Transmitter-receiver system utilizing pulse position modulation and pulse compression

TLDR: In this article, the PPM pulses in the first and second channels are translated into pulse-width modulated pulses which are then demodulated and the original data is recovered while at the same time the sampling frequency is filtered out.

Abstract: Transmitter are receiver systems are disclosed including an encoder and a decorder, respectively. The encoder samples an incoming analog video signal and operates a periodic bipolar pulse pair whose phase separation is proportional to the amplitudes of the sampled data, thus pulse position modulation (PPM). In one embodiment of the invention the coded in-phase pulses are applied to a first channel having an intermediate frequency (IF) dispersive delay line with a positive-sloped transfer function. The out-of-phase pulses are applied to a second channel having a dispersive delay line with a negative-sloped, or conjugate, transfer function. The two channels of positive and negative dispersed pulses are added together resulting in a complex IF waveform. The complex IF waveform is frequency translated to a suitable time varying DC voltage waveform for controlling a transmitter. The receiver system includes a decoder having first and second channels with respective first and second conjugate pulse compression lines or chirp filters for recovering the original bipolar coded data. The first pulse compression line, with a negative-shaped transfer function recovers the in-phase PPM pulses of the bipolar pulse pair. The second pulse compression line, having the conjungate slope, recovers the out-of-phase PPM of the bipolar pulse pair pulses. The PPM pulses in the first and second channels are translated into pulse-width modulated pulses which are then demodulated. The demodulated pulses are subtracted and the original data is recovered while at the same time the sampling frequency is filtered out.