EDACS REPEATERS
2-20
Rx Sensitivity
The Rx Sensitivity test determines the sensitivity of the repeater receiver.
The test fails if the sensitivity is below the prescribed limit.
The Service Monitor generates an RF carrier, modulated with 1 kHz frequency at the nominal
modulation level. The Service Monitor then reduces the RF level in steps, while measuring the Rx
SINAD until the Rx SINAD threshold is passed.
Failure messages are:
*FAIL* ABORTED BY USER User halted program before test was complete.
*FAIL* DROPPED OUT Repeater has dropped the call because the RF
generator level was to low.
*FAIL* LOW DEMOD LEVEL Receiver audio level <20 mV
*FAIL* LOW SINAD LEVEL Unable to reach reference SINAD level at -80 dBm
Rx Expansion
Receiver demodulation expansion.
The Rx Expansion test measures the audio output level from the repeater for various levels of
carrier deviation to test the operation of the demodulated signal expander circuits. (Refer to Tx
Compression test earlier in this section).
The Service Monitor generates an RF carrier modulated at the nominal modulation level. It
increases the modulation level by 5 dB and measures the AF level from the repeater. It then
decreases the modulation level by 10 dB and again measures the AF level. The expansion is the
ratio of low to high AF level measurements.
Other failure messages are:
*FAIL* NO DEMODULATION
+10 dB change in modulation level produced
insufficient change in received AF level.
*FAIL* ABORTED BY USER User halted program before test was complete.
Selecting the AUTORUN test program
[PROGRAM]
The [PROGRAM] soft key gives you access to the selection of five test programs. Each test
program is made up of selected tests. These tests have been described in detail earlier in this
chapter under Description of Tests.
The three programs are:
QUICK TESTING
GENERAL TESTING
USER DEFINED TEST
Making tests on repeaters
Connections
RF connections
For most repeaters, the RF connection of the repeater is connected to the 'N type' RF connector of
the Service Monitor using a suitable RF cable.
WARNING
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