Nokia 9000i, Service Manual

Page: 236 / 434

After Sales
Technical Documentation
RAE/RAK–1N
Service Software
Page 7– 78
Amendment 1 04/97
3. I/Q Modulator Amplitude Balance and Phase Shift Tuning
The purpose of this tunig operation is to adjust the I/Q modulator d.c.
offsets and the I/Q modulator amplitude balance and phase shift.
I/Q modulator d.c. offsets, amplitude balance and phase shift tuning:
– Connect spectrum analyzer (with attenuator if needed) to external RF
connector.
– Select adjustment menu option ”TX I/Q Tuning” and press <Enter>.
– Check that TX power level is level 10, Cont. mode channel is 60 and
TX data type is 1.
– Adjust spectrum analyzer centre frequency to 902 MHz, Span 200
kHz, Res BW 10 kHz, Video BW 1 kHz and Sweep time 0.5 s.
–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:
– Select option ”TX I d.c. offset” and press <Enter>.
– Adjust the level of centre frequency (CHF signal) to minimum by
varying D/A converter value with <+> and <–> keys.
– When value is OK press <Esc>.
– Select option ”TX Q d.c. offset” and press <Enter>.
– Adjust the level of signal CHF to minimum by varying D/A converter
value with <+> and <–> keys.
– When value is OK press <Esc>.