VOICE PRIVACY EQUIPMENT FOR LAW ENFORCEMENT COMMUNICATIONS SYSTEMS - LAW ENFORCEMENT STANDARDS PROGRAM

• NCJ Number: 13386
• Author(s): G R SUGAR
• Date Published: 1974
• Length: 42 pages
• Sponsoring Agency: US Dept of Justice; US Dept of Justice NIJ Pub
• Corporate Author: US Dept of Justice
• Sale Source: Superintendent of Documents, GPO; National Technical Information Service; National Institute of Justice/
• Publication Type: Best Practice/State-of-the-Art Review
• Language: English
• Country: United States of America
• Note: NATIONAL INSTITUTE OF LAW ENFORCEEMNT AND CRIMINAL JUSTICE STANDARD PREPARED BY NATIONAL BUREAU STANDARDS

Annotation

DESCRIPTION OF VOICE PRIVACY TECHNIQUES AND COMMERCIALLY AVAILABLE SCRAMBLERS, AND A DISCUSSION OF THE CONCEPTS OF INTELLIGIBILITY AND PRIVACY.

Abstract

LAW ENFORCEMENT AGENCIES ARE FINDING AN INCREASING NEED FOR VOICE-SCRAMBLING EQUIPMENT TO PROVIDE PRIVACY ON THEIR TWO-WAY RADIO COMMUNICATION SYSTEMS. 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. WORK IS UNDERWAY AT THE NATIONAL BUREAU OF STANDARDS, UNDER THE SPONSORSHIP OF THE NATIONAL INSTITUTE OF LAW ENFORCEMENT AND CRIMINAL JUSTICE (NILECJ), TO DEVELOP PERFORMANCE STANDARDS FOR VOICE SCRAMBLERS. THE FOUR AREAS BEING CONSIDERED ARE SPEECH INTELLIGIBILITY, VOICE QUALITY, VOICE PRIVACY, AND GENERAL SYSTEM CHARACTERISTICS. 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 ON HOW TO PROCEED IN THE ABSENCE OF A STANDARD, AND A BIBLIOGRAPHY OF TECHNICAL PUBLICATIONS ON VOICE SCRAMBLING. (AUTHOR ABSTRACT) (SNI ABSTRACT)