Appliance theft alarm using voltage magnitude switch

Claim 2

In a signal distribution system including an antenna system for receiving signals, a plurality of remote devices each having a signal input, and a signal distribution system for distributing the signals received by the antenna system to the signal inputs of the plurality of remote devices by means of a plurality of signal distribution lines extending between the antenna system and termination points with the signal inputs of a number of the remote devices connected to each of the signal distribution lines, a theft alarm system comprising continuous loops of a signal distribution line extending respectively through each of the remote devices having signal inputs connected to that signal distribution line in a manner such that a loop cannot be removed without destroying the device or cutting the continuous loop of signal distribution line, voltage source means attached to the termination point of each of the signal distribution lines for applying a voltage to each of the signal distribution lines which voltage does not interfere with transmission of signals from the antenna system along the signal distribution lines, voltage sensing means connected to each of the signal distribution lines for detecting the voltage thereon, said voltage sensing means adapted to generate an alarm in response to a change in value of said voltage on a signal distribution line which occurs when the signal distribution line is open-circuited or short-circuited.

Claim 3

In a signal distribution system including an antenna system for receiving signals, a plurality of remote devices each having a signal input, and a signal distribution system for distributing the signals received by the antenna system to the signal inputs of the plurality of remote devices by means of a plurality of signal distribution lines extending between the antenna system and termination points with the signal inputs of a number of the remote devices connected to each of the signal distribution lines, a theft alarm system comprising continuous loops of a signal distribution line extending through each of the remote devices having signal inputs connected to that signal distribution line in a manner such that a loop cannot be removed without destroying the device or cutting the continuous loop of signal distribution line, voltage source means in each of the signal distribution lines for applying a voltage to each of the signal distribution lines which does not interfere with transmission of signals from the antenna system along the signal distribution lines, voltage sensing means connected to each of the signal distribution lines for detecting the voltage thereon, said voltage sensing means comprising a plurality of voltage sensing switches, a voltage selective detector and an alarm, each of said voltage sensing switches having two inputs and an output, each of said voltage sensing switch inputs coupled to a signal distribution line, each of said voltage sensing switch outputs coupled to said voltage selective detector and adapted to generate a voltage output in response to open or short-circuitring of any of said signal distribution lines coupled to said voltage sensing switch, said voltage selective detector responsive to said voltage output to actuate said alarm.

Claim 4

In a signal distribution system including an antenna system for receiving signals, a plurality of remote devices each having a signal input, and a signal distribution system for distributing the signals received by the antenna system to the signal inputs of the plurality of remote devices by means of a plurality of signal distribution lines extending between the antenna system and termination points with the signal inputs of a number of the remote devices connected to each of the signal distribution lines, a theft alarm system comprising continuous loops of a signal distribution line extending through each of the remote devices having signal inputs connected to that signal distribution line in a manner such that a loop cannot be removed without destroying the device or cutting the continuous loop of signal distribution line, voltage source means in each of the signal distribution lines for applying a voltage to each of the signal distribution lines which does not interfere with transmission of signals from the antenna system along the signal distribution lines, voltage sensing means connected to each of the signal distribution lines for detecting the voltage thereon, said voltage sensing means comprising a plurality of voltage sensing switches, a voltage selective detector and an alarm, each of said voltage sensing switches having two inputs and an output, each of said voltage sensing switch inputs coupled to a signal distribution line, each of said voltage sensing switch outputs coupled to said voltage selective detector and adapted to generate a voltage output in response to open or short-circuitring of any of said signal distribution lines coupled to said voltage sensing switch, said voltage selective detector responsive to said voltage output to actuate said alarm.

Claim 5

The theft alarm system of claim 2 wherein the magnitude and polarity of said voltage output is indicative of which of said signal distribution lines is open or short-circuited and wherein said voltage selective detector actuates different alarms depending upon the magnitude and polarity of said voltage output.

Claim 6

The theft alarm system of claim 2 wherein said voltage source means coupled to said signal distribution lines which form said two inputs to a particular one of said voltage sensing switches comprises two complementary voltage sources for applying complementary voltages to said signal distribution lines.

Claim 7

The theft alarm system of claim 4 wherein each of said voltage sensing switches comprises a pair of complementary transistors each having an input and having a common output, said transistor inputs respectively coupled to said complementary voltage sources over said signal distribution lines, each of said pair of complementary transistors normally biased off by said complementary voltage source connected to said input but adapted to be biased on and generate said voltage output in response to open or short-circuiting of said signal distribution line whereby said complementary voltage source is no longer coupled to said input.

Claim 8

The theft alarm system of claim 3 wherein said voltage selective detector comprises a plurality of silicon controlled switches, one for each of said signal distribution lines, each said silicon controlled switch having an alarm actuated in response to conduction of said silicon controlled switch, each said silicon controlled switch having an input and a resistance-capacitance network for connecting said input to said voltage output, each of said silicon controlled switches adapted to conduct in response to voltage of a particular magnitude and polarity of said voltage output.

Claim 9

In a signal distribution system including an antenna system for receiving signals, a plurality of remote devices each having a signal input, and a signal distribution system for distributing the signals received by the antenna system to the signal inputs of the plurality of remote devices by means of a plurality of signal distribution lines extending between the antenna system and termination points with the signal inputs of a number of the remote devices connected to each of the signal distribution lines, a theft alarm system comprising continuous loops of a signal distribution line extending respectively through each of the remote devices having signal inputs connected to that signal distribution line in a manner such that a loop cannot be removed without destroying the device or cutting the continuous loop of signal distribution line, voltage source means in each of the signal distribution lines for applying a voltage to each of the signal distribution lines which voltage does not interfEre with transmission of signals from the antenna system along the signal distribution lines, voltage sensing means connected to each of the signal distribution lines for detecting the voltage thereon, said voltage sensing means adapted to generate an alarm in response to a change in value of said voltage on a signal distribution line which occurs when the signal distribution line is open-circuited or short-circuited.

Claim 10

In a signal distribution system including an antenna system for receiving signals, a plurality of remote devices each having a signal input, and a signal distribution system for distributing the signals received by the antenna system to the signal inputs of the plurality of remote devices by means of a plurality of signal distribution lines extending between the antenna system and termination points with the signal inputs of a number of the remote devices connected to each of the signal distribution lines, a theft alarm system comprising continuous loops of a signal distribution line extending respectively through each of the remote devices having signal inputs connected to that signal distribution line in a manner such that a loop cannot be removed without destroying the device or cutting the continuous loop of signal distribution line, voltage source means in each of the signal distribution lines for applying a voltage to each of the signal distribution lines which voltage does not interfEre with transmission of signals from the antenna system along the signal distribution lines, voltage sensing means connected to each of the signal distribution lines for detecting the voltage thereon, said voltage sensing means adapted to generate an alarm in response to a change in value of said voltage on a signal distribution line which occurs when the signal distribution line is open-circuited or short-circuited.