NCJ Number
79625
Date Published
Unknown
Length
44 pages
Annotation
Based on interviews with police officials, law enforcement requirements for scrambler technology are presented and the usefulness of the most common scrambler technologies is reviewed.
Abstract
Interviews with police officials indicate an increasing need for radio communications privacy, largely as the result of the widespread availability of monitors to the general public and criminals. There appears to be a willingness to purchase scrambler units, if such units can satisfy agency requirements. The fundamental requirements for scrambler units are an acceptable level of privacy, ability to function within available bandwidths, and reasonable price. The most common scrambler technologies are (1) digital, which converts the voice signal into a stream of numbers which are transmitted; (2) frequency domain, which rearranges the frequency components of the speech signal to produce unintelligible sounds; and (3) time domain, which divides the speech signal into brief time segments and rearranges those segments for transmission. No scramblers being currently marketed in the United States meet law enforcement requirements. Digital units fail to meet cost and bandwidth requirements, frequency domain units miss on various combinations of all three criteria, and time domain units have been too costly. Technical breakthroughs may eventually permit the development of inexpensive digital scramblers that will work within the available bandwidths. Only time domain scramblers appear to have near term potential for satisfying all three requirements; however, their development is receiving little attention in the United States. Tables and figures are included. A summary of the interviews is appended. (Author summary modified)