Data telecommunications system and method for transmitting compressed data
US4748638A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 30, 1985 |
| Grant date | May 31, 1988 |
| Priority date | — |
| Expiry date | Oct 30, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M7/42
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Disclosed is a data compressing modem for connection to a decompressing modem over communication lines. The compressing modem receives an input data stream, and each character in the data stream is recodified with a compressed character code, the length of which is dependent on the frequency of the character in the data stream. A frequency table is maintained so that changes in the relative frequency of characters in the data stream will be recognized by the compressing modem and the compressed character codes representing such characters will be exchanged accordingly. A decompressing modem, which is connected over communication lines to the compressing modem, processes the compressed character code in a reverse order from the manner in which the compressing modem processing the codes. The decompressing modem also maintains a relative frequency table and as the relative frequencies of the various characters change, the actual characters represented by the compression codes must also change.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.