User Guide

PAMS
Technical Documentation
NME–3
Service Software Instructions
Page 13
Issue 1 10/99
3. I/Q Modulator Alignments
Procedure:
Connect the spectrum analyzer to the phone antenna connector. The
recommended 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 GSM is 60 (902
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 ”OK” button to store the
values to phone EEPROM.
Targets:
The level of the centre frequency CHF should be at least 30 dB down to
the wanted sideband CHF - 67.71 kHz.
The level of the unwanted sideband CHF + 67.71 kHz should be at least
35 dB down to the wanted sideband CHF - 67.71 kHz.