn (AM5XT)

-80 to 9 dBm (AM5eXT)

Note: The right-hand display does not operate during idle channel NOISE

measurements.

Filter Selection

For the AM5XT, the usual noise-weighting filter used for Idle Channel NOISE
measurements is the C-Message filter (key [2]). For the AM5eXT, the usual filter
used for Notch Noise measurements is the Psophometric filter (key [2]).

In general, any of the filters listed in Table 8-1 can be used.

8.5

0022-S08.G_ 308 October 17, 2000

3

NOTCH NOISE (Noise-with-Tone)

The Notch Noise Test measures the noise, through a selected filter, on a line that
has a 1004 Hz tone. The 1004 Hz tone is removed in the measuring circuit through
a 1010 Hz “notch” filter, then the residual noise is measured. This test is
sometimes referred to as a “noise-with-tone” measurement.

Send Function

Set the Send Function to 1004 Hz (¶7.3).

8-9

Measure Functions (18-0022) AM5XT/eXT Voice/Data Transmission

DATA DISPLAY

8.6

Measured noise level

10 to 99 dBrn (AM5XT)

-80 to 9 dBm (AM5eXT)

Holding Tone frequency

Note: In order for the Notch Noise measurement to be valid, the “HOLD TONE”

indicator green LED must be ON, indicating that the 1004 Hz tone is
present at the proper frequency and level. Acceptable frequency is from
995 Hz to 1025 Hz at a level of greater than -40 dBm. The right-hand
display will also indicate the frequency of the received tone for further
verification.

Filter Selection

For the AM5XT, the usual noise-weighting filter used for Notch Noise
measurements is the C-Message filter (key [2]). See Figure 9-2 for a graph of the
C-Message filter. For the AM5eXT, the usual filter used for Notch Noise
measurements is the Psophometric filter (key [2]).

In general, any of the filters listed in Table 8-1 can be used.

Note: If no filter is selected, the AM5eXT Psophometric filter is automatically

selected.

4

NTG (Noise-to-Ground)

Noise-to-Ground is measured by internally summing the signals on the Tip and
Ring wires of the receive (RX) line within the AM5XT/eXT, then measuring the
noise, through a selected filter, with reference to ground. For the ground
reference, use either the ground screw terminal on the rear panel (item 8 in Figure
3-3) or the sleeve contact of the RX front panel Bantam Jack.

Send Function

Set the Send Function to QUIET (¶7.2).

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AM5XT/eXT Voice/Data Transmission (18-0022) Measure Functions

DATA DISPLAY

Measured Noise-to-Ground

40 to 129 dBrn (AM5XT)

-50 to 39 dBm (AM5eXT)

Note: The right-hand display does not operate during NTG measurements.

Filter Selection

For the AM5XT, the usual noise-weighting filter used for Noise-to-Ground
measurements is the C-Message filter (key [2]). For the AM5eXT, the usual filter
used for Noise-to-Ground measurements is the Psophometric filter (key [2]).

In general, any of the filters listed in Table 8-1 can be used.

8.7

5

S/N (Signal-to-Noise Ratio)

Signal-to-Noise Ratio measurement is similar to the notch noise measurement in
that a 1004 Hz test tone is expected at the received end. The receive circuit
contains an average detector, a 1004 Hz notch filter, a noise weighting filter, and
an RMS Detector (RMS Detector or Quasi-Peak Detector for AM5eXT).

1. The average detector measures the amplitude of the received test tone
(primarily 1004 Hz) and the microprocessor keeps this value in memory.
This is the “signal” reading.

2. The RMS or Quasi-Peak detector measures the value of the residual noise
after the 1004 Hz tone is notched out. This value is also kept in memory
by the microprocessor. This is the “noise” reading.

3. The microprocessor computes the difference, in dB, between the value in
“1” and the value in “2”. This is the Signal-to-Noise Ratio.

Send Function

Set the Send Function to 1004 Hz (¶7.3).

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Measure Functions (18-0022) AM5XT/eXT Voice/Data Transmission

DATA DISPLAY

8.8

Measured S/N Ratio

0 to 60 dB

Holding Tone frequency

Note: In order for the Signal-to-Noise measurements to be valid, the “HOLD

TONE” indicator green LED must be ON, indicating that the 1004 Hz tone
is present at the proper frequency and level. Acceptable frequency is
from 995 Hz to 1025 Hz at a level of greater than -40 dBm. The right hand
display will also indicate the frequency of the received tone for further
verification.

Filter Selection

For the AM5XT, the usual noise-weighting filter used for Signal-to-Noise
measurements is the C-Message filter (key [2]). For the AM5eXT, the usual filter
used for Signal-to-Noise measurements is the Psophometric filter (key [2]).

In general, any of the filters listed in Table 8-1 can be used.

6

PAR (Peak-to-Average Ratio)

Definition of P/AR

P/AR (Peak-to-Average Ratio) measurements are made by applying a special 16
tone (PAR) signal at the distant end of the line under test. At the near end, the
AM5XT simultaneously measures the peak value and average value of the received
test signal. The Ratio of the Peak value to the Average value of the transmitted

signal is arbitrarily assigned a value of 100.

