Noise suppression gate circuit for AM radio receiver - has second gate and second demodulator to fill breaks when first noise gate opens

摘要

The noise suppression circuit, for an AM radio receiver, has a gate in the LF signal path opened, when a noise pulse is detected. The gate is connected to the output of the mixer/filter stage andis followed by a bandpass filter, amplifier and the AM demodulator. The amplifier output is gated by a second gate operating out of phase in relation to the first one, to a second bandpass filter and a second AM demodulator. The outputs of the two demodulators are added and the sum used to drive the loudspeaker output stage. The second demodulator compensates for the break caused by the opening of the first gate due to noise.