Black Box | AC1037A-XMIT | COM-120B Evaluation Guide

COM-120B Evaluation Guide
http://www.avionteq.com/IFR-Aeroflex-COM-120B-Communications-Service-Monitor.aspx
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Rev. 1.0
Page 1
Rev. 1.0
Page 2
Thank you for taking the time to evaluate the IFR COM-120B. We know
that your time is valuable, so we have included a demonstration kit
complete with all of the accessories that you will need to evaluate the
advanced features of the COM-120B.
This instrument is also supplied with a step by step procedure to lead
you through the evaluation. In addition to the procedure, this instrument
has been configured with a software application that will configure the
equipment for each experiment.
Please use this guide and software, as it will allow you to rapidly see
many of the advanced features offered by the COM-120B in a minimal
amount of time.
The Operators guide and Programmers manual are also included if you
would like to gain even more detailed information.
We invite you to contact our Tech Support group techsupport@ifrsys.com to
receive a handy guide, the “RF DATAMATE” which provides much
useful information for anyone working in the wireless industry. Just drop
them a line and include your shipping information and one will be sent to
you.
If you have any suggestions or comments to improve this procedure or if
we have left something out, please drop us a line and we will try to
implement the addition or change if possible.
EMAIL requests to:
TO: info@ifrsys.com
Subject: RTS Evaluation
Thank you again for taking the time to evaluate the IFR COM-120B.
Rev. 1.0
Page 3
!
!
!
!
!
RF Inputs and Outputs
Audio Inputs and Outputs
Rear Panel
Basic Operation / Navigation
Using the SETUP software
! Transmitter Testing
! Power
! Frequency
! Voice Deviation
! Scope Peak/Min Hold
! Tone Decoding
! CTCSS / DCS tone decode
! CTCSS / DCS tone deviation
! DTMF Decode
! Transmitter Distortion
! Receiver Testing
! Sensitivity
! Audio Output Power
! Cross-band Duplex
! Spectrum Analyzer
! Filter Tuning
! Cable Fault
! Return Loss
If you need assistance or have any questions about the COM-120B or performing any of the experiments
in this guide, do not hesitate to call our toll free number: (800) 835-2352 and select menu item 1. You
will be able to speak to a trained specialist who is well versed with this product.
Rev. 1.0
Page 4
The Antenna port is designed for low
level off-the-air signals but has input
protection for up to 10 Watts in case of
accidental connection to transmitter.
Off the Air
Transmitter
connection
Full Duplex
Testing
Receiver
Half-Duplex
testing
+13 dBm
Tracking
Generator
Output
Rev. 1.0
Page 5
Transmitter
Input
Up to 50
Watts
Continuos
Scope / DVM Input
(200 VRMS Max)
AUDIO / DATA
GEN OUT
0 – 1.7 VRMS
AUDIO / DATA
SINAD IN
(15mV – 15V)
DEMOD
OUT
EXT MOD IN
2 kHz / Vpk Narrow
10 kHz / Vpk Wide
Microphone
Input
Rev. 1.0
Page 6
External Mod
source for radio
under test
External Audio
Analysis
Master Power
Switch
Battery
Compartment
Replaceable
Battery
(Carry a Spare)
Ext. DC
Input
12-30 VDC
10 MHz Ext.
Reference Input
RS-232 Serial I/O
Direct pin to pin
connection to PC
Optional
GPIB
Interface
LID / Storage Unit
AC Line Cord
DC Line Cord
Antenna
Fuses
Extra room for cables and connectors
Rev. 1.0
Page 7
For the purpose of demonstration, this demo unit has been configured
with software to perform specific setups that coincide with this
document. A description of the test setup is also provided. For
maximum benefit, a kit has been included to allow testing of a radio,
tuning of a filter and measurement of return loss.
The COM-120B provides a powerful set of insturments to allow repair,
calibration and diagnostic evaluations of communications systems. The
COM-120B organizes test functions into screens that can be selected
and altered to perform specific tests. A powerful memory system allows
storage and recall of test setups, frequency lists and test software for
quick evaluation.
