Patent ID: 7359462

Claim:
A channel search device, comprising: a quasi-synchronization quadrature detector for inputting a PSK modulation signal and a carrier frequency set value, and outputting an I-axis signal and a Q-axis signal obtained by performing, based on the carrier frequency set value, quasi-synchronization quadrature detection on the PSK modulation signal; a timing reproducer for inputting the I-axis signal, the Q-axis signal, and a symbol rate set value, and reproducing and outputting the I-axis signal and the Q-axis signal while correcting an error of the symbol rate set value; a dispersion detector for inputting the I-axis signal and the Q-axis signal outputted by said timing reproducer, and detecting and outputting a dispersion between an amplitude of a symbol, comprising the I-axis signal and the Q-axis signal, and a reference amplitude; and a judging unit for monitoring the dispersion while varying the carrier frequency set value and the symbol rate set value, and judging that a channel exists at a position of a current symbol rate set value and a current carrier frequency set value when the size of the dispersion detected by said dispersion detector becomes an extremal value.