Surveillance system
First Claim
1. In a surveillance system which comprises a central unit connected, by the intermediary of a communication channel to a plurality of local terminal units in order to receive information from these units concerning changes of status in sensors connected to said terminal units, the improvement wherein said terminal unit comprises:
- a. a transfer blocking register with a memory cell for each sensor in at least one group of the sensors connected to said terminal unit, said memory cells having two states and being switchable between these states by control information transferred from said central unit; and
a sensing device for achieving, on a change of status in any one of the sensors of the group, transfer of information on such change to the central unit only when the corresponding memory cell in the transfer blocking register is in one of its two states.
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Accused Products
Abstract
A surveillance system comprises a central unit connected, by the intermediary of a communication channel, to a plurality of local terminal units in order to receive information from these units concerning changes of status in sensors connected to the terminal units. Each terminal unit comprises a transfer blocking register with a memory cell for each sensor in at least one group of the sensors connected to the terminal unit. These memory cells have two states and are switchable between these states by control information transferred from the central unit. Moreover, a sensing device is provided for achieving, on a change of status in any one of the sensors of the group, transfer of information on such change to the central unit only when the corresponding memory cell in the transfer blocking register is in one of its two states.
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Citations
15 Claims
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1. In a surveillance system which comprises a central unit connected, by the intermediary of a communication channel to a plurality of local terminal units in order to receive information from these units concerning changes of status in sensors connected to said terminal units, the improvement wherein said terminal unit comprises:
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a. a transfer blocking register with a memory cell for each sensor in at least one group of the sensors connected to said terminal unit, said memory cells having two states and being switchable between these states by control information transferred from said central unit; and a sensing device for achieving, on a change of status in any one of the sensors of the group, transfer of information on such change to the central unit only when the corresponding memory cell in the transfer blocking register is in one of its two states. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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- 9. A surveillance system comprising a central unit which is connected, by the intermediary of the telephone network, to a plurality of local terminal units for receiving from such terminal units information on changes of status in sensors connected to said terminal units, each terminal unit having an automatic dial-up unit for establishing communication between said terminal unit and said central unit via the telephone network for transmission of said information, wherein each terminal unit includes a register for establishing communication between such terminal unit and said central unit, for the purposes of checking, by energization of said automatic dial-up unit at a point in time determined by data stored in said register, each such terminal unit further including means for entering data into the register determining a new point in time after each establishment of the communication.
Specification