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Tx power level tuning (GSM)
Context
Because of variations at IC process and discrete component values, the 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.
In dual or triple band phones, the power level tuning is made for both high and low PA Modes (Power Amplifier
Mode) in the GSM900 band but only for high PA mode in GSM1800/GSM1900 bands
For EDGE transmission the bias settings of the GSM PA 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.
Start Phoenix service software.
3.
From the "Operating mode" dropdown menu, set mode to "Local".
4.
From the Tuning menu, choose GSM -> Tx Power Level Tuning.
5.
Set the spectrum analyzer for power level tuning:
Frequency
Span
Sweep time
Trigger
Resolution BW
Video BW
Reference level offset
Reference level
A power meter with a peak power detector can be also used. Remember to take the attenuations in the
account!
Page 7–42
Company Confidential
Copyright ©2005 Nokia. All Rights Reserved.
RF Troubleshooting and Manual Tuning Guide
channel frequency (897.4MHz GSM900, 1747.8MHz
GSM1800, 1880MHz GSM1900)
200 kHz
3s
Video triggering: Free run
3 kHz
3 kHz
sum cable attenuation with module jig
attenuation
33dBm
RM-36
Issue 1
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