DIGITAL COMMUNICATION APPARATUS

摘要

PROBLEM TO BE SOLVED: To obtain a digital communication apparatus which does not exert an influence upon a communication success rate by lowering the probability of the incorrect detection of a carrier due to noise without complicating a carrier detecting requirement or generating carrier detection disability. SOLUTION: A device for detecting a carrier by inputting a signal obtained by superposing a multi-carrier with the same data via a distribution line and comparing a signal in which a component of each frequency is extracted by fast Fourier transform 14 with carrier detecting requirements determined by a period in which a signal level and a phase are continued by a carrier detector 20, includes a synchronous circuit 10a for synchronizing the carrier detected by the detector 20 and a history holding circuit 10d for holding the information of right or wrong of the synchronization with the signal level. The carrier detecting requirement of the signal this time extracted by the fast Fourier transform 14 is changed based on the history information held in the holding circuit 10d. COPYRIGHT: (C)2004,JPO