问题2： 要发现收到的报文中的错误，最 straight forward的方法是什么？ Example 2.Even parity, Using even parity,the codes for A,B,and C now become A=010000012, B=010000102, C=110000112 Suppose an A is sent and a transmission error in the sixth bit is caused by noise over the communication channel so that (0100 0101)is received
问题2： 要发现收到的报文中的错误，最 “straight forward”的方法是什么？ Received Word 000 001 010011 100 101 110 111 Transmitted 000 0 1 1 2 1 2 2 3 Codeword 111 3 2 1 2 1 1 0 Table 8.1.A repetition code Example 3.Suppose that our original message is either a 0 or a 1,and that 0 encodes to (000)and 1 encodes to (111).If only a single error occurs during transmission,we can detect and correct the error
问题2： 要发现甚至纠正收到的报文中的错误， 最“straight forward的方法是什么？ 无论是发现，甚至在某种假设下发现及纠正错误，总有 冗余 的存在，必须的吗？
冗余 无论是发现，甚至在某种假设下发现及纠正错误，总有 的存在，必须的吗？
问题3： 我们必须考虑物理信道会出错，但又假设 出错“不多”，这是为什么？ We will also assume that a received n-tuple is decoded into a codeword that is closest to it;that is,we assume that the receiver uses maximum-likelihood decoding
阿题48 一个“貔码方案”究凳 是什么？