Digital demodulator

Abstract

A digital demodulator which will need no absolute phasing circuit is provided. A known-pattern BPSK signal generating circuit generates the same known-pattern BPSK signal as a known-pattern BPSK signal in a received digital modulated wave in synchronism with the known-pattern BPSK signal in the received digital modulated wave, a carrier-reproducing phase error detecting circuit has a phase error table where one of reference phases in a signal point position of a demodulation baseband signal is made a convergence point, a phase error voltage corresponding to a phase error between a phase determined from the signal point position of the demodulation baseband signals and a phase convergence point is sent out, by enable-controlling a carrier-reproducing loop filter according to the known-pattern BPSK signal outputted from the known-pattern BPSK signal generating circuit , the phase error voltage is smoothed, and carrier reproduction is performed while controlling the frequency of a reproduced carrier according to the smoothed output so that the phase in the signal point position coincides with the phase convergence point.