Primary Screens:
GEN
Test Receivers
REC
Test Transmitters
DPLX
Simultaneous Transmitter / Receiver test
SPCL
Access optional Trunking Features and Tests
Memory Functions:
STORE
RCL
SHOW LIST
Rev. 1.0
Store and Label a test setup
Recall a stored test setup
Access test software
Page 8
1. Remove the connector kit from the Evaluation Kit and Connect the NBNC adapter to the COM-120B’s T/R RF IN/OUT connector located
in the lower left corner of the instrument.
2. Remove the TNC-BNC adapter from the Evaluation Kit and connect
the COM-120B’s Antenna Input located in the upper right corner of
the instrument.
3. Connect the AC Line cord to the COM-120B’s rear panel receptical
and apply power with the power switch located in the lower left corner
of the instrument.
The COM-120B will begin it’s power on sequence followed by a selftest.
The Selftest can be aborted by pressing a mode key such as [REC].
The COM-120B should be preset to factory
default conditions prior to performing any of
the following procedures. To do this, press
the [SETUP] key to access the system
setup screen.
Press the down arrow key until item 12 is
selected as indicated by the cursor box.
Press the [ENTER] key to activate Factory
Defaults.
Rev. 1.0
Page 9
Basic Operation and Navigation
This guide will provide some basic operational knowledge to allow
configuration of the COM-120B but you should consult the Operators
Guide for more detailed information.
Begin by selecting a test mode of operation. Press the
[REC] key now to enable the Transmitter Test screen.
Screen settings are accomplished by positioning a
cursor to a field label and establishing the desired
setting. The cursor can be moved to a different field
through use of the 4 arrow keys on the COM-120B’s
front panel. These keys are located to the left of the
large knob in the DATA SCROLL section of the front
panel.
Cursor
Changing Numeric fields:
To change the value of a numeric field such
as the RF frequency:
1. Position the cursor the field label (RF).
2. Use the numeric keypad to directly enter
the frequency and terminate entry by
pressing the [ENTER] key.
OR
Function Keys F1 – F6
3. Press the [ENTER] key to highlight the
frequency field.
4. Use the left or right arrow keys to position the cursor to the digit to be
changed and use the up and down arrows or the knob to adjust the
value of the selected digit. Terminate the entry with the [ENTER]
key.
Other Field types:
Another type of field allows selection of an item by list or menu. The
INPUT field (located just below the RF Frequency field) is an example of
this type. Position the cursor to the INPUT field and press the [ENTER]
key. With the field highlighted, press the up or down arrow key to cycle
through the available list of selections. Set this field to TR and terminate
the entry with the [ENTER] key.
Rev. 1.0
Page 10
With the cursor still on the INPUT field, notice that the F1 and F2 key
labels offer quick entry of the available selections. Quick entry is
available when there are only a few available options.
Some Field labels allow selection by
MENU as shown in the screen image to
the right. Position the cursor to the
indicated position with the arrow keys.
The Menu is selected by pressing the F1
key below the MENU label. When the
menu is displayed, a selection can be
made by using the arrow keys to position
the cursor to the desired selection. Press
the ENTER key to terminate the
selection.
A Zooming feature allows expanded
controls for the Scope, Spectrum
Analyzer and Meter functions.
By
positioning the cursor to an appropriate
field selection the F1 key will offer a
ZOOM option. In the case of the Scope
or Spectrum Analyzer, the selected
instrument will expand to consume the
entire screen and more controls of that
instrument will become available. Using
the arrow keys, position the cursor to the
ANALYZER field label and press the F1
key to ZOOM in on that function.
To return to the originating screen
function, press the desired mode key,
[REC] in this case.
Rev. 1.0
Page 11
Meter functions allow for zooming as
well. In the example to the right, the
cursor is placed on the RF Power meter
field label. This allows access to the
zoom feature for the meter. Pressing the
[F1] key will zoom in on the RF Power
meter allowing additional features to be
accessed. When a meter function is
zoomed, the meter will display a bar
graph, scope or spectrum analyzer and
meter control functions.
