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Synthesizer description and troubleshooting
Frequency synthesizers
The VCO frequency is locked by a PLL (phase locked loop) into a stable frequency source giv-
en by a VCTCXO which is running at 26 MHz. The frequency of the VCTCXO is in turn locked
into the frequency of the base station with the help of an AFC voltage which is generated in
UEM by an 11 bit D/A converter. The PLL is located in Honi and it is controlled through the RF-
Bus.
The required frequency dividers for modulator and demodulator mixers are integrated in Honi.
Loop filter filters out the comparison pulses of the phase detector and generates a DC control
voltage to the VCO. The loop filter determines the step response of the PLL (settling time) and
contributes to the stability of the loop.
The frequency synthesizer is integrated in Honi except for the VCTCXO, VCO, and the loop
filter.
General instructions for synthesizer troubleshooting
To start synthesizer troubleshooting:
1. Connect the test jig (MJ-83) to a computer with a DAU-9S cable or to an FPS-8
flash prommer with an XCS-4 modular cable.
Make sure that you have a PKD-1 dongle connected to the computer's parallel port.
2. Connect a DC power supply or FPS-8 to the module test jig with a PCS-1 cable.
3. Set the DC supply voltage to 3.6V and set the jumper connector on test jig to "by-
pass" position.
4. Set the phone module to test jig and start Phoenix service software
5. Initialize connection to the phone. (Use FBUS driver when using DAU-9S and
COMBOX driver when using FPS-8).
6. From the File menu, choose "Choose Product".
7. From the list, select RA-8.
8. From the toolbar, set operating mode to "Local"
9. From the Testing menu, choose "RF Controls".
10.In the "RF Controls" window:
- Select band "GSM900", "GSM 1800" or "GSM1900" (Default = "GSM900").
- Set Active unit to "Rx" (Default = "Rx").
- Set Operation mode to "Continuous" (Default = "Burst").
- Set Rx/Tx channel to 37 on GSM900 band, 700 on GSM1800 band, 661 on
GSM1900 band (Defaults).
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COMPANY CONFIDENTIAL
Copyright © 2005 Nokia. All Rights Reserved.
7 - RF Description and Troubleshooting
RA-8
Issue 1 11/05
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Troubleshooting
