Tamper protection for an automatic remote meter reading unit
First Claim
1. A tamper protection arrangement for a remote meter reading unit, the arrangement comprising:
- an encoder (302) at a remote location for receiving an output signal of an associated meter (300), the output signal of the meter reflecting the usage of a specific unit quantity and the encoder changing the output signal of the meter into a form suitable for sending over a transmission line (370);
a decoder (350) connected to the transmission line for receiving the output signal from the encoder section CHARACTERIZED IN THATthe encoder includes clocking means (300, 330,
340) for providing a control signal consisting of clock pulses of a first time period, a second time period, or a third time period over the transmission line; and
the decoder includes a first detector (389-394) responsive to clock pulses of the second time period, and a second detector (380-385) responsive to pulses of the third time period, pulses with the second time period being reflective of the usage of a specific unit quantity measured by the meter, and pulses with the third time period being reflective of a tamper to the meter reading unit.
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Accused Products
Abstract
In a remote meter reading system, a tamper protection circuit provides a warning at a central station upon the disconnecting or tampering with a remote utility meter. Tamper protection is provided for the meter and for the transmission line carrying energy usage information to a transponder (500) such that any interruption of the circuit path causes an alarm to be generated. The circuitry includes an encoder (302) associated with each remote meter (300) to be protected and a centrally located decoder (350) for receiving the signal transmitted by the encoder. When usage information is not being transmitted, the encoder is considered to be in a quiescent state providing a pulsed carrier signal to the decoder. For the transmission of usage information, the encoder modifies the pulsed carrier signal by causing a single pulse of a greater period to be superimposed on the carrier and transmitted therewith over the line to the decoder. Any interruptions of the circuit path which could be caused by disconnecting the meter or tampering with the line connected thereto will interrupt the pulsed carrier signal and cause pulses corresponding to the interruptions to be placed on the line. Each of these pulses has a period longer than the usage information pulse and is sensed by a detector (380-385) in the decoder. This detector responds to each of these pulses by causing an alarm signal to be transmitted over a communications link to the central station.
60 Citations
9 Claims
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1. A tamper protection arrangement for a remote meter reading unit, the arrangement comprising:
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an encoder (302) at a remote location for receiving an output signal of an associated meter (300), the output signal of the meter reflecting the usage of a specific unit quantity and the encoder changing the output signal of the meter into a form suitable for sending over a transmission line (370); a decoder (350) connected to the transmission line for receiving the output signal from the encoder section CHARACTERIZED IN THAT the encoder includes clocking means (300, 330,
340) for providing a control signal consisting of clock pulses of a first time period, a second time period, or a third time period over the transmission line; andthe decoder includes a first detector (389-394) responsive to clock pulses of the second time period, and a second detector (380-385) responsive to pulses of the third time period, pulses with the second time period being reflective of the usage of a specific unit quantity measured by the meter, and pulses with the third time period being reflective of a tamper to the meter reading unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification