Security alarm transmission system
First Claim
1. In a security alarm system for a protected area, communicating apparatus comprising a plurality of transmitter units in said protected area, each of said transmitter units including condition sensing means and a transmitter circuit controlled by its associated sensing means to provide an information signal in response to a change in a condition as sensed by its associated sensing means, receiver means at said protected area, and signal coupling means including conductor means extending around the periphery of the area protected in a loop and having first and second ends connected to respective first and second inputs of said receiver means, said conductor means defining a controlled area of influence in which inductive signal coupling is provided between an output stage of each transmitter circuit located within said controlled area of influence and said conductor means to permit the information signals provided by transmitter circuits located within said controlled area of influence to be inductively coupled over said conductor means to said receiver means connected thereto and to limit the response of said receiver means to information signals provided by transmitter circuits located within said controlled area of influence, detecting means in said receiver means for detecting information signals coupled to said receiver means over said conductor means, and means controlled by said detecting means to provide an indication of the change in a monitored condition.
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Abstract
A security alarm transmission system for protecting a building includes a plurality of alarm transmitter units each having a transmitter circuit controlled by associated condition sensors to generate coded alarm signals which are inductively coupled to a pick-up loop extending around the periphery of the building and extended to a receiver connected to the loop which decodes the alarm signals and provides a suitable alarm indication. The alarm transmitter unit is adaptable to provide different alarm outputs for indicating fire in the building or an unauthorized entry of the building, or an emergency condition, for example. The multipurpose alarm transmitter unit comprises a housing unit for containing the transmitter circuit, the housing permitting the transmitter circuit to be controlled by normally open or normally closed switches, and a mounting assembly which permits convenient installation of the transmitter unit at desired locations.
75 Citations
16 Claims
- 1. In a security alarm system for a protected area, communicating apparatus comprising a plurality of transmitter units in said protected area, each of said transmitter units including condition sensing means and a transmitter circuit controlled by its associated sensing means to provide an information signal in response to a change in a condition as sensed by its associated sensing means, receiver means at said protected area, and signal coupling means including conductor means extending around the periphery of the area protected in a loop and having first and second ends connected to respective first and second inputs of said receiver means, said conductor means defining a controlled area of influence in which inductive signal coupling is provided between an output stage of each transmitter circuit located within said controlled area of influence and said conductor means to permit the information signals provided by transmitter circuits located within said controlled area of influence to be inductively coupled over said conductor means to said receiver means connected thereto and to limit the response of said receiver means to information signals provided by transmitter circuits located within said controlled area of influence, detecting means in said receiver means for detecting information signals coupled to said receiver means over said conductor means, and means controlled by said detecting means to provide an indication of the change in a monitored condition.
- 7. In a security alarm system for a building, an alarm apparatus for providing a first alarm for indicating unauthorized entry of the building and a second alarm for indicating the presence of fire or smoke within the building, said alarm apparatus comprising a plurality of transmitter units, a first one of said transmitter units being associated with a protected entrance of the building and having a first transmitter circuit and entry switch means responsive to an unauthorized entry of the building to enable said first transmitter circuit to provide alarm signals at a first frequency, and a second one of said transmitter units having a second transmitter circuit and sensor means responsive to the presence of fire or smoke within the building to enable said second transmitter circuit to provide alarm signals at a second frequency, receiver means in said building, and signal coupling means including conductor means extending around the periphery of said building in a loop and having first and second ends connected to respective first and second inputs of said receiver means, said conductor means defining a controlled area of influence in which inductive signal controlling is provided between an output stage of each transmitter circuit located within said controllled area of influence and said conductor means to permit the alarm signals provided by said first and second transmitter circuits to be inductively coupled over said conductor means to said receiver means connected thereto and to limit the response of said receiver means to alarm signals provided by transmitter circuits located within said controlled area of influence, said receiver means including detector means for detecting said alarm signals coupled to said receiver means over said conductor means, and operable to provide a first output signal in response to said alarm signals at said first frequency to effect the generation of said first alarm, and to provide a second output signal in response to said alarm signals at said second frequency to effect the generation of said second alarm.
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15. In a security alarm system for building, an alarm apparatus for providing a first alarm for indicating unauthorized entry of the building and a second alarm for indicating the presence of smoke within the building, said alarm apparatus comprising a plurality of transmitter units, a first one of said transmitter units being associated with a protected entrance of the building and having a first transmitter circuit, power circuit means for supplying DC power from a battery to said first transmitter circuit, and entry switch means responsive to an unauthorized entry of the building to enable said first transmitter circuit to provide alarm signals at a first frequency, and a second one of said transmitter units having a second transmitter circuit, power circuit means for supplying DC power from a battery to said second transmitter circuit and sensor means responsive to the presence of smoke within the building to enable said second transmitter circuit to provide alarm signals at a second frequency, receiver means, and signal coupling means including conductor means extending around the periphery of said building in a loop and having first and second ends connected to responsive first and second inputs of said receiver means, said conductor means defining a controlled area of influence in which inductive signal coupling is provided between an output stage of each transmitter circuit located within said controlled area of influence and said conductor means to permit the alarm signals provided by said first and second transmitter circuits to be inductively coupled over said conductor means to said receiver means connected thereto, said receiver means including detector means for detecting said alarm signals coupled to said receiver means over said conductor means, and operable to provide a first output signal to response to alarm signals at said first frequency to effect the generation of said first alarm, and to provide a second output signal in response to alarm signals at said second frequency to effect the generation of said second alarm, said receiver means further including signal generating means for periodically generating power signals at a predetermined frequency and means for coupling said power signals to said conductor means to permit said power signals to be inductively coupled to the output state of each of said transmitter units, the power circuit means of at least certain ones of said transmitter units including battery charging circuit means having means for detecting said power signals and circuit means responsive to the detected power signals for supplying charging current to the battery.
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16. In a security alarm system for a protected area, communicating apparatus comprising a plurality of transmitter units in said protected area each of said transmitter units including condition sensing means and a transmitter circuit having alarm signal generating means and power circuit means for supplying DC power from a battery to the associated alarm signal generating means, each alarm signal generating means being controlled by its associated sensing means to provide an alarm signal in response to a change in a condition as sensed by its associated sensing means, receiver means, and signal coupling means including conductor means extending around the periphery of the area protected in a loop and having first and second ends connected to respective first and second inputs of said receiver means, said conductor means defining a controlled area of influence in which inductive signal coupling is provided between an output stage of each transmitter circuit located within said controlled area of influence and said conductor means to permit the alarm signals provided by said transmitter circuits to be inductively coupled over said conductor means to said receiver means connected thereto, detecting means in said receiver means for detecting alarm signals coupled to said receiver means over said conductor means, means controlled by said detecting means to provide an indication of the change in a monitored condition, said receiver means further including means for generating power signals at a preselected frequency and means for applying said power signals to said conductor means, at least one of said power circuit means including battery charging circuit means responsive to power signals applied to said conductor means by said receiver means to provide charging current for the battery.
Specification