If the transmission channel were non-dispersive, the received Peak-to-Average
Ratio would also have a value of 100. A typical telephone channel causes
smearing or Intersymbol Interference however, and a value other than 100 is
observed.

Table 8-2 shows some typical values that might be used to judge the acceptability
of a telephone line to reliably transmit data.

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8-12

AM5XT/eXT Voice/Data Transmission (18-0022) Measure Functions

Example: If a modem requires a C2 conditioned line, and a P/AR of 50 is

measured, this line is likely to encounter transmission problems. On the other
hand, if a P/AR of 78 is measured, Intersymbol Interference will not cause
problems.

Table 8-2. P/AR Requirements of Telephone Lines

CIRCUIT CONDITIONING TYPICAL P/AR VALUES

Basic Channel 45

C1 48
C2 78
C4 87
C5 95

The P/AR value of the received (distorted) signal is made according to the following formula:

P/AR = 100* (K P/Afw-1)

Where P = peak voltage of received signal

Afw = full-wave average of the received signal
K = a constant

The constant K is derived by giving undistorted signal a nominal value of 100. Therefore:

K = 2Afwo/Po

Where Po = peak voltage of the undistorted (original) signal

Afwo = full-wave average of the undistorted (original) signal

Therefore:

P/AR = 100* [2(P/Po) / (Afw/Afwo) - 1]

or P/AR = 100* [2(Pn/Afwn) – 1]
Where Pn = normalized peak voltage of the received signal

Afwn = normalized full-wave average of the received signal

Factors Which Affect P/AR

P/AR is most sensitive to envelope delay distortion and return loss problems. To
a lesser degree, it is affected by attenuation distortion, noise, and nonlinear
(intermodulation) distortion. It is basically unaffected by transient phenomena
such as impulse noise and phase and gain hits.

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Measure Functions (18-0022) AM5XT/eXT Voice/Data Transmission

Envelope Delay Distortion

There is a high correlation between measured P/AR values and values calculated
from a plot of envelope delay distortion. In fact, for an envelope delay response
containing significant ripples, P/AR is a better indication of the ability of the
network to pass data reliably. Return loss problems are a common source of
envelope delay ripple.

Effect of Noise

Noise can have a significant affect on P/AR measurement. For this reason, it is
important to measure signal-to-noise ratio (or noise-with-tone) before making a
P/AR measurement. If the signal-to-noise ratio is less than 25 dB, the P/AR
reading will be significantly reduced by noise alone.

Effect of Nonlinear Distortion

Nonlinear (Intermodulation) Distortion can similarly affect the P/AR reading.
The effect depends on whether the second or third order products dominate as the
source of distortion. If the third order products dominate, they increase or
decrease the P/AR value, depending upon the sign of the added products.

Send Function

Set the Send Function to PAR (¶7.7), a composite wave form per Bell 41009
specifications, made up of 16 specific phrase-related frequencies.

DATA DISPLAY

Measured Level P/AR reading: 0 to 120 P/AR

Note in the DATA DISPLAY that the left reading is the RMS level of the received
P/AR waveform in dBm, and the right reading is the Peak-to-Average Ratio in
P/AR units (100 P/AR = value for transmitted signal).

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AM5XT/eXT Voice/Data Transmission (18-0022) Measure Functions

8.9

7

RET LOSS (Return Loss)

Definition

Return Loss is the ratio, in dB, of the power incident on a transmission system
discontinuity to the power reflected from the discontinuity. It indicates how well
the input and output impedances are matched throughout a circuit. Return Loss
measurements are made on both 2-wire and 4-wire circuits.

Setup

A test signal is transmitted from the near end while the far end is Quiet
terminated. At the near end, the level of the transmitted test tone (TX) is
compared with the measured level on the receive line (RX). The difference
between the transmit and receive signal is the Return Loss in dB.

Test Signals

Four (4) possible test signals can be transmitted:

1. Echo Return Loss (ERL) signal

2. Singing Return Loss (SRL) LO signal

3. Singing Return Loss (SRL) HI signal

4. Sine Wave (VAR HZ) in 200 Hz to 5 kHz band, per ¶7.4

ERL, SRL LO, and SRL HI are band-limited white-noise test signals (see ¶7.8).
Since the Return Loss measurement is the ratio between transmitted energy and

received energy, the absolute amplitude of transmit energy is somewhat
immaterial. The AM5XT/eXT, however, has the ability to generate the ERL, SRL
LO, and SRL HI waveforms anywhere between -10 dBm and -2 dBm (see ¶7.8).

2-Wire Return Loss

In 2-wire Return Loss measurements, the test signal is applied to the transmit pair
(TX) of the internal 4-wire to 2-wire hybrid, and at the same time the RMS
detector measures the energy on the receive pair (RX) of the hybrid. The hybrid
balancing impedance is the selected line impedance (¶6.2) in series with 2.16µF.
If the 2-wire circuit under test is properly terminated and free of send/receive
coupling, very little of the transmitted energy will be returned on the receive pair
and the Return Loss reading in dB (which is a measure of the transmitted energy
versus received energy) will be a large reading.

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8-15