EP0155980A2
Expired / Lapsed
EP
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Digital data compression method and means
Assignee: CTI Partners
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Filing: 1984-06-19
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Granted: —
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Expires: 2004-06-19
Abstract
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.
Inventors
- 👤 David Chung
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 00:21
CPC Classifications
H; H03; H03M; H03M7/00; H03M7/30
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
115 words
The method of compressing digital data comprising the steps of A. maintaining a code table of plaintext symbols at a transmitting location; B. encoding blocks of plaintext symbols in a message using said code table; C. updating said code table according to an update algorithm; D. transmitting the codes for said blocks to a receiving location; E. maintaining a code table at the receiving location; F. decoding the transmitted symbols using the code table at the receiving location; and G. updating the receiving location code table by applying to the plaintext symbols recovered during the decoding process the same update algorithm used at the transmitting location so that the two two code tables remain identical.
Claim 2
Independent Claim
115 words
The method of compressing digital data comprising the steps of A. maintaining a code table of plaintext symbols at a transmitting location; B. encoding blocks of plaintext symbols in a message using said code table; C. updating said code table according to an update algorithm; D. transmitting the codes for said blocks to a receiving location; E. maintaining a code table at the receiving location; F. decoding the transmitted symbols using the code table at the receiving location; and G. updating the receiving location code table by applying to the plaintext symbols recovered during the decoding process the same update algorithm used at the transmitting location so that the two two code tables remain identical.
Claim 3
Dependent Claim
28 words
The method defined in claim 1 wherein the updating of the code tables accounts for the frequencies of occurrence of the various plaintext symbol blocks in the message.
Claim 4
Dependent Claim
38 words
The method defined in claim 1 wherein the maintaining of each code table is accomplished by storing said plaintext symbol blocks in a memory whose memory locations are defined by code numbers and plaintext symbols in the message.
Claim 5
Dependent Claim
126 words
The method defined in claim 3 wherein the transmitting step is controlled so that A. if a symbol in the message is transmitted in plaintext, the next block of symbols is transmitted in code if that block is found in a memory location whose address comprises that symbol; otherwise the next symbol in the message is sent in plaintext; B. if a symbol is the last symbol in a block transmitted in code, the next block is transmitted in code if it is found in a memory location adressed by that symbol; otherwise the next symbol is sent in plaintext; and C.' if a symbol is in a block transmitted in code but it is not the last symbol in a block, no action is taken.
Claim 6
Dependent Claim
26 words
The method defined in claim 1 and including the additional step of identically preloading both code tables with plaintext symbols prior to commencement of the transmission.
Claim 7
Independent Claim
120 words
A system for compressing digital data comprising A. means defining a code table of plaintext symbols at a transmitting location; B. means for encoding blocks of plaintext symbols in a message using said code table; C. means for updating said table according to an update algorithm; D. means for transmitting the codes for said blocks to a receiving location; E. means defining a code table at the receiving location; F. means for decoding the transmitted symbols using the code table at the receiving location; and G. means for updating the receiving location code table by applying to the plaintext symbols recovered during decoding the same update algorithm used at the transmitting location so that the two code tables remain identical.
Claim 8
Independent Claim
120 words
A system for compressing digital data comprising A. means defining a code table of plaintext symbols at a transmitting location; B. means for encoding blocks of plaintext symbols in a message using said code table; C. means for updating said table according to an update algorithm; D. means for transmitting the codes for said blocks to a receiving location; E. means defining a code table at the receiving location; F. means for decoding the transmitted symbols using the code table at the receiving location; and G. means for updating the receiving location code table by applying to the plaintext symbols recovered during decoding the same update algorithm used at the transmitting location so that the two code tables remain identical.
Claim 9
Dependent Claim
31 words
The system defined in claim 6 wherein the updating means include means for controlling the updating so that the code tables always contain the more commonly occurring blocks in the message.
Claim 10
Dependent Claim
23 words
The system defined in claim 6 wherein both said code -tables have identical plaintext symbol contents prior to the beginning of the transmission.
Claim 11
Dependent Claim
25 words
The system defined in claim 6 wherein the code table defining means comprises a memory addressed by code numbers and plaintext symbols in the message.
Claim 12
Dependent Claim
131 words
The system defined in claim 9 wherein the transmitting means transmit said codes in accordance with the following algorithm: A. if a symbol in the message is transmitted in plaintext, the next block of symbols is transmitted in code if that block is found in a memory location whose address comprises that symbol; otherwise the next symbol in the message is sent in plaintext; B. if a symbol is the last symbol in a block transmitted in code, the next block is transmitted in code if it is found in a memory location adressed by that symbol; otherwise the next symbol is sent in plaintext; and C. if a symbol is in a block transmitted in code but it is not the last symbol in a block, no action is taken.
References Cited (Backward Citations)
No citation records indexed.
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