AMERITEC AM-48 User manual

Models AM-48 and AM-48E
Personal Transmission
Test Set
INSTRUCTION MANUAL

Models AM-48 and AM-48E
Personal Transmission
Test Set
Instruction Manual
February 4, 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. 18-0015 © 2000 Ameritec Corporation

0015-TPG
ii
Record of Revisions
ASeptember 1992 Initial Release.
BJanuary 28, 1998 Minor Update Changes.
COctober 2, 1998 Changed Generator
Accuracy Specs.
C1 October 9, 1999 Changed Distortion
specification on 1-6.
DFebruary 4, 2000 Reformatted Manual to
provide new soft copy.
EJanuary 19, 2004 Made a Better PDF
FApril 19, 2004 Option

AM-48 Test Set (18-0015) Table of Contents
0015-TOC iii
Table of Contents
1. INTRODUCTION ...................................................................................... 1-1
1.1 Manual Overview...............................................................................1-1
1.2 General Description...........................................................................1-2
1.3 AM-48 Technical Specifications........................................................1-4
1.4 AM-48E Technical Specifications....................................................1-11
2. RECEIVING AND UNPACKING..............................................................2-1
2.1 Introduction ........................................................................................ 2-1
2.2 Inspection when Received ................................................................2-1
2.3 Verification of Contents .....................................................................2-1
3. PHYSICAL & FUNCTIONAL DESCRIPTION.........................................3-1
3.1 Introduction ........................................................................................ 3-1
3.2 General ..............................................................................................3-1
3.3 Component Location..........................................................................3-2
3.4 Connectors and Cables.....................................................................3-3
3.5 Switches............................................................................................. 3-5
3.6 Keyboard.......................................................................................... 3-14
3.7 Display .............................................................................................3-17
3.8 Microphone/Speaker........................................................................3-19
3.9 Hand-Held Printer............................................................................3-20
3.10 Impedance Adapter .......................................................................3-24
4. POWER CONSIDERATIONS..................................................................4-1
4.1 General ..............................................................................................4-1
4.2 Battery Compartment ........................................................................4-1
4.3 Battery-Selector Switch.....................................................................4-1
4.4 Battery Installation.............................................................................4-3
4.5 Battery Information ............................................................................4-3
4.6 AC Power...........................................................................................4-4
4.7 Power On/Off Switch ......................................................................... 4-4

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iv
5. SELF-TEST INSTRUCTIONS.................................................................. 5-1
5.1 General ..............................................................................................5-1
5.2 Self-Test Setup.................................................................................. 5-1
5.3 Quiet Send Mode............................................................................... 5-4
5.4 Send 1004 Hz.................................................................................... 5-5
5.5 Send PAR (Peak-to-Average Ratio).................................................. 5-7
5.6 Dialing ................................................................................................ 5-8
5.7 Parameter Values for Send Sweep.................................................5-10
6. CONNECTION AND CONFIGURATION.................................................6-1
6.1 Introduction ........................................................................................ 6-1
6.2 General ..............................................................................................6-1
6.3 Connectors and Cables.....................................................................6-2
6.4 600Ω/900ΩLine Termination Impedances......................................6-7
6.5 Impedance Adapter ...........................................................................6-9
6.6 Configurations.................................................................................. 6-10
7. OPERATING INSTRUCTIONS................................................................7-1
7.1 Introduction ........................................................................................ 7-1
7.2 General Instructions and Notes.........................................................7-3
7.3 General Operating Notes................................................................... 7-3
7.4 Figure Format ....................................................................................7-4
7.5 General Switch Setup........................................................................7-6
7.6 Multiple Use of Keys.......................................................................... 7-8
7.7 Memory..............................................................................................7-9
7.8 General Procedure to Set New Parameter Values.........................7-12
7.9 Send (Generator) Modes and Parameter Settings......................... 7-13
7.10 Types of Send Signals................................................................... 7-13
7.11 Send Quiet....................................................................................7-14
7.12 Set Parameters from Quiet Display .............................................7-15
7.13 Send Momentary Variable Tones................................................. 7-17
7.14 Send 1004 Hz............................................................................... 7-18
7.15 Send Continuous Variable Tone.................................................. 7-19

