Nokia 8850 Manual Do Serviço

NSM–2

Service Software Instructions

PAMS Technical Documentation

Page  93

Issue 1  12/1999

 Nokia Mobile Phones Ltd.

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.

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.