Boots – shoes – and leggings
Patent
1980-06-02
1983-05-31
Zache, Raulfe B.
Boots, shoes, and leggings
G06F 500
Patent
active
043864163
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates generally to data compression systems, and more specifically relates to a telecommunication system for compressing text or similar data, encrypting the compressed data, if desired, transmitting the compressed data to a remote station using a conventional telecommunications network, and for receiving, decrypting, and decompressing data transmitted from a remote station. The sytem may be used to compress data prior to storage and decompress the data after storage. This invention further relates to a unique data compression apparatus and method particularly suited for use in telecommunication systems.
DESCRIPTION OF THE PRIOR ART
Text data is normally transmitted using a fixed length binary code to represent each character. ASCII is a typical, standardized seven bit code for representing alphanumeric data of the type used to compile text messages. A typical English language word of five characters would thus require thirty-five bits. Common telecommunications systems such as "Telex" and "TWX" send the bits serially at a relatively slow rate by modern data processing standards. The cost of sending a message is directly related to the on-line time required for the message, so that a reduction in the length of a message results in a direct reduction in cost. Substantial efforts have been made to increase the speed of operation of data transmission systems to increase the number of bits of data transmitted in a given time interval. However, a vast amount of equipment having relatively low rates of data transmission is presently in place and cannot be easily ungraded. Color television can be digitally transmitted using a twentyfour bit code for each color pixel, but the bandwidth required to transmit this volume of information in real-time is very substantial. There are also many instances where large volumes of data are to be stored, and a reduction in the number of bits provides valuable data compression.
An alternative approach to increasing the rate at which data is transmitted over the network is to decrease the amount of data to be transmitted by more efficient coding techniques, thus effectively reducing the time of transmission or the bandwidth. It is generally recognized that data compression can be achieved by using variable length coding where the most commonly used characters are represented by a code having the mimimum bit length. This type of code is commonly referred to as a "Huffman" code, and several techniques of this type are disclosed in U.S. Pat. No. 3,694,813 entitled "Method of Achieving Data Compaction Utilizing Variable Length Dependent Coding Techniques", issued Sept. 26, 1972, to Lewis S. Loh, et al.
Message security is a recognized problem in the art and the United States National Bureau of Standards has developed a system for encrypting data to achieve such security. The encryption system has been implemented by a set of large scale integrated circuits which are presently commercially available.
SUMMARY AND OBJECTS OF THE INVENTION
The present invention is concerned with methods and apparatus which can be used in existing data handling systems to compress a data stream comprised of binary bits arranged into units of a set where the number of units in the set is very large. For example, if the words of the English language are the data units, there are approximately 65,000 words or units in common usage. Each word is comprised of one or more alphabetical characters, each of which is customarily represented by a binary code comprised of a predetermined number of binary bits, typically seven. The number of characters in each word-unit varies from one, or more by definition, to twenty or thirty. English language words can also be broken into common components referred to as prefixes, infixes, radixes, suffixes, etc., each of which can be defined as "word/units" to achieve very significant compression, in accordance with the present invention. A frequency of use analysis would reveal that a relatively small proportion of the words are use
REFERENCES:
patent: 3535696 (1970-10-01), Webb
patent: 3694813 (1972-09-01), Loh et al.
patent: 4021782 (1977-05-01), Hoerning
Fiest Robert R.
Giltner Michael E.
Mueller Jack C.
Mostek Corporation
Zache Raulfe B.
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