Method and apparatus for multiple frequency transmission of information in a digital communication system
First Claim
1. In an apparatus for for transmitting information, in the form of a modulated carrier frequency, through a communications medium in response to a received command, a method of minimizing errors in said information attributable to said communications medium, said method comprising the steps of:
- a. providing means for transmitting said information using any one of at least two different selectable carrier frequencies;
b. transmitting said information at a first carrier frequency, selectable by a portion of a first received command;
thenc. transmitting said information using at least one other carrier frequency;
selectable by a portion of at least one additional received command.
1 Assignment
0 Petitions
Accused Products
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.
42 Citations
21 Claims
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1. In an apparatus for for transmitting information, in the form of a modulated carrier frequency, through a communications medium in response to a received command, a method of minimizing errors in said information attributable to said communications medium, said method comprising the steps of:
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a. providing means for transmitting said information using any one of at least two different selectable carrier frequencies; b. transmitting said information at a first carrier frequency, selectable by a portion of a first received command;
thenc. transmitting said information using at least one other carrier frequency;
selectable by a portion of at least one additional received command. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for transmitting information in the form of a modulated carrier frequency in response to a received command, said apparatus comprising:
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a. means for transmitting said information using any one of at least two different selectable carrier frequencies; b. means for receiving a command having at least an address field portion and a frequency rotation field portion; and c. decode means responsive to said received command for effecting the transmission of said modulated carrier at one of said carrier frequencies selected by command data contained in said address and frequency rotation fields of said received command. - View Dependent Claims (8, 9)
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10. A remote automatic utility monitoring and control system including a terminal unit connected to a power line, said terminal unit comprising:
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a. means for transmitting information in the form of a modulated carrier having a selectable one of at least two different frequencies; b. means for receiving a command having at least an address field portion and a frequency rotation field portion; and c. decode means responsive to said received command for effecting the transmission of said modulated carrier at one of said carrier frequencies, selected by command data contained in said address and frequency rotation field portions of said received command. - View Dependent Claims (11, 12)
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13. A remote automatic utility monitoring and control system including a group of terminal units connected to a power distribution network, said group including at least two terminal units, each terminal unit comprising:
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a. means for transmitting information in the form of a modulated carrier having a selectable one of an assigned nominal carrier frequency which is different from the nominal carrier frequencies assigned to the other terminal units comprising said group and at least one additional carrier frequency which is different from said assigned nominal carrier frequency, the number of said additional carrier frequencies being equal to the number of said terminal units comprising said group, minus 1; and
each of said additional carrier frequencies being equal to a different one of the nominal carrier frequencies assigned to the other terminal units comprising said groups;b. means for receiving a command having at least an address field portion and a frequency rotation field portion; and c. decode means responsive to said received commands for effecting the transmission of said modulated carrier at one of said carrier frequencies selected by command data contained in said address and frequency rotation field portions of said received command. - View Dependent Claims (14, 15)
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16. In a remote automatic utility monitoring and control system including a remote terminal unit for acquiring information and transmitting said acquired information, in the form of a modulated carrier frequency, to a central reading and control unit over a power distribution network, in response to a command from said control unit, a method of minimizing errors in said information attributable to said power distribution network, said method comprising the steps of:
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a. providing means for transmitting said information using any one of at least two different selectable carrier frequencies; b. transmitting said information at a first carrier frequency, selectable by a portion of a first received command;
thenc. transmitting said information using at least one other carrier frequency, selectable by a portion of at least one additional received command. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification