Communications: electrical – Systems – Call station
Patent
1975-05-27
1977-08-02
Swann, III, Glen R.
Communications: electrical
Systems
Call station
325308, 340216, 340310R, G08B 1322
Patent
active
040400450
ABSTRACT:
A method and apparatus for detecting theft of television sets from motels and similar establishments which provide unattended television sets and service as a convenience for customers. The invention uses existing trunk lines utilized in a master antenna television system (MATV) for transmitting television signals to the sets, and does not require installation of additional conductors. A source of low 60 Hertz voltage is applied to each of the trunk lines, and there is associated with each television set a resistor. When the connection of a set to a trunk line is disturbed, the disturbance is detected as a change in resistance and the level of 60 Hz current flowing through the trunk line is caused to change. This change in current is detected at a central location to create an alarm condition. An audible alarm is also created at the location of the television set which was disturbed.
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Bickel Richard L.
Osborne Richard C.
Swann III Glen R.
Turner Robert W.
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