摘要
针对欧标应答器报文编码耗时不确定问题,在分析应答器报文格式和编码算法流程的基础上,从2个重点方向对算法的多个步骤进行优化提升:一是提高计算效率,如通过查表法提高加扰、校验位、汉明距的计算效率;通过一个整型数存储2个11 bit字,从而有效减少移位操作,并且基于此使得有效字检查与移位操作可并行执行;借助整型数实现一次执行获得4 bit的漏取样操作等。二是避免大量无效计算,如调整同步偏离解析条件检查的左右移位执行顺序;通过贪心算法检查连续有效字;并行执行加扰与部分同步偏离解析条件有效字检查;并行执行校验位计算与字母表条件检查等。采用盐通高铁应答器报文进行性能测试,验证基于本编码优化算法的通用CPU代替专用编码单元的可行性,从而降低设备成本,提高系统可靠性。
To address the ancertainty of the encoding time-consuming of the Eurobalise message,the encoding algorithm process is strategically refined on the basis of the analysis on the balise message format and the encoding algorithm process.This involves optimizing and improving multiple algorithm steps in two key areas:On the one hand,enhancing computational efficiency—such as by utilizing look-up tables to improve computational efficiency of scrambling,check bits and Hamming distance,storing two 11-bit words in an integer number to effectively reduce shift operations and enable parallel execution of valid word check and shift operation,and employing integer numbers to achieve 4-bit under-sampling operation in one execution;On the other hand,minimizing invalid calculations—by adjusting the left-right shift execution order of Off-Synch-Parsing condition test,checking consecutive valid words using a greedy algorithm,executing scrambling and partial Off-Synch-Parsing condition test for valid word in parallel,and performing check bit calculations and alphabet condition checks in parallel.Performance testing on the Yancheng-Nantong High-speed Railway's balise message confirms the viability of replacing the special encoding unit with a general CPU based on the optimized algorithm,leading to reduced equipment costs and improved system reliability.
作者
卓鹏
刘江沙
方志刚
ZHUO Peng;LIU Jiangsha;FANG Zhigang
出处
《铁道通信信号》
2024年第8期34-40,共7页
Railway Signalling & Communication
关键词
欧标应答器
报文
编码
查表法
循环冗余校验码
Eurobalise
Telegram
Encoding
Look-up table method
Cyclic Redundancy Check(CRC)
