Nokia Customer Care
Appendix A: RF Troubleshooting
A-24
Company Confidential
Copyright
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2005 Nokia. All rights reserved
3. DOES THE PHONE REGISTER TO THE NETWORK AND MAKE A CALL (GSM)?
•
Test against a GSM communication tester or real GSM network with a proper SIM.
3.1 GSM transmitter power levels and transmit frequency ok?
•
Attach the phone to the product specific test jig and a spectrum analyser to the RF-coupler.
Coupler attenuation should be also taken into account during measurements.
•
Set GSM Tx ON. Procedure is explained in section “Transmitter troubleshooting”.
•
Spectrum analyser centre frequency should be set according the used TX channel (See section
“Frequency mappings”).
•
Spectrum analyser RBW = VBW = 1 MHz, Span 0 MHz, sweep time 1 ms. Notice that GSM
transmission has pulsed nature and power should be measured during TX burst (triggering
needed). Another possibility is to use following settings: RBW = VBW = 1 MHz, Span 200 kHz and
sweep time at least 2.5 seconds.
•
Test at least the maximum and minimum power levels:
-
EGSM900: The maximum power level is “5” (31 – 34 dBm, typ. value +33 dBm)
The minimum power level is “19” (3 – 7 dBm, typ. value +5 dBm)
-
GSM1800: The maximum power level is “0” (28 – 32 dBm, typ. value +30 dBm)
The minimum power level is “15” (-2 - +2 dBm, typ. value +0 dBm)
-
GSM1900: The maximum power level is “0” (28 – 32 dBm, typ. value +30 dBm)
The minimum power level is “15” (-2 - +2 dBm, typ. value +0 dBm)
•
If power is not as expected separate the phone into parts and place to the module jig. Connect the
spectrum analyser to the module jig GSM RF connector and measure power levels again (
Notice
that there are three antenna connectors in the module jig, one for GSM, one for WCDMA and one for
Bluetooth. Make sure that all connections are made to the correct RF-connector
).
-
Power levels ok in the module jig: Antenna or antenna connection bad. Replace the antenna
-
Power levels still wrong or no TX signal found at all: Continue troubleshooting
•
If TX signal is not found at all use wider span setting and check if the transmitter is transmitting
on wrong frequency. If the signal is found to be on wrong frequency or frequency is not stabile,
see section
3.1.3. "GSM transmitter frequency correct".
3.1.1 Does GSM TX transmit RF-power at all?
