Transmitter; General Instructions For Egsm Tx Troubleshooting - Nokia NEM-4 Series Troubleshooting Instructions

NEM-4
RF Troubleshooting
The resulting BB signal is further amplified in the BB chain. For that no external circuitry
is required:
• Base band amplifiers (BBAMP1). That amplifiers implement the initial channel filter-
ing.
• Low pass filters (LPF1).
• DC compensation / AGC amplifiers (DCN1). They implement gain steps from 0dB to
24dB in 6dB steps.
• Attenuators (AGC). They implement gain steps from -48dB to 0dB in 6dB steps,
yielding a total gain range of 72dB together with DCN1.
• Bi-quad filters (LPF2).
• DC compensation amplifiers (DCN2).
The differential base band outputs are internally DC coupled and can be connected
directly to the ADC inputs of the RF converter chip. The common mode level is set equal
to the VBEXT reference voltage.

Transmitter

General instructions for EGSM TX Troubleshooting

Apply a RF-cable to the RF-connector to allow the transmitted signal to act as normal.
RF-cable should be connected to measurement equipment (GSM Test equipment, Power-
meter, Spectrum Analyzer, or similar). Be sure to use at least a 10-dB attenuator, other-
wise the results may be incorrect.
Connect the phone to a PC with DAU-9S cable and dongle and follow the following
instructions:
Set the mode switch to 'Local' and connect the phone to a power supply (3.6V). When
using an MJS-80 module jig, a 4.2V supply is needed.
Open Phoenix and log in with your user ID.
Select File [Alt-F] -> Manage Connections [M] -> FBUS -> Apply -> Close window.
Select File -> Scan Product [Ctrl-R].
When the product has been found, the phone SW version can be read from the lower
edge of the Phoenix screen.
If the Operation is not shown, click Read button to see that Local mode has been
selected. Select Testing [Alt-S] -> RF controls [R].
Before choosing the band and Tx as Active Unit, and if the spectrum analyser is used,
make sure that the spectrum analyser reference level is higher than the expected TX
power.
Use the automatically selected channel.
Set Operation Mode to 'Burst'.
Choose the Power level you want the phone to operate at.
Page 6(b)-70
Company Confidential
Copyright  2003 Nokia Corporation
Company Confidential
CCS Technical Documentation
Issue 1 09/2003