High speed communications system for analog subscriber connections
DCFirst Claim
1. A high speed data transfer encoder that generates digital signals for transmission over a digital telephone network and an analog loop to a subscriber, comprising:
- a converter that converts a source data stream into a sequence of codewords selected from a predetermined set of codewords corresponding to quantization values utilized by said telephone network, said converter comprising a serial to parallel converter and a compensator coupled to said serial to parallel converter; and
an interface to the digital telephone network, said interface being coupled to the compensator.
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Abstract
A new data communication system is described which enables data transmission over existing telephone lines at rates higher than possible with existing methods, including conventional modems. By using a novel asymmetric configuration of the two communication endpoints, the currently-accepted maximum theoretical limits on the data rate are no longer applicable. One endpoint is connected directly to a digital telephone network, whereas the other endpoint uses a conventional telephone connection. This reduces the transmission problem to compensation for a single telephone line interface and a single analog local loop. Means of providing this compensation and the required clock synchronization were also created, enabling a practical implementation of the system. The new system can achieve rates up to 64,000 bits-per-second and has broad utility in several active areas including wide-band audio transmission, video transmission, networking, facsimile transmission, and remote computer access.
120 Citations
35 Claims
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1. A high speed data transfer encoder that generates digital signals for transmission over a digital telephone network and an analog loop to a subscriber, comprising:
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a converter that converts a source data stream into a sequence of codewords selected from a predetermined set of codewords corresponding to quantization values utilized by said telephone network, said converter comprising a serial to parallel converter and a compensator coupled to said serial to parallel converter; and an interface to the digital telephone network, said interface being coupled to the compensator. - View Dependent Claims (2, 3)
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4. A high speed data transfer encoder that generates digital signals for transmission over a digital telephone network and an analog loop to a subscriber, comprising:
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a converter for converting a source data stream into a sequence of codewords selected from a predetermined set of codewords, wherein said predetermined set of codewords comprises a subset of digital telephone network codewords, said digital telephone network codewords corresponding to a set of quantization values applied in a line interface which couples said digital telephone network to said analog loop; and an interface to the digital telephone network, said interface being coupled to said converter. - View Dependent Claims (5, 6)
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7. A high speed data transfer encoder as claimed 4, wherein said digital telephone network codewords comprise A-law encoded codewords.
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8. A high speed data transfer encoder that generates digital signals for transmission over a digital telephone network and an analog loop to a subscriber, comprising:
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a converter that converts a source data stream into a sequence of codewords selected from a predetermined set of codewords, wherein said predetermined set of codewords is determined based upon a transfer characteristic of said analog loop and corresponding to quantization values utilized by said telephone network; and an interface to the digital telephone network, said interface being coupled to said converter. - View Dependent Claims (9, 10, 11, 12)
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13. A high speed data transfer encoder for producing a sequence of digital codewords for transmission, over a digital connection to a digital telephone network and a single analog loop, to a subscriber, comprising:
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a converter having an input and an output, said input being coupled to receive a digital data stream; and an interface coupled between the output of said converter and said digital telephone network; wherein said encoder produces said sequence of digital codewords in response to receiving said digital data stream and each of said codewords is associated with a predetermined quantizing level utilized by said digital telephone network. - View Dependent Claims (14, 15, 16)
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17. A high speed data transfer encoder for generating a plurality of digital signals for transmission over a digital telephone network to a plurality of analog subscribers, comprising:
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means for converting at least two source data streams into at least two corresponding sequences of codewords selected from a predetermined set of codewords corresponding to quantization values utilized by said telephone network; a server connection coupling said converting means to said digital telephone network; and a compensator coupled between said converting means and said server connection. - View Dependent Claims (18, 19, 20)
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21. A high speed data transfer encoder for generating a plurality of digital signals for transmission over a digital telephone network to a plurality of analog subscribers, comprising:
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means for converting at least two source data streams into at least two corresponding sequences of codewords selected from a predetermined set of codewords, wherein said predetermined set of codewords comprises a subset of digital telephone network codewords, said digital telephone network codewords corresponding to a set of quantization values applied in a line interface which couples said digital telephone network to said analog subscribers; and a server connection coupling said converting means to said digital telephone network.
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22. A high speed data transfer encoding method for communicating from a data source to a subscriber, wherein said subscriber is connected to a digital telephone network by an analog loop and said data source is connected through a digital connection to said digital telephone network, said method comprising the steps of:
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selecting a subset of digital codewords from a set of digital telephone network codewords, said digital telephone network codewords corresponding to a set of quantization values applied at a line interface which couples said digital telephone network to said analog loop; converting a data stream produced by said data source into a sequence of digital codewords from said subset of digital codewords; sampling said sequence of digital codewords at a predetermined rate; and transmitting said samples through said digital connection to said digital telephone network. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A high speed data transfer encoder for communicating digital data to a recipient coupled to a digital telephone network by an analog subscriber line, comprising:
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a converter for receiving said digital data and for converting said digital data into a sequence of codewords selected from a set of codewords associated with a digital-to-analog converter located at an interface between said digital telephone network and said analog subscriber line and corresponding to quantization values utilized by said telephone network; a DC eliminator coupled to said converter, said DC eliminator comprising a two-input selector having an output, wherein a first input to said two-input selector is coupled to said converter and a second input to said two-input selector is coupled to said output by a summer; and an interface for digitally coupling the output of the two-input selector to said digital telephone network.
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Specification