Patent ID: 7650128

Claim:
A radio wave reception device comprising: radio wave reception means which receives an amplitude modulation signal; gain control means which outputs gain control signals; amplitude modulation signal amplification means which amplifies the amplitude modulation signal received from said radio wave reception means, according to a first gain control signal output from said gain control means; oscillation means which outputs a signal of a predetermined frequency; frequency conversion means which mixes the signal output from said amplitude modulation signal amplification means with the signal output from said oscillation means, and outputs an intermediate frequency signal; intermediate frequency signal amplification means which amplifies the intermediate frequency signal output from said frequency conversion means, according to a second gain control signal output from said gain control means; and detection means which detects the signal output from said intermediate frequency signal amplification means, and outputs a detection signal, wherein: said detection means includes extraction means which extracts a modulation signal from the signal output by said intermediate frequency signal amplification means; said gain control means includes gain control signal generating means which generates a third gain control signal based on a comparison of the modulation signal extracted by said extraction means with a predetermined voltage level; said detection means further includes detection signal output means which generates and outputs said detection signal, based on the modulation signal extracted by said extraction means and the third gain control signal generated by said gain control signal generating means; and said detection signal output means includes: multiplication means which multiplies the modulation signal and the third gain control signal, and output means which outputs the signal multiplied by said multiplication means as said detection signal.