Press the [REC] key to return to the
Receiver screen.
Pressing the TAB key allows direct
access to any field label on the displayed
screen. After pressing the TAB key,
each field label will be identified by a
numeric value. In the example to the
right, the cursor can be moved directly to
the RF Power meter field by pressing
[TAB] [1] [5] [ENTER].
Rev. 1.0
Page 12
Setting up the Demonstration Software
To access the System Setup Software used in this document, a program
must be activated from the COM-120B’s file system. To do this, follow
the procedure below.
1. Press the
SHOW
List
key.
2. Press the F3 key “STORED FILES” to
access the file directory.
3. With the arrow keys, position the cursor to
the filename SETUPS.APP and press the
F1 key “OPEN”.
4. This has activated the COM-120B Test
Functions Software.
5. Press F6 “Exit” to exit the program. The
program can be accessed in the future by
pressing the START key for quick
STOP
access.
Note: This procedure must be performed only once after
power up.
Rev. 1.0
Page 13
REC – Transmitter Test Screen
Exploded view of the function screens that are available in the REC
screen.
Rev. 1.0
Page 14
1
Interconnect:
1. Connect the supplied Transmitter RF Output to the COM-120B’s T/R
Input.
2. Turn the radio to the ON position and set to Channel 2.
3. It is not necessary to connect any audio cables at this time.
The following procedures will lead through the process of:
! Finding an unknown transmitter frequency.
! Frequency Tuning
! Voice Deviation Test
! Squelch test
! CTCSS Tone
! DCS Code
! Squelch Tone Deviation
! DTMF Decode
! Transmit Audio Distortion
Rev. 1.0
Page 15
Find Transmit Frequency
Setup:
1. This COM-120B has been pre-configured for common transmitter test
setups.
START
STOP
2. Press the
Utility software.
key to access the COM-120B System Setup
3. The menu to the right will appear.
4. Select STEP 1 by positioning the
cursor and pressing F1 Execute.
5. The COM-120B will now configure itself to find a transmitter
frequency. The receive screen is selected and the COM-120B is
monitoring the Power meter for the presence of RF Power.
6. Key the Transmitter and the COM-120B will switch screens to the
stand alone spectrum analyzer to find the transmitter signal. Once
the signal is found, the COM-120B will return to the Receive screen
to allow evaluation of the transmitter. Keep the transmitter keyed
until the COM-120B has completed this task. This procedure can be
repeated if desired for a different radio channel.
7. This transmitter has been configured for a
transmit frequency of 151.6250 MHz on
channel 2. This should be the frequency
that the COM-120B found.
Rev. 1.0
Page 16
TX Frequency Tuning
Either the Scope or Spectrum Analyzer can
be viewed by positioning the cursor to the
SCOPE or ANALYZER field and selecting the
desired display with the F2 key.
TX Frequency can be tuned by
positioning the cursor to the RF
ERROR label and pressing the
F1 key “ZOOM” to expand the
meter to full screen mode.
(Remember the TAB key)
Frequency tuning can be
easily done by setting the
Range to a fixed range.
Set the Gate time to 0.1 S to
take fast readings.
Use the bar graph meter to
align transmitter frequency.
Note: Frequency tuning can be simulated by moving the
cursor to the RF field and adjusting the last digit with the
DATA SCROLL Knob.
Rev. 1.0
Page 17
Signal Find Feature
The Signal find feature is a function of the Spectrum Analyzer. To view
the Spectrum Analyzer press the ANLYZ key on the front panel.
Positioning the cursor to the RF Frequency field allows configuration of
the signal find features. The entire RF spectrum or a small piece of the
RF spectrum can be searched.
2) Set the Level Threshold
1) Set Frequency to 500 MHz
4) Activate Find
3) Set the Sweep Bandwidth
5) The Spectrum
analyzer searches
until a signal exceeds
the threshold level.
