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5 Tx VCO
5.1
What is TxVCO – Calibration
In the GSM900-system a phone can communicate with the base station at 124 frequencies in
each direction, 890.2 - 914.8 MHz for the transmitter and 935.2 - 959.8 MHz for the receiver.
In the GSM1800-system is it possible to communicate at 374 frequencies in each direction,
1710.2 – 1784.8 MHz for the transmitter and 1805.2 – 1879.8 MHz for the receiver.
The communication between the base station and the phone are done switched.
The system makes it possible to change frequency between each burst.
For every new burst the transmitter synth of the phone has to lock on again at the frequency that
the base station expect, before activating the transmitter.
Two simplified schedules over the lock-on of the TX-synth are shown below.
The frequencies are for channel 62 GSM900 Fig5.1.
And for channel 699 GSM1800 Fig.5.2.
4/00021-3/FEA 209 544/18 B
Fig5.1
Trouble Shooting Guide, Advanced
21(121)
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