Digital pulse position modulation communications system with threshold extension

Abstract

A digital pulse position modulation (PPM) communications system with threld extension including a radio receiver for achieving optimum coherent detection of a pulse position modulated communication signal including a coherent video detector coupled to the IF output of the radio receiver and a pulse repetition frequency loop locked to the detected video signals containing position modulation. The pulse repetition frequency loop includes a time discriminator, a filter, a voltage controlled oscillator, and a split gate generator providing a split gate no greater than the width of the applied video signal. The split gate is applied to the time discriminator resulting in the detected video signal being multiplied by itself or coherently detected. A low pass filter is connected to the output of the discriminator to provide a demodulated communications analog or quasi-analog output signal such as a voice signal, transmitted to the receiver from a digitally coded PPM communications transmitter.

Dependencies are inferred from the claim text.