Rev. 1.0
Page 18
Test Voice Deviation
Setup:
1. This COM-120B has been pre-configured for common transmitter test
setups.
START
STOP
2. Press the
Utility software.
key to access the COM-120B System Setup
3. The menu to the right will appear.
4. Select STEP 2 by positioning the
cursor and pressing F1 Execute.
5. With the radio still configured to
channel 2, key the radio and whistle or
speak into the radio’s microphone.
6. The voice deviation can be observed on the High Performance Scope
as well as the Deviation meter. Additionally, the RF Power and
Frequency can be evaluated.
7. Adjust the COM-120B’s volume and
squelch control s to hear the audio
through the speaker when the
transmitter is keyed.
The frequency is
displayed as both
the frequency in
MHz as well as the
frequency error from
the selected channel
frequency.
Rev. 1.0
Page 19
Power is displayed
in Watts and dBm.
A compensation
factor can be
entered to correct
the power meter
reading to account
for cable loss.
Deviation can also
be measured as
Peak+ and Peak-.
8. Position the cursor to the Scope
Label by pressing [TAB] [1] [ENTER]
on the COM-120B’s keypad.
9. Press the F1 key labeled “ZOOM” to
expand the scope to a full sized
scope.
10. With the Transmitter keyed, press
the function keys that are labeled “PK
HOLD” and “MIN HOLD”. The scope
display will now keep the maximum
and minimum deviation extremes on
the scope for evaluation of peak
deviation.
11. Press the “PK HOLD” and “MIN
HOLD” keys again to turn off the peak
hold feature.
The Modulation meter
has been configured
for a CMSG filter for
this test.
Rev. 1.0
Page 20
Test TX Squelch (CTCSS)
Setup:
1. This COM-120B has been pre-configured for common transmitter test
setups.
START
STOP
2. Press the
Utility software.
key to access the COM-120B System Setup
3. The menu to the right will appear.
4. Select STEP 3 by positioning the
cursor and pressing F1 Execute.
5. The COM-120B will configure itself
for testing Transmitter Squelch or
SUB Audible deviation.
6. Configure the radio to channel 3, key the radio and observe the
CTCSS tone on the Scope and Deviation meter.
7. The CTCSS tone frequency is measured and displayed by the AF
FREQUENCY counter.
8. To increase the resolution of the
Audio Counter reading, zoom in
reading by pressing [TAB] [1]
[4] [ENTER] and press the F1
key to zoom in on the Audio
Counter.
The AF Counter
measures the
CTCSS code to 1 Hz
resolution. For
greater resolution,
this meter can be
expanded.
Rev. 1.0
Page 21
The Modulation meter
and Audio Frequency
Counter have been
configured for a 300 Hz
Low Pass filter for this
test.
Test TX Squelch (DCS)
Setup:
1. This COM-120B has been pre-configured for common transmitter test
setups.
START
STOP
2. Press the
Utility software.
key to access the COM-120B System Setup
3. The menu to the right will appear.
4. Select STEP 3 by positioning the
cursor and pressing F1 Execute.
5. The COM-120B will configure itself
for testing Transmitter Squelch or
SUB Audible deviation.
6. With the radio configured to channel 4, key the radio and observe the
DCS signal on the Scope and on the Deviation meter.
7. The DCS code is decoded and displayed.
8. DCS deviation should be
approximately 500 Hz or 0.5 kHz.
The Modulation meter
and Data Decoder
have been configured
for a 300 Hz Low Pass
filter for this test.
Rev. 1.0
Page 22
Test TX DTMF Decode
Setup:
1. This COM-120B has been pre-configured for common transmitter test
setups.
START
STOP
2. Press the
Utility software.
key to access the COM-120B System Setup
3. The menu to the right will appear.
4. Select STEP 4 by positioning the cursor
and pressing [F1] Execute.
5. The COM-120B will configure itself for
decoding Transmitter DTMF codes.
