Carrier reproducing circuit for phase shift keying signals

Claim 1

A carrier reproducing circuit for signals transmitted in carrier suppressed modulation comprising: frequency converting means for converting said transmission signal to a frequency of a carrier to be reproduced; demodulator means, coupled to said frequency converting means, for demodulating transmission data, said demodulator means including carrier reproducing means for producing said carrier, voltage controlled oscillator means, coupled to said carrier reproducing means, for generating an oscillation output and for supplying said oscillation output to said carrier reproducing means, and phase comparing means, coupled to said carrier reproducing means and said voltage controlled oscillator means, for comparing the phase of said reproduced carrier and said oscillation output and for generating a control voltage, said voltage controlled oscillator means being controlled by said control voltage; error detecting means coupled to said demodulator means for detecting the bit error rate of said demodulated data; and frequency correction data generator means coupled to said error detecting means for generating a correction voltage in accordance with said detected bit error rate, said frequency correction data generator being coupled to said voltage controlled oscillator means so as to superimpose said correction voltage onto said control voltage.