Encore’s V.42 module implements ITU-T V.42 error correction protocol for use with V-series data pump to accept asynchronous data from DTE’s and transmits in synchronous mode. This works on the principle of error detection and retransmission.

• This implements an HDLC based protocol referred to as the Link Access Procedure for Modems (LAPM).
• Error detection through the use of a cyclic redundancy check.
• Error correction through the use of automatic retransmission of data.
• synchronous transmission through the conversion of start-stop data to HDLC frames.
• An initial handshake in start-stop format which minimizes disruption to the DTEs.

Encore’s V.42bis module implements ITU-T V.42bis data compression protocol, which is used above V.42 error correction procedures and providing improved error performance.

• Improved throughput through the use of data compression procedures.
• Compression procedure based on an algorithm which encodes strings of characters.
• Decoding procedure which recovers the strings of characters from received codewords.
• An automatic transparent mode of operation when uncompressible data is detected.
• Currently V.42/V.42bis protocol implementation is available on TI’s TMS320C64x, TMS320C62x, TMS320C54x and Microchip’s dsPIC and ARM9 platforms.

V.42 and V.42bis Product Brief - Download PDF

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