1
2
2
Interconnect:
1. Connect the Transmitter RF Output to the COM-120B’s T/R Input.
2. Connect the COM-120B’s Audio/Data Gen Out to the Radio’s
Microphone Input.
Rev. 1.0
Page 23
3. The supplied transmitter does not have a DTMF keypad so the COM120B’s internal DTMF generator will be used to simulate pressing
keys on a radio’s DTMF keypad. The COM-120B’s DTMF generator
will externally modulate the transmitter and the COM-120B’s receiver
and DTMF decoder will decode the transmitted DTMF tone codes.
4. Set the radio channel to 2 and Key the radio.
DTMF codes are decoded
and displayed here.
Rev. 1.0
Page 24
Test TX Distortion
Setup:
1. This COM-120B has been pre-configured for common transmitter test
setups.
START
STOP
2. Press the
Utility software.
key to access the COM-120B System Setup
3. The menu to the right will appear.
4. Select STEP 5 by positioning the
cursor and pressing F1 Execute.
5. The COM-120B will configure itself
for testing Transmitter Distortion.
1
2
2
Interconnect:
1. Connect the Transmitter RF Output to the COM-120B’s T/R Input.
2. Connect the COM-120B’s Audio/Data Gen Out to the Radio’s
Microphone Input.
Rev. 1.0
Page 25
Measuring TX Distortion:
1. With the radio configured to channel 2, key the radio and observe a 1
kHz tone on the Scope at a level of 3 kHz deviation on the Deviation
Meter.
The Internal function generator is
used to externally modulate the
transmitter for this test.
2. If necessary, position the cursor to the AF GEN OUT field, Press F1
to ZOOM and adjust the audio injection level to achieve 3.0 kHz
deviation.
3. The audio distortion is displayed in % and the indication should be
less than 10%.
Rev. 1.0
Page 26
This concludes the Transmitter test section of this procedure. If you
would like ot try it out with one of your own radios, you may do so at this
time. Use the software for setups as you did with our demonstration
radio. Begin by using the Signal find feature to find your transmitter
frequency and the rest of the setups will operate accordingly.
Once you have done this, continue on with the procedure to observe
Receiver testing.
Rev. 1.0
Page 27
GEN – Receiver Test Screen
Exploded view of the function screens that are available in the GEN
screen.
The generate screen provides all of the
features that are required to provide
stimulus to a receiver to evaluate
performance characteristics.
The Audio Level meter can
be configured to measure
VRMS, dB or dBm.
Rev. 1.0
Page 28
GEN – Receiver Test Screen
Modulation Sources
The COM-120B can be simultaneously modulated by up to 6
modulation sources. AM and FM can be mixed.
This area identifies what sources are
turned on
GEN1 indicates that FGEN 1 is turned
on
GEN1B indicates that FGEN1 is turned
on but is in BURST mode
The Gen 1 Source field
can be configured for a
standard 1 kHz tone or a
tone format.
The Gen 2 Source
field can be
configured for a
CTCSS Tone
OR
The DATA
generator could
be used to
configure a DCS
code for digital
squelch systems.
Rev. 1.0
Page 29
Setup:
1. This COM-120B has been pre-configured for common receiver test
setups.
START
STOP
2. Press the
key to access
the COM-120B System Setup
Utility software.
3. The menu to the right will appear.
4. Select STEP 6 by positioning the
cursor and pressing F1 Execute.
5. The COM-120B will configure itself for testing Receiver Sensitivity.
1
2
2
Interconnect:
1. Connect the COM-120B’s T/R port (Generator Output) to the Antenna
Input of the Radio under test.
2. Connect the radio’s Audio Output to the COM-120B’s SINAD Input.
3. With the radio configured to channel 2, adjust the radio’s volume
control for a 2 Vrms indication on the COM-120B’s AF LEVEL meter
as shown on the next page.
Rev. 1.0
Page 30
The COM-120B has been
configured
with
the
AUDIO/DATA Input routed
to the scope to view the
radio’s demod output. This
is the same signal that the
SINAD meter will evaluate.
