Communications security devices (CSD) — Techniques, constraints, and selection

Abstract

There are a variety of processing techniques employed in different CSD's. In general, any technique can be evaluated based on the degree to which the voice signal is fragmented into irregular time/frequency elements; the speed and irregularity at which rearrangement takes place; the ability to operate over a particular type of channel; and of great importance, the quality of the recovered (decoded) voice.