FM receiver having improved audio quality in response to Rayleigh faded received signals

摘要

The present invention minimizes noise pops due to Rayleigh fades by controlling receiver gain relative to the average received signal strength so that only a predetermined level of limiting occurs prior to the recovery of the audio information. The amount of limiting is selected so that a significant Rayleigh fade will cause the amplified IF signal to drop below the limiting level and enter the linear amplification region. During the fade the magnitude of the signal provided to the discriminator decreases thereby decreasing the discriminator's output and minimizing the magnitude of the audio pop. Additional minimization of the subject noise pops is achieved by utilizing a discriminator which has a square law transfer characteristic so that the recovered audio level will decrease 2 dB for every 1 dB decrease in input signal level.