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0015-TOC v
7.16 Send Set of Slope Tones .............................................................7-19
7.17 Send Variable Sweep...................................................................7-20
7.18 Send PAR Waveform ...................................................................7-22
7.19 Send Momentary 2713 Hz Tone.................................................. 7-22
7.20 General Instructions and Notes for MEASURE Modes...............7-22
7.21 Accuracy of Measurements.......................................................... 7-22
7.22 Absolute and Relative Measurements......................................... 7-23
7.23 Special Measurement Requirements........................................... 7-24
7.24 Timed Tests..................................................................................7-26
7.25 MEASURE Modes........................................................................ 7-27
7.26 Measure Level and Frequency.....................................................7-27
7.27 Measure Noise..............................................................................7-28
7.28 Measure PAR................................................................................ 7-29
7.29 Measure Impulse Noise................................................................7-29
7.30 Measure Notched Noise...............................................................7-32
7.31 Measure S/N Ratio ....................................................................... 7-34
7.32 Measure Phase Jitter....................................................................7-34
7.33 Measure Amplitude Jitter..............................................................7-35
7.34 Measure Transients......................................................................7-36
7.35 Miscellaneous Operations............................................................7-40
7.36 Store and Recall...........................................................................7-40
7.37 Dialing...........................................................................................7-43
7.38 Talking........................................................................................... 7-45
7.39 Printing.......................................................................................... 7-45
7.40 Auto Study Result Save................................................................7-56
7.41 Impedance Adapter Measurement Corrections........................... 7-56
7.42 Auto Calibrate............................................................................... 7-59
8. EXPLANATION AND APPLICATION OF MEASUREMENTS............... 8-1
8.1 Introduction ........................................................................................ 8-1
8.2 Units of Measurement .......................................................................8-1
8.3 Level (Loss or Gain) and Frequency.................................................8-4
8.4 Idle Channel Noise ............................................................................8-4

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vi
8.5 Notched Noise (Noise with Tone) .....................................................8-4
8.6 Signal-to-Noise (S/N) Ratio...............................................................8-5
8.7 P/AR Measurements.......................................................................... 8-6
8.8 Gain Slope .........................................................................................8-8
8.9 Idle Channel Impulse Noise ..............................................................8-9
8.10 Phase Jitter....................................................................................8-11
8.11 Amplitude Jitter..............................................................................8-11
8.12 Notched Impulse Noise .................................................................8-12
8.13 Phase Hits......................................................................................8-12
8.14 Gain Hits ........................................................................................8-12
8.15 Dropouts......................................................................................... 8-12
9. CIRCUIT DIAGRAMS............................................................................... 9-1
9.1 Introduction ........................................................................................ 9-1
9.2 AM-48 Simplified Block Diagram.......................................................9-1
9.3 Impedance Adapter Schematic......................................................... 9-3
10. WARRANTY, SERVICE, AND CALIBRATION .................................. 10-1
10.1 Warranty......................................................................................... 10-1
10.2 Service Policy ................................................................................10-1
10.3 Calibration Policy...........................................................................10-1
10.4 Return of Unit.................................................................................10-2
11. GLOSSARY...........................................................................................11-1

