US4700175A
Expired / Lapsed
US
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Data communication with modified Huffman coding
Assignee: Racal Data Communications Inc
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Filing: 1986-10-23
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Granted: 1987-10-13
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Expires: 2006-10-23
Abstract
Abstract A method and apparatus for compression of data includes first encoding data characters according to a relative frequency of use table for each character to produce a frequency code. This frequency code is then compressed using a modified Huffman code. The code is modified by restricting the maximum word length to a predetermined number of bits. Different types of text can be encoded according to different frequency of use tables to maximize compression efficiency for various types of source data with minimum data processing.
Inventors
- 👤 Robert E. Bledsoe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:28
CPC Classifications
H; H03; H03M; H03M7/00; H03M7/30; H03M7/40; H03M7/42; G; G06; G06T; G06T9/00; G06T9/005
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
68 words
A method of encoding data characters, comprising the steps of: sorting said data characters according to approximate frequency of occurrence to produce a first frequency table; artificially altering the frequency of occurrence of one of the least frequently used data characters, thereby creating a modified frequency table; and Huffman encoding said data according to said modified frequency table to produce a modified Huffman encoding of said data characters.
Claim 2
Independent Claim
68 words
A method of encoding data characters, comprising the steps of: sorting said data characters according to approximate frequency of occurrence to produce a first frequency table; artificially altering the frequency of occurrence of one of the least frequently used data characters, thereby creating a modified frequency table; and Huffman encoding said data according to said modified frequency table to produce a modified Huffman encoding of said data characters.
Claim 3
Dependent Claim
29 words
The method of claim 1, wherein said Huffman encoding step includes the step of encoding each of said characters with a code word having a predetermined maximum word length.
References Cited (Backward Citations)
US3694813A
Cited
US4386416A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-10-12 | 1991-04-13 | 1991-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-10-12 | 1995-04-13 | 1995-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-10-12 | 1999-04-13 | 1999-10-13 | $7700.00 | Window Closed / Lapsed |