The COM-120B injects a
carrier modulated with a 1
kHz tone at 3.3 kHz
deviation into the radio’s
reciever.
4. Position the cursor to the Level field. [TAB] [4] [ENTER]
5. Press the [ENTER] key to highlight the RF Level value and adjust
with the Knob control to reduce the level until the COM-120B’s
SINAD meter indicates approximately 12 dB. Note: The monitor
button on the radio may need to be held down to defeat the radio’s
squelch operation.
RF Signal
Generator
Receiver
Under Test
Audio Output
Audio
Filter
SINAD =
Signal + Noise + Distortion
Noise + Distortion
1 kHz Tone + Noise + Distortion products
R.M.S.
Voltmeter
Notch Filter
Notch Filter removes 1 kHz tone
R.M.S.
Voltmeter
Rev. 1.0
Page 31
The SINAD meter can be expanded to allow more control by positioning
the cursor to the SINAD meter label [TAB] [1] [6] [ENTER] and pressing
the F1 key “ZOOM”
TAB
1
6
ENTER
ZOOM
" Ensure the C-MSG Filter is enabled
" Enable SINAD Average to 10 for manual
"
"
"
"
Scope source can be set to view Internal
Modulation source, Audio/Data Input port
or Notch Residual to evaluate receiver
performance.
Rev. 1.0
Page 32
measurements or turn Averaging OFF
for Automatic measurements.
Move Cursor to RF LEVEL (TAB, 2,
ENTER)
Select SINAD = and set the desired
SINAD point, (12 or 20 dB typical)
Activate Auto SINAD S = On/OFF
STAND BACK AND WATCH
Note: Averaging should be turned
off when performing automatic
SINAD search operations.
DUPLEX Operation Mode
Duplex
Mode
Simultaneous Generate and Receive operation for Full Duplex
Any Offset between Generate and Receive frequencies in 2.5 kHz steps
Rev. 1.0
Page 33
The Duplex screen offers the ability to generate and receive at the same
time. Additionally, the Generate and Receive frequencies may be set to
any frequency within the limitation of either the Receiver or the
Generator. The Receiver could be set to 10.7 MHz or 455 kHz while the
Generator is set to 151.625 MHz allowing signal tracing through IF
strips. This feature allows the spectrum analyzer to be used for signal
tracing while the RF Signal generator is being used to stimulate the
Receiver at the channel frequency. The Duplex screen is also
commonly used to test cross-band repeaters. The generator could be
used in the VHF band while the receiver is operating in the UHF band.
The DUPLEX screen allows
control of primary features of the
RF Generator and the Receiver.
The more comprehensive standalone Receive or Generate
screens can be selected by
positioning the cursor to the
respective field and pressing the
F1 key to ZOOM. Zooming in on
the RECEIVE function allows
access to the Spectrum Analyzer
in the Receive screen while
leaving the generator operational.
Rev. 1.0
Page 34
This concludes the Receiver test procedure. There are other tests that
can be performed on the receiver but are beyond the scope of this guide
at this time.
Please turn the radio power to the OFF position now and return it to the
evaluation kit.
Rev. 1.0
Page 35
Measuring Filters
2
1
Interconnect:
1. Connect an RF cable to the COM-120B’s AUX RF Output.
2. Connect an RF cable to the COM-120B’s Antenna Input.
3. Using a BNC Barrel, connect the two RF cables together forming a
loop with two cables from the AUX RF Output to the Antenna Input of
the COM-120B. This will configure the COM-120B to zero out test
cables for making insertion loss measurements.
Setup:
1. This COM-120B has been pre-configured for common Analyzer test
setups.
START
STOP
2. Press the
Utility software.
key to access the COM-120B System Setup
3. The menu to the right will appear.
4. Select STEP 8 by positioning the
cursor and pressing F1 Execute.
5. The COM-120B will configure itself
for filter measurements.
Rev. 1.0
Page 36
The Tracking Generator function allows analysis of:
!