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List of Figures
Figure 3-1. AM-48 Location of Components................................................ 3-3
Figure 3-2. AM-48 Connectors.....................................................................3-4
Figure 3-3. Standard AM-48 Cables ............................................................3-4
Figure 3-4. Optional AM-48 Cables..............................................................3-5
Figure 3-5. AM-48 Switch Identification Numbers ....................................... 3-6
Figure 3-6. AM-48 Keyboard Identification Numbers ................................3-15
Figure 3-7. AM-48 Liquid Crystal Display ..................................................3-18
Figure 3-8. Hand-Held Printer, External View............................................3-22
Figure 3-9. Hand-Held Printer, Internal View............................................. 3-23
Figure 3-10. Impedance Adapter................................................................ 3-24
Figure 4-1. Battery Installation and Selector Switch.................................... 4-2
Figure 5-1. AM-48 Setup for Self-Test (Looped Back)................................ 5-2
Figure 5-2. General Switch Setup for Self Test...........................................5-3
Figure 5-3. Quiet Send Mode Self Test........................................................ 5-4
Figure 5-4. Send 1004 Hz Self Test, Switch Settings.................................. 5-6
Figure 5-5. Send 1004 Hz Self Test, Displays.............................................5-7
Figure 5-6. Send PAR (Peak-to-Average Ratio).......................................... 5-8
Figure 5-7. Dialing....................................................................................... 5-10
Figure 5-8. Default Parameter Settings for SWEEP Send Mode.............. 5-14
Figure 6-1. 2-Wire AM-48 Line Connections................................................ 6-3
Figure 6-2. 4-Wire AM-48 Line Connections................................................ 6-4
Figure 6-3. AM-47 Hand-Held Printer Connection with AC Power..............6-5
Figure 6-4. 4-Wire End-to-End Testing...................................................... 6-11
Figure 6-5. 4-Wire Testing with Responder...............................................6-13
Figure 6-6. 2-Wire Network Testing with Responders............................... 6-14
Figure 7-1. Parameter Settings from QUIET SEND Display..................... 7-15
Figure 7-2. Parameter Settings from 1004 Hz and VAR Tone Displays ...7-18

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viii
Figure 7-3. Parameter Settings from 3-TONE Slope and
PAR SEND Displays......................................................... 7-20
Figure 7-4. Parameter Settings from SWEEP SEND Display................... 7-21
Figure 7-5. L/F, NOISE, and PAR MEASURE Displays............................7-28
Figure 7-6. IMPLS MEASURE Displays..................................................... 7-32
Figure 7-7. Notched NOISE and S/N Ratio MEASURE Displays ............. 7-33
Figure 7-8. Phase JTR and Amplitude JTR MEASURE Displays............. 7-35
Figure 7-9. TRANS MEASURE Displays..........................................7-39, 7-40
Figure 7-10. Recall and Store Operations .................................................7-42
Figure 7-11. SEND Printouts...................................................................... 7-52
Figure 7-12. MEASURE Printouts, Absolute Measure Mode....................7-54
Figure 7-13. MEASURE Printouts, Relative Measure Mode.....................7-55
Figure 7-14. Impedance Adapter Correction Value Memory Aid...............7-58
Figure 7-15. AM-48 Auto Calibrate Prompts..............................................7-60
Figure 8-1. Level and Noise Units of Measurement....................................8-2
Figure 8-2. Impulse Noise Thresholds and Blanking Intervals.................. 8-10
Figure 9-1. Simplified Block Diagram of the AM-48.....................................9-2
Figure 9-2. Schematic Diagram of the Impedance Adapter........................ 9-4

AM-48 Test Set (18-0015) Table of Contents
0015-TOC ix
List of Tables
Table 1-1. AM-48 General Technical Specifications ...................................1-5
Table 1-2. AM-48 Generator (Send) Technical Specifications.................... 1-6
Table 1-3. AM-48 Receiver (Measure) Technical Specifications................ 1-8
Table 1-4. AM-48 Power/Physical Technical Specifications ..................... 1-11
Table 2-1. AM-48 Standard Equipment.......................................................2-2
Table 2-2. AM-48 Optional Equipment ........................................................2-2
Table 3-1. Front Panel/Switches Color Coding............................................3-2
Table 3-2. AM-48 SEND, MEASURE, and FILTER Menus....................... 3-19
Table 3-3. AM-47 Hand-Held Printer Technical Specifications.................3-21
Table 7-1. Setup Requirements for Different Keyboard Applications .........7-8
Table 7-2. Steps for Up and Down Arrow Keys...........................................7-9
Table 7-3. User-Programmable Parameter Values Stored in Memory..... 7-11
Table 7-4. Acceptable Holding Tone Ranges............................................ 7-25
Table 7-5. Special Measurement Requirements........................................7-26
Table 7-6. Setup Requirements for Dialing................................................7-44
Table 7-7. MF and DTMF Tone Pairs.........................................................7-44
Table 7-8. Impedance Adapter Correction Values..................................... 7-57
Table 8-1. P/AR Requirements of Telephone Lines....................................8-6

