Patent ID: 6078578
Filing Date: 2000-06-20
Classification: H04L

Abstract:
A method of controlling a frequency offset correcting function of a communication apparatus, comprising:inputting as a received signal a time division multiple access (TDMA) signal angle-modulated by a signal containing a synchronization signal, a level of which is not deviated;including a local oscillator for oscillating a local oscillation signal having a changeable oscillation frequency, and converting a carrier wave frequency of said received signal on the basis of said local oscillation signal and outputting a frequency-converted signal;demodulating said frequency-converted signal and outputting a demodulation signal;removing a direct current element from said demodulation signal and outputting a demodulation signal without a direct current element;comparing said synchronization signal contained in said demodulation signal without said direct current element with a known signal pattern to thereby carry out a synchronization detection, and outputting a synchronization detection signal when detecting a synchronization state; andwith said synchronization detection signal as a trigger, calculating a frequency offset of said demodulation signal, and supplying said calculated frequency offset as an AFC signal to said local oscillator, thereby changing an input carrier wave frequency.