Intrusion warning system

Details Intrusion warning system Intrusion warning system

1981-03-30

1983-05-03

Caldwell, Sr., John W.

Communications: electrical

Condition responsive indicating system

Specific condition

333 17M, 340561, 455 69, 455123, G08B 1326

Patent

active

043822525

ABSTRACT:
An intrusion warning system for indicating the presence of an intruder to a given area includes an antenna provided around the area and which is insulated from the ground. An oscillator is provided for feeding an alternating current signal to the antenna, and a coupling impedance is connected between an output of the oscillator and the antenna. The coupling impedance includes an arrangement to vary the impedance to an appropriate value such that the voltage fed to the antenna is approximately 50% of the voltage fed from the oscillator to the coupling impedance. By this arrangement the detection sensitivity is always kept at an optimum. The system also includes a signal processing apparatus for producing an output signal responsive to a change in the voltage of the alternating current on the antenna exceeding a predetermined level.

REFERENCES:
patent: 2490238 (1949-12-01), Simons
patent: 3281721 (1966-10-01), Clark
patent: 3384887 (1968-05-01), Trimble
patent: 3445835 (1969-05-01), Fudaley
patent: 3462692 (1969-08-01), Bartlett
patent: 4174518 (1979-11-01), Mongeon
patent: 4300116 (1981-11-01), Stahovec

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