NCJ Number
148774
Date Published
1975
Length
45 pages
Annotation
This report is designed to inform law enforcement offices about the application and functioning of undercover communications equipment and to act as the forerunner of a voluntary standard to be used in the selection, evaluation, and procurement of such equipment.
Abstract
The data used were derived from law enforcement personnel, manufacturers, publications, and laboratory measurements. The equipment discussed in the report are concerned only with the interception of voice or audio communications; this report does not cover video or optical techniques. The first section deals with radiating devices and receivers, and discusses power output, operating time, and operating distance; crystal control vs. free-running oscillators; ease of detection; modulation and audiofrequency response; packaging; antennas; propagation conditions; and telephone tapping transmitters. Subsequent chapters examine tests of radiating devices, nonradiating devices, and tape recorders. 2 appendixes