AM-48 Test Set (18-0015) Introduction
0015-S01 1-1
1. INTRODUCTION
1.1 Manual Overview
This instruction manual describes Ameritec Corporation’s AM-48
and AM-48E Personal Transmission Test Sets.
Note: Throughout this manual, all references to the "AM-48" also
apply to the "AM-48E", unless otherwise noted. See ¶1.4
for a summary of the differences between the AM-48 and
the AM-48E.
The other paragraphs in this Introduction section are:
1.2 General Description
1.3 AM-48 Technical Specifications
1.4 AM-48E Technical Specifications
The balance of the manual is divided into the following sections:
2. Receiving and Unpacking
3. Physical and Functional Description
4. Power Considerations
5. Self-Test Instructions
6. Connection and Configuration
7. Operating Instructions
8. Explanation and Application of Measurements
9. Circuit Diagrams
10. Warranty, Service, and Calibration
11. Glossary
Index

Introduction (18-0015) AM-48 Test Set
0015-S011-2
Note: It is suggested that the foldout at the back of the manual be
extended when using this manual. The FOLDOUT, a front view
of the AM-48, defines the numbers of the switches which are
used to identify the switches throughout this manual.
Glossary. Refer to the Glossary to become familiar with the
terminology used in this manual.
Power. Be sure to read Section 4 and observe the WARNING in ¶4.3
before powering up the AM-48.
Self Test. Perform the Self Test in Section 5 to:
1. confirm that all AM-48 circuits and basic functions are
working properly, and
2. obtain "hands-on" experience with the AM-48 to learn how
the controls operate.
Transmission Measurements. Note that Section 7, Operating
Instructions, gives procedures to perform transmission measurements.
For explanation and application of the measurements, see Section 8.
1.2 General Description
Definition and Purpose. In one (1) hand-held unit, the AM-48
provides the field engineer with two (2) instruments:
1. a transmission test set, and
2. a telephone "butt-set".
The transmission test set tests the integrity and quality of 2-wire or
4-wire voice and data transmission lines by sending selected analog
signals and measuring standard parameters of the received signals.

AM-48 Test Set (18-0015) Introduction
0015-S01 1-
3
The telephone "butt set" enables the field engineer to dial up and
speak back-and-forth with a field engineer at the far end of the
system. The compact and light-weight AM-48 eliminates the need to
carry multiple, bulky test sets.
Functional Overview
AM-48 can send:
•any frequency from 200 Hz to 20 kHz @ -50 to +10 dBm
•continuous 3-tone slope (404, 1004, 2804 Hz)
•continuous, user-defined, sweep tones
•fixed 1004 Hz
•P/AR waveform
•momentary 2713 Hz for WECO 829 loopback
AM-48 can measure:
•level, -65 to +10.9 dBm (absolute or relative)
•frequency, 0 to 19,999 Hz
•idle channel noise
•noise with tone
•three-level impulse noise
•phase jitter
•gain jitter
•transients (dropouts, phase and gain hits, impulse noise)
•signal-to-noise (S/N) ratio
•peak-to-average ratio (P/AR)
Noise filters provided (each with optional 1010 Hz notch)::
•C-Message (Psophometric for AM-48E)
•3 kHz
•15 kHz
•Program (Sound-weighted for AM-48E)

