一种应用于无线时间同步系统的捕获算法

An acquisition algorithm applied to the wireless time synchronization system

无线收发模块是集成在高精度双向无线时间同步系统中的关键单元,它具有发射无线时间同步信号、接收信号并捕获的功能。传统的导航信号,数据码首先与伪码异或相加而实现扩频,然后两者的组合码通过调制依附在载波上。该设计方式长相干积分受数据位跳变的影响,从而降低捕获和跟踪的灵敏度,同时增加了计算量,不适用于高灵敏度的无线收发模块。在无线双向时间同步系统收发模块中提出一种导频和数据通道相结合的方法,在接收通道对无线时间同步信号进行相关运算,实现导频和数据双通道组合捕获。其中导频通道专门用于扩频码信号的跟踪、捕获,并提供精确的伪距观测量,而数据通道接收导航电文。同时,论文分析比较了传统的相干积分捕获、半比特捕获以及导频与数据双道组合捕获算法的性能。其结果表明:采用导频和数据通道分别进行相关,在避开比特跳变的基础上最大程度地提高了相干积分时间,提高了无线接收机捕获的灵敏度。

The wireless transceiver module is a key unit integrated in a high-precision two-way wireless time synchronization system.It has the function of transmitting wireless time synchronization signals,receiving signals and acquisition.For the conventional navigation signals,the data code is XORed with the pseudo code firstly to achieve spreading,then the combined code of the two is attached to the carrier by modulation.This design method not only affects the coherent integration data due to data bit hopping,but also sacrifices the sensitivity of the acquisition and tracking,and increases the amount of calculation,which is not suitable for the high sensitivity wireless transceiver module.This study proposed a method for combining pilot and data channels in a two-way wireless time synchronization system transceiver module,and performs correlation operations on the wireless time synchronization signal in the receiving channel to realize combined acquisition of pilot and data.The pilot channel is dedicated to tracking and acquisition the spread spectrum code signal and provides accurate pseudorange observation,while the data channel receives the navigation message.The study also analyzed and compared the performance of the traditional coherent integration acquisition,half-bit acquisition and pilot-data dual-channel acquisition algorithms.The results show that while used pilot and data channels for the correlation separately,the coherent integration time is maximized on the basis of avoiding bit hopping,which improves the sensitivity of wireless receiver acquisition and optimizes the code tracking performance.