Figure 14-4. Receive BER
14-4.1 Radios Without BER Test Capability
Radio receivers can be tested using the analyzer
in the duplex mode. The test is performed by
outputting an RF test pattern from the analyzer
and feeding back the received baseband digital
test pattern from the radio. The received digital
bit stream can be monitored for errors. This test
requires that the receiving radio be opened to
provide access to the digital data at a point before
it enters the decrypter. (Consult the radio
maintenance manual to determine this point.)
To set up the analyzer for the Duplex BER test,
perform the following sequence:
1. Connect the RF input port of the radio
under test the GEN OUT port of the
analyzer.
2. Place the cursor in the RF Zone and
configure the analyzer as shown below.
Set the monitor frequency of the radio to
be tested. The default offset frequency is
+45 MHz, but is unimportant because the
signal being returned from the radio is
baseband.
3. Set the controls in the Audio Zone as
follows:
Securenet: 4.0 kHz
Code: BER
4. Press the SPF hardkey to access the
special functions screen and select
External Input under “Decoding.” Press
the return softkey to return to the main
screen.
5. With the cursor on RF Display, press the
more softkey and select BER. The BER
metering will appear in the top left corner
of the screen.
6. Place the cursor on Display and select Ext
Scope.
7. Turn on the radio. Connect a probe to the
VERT input on the analyzer and sample
the digital data at the point indicated
above.
196
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