Importance

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Abstract

A meter terminal unit, for acquiring information and transmitting the acquired information to a central reading and control unit over utility power transmission lines, includes a transmitter portion for synthesizing and modulating carrier waveforms, the frequencies of which are selectable by command data contained in frequency rotation and address fields of a command received from the central reading and control unit. The meter terminal unit receives and decodes the command and adds, in modulo form, the contents of the frequency rotation field to the contents of a portion of the address field to obtain a resultant sum which uniquely identifies the selected waveform. This sum is used to access a portion of a read only memory (ROM) having the selected waveform stored therein in digital data form. The selected waveform is reconstructed by outputting the digital data from the ROM to a digital to analog converter. The reconstructed carrier waveform is then phase-shift-keyed by the acquired information, which has been placed in digital form, and the resultant modulated carrier is transmitted to the central reading and control unit over the power lines.

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First Claim