Forward link text compression in satellite messaging
AssigneeTranscore Link Logistics Corporation
InventorHans Haugli
Life of this patent
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Abstract
A method of transmitting communication information employing a coding scheme being defined by a character set is disclosed. The characters of the character set are encoded into codewords of a sequence of bits, the codewords being of varying length. The characters are divided into at least two categories. The categories may be a first category of shifted characters and a second category of unshifted characters. Where a shifted character is encountered during encoding a shift codeword is inserted in the sequence of bits. This allows each category to use overlapping codewords. Then the sequence is converted to ASCII characters to be transmitted.
Claims25
A method of transmitting information represented by characters of a defined character set over a communications channel, comprising the steps of:
- dividing said character set into subsets;
- encoding the characters in each subset with codewords of varying length dependent on the probability of occurrence of the encoded character, said subsets employing overlapping codewords, and each codeword within each said subset comprising a unique sequence of bits;
- and
- transmitting a unique indicator to identify a said subset to which transmitted characters belong.
A method of compressing textual data defined by characters forming part of a character set, wherein the characters are encoded by binary codewords of variable length, comprising the steps of:
- dividing said character set into subsets;
- encoding the characters in each subset with codewords of varying length dependent on the probability of occurrence of the encoded character, said subsets employing overlapping codewords, and each codeword within each said subset comprising a unique sequence of bits;
- and
- inserting a unique indicator in the compressed data to identify the subset to which said encoded characters belong.
An apparatus for compressing textual data defined by characters forming part of a character set, wherein the characters are encoded by binary codewords of variable length, comprising:
- an input device for receiving said characters;
- an output device for outputting compressed data;
- and
- a processor for encoding the characters in each subset with codewords of varying length dependent on the probability of occurrence of the encoded character, said subsets employing overlapping codewords, each codeword within each said subset comprising a unique sequence of bits, and inserting a unique indicator in the compressed data to identify the subset to which said encoded characters belong.
Dependencies are inferred from the claim text.