User's Manual

84 Preparation for Operation TB7100 Installation and Operation Manual
© Tait Electronics Limited December 2005
7.3.7 Receiver Functional Testing
This section describes how to test some parameters which are commonly
monitored.
Sensitivity The sensitivity can be measured using either the balanced or unbalanced
audio output.
1. Connect the required audio output from the CTU to the audio input
port on the test set.
2. Connect the RF output from the test set to the Rx input on the rear
panel.
3. Set up the test set to measure the SINAD level.
4. Set the RF signal generator to the correct RF frequency, modulated
with a 1kHz audio tone at 60% of full system deviation.
5. Set the RF output level to -70dBm.
6. Verify that the receiver gate opens and the busy LED turns on.
7. Reduce the RF level until 12dB SINAD is obtained.
Note This level will vary depending on the bandwidth and frequency
response of the channel. Consult the specifications manual for val-
ues.
Note If the mute closes before 12dB SINAD is reached then squelch
override may be programmed to a function key.
Pressing this key will prevent the mute from closing.
RSSI Level 1. Connect a voltmeter to the RSSI test point on the CTU.
2. Set the RF signal generator to the correct RF frequency.
3. Set the RF level to -100dBm.
4. Verify the RSSI voltage is 1.1V
±300mV.
Note If necessary adjust the RF level from –50dBm to –115dBm and
verify that the RSSI voltage changes at 25mV/dB.
Mute Thresholds The mute thresholds can be measured using either the balanced or
unbalanced output.
1. Connect the required audio output from the CTU to the audio input
port on the test set.
2. Set up the test set to measure the SINAD level.