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Semi-static data compression/expansion method

  • US 5,323,155 A
  • Filed: 12/04/1992
  • Issued: 06/21/1994
  • Est. Priority Date: 12/04/1992
  • Status: Expired due to Fees
First Claim
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1. A method of transmitting compressed data using a well-known Ziv-Lempel (ZL) compression/expansion algorithm, comprising the steps of:

  • inputting a sequence of records containing characters of data to an adaptive Ziv-Lemel (AZL) process at a transmitting location for compressing the data including;

    generating an AZL dictionary in computer storage by inserting an entry therein at an assigned index for each inputted character string not found in the dictionary, detecting indicies in the dictionary for the inputted character strings in the sequence of records to represent compressed records; and

    transmitting the compressed records to a receiving location;

    generating a corresponding AZL dictionary at the receiving location from received indices of the transmitted compressed records;

    freezing the AZL dictionary to maintain its current content at the transmitting location to provide an SZL (static Ziv-Lempel) dictionary when the AZL dictionary has been generated to a mature state to enable SZL processing; and

    sending a switch-over signal by the transmitting location to the receiving location to indicate a synchronization point in the sequence of transmitted compressed records to enable the receiving location to freeze the corresponding AZL dictionary with an identical current content for enabling an SZL process to expand data by statically using the current content following the synchronization point in the transmitted compressed records.

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