Simultaneous amplitude and angle modulation using detection of complex zeroes

摘要

Modulation of a carrier signal using both amplitude and angle modulation increases the information capacity of transmission without increasing bandwidth. Complex zeros in an amplitude modulating signal are detected and a conjugation function dependent on the time of occurrence and imaginary root values of the zeros is generated. The conjugation function is inverted or not inverted in accordance with a binary data signal and used to control the frequency of an oscillator whose output is an angle modulated carrier signal which is then amplitude modulated. On reception the amplitude modulating signal is recovered by an envelope detector and the data signal by a phase locked loop.