Practical Implementation AX25 frames plus frame relay header are encoded into RS(255,239) code words, giving an error correction capability of 8 symbo
{"Image DocumentName": "Practical Implementation", "Image ImageDescription": "AX25 frames plus frame relay header are encoded into RS(255,239) code words, giving an error correction capability of 8 symbols. Code words are encapsulated in normal HDLC for transmission on physical layer. Upon receive, HDLC CRC is ignored and the (possibly corrupt) codeword is decoded to an ax25 frame. The scheme I have implemented in Xrouter is basically as follows: Firstly, ordinary AX25 frames are given a 4 byte frame relay header, then encoded into RS(255,239) code words, using 16 bytes of parity to give an error correction capability of 8 symbols. This was deemed to be the optimum compromise between error correction and overhead, given the next bit\u2026 The code words are then encapsulated in normal HDLC for transmission on the physical layer. Upon receive, the HDLC Cyclic Redundancy Check is ignored and the possibly corrupt codeword is decoded back to an ax25 frame, provided the number of errors does not exceed the error correction capacity of the code.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}