Introduction (18-0015) AM-48 Test Set
0015-S011-4
Other features:
•High impedance bridge, 600 or 900 Ohm termination
•Display prompts help in set-up and testing sequences
•On-board memory can store & recall up to 10 user-defined
test set-ups
•Dials: pulse, DTMF, and MF
•Talk/Listen capability
•Printer interface for hard copy of set-up and test results
•Battery life: Alkaline, 6 to 7 hours; NiCad, 3 to 4 hours
•NiCad batteries can be recharged without removing them
from the unit
Testing Configurations: (For details, see ¶6.6)
There are three (3) basic AM-48 configurations used to test
2-wire/4-wire telephone/data communication lines:
1. End-to-end -- requiring two (2) AM-48 units
2. Loopback
3. Testing with responders
1.3 AM-48 Technical Specifications
AM-48 technical specifications are presented in four (4) parts:
1. General (Table 1-1)
2. Generator (Send) (Table 1-2)
3. Receiver (Measure) (Table 1-3)
4. Power/Physical (Table 1-4)

AM-48 Test Set (18-0015) Introduction
0015-S01 1-
5
Table 1-1. AM-48 General Technical Specifications
Characteristic Specification
Measurements
Level -65 to +10.9 dBm
Frequency 0 to 19,999 Hz
Noise 10 to 99 dBrn
Notched Noise 10 to 99 dBrn
Signal to Noise 0 to 60 dB
P/AR 0 to 120
Amplitude Jitter 0.0 to 25.0%
Phase Jitter 0.0 to 25.0 degrees
3-Level Impulse Noise Counts from 0 to 9999
Transient Measurements
Dropouts 0 to 9999
Gain Hits 0 to 9999
Phase Hits 0 to 9999
3-Level Impulse Noise Counts from 0 to 9999
Dial Built-in 16 button keypad for dial pulse, DTMF (Touch
Tone), or MF dialing.
Talk Built-in microphone and speaker with push-to-talk
operation on both 2-wire and 4-wire lines. Earphone
jack for optional earphone.
Holding A single line holding circuit is provided for 2-wire
operation, or the send pair of 4-wire circuits. It
electronically simulates a holding coil with a DC
resistance of approximately 200 ohms. The AC
impedance is high enough to give no more than 0.2 dB
loss at 600 ohm impedance.
Impedances 600 and 900 ohm.
Balance > 60 dB below 4 kHz, decreasing 6 dB.octave
above 5 kHz.
Return loss > 30 dB 200-5000 Hz, > 15 dB 5-20 kHz.
DC blocking - 150 Volts.
Bridging impedance > 25 kohms.

Introduction (18-0015) AM-48 Test Set
0015-S011-6
Characteristic Specification
Printer Current loop interface to optional printer for hard copy
of unit setup and measurement results
Store/Recall 10 complete unit setups may be stored by user in
internal nonvolatile memory, and recalled for ease of
repeating frequently-used tests. In addition, the results
of the last impulse or transient study (along with the
associated setups) are stored to nonvolatile memory at
the completion of the study. They are recalled
automatically whenever the unit is turned on.
Also stored in nonvolatile memory are four (4) user-set
parameters (each set from the QUIET mode):
1. Touch Tone/MF Dial Level
2. Power Down Time with momentary power switch
3. Blanking interval for impulse and transient tests
4. 10 user-programmable momentary frequencies
Table 1-2. AM-48 Generator (Send) Technical Specifications
Characteristic Specification
Variable Frequency: 200 Hz to 19,999 Hz in 1 Hz steps.
Frequency may be entered directly via the keypad or
stepped up or down in 10 Hz steps with auto-repeat
steps of 100 Hz (4 steps/second) for fast frequency
slewing. Frequencies are crystal-controlled and
accurate to ±.72 Hz ±.01%.
Level: -50.0 dBm to +10.0 dBm in .1 dB steps. Level
may be entered directly via the keypad or stepped up
or down in .1 dB steps with auto-repeat steps of 1.0 dB
(4 steps/second) for fast level slewing. Level accuracy
is as follows:
±0.2 ±0.5
±0.5 ±1.0
200 Hz
+10 dBm
-40 dBm
-50 dBm
15 kHz 20 kHz
1004 Hz A fixed 1004 Hz holding tone is provided. The
frequency is accurate to ±.025%. Level is the same as
variable.

