Nokia NSB-7 Series Service Manual page 213

PAMS Technical Documentation
• Tune the phone at three power levels (0, 11, and 15) to the target values.
• Press "calculate" and then "save".
3. RX Filter Calibration
BB-filter tuning is fully internal operation. External signal generators etc. are not needed,
only command for phone to execute filter calibration procedure.
Troubleshooting
If the calibration does not succeed the software normally reports "Unable to read data
from phone" or "Failed to set high reference" or "Failed to set low reference".
In this case check first the basic functionality of the receiver chain: RF generator fre-
quency set as in the calibration and level for example to the high reference value.
Then go to the RSSI reading menu (under RF controls). If the reading is very low there is
something broken in the receiver and must be found by measuring voltages and signal
levels at different places (information of these can be found in Disassembly & Trouble-
shooting Chapter of this manual).
If the RSSI reading seems to be within 5 - 10 dB the same as the RF input level check
that the VCTCXO frequency is close enough the wanted frequency. This is most easiest
done by measuring VCO frequency in GSM1900 middle channel 661 (VCO frequency is be
3920 MHz). If the deviation is bigger than about +/-50 kHz it is probable that the
VCTCXO is not operating correctly.
If both of these (RSSI reading and the frequency) seem to be correct and calibration still
fails the most probable reason is that there must be some missing gain step in Hagar or
then the problem must be in COBBA.
Issue 1 06/00
Center frequency 1960 MHz
Res BW 10 MHz Max.
Video BW 10 MHz Max.
Span 0 Hz
Sweep time 2 ms
REF level 35 dBm
REF level offset (e.g. attenuator 10 dB + cable 0.5 dB + coupler
attenuation e.g. 4 dB) 14.5 dB
Set marker to point a peak value
ãNokia Mobile Phones Ltd.
Service Software Instructions
NSB-7
Page 107