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PROTECTIVE SYSTEMS CONCEPT
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actuated agencies alarm circuits alarm line alarm signal alarm transmission ambient noise level annunciator applicable areas arson arsonists attempts automatic dial alarm barriers beam building burglars business establishments business hours cameras cause CCTV circuit circuitry commercial central station configuration costs counterforce coverage crime criminal attack designed detection systems direct wire dispatcher doors effective electrical electromechanical employed enter entry equipment false alarms frequency gages guard holdup illegal act infrared initiate an alarm installation intruder larceny-theft light locks loud-sounding device magnetometer maintenance ment metal motion detection objects operations percent perimeter physical protection police departments police patrol police station proprietary protected premises protective systems radio rates Resistance to Defeat response robbery sensors silent alarm strain gages subscriber subscriber's subsystems supervision switch tampering techniques telephone tion transmitted trigger unauthorized persons unit vandalism vaults vibration wafer watchmen wheatstone bridge