Voice Privacy Equipment for Law Enforcement Communication Systems. Law Enforcement Standards Program,

摘要

One of the ways to increase the privacy of communications is to use electronic devices that encode voice signals for transmission and decode them at the receiver. These devices,loosely referred to as 'scramblers',rearrange the voice signals so that,in principle,they are unintelligible to a listener who is not equipped with the proper decoding equipment. This report first defines a set of special terms,then describes a number of types of scramblers that are now available for law enforcement use. Some inherent problems and weaknesses are discussed. The concepts of intelligibility and privacy are explored in detail. The potential contents of the standard are described,and some problems inherent in preparing and using the standard are discussed. The report concludes with some material intended to be of immediate assistance to the prospective purchaser of scramblers: a survey of units now on the market,some hints of how to proceed in the absence of a standard,and a bibliography of technical publications on voice scrambling.