User Guide

NPL-4/5 Company confidential
Troubleshooting Instructions Nokia Customer Care
Page 22 Copyright © 2004 Nokia Corporation. All rights reserved. Issue 1 05/04
- Check if AGC calibration is within limits
- Check if SNR reading is OK.
- Use an Oscilloscope to check levels of “RXI” and “RXQ”.
The RF ASIC generates only single ended I and Q signals (RXI, RXQ). As the A/D converter
in UEM requires two differential signals, an artificial mid voltage is generated from
VrefRF02.
The BB part is used to measure those signals by means of RSSI reading. This works only if
correct calibration has been carried out in production.
RSSIreading [dBm] = 20log(U
BB
/U
LSB
) - AGC
calibrated
If both RX and TX path seem to be faulty it has to be checked if the synthesizer is work-
ing.
Figure 12: Receiver Fault Chart 1
Make sure that
Synthesizer is working
see
Synthesizer Fault
Finding Tree
Rx chain is functional
and calibrated
Selected band is working and
calibrated.
A
re all 3 bands measured?
Yes
No
Yes
Signal Generator:
Level: –80dBm
Frequency: calculated from
Phoenix + 67.71kHz
No
Phoenix:
Phone: local mode
Open
RF Controls
:
Active Unit: Rx
Op. Mode: Burst
Rx/Tx channel: default (mid)
All 3 bands
Phoenix:
Open
RSSI reading
Check RSSI Level = -80dBm
Yes Next band No
Execute Rx Calibration in selected
band
A
re calibration results within limits?
Yes
No
A
re all 3 bands measured?
No
Yes
Receiver
Fault Chart 1.