BASIC CRITERIA FOR A SECURITY SYSTEM ARE (1) IT SHOULD BE FAIL SAFE, (2) ITS WIRING SHOULD BE DIFFICULT TO SEVER, AND (3) IT SHOULD BE OPERABLE WHEN THERE IS A POWER FAILURE. CLOSED CIRCUIT TELEVISION IS USED IN LARGE RESEARCH LABORATORY TO PROTECT SECRET WORK BEING PERFORMED, IN HIGH-RISE BUILDINGS, WHARFS, AND IN APARTMENT BUILDINGS. TWO-WAY RADIO AND ONE-WAY RADIO PAGING ARE WIDELY USED IN SECURITY APPLICATIONS, WITH TWO-WAY RADIO EMPLOYED FOR INTERCOMMUNICATION BETWEEN SECURITY GUARDS AND FOR COMMUNICATION BETWEEN GUARDS AND THE SECURITY OFFICE. RADIATING COAXIAL CABLES HAVE BEEN INSTALLED FOR USE BY SECURITY GUARDS IN A HIGH-RISE OFFICE BUILDING. RADIO ALARM TRANSMITTERS ARE USEFUL IN PREVENTING THE HIJACKING OF TRUCKS AND THE THEFT OF MERCHANDISE FROM PARKED HIGHWAY TRAILERS AND IN MINIMIZING TAXICAB ROBBERIES. TRUCK ACCESS CONTROL MEASURES ARE FEASIBLE FOR TERMINAL AREAS. POCKET RADIO PAGING RECEIVERS, WORN IN THE POCKET, CAN RESOLVE SHOPLIFTING PROBLEMS, AND RADIO TRANSMITTERS CAN ASSIST IN INDUSTRIAL COMPLEX SECURITY PROBLEMS. WIRELESS INTERCOM UNITS AID IN MINIMIZING BAGGAGE THEFT AT RAILROAD DEPOTS AND OTHER TRANSPORTATION CENTERS AND ALSO SOLVE SWITCHBOARD PROBLEMS OF HOTELS AND BUSINESS ORGANIZATIONS. THE FEDERAL COMMUNICATIONS COMMISSION, HOWEVER, PROHIBITS THE USE OF THESE UNITS OR ANY FORM OF SPEECH SCRAMBLER ON CITIZEN'S BAND CHANNELS. CASSETTE TAPE RECORDING SYSTEMS CAN BE DESIGNED TO RECORD PHONE CONVERSATIONS. TELEPHONE LINE VOLTAGE SENSING DEVICES ARE AVAILABLE TO KEEP BURGLARS AWAY. OTHER SECURITY DEVICES INCLUDE THE USE OF TONE SIGNALS TO PROTECT PAGING SYSTEMS, AIR IONIZERS TO DISSUADE SHOPLIFTERS, LOOP DETECTORS FOR VEHICLES, AND TELEPHONE DIAL SYSTEMS TO DECODE DOOR LATCHES AT KEY ENTRANCES TO FACILITIES. ILLUSTRATIONS OF SOME SECURITY DEVICES ARE INCLUDED. (DEP)