Tx Power Level Tuning (Gsm) - Nokia E62 Service Manual

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I DC offset / Q DC
offset
Ampl
Phase
GSM1800/GSM1900
I/Q DC
Ampl
Phase

Tx power level tuning (GSM)

Context
Because of variations at IC process and discrete component values, actual transmitter RF gain of each phone
is different. Tx power level tuning is used to find out mapping factors called 'power coefficients'. These adjust
the GSM transmitter output power to fulfill the specifications.
For EDGE transmission the bias settings of the FEM are adjusted in order to improve linearity. This affects the
PA gain and hence the power levels have to be aligned separately for EDGE transmission.
Tx power level tuning has to be performed on all GSM bands.
Steps
1. Connect the phone to a spectrum analyzer.
2. From the dropdown menus, set "Operating mode" to Local, "System mode" to GSM, and Band to GSM900.
3. From the Tuning menu, choose GSM -> Tx Power Level Tuning.
4. Set Mode to Automatic and Edge to Off.
5. Set the spectrum analyzer for power level tuning:
Frequency
Span
Sweep time
Trigger
Resolution BW
Video BW
Page 7 –32
Min
-6
-1
85
-6
-1
95
COMPANY CONFIDENTIAL
Copyright © 2006 Nokia. All rights reserved.
RF Troubleshooting and Manual Tuning Guide
Typ
-4
0
90
0.5
0
100
channel frequency (836.6MHz GSM850, 897.4MHz
GSM900, 1747.8MHz GSM1800, 1880MHz
GSM1900)
0 Hz
2ms
Video triggering (-10dBm)
3MHz
3MHz
Max
6
1
95
6
1
110
RM-88
Unit
%
dB
○
%
dB
○
Issue 1