SQUELCH CIRCUIT FOR FM RADIO EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To provide a squelch circuit for an FM radio equipment, in which a squelch level is set to the threshold area of high sensitivity and the operability of a squelch operating element is improved. SOLUTION: This circuit is provided with a variable attenuating means 6 for attenuating the level of a demodulated signal, a noise detecting means 7-8 for detecting the noise level of the demodulated signal attenuated by the variable attenuating means 6 to cut-off the output of an audio signal extracted from the demodulated signal when the detected level is equal to or higher than a fixed reference level and a control means 9 for setting the squelch level by controlling an attenuation quantity in the variable attenuating means 6 on the basis of the operation of a squelch operating means 10 and the control means 9 has a configuration for setting the attenuation quantity high and setting a setting interval small when setting the squelch level to the threshold area of low input field strength.