JPS5571335A - Distortion detection unit of fm receiver - Google Patents

Abstract

PURPOSE:To make it possible to display easily a distortion quantity in demodulation signals by displaying the distortion quantity by signal components which appear in a specific frequency band of signals obtained by multiplying signals synchronized with pilot signals and stereophonic composite signals. CONSTITUTION:Signals which are inputted to input terminal 1 and are demodulated by an FM demodulator are supplied to synchronous multiplier SM consisting of a PLL and multiplier MP. The PLL is locked for pilot signals of 19KHz in stereophonic composite signals and gives synchronizing pilot signals to multiplier MP. Multiplier MP multiplies signals supplied from the PLL and input signals supplied from input terminal 1, and gives the output to band-pass filter BPF. Signal components which passed through band-pass filter BPF become DC signals in rectification filter circuit Rec and are given to display equipment M.