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RH-13
Troubleshooting
Step 1. General checking
The fastest way to get overview of RX status is to measure RSSI (Received Signal
Strength Indicator) level. This can be done by using signal generator and Phoenix. Note
that this is useful only if the phone has been calibrated when it was OK and the mal-
function have occured after tunings.
1 Set signal generator frequency to 1960.06771 MHz and level to -80 dBm.
2 Select RSSI measurement UI in Phoenix (Maintenance => GSM RSSI Meas).
3 Set Band to GSM1900 and Rx/Tx channel to 661
If the cable losses are calibrated correctly the RSSI reading should give reasonable result
(-80 dBm +/- 2 dB). Please note that RSSI result is valid only if there has not been RX
calibration attempts for the faulty phone. If the RSSI level is several dB's lower go to
Step 2 (Local oscillator checking).
Step 2. Local oscillator checking
Carrying out this step VCO signal of 1st and 2nd mixers can be checked. 2nd mixer RX
VHF VCO frequency is constant 266.4 MHz but for the 1st mixer UHF VCO frequency
depends on the channel. The UHF VCO frequencies for the 1st mixer are:
Channel 512:
Channel 661:
Channel 810:
Page 48
Figure 29: GSM RSSI Measurement.
2063.4 MHz
2093.2 MHz
2123.0 MHz
ãNokia Corporation
CCS Technical Documentation
Issue 1 11/02
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Table of Contents
Troubleshooting