AM-48 Test Set (18-0015) Introduction
0015-S01 1-7
Characteristic Specification
3-Tone A three-tone slope frequency mode is provided, which
cycles continuously between 404 Hz, 1004 Hz, and
2804 Hz, giving 5 seconds of each tone. Frequency
accuracy is the same as variable. Level is the same
as variable.
Sweep A programmable frequency sweep generator is
provided. It generates tones continuously from a user-
specified START frequency (200 Hz to 19,999 Hz) to a
user-specified STOP frequency (200 Hz to 19,999 Hz),
at a user-specified frequency STEP interval (1 Hz to
19,999 Hz), and at a user-specified step RATE (0.1
second to 19,999 seconds/frequency). Frequency
accuracy is the same as variable. Level is the same
as variable.
PAR A PAR waveform generator is provided, which
generates the 16 simultaneous frequency PAR
waveform per Bell 41009 specifications. The level
may be set from -40.0 dBm to 0.0 dBm, with 0.1 dBm
resolution. Level accuracy is ±0.5 dBm.
Quiet In quiet mode, the line is terminated with a passive
resistance equal to the line impedance. Also, when in
Quiet, one of 10 user-programmable tones may be
momentarily applied to the line by depressing the (0)
thru (9) keys.
Programmable from this mode are (1) Touch Tone dial
level (-50.0 to 7 dBm), (2) Power down Time Off (1 to
255 minutes), (3) Impulse and Transient test Blanking
Interval (1 to 255 ms), and (4) 10 user-programmable
tones for later instant recall.
Aux Tone A momentary pushbutton is provided for the
generation of an auxiliary tone (2713 Hz), used to
activate remote 829-type loopback devices.
SF Skip A Signaling Frequency (SF) Skip mode prevents the
generation of tones between 2450 Hz and 2750 Hz in
variable or sweep modes.
Distortion Total distortion is < -50 dB @ 1004 fixed tone and
< -40 dB @ any other frequency.

Introduction (18-0015) AM-48 Test Set
0015-S011-8
Table 1-3. AM-48 Receiver (Measure) Technical Specifications
Characteristic Specification
Level/Freq Level is measured with an average responding detector.
Range is -65.0 to +10.9 dBm with 0.1 dBm resolution.
Accuracy is as follows:
±0.2 ±0.5
±0.4 ±0.8
200 Hz
+10 dBm
-40 dBm
-65 dBm
15 kHz 20 kHz
Note: Accuracy is ±0.1 dBm at 1004 Hz from -20
dBm to 0.0 dBm.
Frequency is measured from 200 Hz to 19,999 Hz with an
accuracy of ±.01% ±1 Hz, and a resolution of 1 Hz. Input
level -40 to +10 dBm.
PAR Peak-to-Average Ratio (PAR) is measured from 0 to 120
PAR units to a resolution of 1 PAR unit. Accuracy is ±2
from 30 to 110, ±4 from 0 to 120 over a signal range of -40
to 0 dBm.
PAR signal level is measured from -40 to 0 dBm, with a
resolution of 1 dBm, using an RMS detector.
Noise Noise is measured with an RMS responding detector from
10 to 99 dBrn to 1 dBrn resolution. Accuracy is ±1 dBrn
from 20 to 99 dBrn, and ±2 dBrn from 10 to 20 dBrn.
Weighting Filters are 3 kHz flat, 15 kHz flat, CMSG, and
Program filter.
Notched Noise Notched Noise is the same as noise with the addition of a
1010 Hz notch filter, minimum 50 dB deep from 995 to 1025
Hz.
S/N ratio Signal-to-Noise (S/N) ratio display the ratio of signal
(holding tone) to notched noise. The signal must be -40 to
+10 dBm. The notched noise may be 10 to 70 dBrn. The
S/N ratio may be from 10 to 50 dB. Resolution is 1 dB.
Accuracy is ±1 dB for notched noise 20 to 70 dBrn, and ±2
dB for notched noise from 10 to 20 dBrn.

