User Guide

PAMS
Technical Documentation
RAE-3
8. Troubleshooting
Page 8 – 112
Issue 1 06/01
Measuring with an oscilloscope on “Hagar RXI” or “Hagar RXQ” this picture
should be seen from a working EGSM receiver:
Figure 116.
Signal amplitude 390mV p–p
DC offset 1,1V
Frequency 67kHz
If this picture is not seen, continue to the next section.
5.1.1 Troubleshooting diagram for EGSM Receiver
Apply –95dBm
947.06771 MHz signal from
generator to antenna
connector
Oscilloscope at RXI
Signal 390mV p–p
DC offset 1,1V *
Frequency 67,7kHz
EGSM chain functional
Oscilloscope
VRX 2.7V
Check Hagar serial
interface
Yes
Yes
Yes
Spectrum analyzer
LNA out C610
RFout –43dBm ?
No No
Spectrumanalyzer
1st EGSM SAW
out Z620
–58 dBm at C615?
GSM_RX
–84dBm
No
Spectrumanalyzer
T600, unbal
–45 dBm ?
Check
Z600. T600
No
Yes
Check Hagar
N505
Yes
Check BBNo
Oscilloscope
LNA_G 2.4–2.8V
VLNA = 2.7V ?
Yes
Check RX/TX
Switch
Z900
No
Check Z700
Yes
EGSM Fault tree
No
Oscilloscope
R610 1.9V
R611 0.9v ?
Yes
Oscilloscope
VRX 2.7V
Check Hagar serial interface
Check Hagar
N505
Yes
Check BaseBandNo
Check
R706, R708,
V700,C701,C705,
C718
No
Check
V904
Yes
Change generator
level to –50 dBm
Yes
Figure 117.
*If DC–offset is missing,
check COBBA powering and
solders
Note: RF levels measured with HP85024A RF probe.