TM8100/TM8200 Service Manual Receiver Fault Finding 259© Tait Electronics Limited November 200710.4 Incorrect RSSI ReadingsIntroduction 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 gainIf the receiver is properly calibrated but the fault persists, then the receiversensitivity is suspect.Task 10 —AGC VoltageCalibrationThe 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 nominalsettings should be as listed in Table 10.4. The AGC values dependon which demod IC is fitted (IC400). The IC is either an RF9667 oran RF2667.3. If the settings are correct, go to Task 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 toTask 1 and check the receiver sensitivity.6. Check if the RSSI fault has been removed. If it has, go to “FinalTasks” on page 163. If it has not, go to Task 11.
