Amplitude modulator which forms two phase-shifted pulse trains and combines them

Abstract From the Canadian patent

A system and method for amplitude modulating a carrier signal with an audio or other information input signal relies on multivibrators and comparators initiating a logic controlled processing technique for providing two sinusoids each a funda-, mental frequency waveform the two having a mutual phase rela-, tionship defined by intermediate processing steps such that they differ in phase from 0 to 180 electrical degrees. The comparators output first resultant pulses when the carrier signal is greater than the amplitude of the audio or other information input signal. The first resultant pulses are input to a logic processing network to trigger multivibrators which output overlapping 180° wide …