Nokia NME-2A Series - I;Q Modulator Amplitude Balance and Phase Shift Tuning

P.A.M.S.
Technical Documentation
NME–2A
Tuning Instructions
Page 11
Issue 2 05/2000
3. I/Q Modulator Amplitude Balance and Phase Shift Tuning
The purpose of this tuning 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 phone an-
tenna connector.
– Select adjustment menu option ”TX I/Q Tuning” and press
Enter .
– Press
Y.
– 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:
Figure 3. Amplitude Balance /Phase Shift Graph
– Select option ”TX I d.c. offset” and press Enter .
– Adjust the level of centre frequency (CHF signal) to minimum by vary-
ing D/A converter value with + and – keys.
– The amplitude difference between CHF–67.7 kHz and CHF should be
>30 dB.
– 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.