| 摘要 |
The procedure for detection of base station synchronisation signals by a mobile telephone includes measurement of the demodulated signals, and shifting the local oscillator frequency in order to enable detection of signals from neighbouring base stations. The procedure for acquisition of a synchronisation signal by a mobile telephone includes measurement of the signal (FCCH) transmitted at a given frequency, according to GSM mobile telephone protocol. The received signal is detected, and then with a local oscillator a signal is produced at a demodulation frequency. The detected signals are demodulated with the aid of this signal at a demodulation frequency, and the frequency of the signal is measured in the demodulated signals. The demodulation frequency of the local oscillator signal is shifted by a value equal to the half-sum of two contiguous frequencies augmented by the value of a signal modulating the signals (FCCH) in pure frequency.
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