S模式前导脉冲过零点提取与TOA时间戳精确度研究

Zero⁃Crossing Extraction of S⁃mode Preamble Pulse and TOA Timestamp Accuracy

前导脉冲信号到达时间(Time of arrival,TOA)估计精确度直接影响多点定位精确度。在差分匹配滤波器数学模型基础上,分析理想脉冲信号差分匹配滤波器TOA精确度与采样频率的关系。讨论非理想脉冲信号之间的时间结构关系,提出基于S模式前导四脉冲信号构造差分匹配滤波器校准时间戳的改进算法,实现过零点的准确估计。从信噪比、采样频率和复杂度仿真数据输出的均方根误差对比可见,通过四脉冲滤波获得的TOA精确度要比单脉冲和双脉冲滤波获得TOA精确度高。匹配滤波器和差分匹配滤波器TOA精确度对比分析结果表明,修正的差分匹配滤波器算法有更好的效果。在采样频率40 MHz、信噪比为40 dB时,四脉冲信号差分匹配滤波器TOA精确度为0.4027μs,远远小于国际民航组织规定的时间误差精度最大值25μs。最后实际空管运行数据验证结果证明了本文修正算法估算TOA的精确度和可用性。

The positioning accuracy of multilateration will be directly affected by the estimation error of time of arrival(TOA)of the preamble pulse signal.First,on the basis of the mathematical model of the differential matched filter(DMF),the relationship between TOA accuracy and sampling frequency is analyzed.And the time structure relationship between non ideal pulse signals is discussed.Then the modified algorithm is presented,which is used for TOA timestamp marked by zero crossing with four-pulse preamble DMF.The results show that the root mean square error(RMSE)is changed with SNR,sampling frequency,complexity and other parameters,and the TOA accuracy of four-pulse signal detection is higher than that of single pulse and dual-pulse signal detection.Moreover,the TOA accuracy of matched filter and DMF are compared,and results show that the DMF algorithm is more effective.When the sampling frequency is 40 MHz the SNR is 40 dB,the TOA accuracy of the four-pulse signal DMF is 0.4027μs,which is far less than the maximum time error accuracy of 25μs specified by International Civil Aviation Organization(ICAO).Finally,the real operation data are used to verify the accuracy improvement of TOA estimation and the availability of the algorithm.