Fault Finding Chart Of The Receiver - Nokia RH-37 Series Rf Troubleshooting Instructions

RH-37
6(b) - RF Troubleshooting Instructions
Signal amplitude
DC offset
Frequency

Fault finding chart of the receiver

During fault finding, the calibration procedure is used to find out, whether all bands are
affected (error in common part of the Rx chain) or only one band (error in a Rx part of
the failed band). Take care not to save calibration values to the phone memory,
which are out of limits. Find the error first and repair it.
When a defective phone has been calibrated, a possible error in RX front-end might be
masked. In that case, one can get a reasonable RSSI reading, although the front-end
shows excessive losses. If it is not sure that incorrect re-calibration has been made, fol-
lowing steps shall be carried out:
• Check if AGC calibration is within limits.
• Check if SNR reading is o.k.
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
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1.40Vpp
≈ 1.28V as the offset is floating, switch to the operating mode
<Burst> in Phoenix and read the DC offset
67kHz
Nokia Corporation
Nokia Customer Care
Issue 1 07/04