Signal processing circuit for tuner which applies signal processing based on variation in frequency of intermediate frequency signal

摘要

A signal processing circuit for a tuner has a detector band pass filter for extracting a carrier of an intermediate frequency signal, a frequency counter for counting, based on a clock signal, a frequency of a carrier of the intermediate frequency signal which passes through the detector band pass filter, and an intermediate frequency variation signal outputting section for outputting an intermediate frequency variation signal based on a difference between the counted frequency and a frequency of the clock signal. Based on the intermediate frequency variation signal, a frequency selection characteristic of an intermediate frequency band pass filter, a signal detector, an adjacent interference detector, or an S-meter-band pass filter are controlled. In this manner, even when a carrier frequency of an intermediate frequency signal input from a tuner varies, the frequency selection characteristic of the intermediate frequency band pass filter, signal detector, adjacent interference detector, and S-meter-band pass filter can be suitably controlled.