!
!
!
Filter Insertion Loss
Filter Notch Depth
Filter Pass band
Filter Bandwidth
The current hookup and COM-120B configuration is as follows:
The Tracking generator (AUX RF OUT) is connected to the Antenna port
therefore the output is looped back around to the input. This is done so
we may now be able to adjust the Tracking generator Output level for a
0 reference on the spectrum analyzer display. This must be done to
accurately measure insertion loss.
To do this, position the cursor to the
Track Gen field and press the ENTER
key to highlight the value. Use the left
and right arrow keys to select either
the 1 or .1 db digits and then use the
Data Scroll Knob to adjust the Tracking
Generator level for a 0 dBm reference
on the Spectrum Analyzer display.
NOTE: The Tracking generator level
will probably not indicate 0 dBm and it
is not necessary for it to be 0 dBm.
After the reference level has been established we will connect the
provided duplexer to evaluate the above mentioned measurements.
Note: The COM-120B has been placed into a unique Split screen mode
of operation for the comprehensive evaluation of this filter. In Split
screen mode, the COM-120B is essentially operating as two separate
spectrum analyzers allowing one setup to view both the pass band and
the reject band simultaneously.
Rev. 1.0
Page 37
2
1
3
TX
RX
Alignment screws.
To adjust, loosen the nut and then
turn the screw
1. Connect the Duplexer Antenna port to the COM-120B’s AUX RF
Output.
2. Connect the Duplexer 160 MHz port to the COM-120B’s Antenna
port.
3. Connect a 50-ohm Termination to the remaining port.
Spectrum
Analyzer #1
If the filter is properly aligned, the
image to the right will be displayed.
The left side shows the pass band
while the right side shows the reject
band.
With the current setup,
examine the left side for insertion
loss. This can be measured from
the top line to where the trace is on
the display. The object is to have
minimum insertion loss here.
Rev. 1.0
Page 38
Spectrum
Analyzer #2
Position the cursor to the Atten field
and select 0 dB input attenuation by
pressing the F2 key. The right side
may now be evaluated for the reject
band. This image indicates that the
filter has a notch depth of 100 dB
because we had started with a
reference trace set for a 0 dB
indication.
The SCAN width on
spectrum analyzer #2 can be adjusted
down to 100 kHz to allow more finite tuning of frequency. Toggling the
input attenuation between 0 and 30 dB while tuning allows monitoring of
both the reject notch depth and the pass band insertion loss.
Swap the Cable and load between the
160 MHz and the 165 MHz ports on
the duplexer to view the characteristics
of the other filter in the duplexer. The
image to the right indicates that this
filter also has a 100 dB notch depth.
Additional range can be obtained
by reducing the Resolution
Bandwidth and slowing the sweep
d
Set the Input Attenuation back to 30 dB
now to evaluate the insertion loss of
this side of the filter.
Rev. 1.0
Page 39
Measuring Cable Fault
Setup:
1. This COM-120B has been pre-configured for common Analyzer test
setups.
START
STOP
2. Press the
Utility software.
key to access the COM-120B System Setup
3. The menu to the right will appear.
4. Select STEP 9 by positioning the
cursor and pressing F1 Execute.
Note: This item offers a help screen
accessible by pressing the F3 key.
5. The COM-120B will configure itself
for testing Cable Fault measurement.
Interconnect:
Antenna Input
Tee connector on Tracking
Generator (AUX) Output
Cable under test
6. Establish the cable interconnect as shown above.
Rev. 1.0
Page 40
1. Position the cursor to the Marker
field label.
2. Press the F1 key to activate marker.
3. Press the ENTER key to edit the
Marker Frequency.
4. Use the arrow keys to highlight the 1
MHz digit and then the Data Scroll
knob to adjust the frequency value
until the marker is placed directly on
the minimum point of the first dip.
5. Record the marker frequency as F1.
6. Position the marker to the second
dip and record the frequency as F2.
