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一、前 言 龙溪河梯级水电站计算机分级控制系统中,计算机间通讯采用了前向纠错措施。传送的信息字为16位,用BCH编码增加15位校验位后发送,在接收端可以纠正3位随机错误。 编码和译码均用软件实现。编码用信息多项式直接除以(模2除法)生成多项式8FAF获得余式形成15位校验位附于信息位之后发送。对于CK—720机编码速度大于每秒3390字,程序占用内存27个单元。纠错译码建议使用比较法。平均译码时间为信息位无错和校验位有0到3位错时为0.74毫秒;信息位一位错和校验位有0到2位错时为2.1毫秒,信息位两位错和校验位有0到1位错时为12.09毫秒;只有信息位三位错时耗时较长为55.65亳秒。程序占用内存153个单元。 本文对[1]介绍的方法进一步作了改进。编码改用软件查表法,将编码速度提高到每秒8000字。译码仿照法尔码纠突发错误的方法改编纠三位错的程序,将信息位三位错的平均译码时间降低到3.63毫秒,译码速度提高了14倍,大大降低了计算机的开销,提高了效率。现分别介绍如下:
First, the foreword Longxi River cascade hydropower station computer grading control system, computer communication used forward error correction measures. The transmitted message word is 16 bits, which is sent after adding 15 bits of the parity bit with the BCH encoding, which can correct 3 random errors at the receiving end. Both coding and decoding are implemented in software. Encoding Information Polynomial Direct Divide by (modulo-2 division) Generate Polynomial 8FAF Get Residual Form 15-bit parity bits are appended to the information bit and sent. For CK-720 machine coding speed is greater than 3390 words per second, the program takes up 27 units of memory. Error correction decoding recommended comparison method. The average decoding time is 0.74 milliseconds for error-free information bits and 0 to 3 bit errors for parity bits; 2.1 ms for information bit errors and parity bits from 0 to 2 bit errors, two bit errors and parity for information bits 12.09 milliseconds for bit 0 to 1 bit error; only 55.65 milliseconds longer for bit 3 bit error. The program occupies 153 units of memory. This paper further improved the method introduced in [1]. Code to use software look-up method, the encoding speed to 8000 words per second. Decoding Errors by False Code Correction Errors The program to correct three dislocations reduces the average decoding time of three bits of information bits to 3.63 ms and the decoding speed by 14 times, greatly reducing the computer overhead , Improve efficiency. Now introduced as follows: