PAMS Technical Documentation
Troubleshooting Instructions
NHM-8NX
Issue 1 05/02
ã
Nokia Corporation
Page 29
Fault Finding Chart for GSM1800 Receiver
Figure 10:
GSM1800 receiver fault finding chart
By measuring with an oscilloscope at RXIP or RXQP on a working GSM 900 receiver this
picture should be seen.
Signal amplitude peak-peak 588 mV
DC offset 1.33 V
Apply -55 dBm
1842.8 MHz, offset
67.71 kHz
from generator to
antenna connector
Oscilloscope at RX
I/Q
signal 408 mVpp
DC offset 1.33 V
freq. 67.71 kHz
PCN chain
functional
Check RX/TX
switch at RX 1800
Z700
-57 dBm
Oscilloscop
check Vc1 and Vc2
at Z700 signal 0V
Spectrum analyzer
PCN SAW filter
Z601
output -65 dBm
Spectrum analyzer
Check signal after
inductors L611 and
L601
-65 dBm
Check SAW filter
Z601
Oscilloscope
VRX 2.7 V
check Mjoelner
serial interface
Check inductors
L611, L601
Check Base band
Check RX/TX
switch
Check Mjoelner
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
YES
YES
YES
1
2
3
4
1
2
3
4
5
6