7. Calculate the difference (F2 – F1)
To calculate the cable length, measure
the frequency difference in MHz between
two adjacent nulls. By factoring in the
velocity factor of the cable type, the
length can be calculated with the
following formula.
Distance feet =
492 * Velocity Factor
Delta Freq. in MHz
3.148ft =
The velocity factor for RG-58 is 65.9% or 0.659.
Rev. 1.0
Page 41
492 * 0.659
570.0 - 467.0
Measuring Return Loss
REFLECTED
VSWR /
Return Loss
Bridge
SOURCE
LOAD
Interconnect:
1. Connect the Return Loss Bridge as indicated in the graphic above.
2. Connect the Bridge Source Port to the COM-120B’s AUX RF Output.
3. Connect the Bridge Reflected Port to the COM-120B’s Antenna port.
Setup:
1. This COM-120B has been pre-configured for common Analyzer test
setups.
START
STOP
2. Press the
Utility software.
Rev. 1.0
key to access the COM-120B System Setup
Page 42
3. The menu to the right will appear.
4. Select STEP 10 by positioning the
cursor and pressing F1 Execute.
5. The COM-120B will configure itself
for testing Return Loss.
6. Connect the Load port of the Return
Loss bridge to the 160 MHz port of the
Duplexer Filter.
7. Connect 50-ohm terminations to the
remaining ports on the duplexer.
VSWR /
Return Loss
Bridge
8. The resulting return loss for the 160 MHz port of the
duplexer is displayed in dB. In this case, the
indicated Return Loss is approximately 31 dB.
TX
Rev. 1.0
Page 43
RX
This concludes the COM-120B Evaluation procedure. If you would like
information or assistance with tests not covered by this procedure,
please contact our technical staff for assistance at 1-800-835-2352 and
select menu item 1. You will be able to speak to a trained specialist who
is well versed with this product.
Rev. 1.0
Page 44
! RF Signal Generator
! Output Level +13 to -130
! 0.2 PPM TCXO
! 2 uV Receiver with 15, 30 and 300 kHz IF filters
! 50 kHz Scope
! Full band / Dual Mode Spectrum Analyzer
! Digital Voltmeter
! Audio Level Meter
! Dual Audio Function Generators
! Data Generator DCS, DCS INV
! DTMF Generator
! Encode / Decode
! DCS, DTMF, CTCSS
! RF Frequency Error Meter and Counter
! FM Deviation Meter
! AM Modulation Meter
! Phase Modulation Meter
! Audio Frequency Counter
! RF Power Meter (2 mW - 200 W)
! 50 W Continuous
! RF Level Meter
! Distortion Meter
! SINAD Meter (With auto-search)
! RS-232
Rev. 1.0
Page 45
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
0.01 PPM OCXO (120B-xTx)
Internal Rechargeable Battery (AC3001)
Tracking Generator (AC3012)
Return Loss Bridge (AC4105)
EasySweep Software (AC1019)
EasySpan for Windows (AC1009W)
Digital / Analog Signaling (AC3011)
! CCIR, CCIRH, CCIRH4, EEA,
! EIA, NATEL, ZVEI, DZVEI,
! DDZVEI, EURO, 5/6 Tone, POCSAG
RCC Signaling (AC3009)
! Tone Remote, IMTS, MTS, 10 PS, 20 PS
Data Generator / BER Meter (AC3007)
MPT-1327 Trunking (AC9161)
Clear Channel LTR Trunking (AC3014)
EDACS Trunking (AC3016)
7.5 kHz IF Filter (AC9162)
SSB Filter (120B-8xx)
Microphone (AC8645)
Antenna (AC1201)
Heavy Duty Ship case (AC8753)
Soft Padded carry case (AC9925)
IEEE-488 Interface (AC3013)
EasyCom Land Mobile test software (AC1022)
Application Library (AC1023)
Nortel Cellular Base Station Software (AC1037)
Programming Manual (AC0301)
Maintenance Manual (AC0600)
Extended Warranty 3/5 year
Rev. 1.0
Page 46
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