Modem with data compression selected constellation
First Claim
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1. A transmitter/modulator, comprising in combination:
- transmitting means for transmitting information over a transmission line, said information being represented by points in one of a plurality of selectable constellations, each said selectable constellation having a different number of points;
comprissing means for compressing information to be transmitted by said transmitting means; and
selecting means, responsive to said compressing means, for selecting one of said plurality of constellations based upon a level of compression obtained by said compressing means.
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Abstract
A data modem includes a data compression circuit which compresses incoming data prior to transmission. The compression ratio obtained from the compression process is used to select a constellation for transmission of the data. When higher compression rates are achieved, fewer constellation points (symbols) representing fewer bits per point are transmitted. In this manner, incoming data rate can be held constant while utilizing a more robust constellation which has greater immunity to transmission line impairments. This reduces errors and retransmissions which can ultimately lead to reduction in effective throughput in conventional systems.
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Citations
18 Claims
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1. A transmitter/modulator, comprising in combination:
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transmitting means for transmitting information over a transmission line, said information being represented by points in one of a plurality of selectable constellations, each said selectable constellation having a different number of points; comprissing means for compressing information to be transmitted by said transmitting means; and selecting means, responsive to said compressing means, for selecting one of said plurality of constellations based upon a level of compression obtained by said compressing means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of enhancing the error performance of a data transmitter/modulator, comprising the steps of:
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receiving data to be transmitted by said modem; compressing said data; determining whether said data is being compressed at a compression level greater than a predetermined threshold; and changing a constellation used for transmission to a constellation having fewer points in the event said compression level exceeds said predetermined threshold. - View Dependent Claims (11, 12)
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13. In a data transmitter/modulatr, a method of selecting between a plurality of transmission modes, comprising the steps of:
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receiving data to be transmitted by said transmitter/modulator, said transmitter/modulator being capable of tramsmitting said data at a predetermined data rate; compressing said data; determining a compression level obtained in said compressing step; and selecting a transmission mode which utilizes the bandwidth made available by said compressing step to enhance the error performance while maintaining a data throughput which is at least as great as said predetermined data rate. - View Dependent Claims (14, 15)
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16. A method of enhacing the error performance of a transmiter/modulator, comprising the steps of:
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freeing bandwidth by compressing information to be transmitted by said transmitter/modulator; and utilizing said free bandwidth to enhance the reliability of transmission by said transmitter/modulator by utilizing a more reliable transmission method, said transmission method being selected depending upon the degree of compression obtained. - View Dependent Claims (17)
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18. A receiver/demodulator, comprising in combination:
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receiving means for receiving a plurality of synchronous transmitted data symbols, said transmitted data symbols each being part of one of a plurality of constellations of symbols; a slicer for determining which of said transmitted data symbols from a particular one of said plurality of constellations are received; detecting means for detecting and embedded constellation change symbol within said plurality of transmitted data symbols; control means responsive to said detecting means for modifying operation of said slicer so that received data symbols are sliced according to a different one of said plurality of constellations; decoding means for decoding each of said data symbols into compressed data symbols; and adaptive data expanding means for expanding said compressed data symbols.
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Specification