AM-48 Test Set (18-0015) Introduction
0015-S01 1-
9
Characteristic Specification
Amplitude Jitter Displays the incidental amplitude modulation of a holding
tone. The holding tone must be -40 to +10 dBm, 990 to
1030 Hz. Amplitude jitter is displayed from 0.0 to 25.0%
with a resolution of .1% and an accuracy of ±.2%, ±5% of
reading.
Weighting filter selection: 20-300 Hz or 4-300 Hz.
Phase Jitter Displays the incidental phase modulation of a holding tone.
The holding tone must be -40 to +10 dBm, 990 to 1030 Hz.
Phase jitter is displayed in degrees from 0.0 to 25.0
degrees with a resolution of .1 degree and an accuracy of
±.2 degree, ±5% of reading.
Weighting filter selection: 20-300 Hz or 4-300 Hz.
Impulse Noise Three (3) noise thresholds are established: Low, Middle,
and High levels, with an equal interval between them called
the Delta. The maximum High threshold is 105 dBrn for
600 ohm impedance (or 104 dBrn for 900 ohm). The
minimum Low threshold is 30 dBrn. Delta can be 2, 3, 4, or
6 dB. Threshold accuracy: ±1 dB. A user-selected
blanking interval of 1 to 255 ms for each threshold, blocks
further counting of impulses at that threshold.
The study duration timer may be set from .1 minute to
1999.9 minutes in .1 minute steps, or continuous. Each
threshold has a count capacity of 0-9999. Weighting filters
same as noise.
Transients Counts dropouts, gain hits, phase hits, and 3-level impulse
noise with tone. Holding tone must be -40 to +10 dBm, 995
to 1025 Hz
Dropout threshold is -12 dB from the initial level of the
holding tone. A dropout will be counted if the holding tone
drops below the threshold for at least 4 ms ±.5 ms.
Counting of dropouts, gain hits, phase hits, and impulses is
inhibited for a blanking interval which lasts until 1 second
after the holding tone is restored to a level above the
dropout threshold.

Introduction (18-0015) AM-48 Test Set
0015-S011-10
Characteristic Specification
Transients
(cont.)
Gain hit threshold can be 2, 3, 4, or 6 dB. A gain hit will be
counted if the level of the holding tone changes up or down
by more than the threshold for at least 4 ms ±.5 ms. A
blanking interval, that is user-set from 1 to 255 ms, blocks
further counting of gain hits.
Phase hit threshold can be 5 to 45 degrees in 1 degree
steps, with an accuracy of ±.5 degrees ±10% of the setting.
A phase hit will be counted if the phase of the holding tone
changes by more than the threshold fro at least 4 ms ±.5
ms. A blanking interval, that is user-set from 1 to 255 ms,
blocks further counting of phase hits.
The three-level impulse noise low threshold can be set from
30 to 110 dBrn with threshold differences of 2, 3, 4, or 6 dB.
Threshold accuracy: ±1 dB. An independent blanking
interval for each threshold, user-set from 1 to 255 ms,
blocks further counting of impulses at that threshold.
The study duration timer may be set from .1 minute to
1999.9 minutes in .1 minute steps, or set to 0 for a
continuous study.
Each transient has a count capacity of 0-9999.
Filters same as noise.
Damping A damp mode reduces the display update rate from
approximately 4 times/second to approximately 2
times/second for reading widely fluctuating measurements.
The same switch, when in <DAMP> position, also changes
the monitoring point of the receive (RCV) monitor speaker
to the output of the auto-range amplifier (significantly
increasing the speaker level).
Term/Bridge When in terminate, the receiver terminates the line in the
selected impedance. When in bridge, the line is bridged by
a high impedance, causing no more than .2 dB loss on a
600 ohm line.