The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 08, 1988
Filed:
Sep. 19, 1986
John E MacCrisken, Palo Alto, CA (US);
Adaptive Computer Technologies, Santa Clara, CA (US);
Abstract
A data compression system for increasing the speed of data transmission system over a communication channel with a predefined data transmission rate. The system has two data compression units--one on each end of the channel, coupled to first and second data processing systems. Input data from either data processing system is encoded using a selected one of a plurality of encoding tables, each of which defines a method of encoding data using codes whose length varies inversely with the frequency of units of data in a predefined set of data. Whenever an analysis of the encoded data indicates that the data is not being efficiently compressed, the system invokes a table changer for selecting from among the encoding tables the one which minimizes the bit length of the encoded data for a preselected sample of the input data. If a new table is selected, a table change code which corresponds to the selected table is added to the encoded data. Also, a dynamic table builder builds a new encoding table to be including in the set of available encoding tables using a preselected portion of the previously encoded input data which an analysis of the encoded data indicates that a new encoding table will enhance compression. Each data compression unit includes a data decoder for decoding encoded data sent over the channel by the other unit. Thus the data decoder uses a set of decoding tables corresponding to the encoding tables, means for selecting a new table when a table change code is received, and means for building a new decoding table when it receives a table change code which indicates that the encoded data following the table change code was encoded using a new encoding table.