Microcom Systems, Inc.

Microcom Corporation

Nathan R Melhorn

Craig A Richards

Gregory Pearson

Paul Friedman

Michael F Onarato

Anthony P Amundson

A multi-mode modem and a method of transmitting data utilizing the multi-mode modem are disclosed in which different modes of operation may be automatically selected by sending multiple link requests to a receiving modem in order to provide either optimized or non-optimized data transmission according to line conditions.

Multi-mode modem and data transmission method

Method and apparatus are disclosed for a data communications system in which data packets are transmitted between two data terminal units wherein idle packets are transmitted whenever there is no data packet to send and such idle packets are utilized for detecting transmission errors in order to optimize data transmission efficiency by continually increasing, decreasing or leaving unchanged the size of data packets as a function of transmission errors.

Method and apparatus for effecting efficient transmission of data

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 compresing 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.

Data telecommunications system and method for transmitting compressed

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.

Disclosed is a data telecommunications system and method in which at least one modem which, capable of operating at a variety of transmission speeds, selects the proper speed at which to operate. An initiating modem capable of operating at a plurality of operating speeds compares the maximum operating speed of a receiving modem, and if a match is found, operation begins at that operating speed. If no match is found, operation begins at a default transmission speed.

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Framingham, MA, United States of America

Nathan R Melhorn