SEKERHETSANLEGGNING

• Main Authors: LEWIS J, GILMOUR W D
• Format: Patent
• Language: Swedish
• Published: 04.04.1977
• Subjects: ALARM SYSTEMS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDEDFOR ELSEWHERE; BASIC ELECTRONIC CIRCUITRY; CHECKING-DEVICES; CONTROL OR REGULATING SYSTEMS IN GENERAL; CONTROLLING; ELECTRICITY; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; GENERATING RANDOM NUMBERS; GENERATION OF NOISE BY SUCH CIRCUITS; GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING,BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN ANON-SWITCHING MANNER; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS ORELEMENTS; ORDER TELEGRAPHS; PHYSICS; REGISTERING OR INDICATING THE WORKING OF MACHINES; REGULATING; SIGNALLING; SIGNALLING OR CALLING SYSTEMS; TIME OR ATTENDANCE REGISTERS; VOTING OR LOTTERY APPARATUS

A security system controls admission of persons to protected areas. An authorised person carries in his pocket a token which generates at two discrete frequencies and when he approaches a door leading to the restricted area, a sensor of his presence sends an initiating signal to a control unit which...