Bi-phase shift keying signal demodulation circuit for RDS receiver

Abstract

A bi-phase shift keying signal demodulation circuit for an RDS receiver receives RDS modulation signal and reproduces RDS data from the RDS modulation signal. The RDS modulation signal is produced by modulating a sub-carrier by a signal modulated by a bi-phase shift keying modulation using the RDS data. The bi-phase shift keying signal demodulation circuit includes: a clock reproducing unit for reproducing an RDS clock signal from the RDS modulation signal; a multiplying unit for operating a logical product of the RDS modulation signal and the RDS clock signal; a phase comparison unit for comparing the phase of the output signal of the multiplying unit with a synchronizing signal of the sub-carrier and producing a phase comparison signal; a pulse converting unit for converting pulses in the phase comparison signal into pulses of higher frequency than that of the phase comparison signal; and an integration/reset unit for monitoring the converted phase comparison signal at every period of the RDS clock signal for phase judgement and producing a bi-phase shift keying demodulation signal from which the sub-carrier component is removed.

Dependencies are inferred from the claim text.