Rf Troubleshooting Instructions; Rx Part - Nokia NME-2A Series Troubleshooting Instructions

NME–2A
Troubleshooting Instructions

RF Troubleshooting Instructions

The RF part consist of RX, TX and synthesizers as main blocks.
Interface to the rest of the radio is mainly through RFI.
In normal use, in the network, it is not possible to localize a malfunction to
any of these parts alone, because all of them may be needed to operate
the radio.
With a GSM tester like HP8922G/H it is possible to operate the radio in a
simple network like manner, and in that way localize some faults,
especially when you monitor the radio with PCLocals at the same time.
If the fault means, that the radio does not work with HP8922G/H then it is
possible via PCLocals in local mode, to operate the parts individually, and
in that way see if the parts can do what they are supposed to. It is also
possible to operate the parts dynamic, to check the switching between the
different modes, and that is more or less sufficient to tell if the RF is OK or
not.
The following descriptions all starts with a simple and top level check. If
that fails or if the radio still has a malfunction, then the checks goes
deeper and deeper into the circuits to help finding the circuit that is
responsible for the malfunction.

RX Part

1. RSSI calibration (Input –57 dBm, channel 60, 947.06771MHz):
Checks the signal path from antenna to RFI and the AGC. The RFI
operates only as level detector in this mode. The offset value is a measure
of the total gain in the RX.
– –37 < Offset < 49 dB
– Calibration values between 2 dB
– If it is OK, go to 2.
– If it fails then select via PCLocals RF control, Active unit RX, Operation
mode continuous, Continuous mode channel 60, AGC 93. Input –57
dBm 947.06771 MHz.
Measure with probe and oscilloscope or with the probe and spectrum
analyzer.
Note: When measuring levels with an oscilloscope probe to the
spectrum analyzer, some calibration is needed!
Page 14
P.A.M.S.
Technical Documentation
Original 08/97