Tait TP9100 - Incorrect RSSI Readings and Mute Faults

TP9100 Service Manual Receiver Fault Finding 261
© Tait Electronics Limited May 2005
11.4 Incorrect RSSI Readings
Introduction If the RSSI readings are incorrect, the receiver calibration is suspect. There
are four tasks, which cover the four types of settings concerned:
■ Task 10: AGC voltage calibration
■ Task 11: FE tune BPF settings
■ Task 12: RSSI delta gain
■ Task 13: AGC delta gain
If the receiver is properly calibrated but the fault persists, then the receiver
sensitivity is suspect.
Task 10 —
AGC Voltage
Calibration
The first settings to check concern the AGC voltage calibration.
1. In the calibration application open the “Raw Data” page and click the
“Receiver” tab.
2. Note the settings listed in the “AGC Voltage Cal Pts” field. The nominal
settings should be as listed in Table 11.3.
3. If the settings are correct, go to Ta sk 11
. If they are not, go to Step 4.
4. Recalibrate the receiver and check the settings again.
5. If the settings are now correct, go to Step 6. If they are not, go to
Task 1
and check the receiver sensitivity.
6. Check if the RSSI fault has been removed. If it has, go to “Final
Tasks” on page 134. If it has not, go to Task 11
.
Table 11.3 Nominal AGC data
Parameter
AGC voltage (mV)
B1 band
AGC0
AGC1
AGC2
1790 ± 40
1960 ± 40
2110 ± 50
AGC voltage (mV)
H5 band H6 band
AGC0
AGC1
AGC2
1860 ± 40
2040 ± 40
2200 ± 50
1870 ± 40
2050 ± 40
2220 ± 50
Receiver input power (dBm)
AGC0
AGC1
AGC2
–50
–60
–68