Voice Encoding for the Space Shuttle Using Adaptive Delta Modulation

Two algorithms for voice encoding are described. One, the modified Abate, is a simplified version that is the type designed for the Space Shuttle. Waveforms of the response of the delta modulators to channel errors are given and performance data that shows the relationship between channel errors and word intelligibility are included. An analytic derivation yielding a comparison between PCM and adaptive delta modulation with respect to channel errors is also given.