Digital data compression method and means
First Claim
1. The method of compressing a digital data stream composed of plaintext symbols comprising the steps ofA. maintaining a code table of plaintext symbols at a transmitting location;
- B. encoding blocks of plaintext symbols in the stream using said code table to produce codes for said blocks;
C. updating said code table according to an update algorithm;
D. transmitting the codes for said blocks plus only plaintext symbols in blocks not previously encoded to a receiving location;
E. maintaining a code table at the receiving location;
F. decoding the transmitted codes for said blocks using the code table at the receiving location to recover plaintext symbols in the data stream; and
G. updating the receiving location code table by applying to the plaintext symbols received from the transmitting location the same update algorithm used at the transmitting location so that the two code tables remain identical whereby the coded symbol blocks in the transmission can be decoded continuously at the receiving location without requiring the separate transmission of codes for said not previously encoded blocks to update the receiving location code table.
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Accused Products
Abstract
A system for compressing digital data maintains a code table of plaintext symbols at a transmitting location. Blocks of plaintext symbols in a message are encoded using the code table which table is updated using an update algorithm. The codes for those blocks are transmitted to a receiving location where a second code table is maintained. At the receiving location, the transmitted symbols are decoded using that second code table. That code table is also updated by applying to the plaintext symbols recovered during the decoding process the same update algorithm used at the transmitting location so that the two code tables are the same at any given point in the transmission.
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Citations
10 Claims
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1. The method of compressing a digital data stream composed of plaintext symbols comprising the steps of
A. maintaining a code table of plaintext symbols at a transmitting location; -
B. encoding blocks of plaintext symbols in the stream using said code table to produce codes for said blocks; C. updating said code table according to an update algorithm; D. transmitting the codes for said blocks plus only plaintext symbols in blocks not previously encoded to a receiving location; E. maintaining a code table at the receiving location; F. decoding the transmitted codes for said blocks using the code table at the receiving location to recover plaintext symbols in the data stream; and G. updating the receiving location code table by applying to the plaintext symbols received from the transmitting location the same update algorithm used at the transmitting location so that the two code tables remain identical whereby the coded symbol blocks in the transmission can be decoded continuously at the receiving location without requiring the separate transmission of codes for said not previously encoded blocks to update the receiving location code table. - View Dependent Claims (2, 3, 4, 5)
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6. A system for compressing a digital data stream composed of plaintext symbols comprising
A. means defining a code table of plaintext symbols at a transmitting location; -
B. means for encoding blocks of plaintext symbols in the stream using said code table to produce codes for said blocks; C. means for updating said table according to an update algorithm; D. means for transmitting the codes for said blocks plus only plaintext symbols in blocks not previously encoded to a receiving location; E. means defining a code table at the receiving location; F. means for decoding the transmitted codes for said blocks using the code table at the receiving location to recover plaintext symbols in the data stream; and G. means for updating the receiving location code table by applying to the plaintext symbols received from the transmitting location the same update algorithm used at the transmitting location so that the two code tables remain identical whereby the coded symbol blocks in the transmission can be decoded continuously at the receiving location without requiring the separate transmission of codes for said not previously encoded blocks to update the receiving location code table. - View Dependent Claims (7, 8, 9, 10)
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Specification