User Guide

NSM–5
Service Software Instructions
PAMS Technical Documentation
Page 93
Issue 1 02/2002
 Nokia Corporation
5. I/Q Modulator Alignments
I/Q modulator alignments has to performed in both bands. See chapter
”Service Software Instructions” and section ”TX I/Q... command” for fur-
ther information.
–67.71 kHz +67.71 kHz
CHF
> 30 dB
> 35 dB
Set this value
to minimum
Amplitude &
phase difference:
Set this value
to minimum
D.C. offset
tunings:
Procedure:
Connect the spectrum analyzer to the phone antenna connector. The rec-
ommended spectrum analyzer settings are: span 200 kHz, resolution BW
10 kHz, video BW 1 kHz, sweep 500 ms, input attenuation 30 dB.
– From
RF controls menu make sure that TX data type is 1.
– Go to
TX I/Q tuning menu. The alignment channel for EGSM is 60
(902 MHz) and for PCN is 700 (1747.8 MHz).
– Select the ”TX I DC offset” option and adjust the level of the centre fre-
quency (CHF) to minimum.
– Select the ”TX Q DC offset” option and adjust the level of the CHF
again to minimum.
– After finding both minima change ”TX I DC offset” by step or two from
the current value to both directions to see, whether better minimum
can be found for CHF.
– Select the ”Amplitude Difference” option and adjust the level of the un-
wanted sideband CHF + 67.71 kHz to minimum.
– Select the ”Phase Difference” option and dajust the level of CHF +
67.71 kHz again to minimum.
– After all the minima have been found press ”Save” button to store the
values to phone EEPROM.
Targets: