基于正弦内插的UM2000信号解码算法  

The UM2000 Signal Decoding Algorithm Based on Sine Interpolation

作　　者：贺广宇[1] 范明[1] 

机构地区：[1]中国铁道科学研究院通信信号研究所,北京100081

出　　处：《中国铁道科学》2010年第5期108-113,共6页China Railway Science

基　　金：科技部科研院所技术开发研究专项资金资助项目(2008EG223199)

摘　　要：UM2000数字轨道电路采用调频方式传输28位码组信息。UM2000信号解码时间按长、短窗设计,解码算法主要由带通滤波、过零检测、滑窗DFT、门限判决和CRC校验组成,其中过零检测解调算法采用正弦内插法对UM2000信号的过零时刻进行计算。影响解码性能的主要因素有信号采样时间、插值算法和正弦内插法使用的采样点数和插值点数。对不同信噪比条件下的仿真信号和测试箱生成信号进行解码测试。仿真信号的测试结果表明:当带内谐波干扰信噪比分别为3,4和5时,1.562 5 s短窗的安全译码率分别为80%,81%和86%,3.125 0 s长窗的安全译码率分别为99%,100%和100%。测试箱生成信号的测试结果表明:1.562 5 s短窗的安全译码率为95.27%,3.125 0 s长窗的安全译码率分别为98.06%,99.91%和98.23%。说明UM2000信号解码算法在满足信号系统实时性要求的条件下,实现了UM2000信号的安全译码。The UM2000 digital track circuit adopts the frequency modulation method to transmit 28 bit code group information.The short and long time windows are designed for demodulating UM2000 signal codes.The decoding algorithm is mainly composed of the bandpass filter,the zero-crossing detection,the sliding window DFT,the threshold decision and the CRC verification.Among which,the zero-crossing detection demodulation algorithm uses the sine interpolation to carry out the computation of the UM2000 signal zero crossing time.The primary factors which influence the decoding performance are the signal sampling time,the interpolation algorithm and the sampling points and the interpolation points used by the sine interpolation.The decoding tests are applied to the test box production signal and the simulation signal with different signal-to-noise ratio.The simulation signal test results show that the short time（1.562 5 s） window′s safe decoding rate is 80%,81%,86% and the long time（3.125 0 s） window′s safe decoding rate is 99%, 100% and 100%,when the signal-to-noise ratio of the in-band harmonic interference is 3,4 and 5 respectively.The test box production signal decoded results show that the safe decoding rate of the short time（1.562 5 s） window is 95.27% and the safe decoding rate of the long time（3.125 0 s） window is 98.06%,99.91% and 98.23%.The test results show that the UM2000 signal decoding algorithm not only can satisfy the request of the real-time feature of the signal system,but also can achieve the safe decoding of the UM2000 signal.

关 键 词：数字轨道电路 UM2000信号 正弦内插法 过零检测 安全译码 

分 类 号：U284.238[交通运输工程—交通信息工程及控制]