Nokia RH-37 Series Service Software And Tuning Instructions page 48

RH-37
Service Sofftware and Tuning Instructions
For an error free initial synchronization, the 26 MHz frequency of the reference oscillator
must be accurate enough. Therefore, the previously calibrated AFC value is written to the
DA converter and the corresponding AFC voltage tunes the VCTCXO to the correct fre-
quency.
The AGC calibration detects the gain values of the RX chain. The RF LNA can be
switched either on or off. The gain difference between on and off state is nominally 30dB
and the baseband gain which is controlled by 15 gain steps called in PHOENIX RSSI 0 to
RSSI 14 each having a graduation of 6 dB. The LNA is switched off at the steps RSSI 0 to
RSSI 4.
AGC calibration detects the gain at the 3 gain steps RSSI 4, RSSI 5, and RSSI 7. All other
steps are calculated.
A value, RF_TEMP, which represents the RF hardware temperature, is determined during
the RX calibration. This temperature value is used by the DSP for RSSI reporting correc-
tion and Tx temperature compensation in the Normal Mode of the phone. Dependent on
the Phoenix version it might be not displayed while calibrating.
The Rx calibration has to be done in a temperature of 25°C due to the detection and sav-
ing of the RF_TEMP value.
The RX calibration is only valid if the results are within defined limits. For the latest
specified limits, please refer to the production limits of the FLALI and FINUI testers' doc-
uments.
If the results are not within these limit ranges, the receiver is faulty.
Rx calibration GSM900, GSM1800 and GSM1900
Open the window <Rx Calibration> in Phoenix Service Software as follows:
Select
Phoenix automatically selects the low band.
Press <Start>
The window <Tuning step 1 of 3 – Rx Calibration with band ...> pops up informing on
power level of the signal generator and frequency to be set. Do accordingly, after con-
necting the signal generator to the antenna port of the test jig respectively to the phone.
Compensate for external RF cable and test jig losses.
If a radio communication tester (CMD 55, CMU 200, HP 8960, MT 8801) is used, assure
that <continuous mode> is switched on and <modulation> switched off.
Press <ok> and the window will close.
Page 48
Tuning
Rx calibration
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Issue 1 07/04