基于参数特征映射的多站时差测量实现

Realization of multi-station time difference measurement based on parameter characteristics mapping

在现代定位系统中,传统的时差测量方法往往受限于信号调制方式、噪声干扰以及硬件实现复杂度等因素,难以保持高精度和实时性。针对上述问题,本文设计一种基于参数特征映射的多站时差定位系统中时差测量方法,由主站检测并产生参考信号,广播至各从站;各站根据此参考信号基于频域互相关算法完成时差测量。该方法有效提高二进制相移键控(binary phase shift keying,BPSK)信号、四相相移键控(quadrature phase shift keying,QPSK)信号、频移-相移复合调制(frequency shift keying-phase shift keying,FSK-PSK)信号等时差测量精度。本文给出了基于现场可编程逻辑门阵列(field programmable gate array,FPGA)时差测量方法的硬件实现,采用实时动态压缩方法,FPGA算法实现资源减少50%;采用抛物线拟合方法,提高时差估计精度;采用基于参数特征映射的数据传输方法,保障多站数据的完备、避免数据缺失和冗余的同时,数据传输量降低95%。仿真与试验测试结果表明,信噪比(signal-to-noise ratio,SNR)大于等于5 dB时,PSK调制信号时差测量精度优于5 ns;对于前沿缓变调制信号,随着脉冲上升沿宽度增大,时差测量精度无明显变化;最后,在外场试验与飞行试验结果中验证方法的有效性与可行性,为高精度多站时差定位系统的实际应用提供了有力支持。

In modern positioning system,traditional time difference measurement methods are often constrained by factors such as signal modulation types,noise interference,and the complexity of hardware implementation,making it difficult to maintain high accuracy and real-time performance.To address these issues,this paper presents a time difference measurement method for multi-station positioning systems based on parameter characteristic mapping.In this approach,the master station detects and generates a reference signal,which is then broadcasted to each substation.Based on this reference signal,each station completes the time difference measurement using frequency domain cross-correlation algorithm.This method effectively improves the accuracy of time difference measurement,such as binary phase shift keying(BPSK)signals,quadrature phase shift keying(QPSK)signals and frequency shift keying-phase shift keying(FSK-PSK)hybrid modulation signals.This paper presents the hardware implementation of the time difference measurement method based on field programmable gate array(FPGA).Real-time dynamic compression method is adopted to reduce FPGA algorithm resources by 50%.Parabolic fitting method is used to improve the accuracy of time difference measurement.Data transmission method based on parameter feature mapping is employed to ensure the completeness of data from multiple stations,avoid data loss and redundancy,while reducing the amount of data transmission by 95%.Simulation and experimental test results show that when signal-to-noise ratio(SNR)is equal to or more than 5 dB,the time difference measurement accuracy for PSK modulation signals is better than 5 ns.For edge-transition modulation signals,the accuracy of time difference measurement remains relatively unchanged as the pulse rising edge width increases.Finally,the effectiveness and feasibility of the method are validated in field tests and flight experiments,providing strong support for the practical application of high-precision multi-station time difference positioning system.