NCJ Number
59948
Journal
Security Management Volume: 23 Issue: 7 Dated: (JULY 1979) Pages: 40-44
Date Published
1979
Length
5 pages
Annotation
TECHNICAL DEVELOPMENTS AND EQUIPMENT ARE DISCUSSED CONCERNING THE IMPROVED SECURITY OF ALARM SYSTEMS AND ALARM LINES AGAINST THE THREAT OF DESTRUCTION OF CIRCUMVENTION.
Abstract
ALTHOUGH THE CENTRAL CONTROL ROOMS FOR SECURITY SYSTEMS CAN BE PHYSICALLY SHIELDED, AND THE ALARM SENSORS CAN BE PROTECTED, THE MOST VULNERABLE COMPONENTS IN A SECURITY SYSTEM ARE THE COMMUNICATIONS LINES WHICH CONNECT THE OTHER COMPONENTS. THE STANDARDS FOR COMMERCIAL AND GOVERNMENT LINE SUPERVISION ARE ARCHAIC AND INADEQUATE. BY 1980, HOWEVER, COMMERCIAL STANDARDS WILL BE UPGRADED TO REQUIRE THE INSTALLATION OF GRADE AA STANDARD SYSTEMS IN HIGH RISK AREAS. ONE WAY IN WHICH ALARM COMPANIES CAN MEET THIS REQUIREMENT IS BY USING EQUIPMENT WHICH PLACES AN ALTERNATING CURRENT TONE ON THE LINE, ALONG WITH THE 50 PERCENT DIRECT CURRENT SUPERVISION. TAMPERING WITH THE LINE RESULTS IN THE ALARM'S TRANSMISSION FROM THE SUPERVISORY UNIT. HIGH SECURITY AREAS SHOULD HAVE THE PROTECTION OF SYSTEMS DESIGNED TO THE HIGHEST SPECIFICATIONS, AND GOVERNMENT CONSTRUCTION CONTRACTS SHOULD REQUIRE THE BEST PROTECTION. AVAILABLE SYSTEMS INCLUDE THE RANDOM-DIGITAL INTERROGATE/REPLY SYSTEM WITH DOUBLE OR SINGLE SCAN MODE. USE OF THE DOUBLE SCAN MODE MEANS THAT THE FIRST TRIGGERING OF THE SECURITY SYSTEM IS IGNORED, AND THAT THE ALARM IS NOT SENT UNTIL SUBSEQUENT SIGNALS ARE RECEIVED. IMMUNITY TO LINE NOISE IS ACHIEVED IN THIS MODE. MULTIPLEX SYSTEMS ARE ALSO AVAILABLE FOR COST-EFFECTIVE SECURITY. ILLUSTRATIONS ARE PROVIDED. (TWK)