Adaptive rate delta modulation for non-synchronous, full duplex, wireless digital communications

Abstract

This paper introduces the concept of a low-cost wireless digital communication system for voice communication based on a technique called adaptive rate delta modulation. This technique uses a tri-level threshold to produce delta-modulated pulses only when the amplitude has changed by a predetermined amount. This technique significantly reduces the average pulse rate required for transmission and lowers the noise generated by delta modulation under zero input conditions. The receiver for such a modulation is reduced to simple pulse detection and a counter to recreate the original signal. The characteristics of delta modulation result in a system that does not require headers, packets or other synchronizing schemes. Multiple users can concurrently use the same channel for "open microphone" communication allowing for simultaneous transmit and receive, and simple voice combining.