NCJ Number
90193
Journal
Police Research Bulletin Issue: 39 Dated: (Spring 1983) Pages: 4-11
Date Published
1983
Length
8 pages
Annotation
This article describes the history and current research of United Kingdom efforts to negotiate and plan new and reduced values for protecting its policy and fire systems from foreign radio interference on its VHF radio frequency bands.
Abstract
The 1979 World Administrative Radio Conference gave the United Kingdom until December 31, 1989, to remove all its police and fire VHF radio systems to new frequency bands. The United Kingdom also agreed to allow some foreign broadcasting stations to come on the air before 1989. To determine how much radio interference to allow on their VHF radio channels before the complete switch would be made in 1989, the Home Office Directorate of Telecommunications studied radio survey records and tested amplitude modulation signals being interfered with by FM broadcasting transmissions. The Directorate established the goal of keeping harmful levels of interference to within a 1-percent value. This proved unsatisfactory however, and the Directorate suggested additional relaxation of protection but only for channels well removed from the broadcasting channel carrier. The next phase of research involves returning of some police and fire schemes to allow at least some high power broadcasting transmitters to be implemented. An experiment being conducted in the Colchester Division of the Essex Constabulary will further investigate the practical tolerance of police and fire radio systems to radio interference from broadcasting stations. This experiment is briefly described. A few graphs and charts are included.