一种宽带信道群时延测量方法

摘要

For VLBI (Very Long Baseline Interferometry) systems,the method of direct phase difference measurement shows contradiction between the measurement accuracy and resolution and the problem of linear least squares fitting method that is not applicable to group delay.A group delay measurement method is used and it is based on nonlinear fitting of broadband channels,at the same time to obtain measured data to verify.Simulation results show that the method is applicable to nonlinear phase systems,and group delay measurement precision is better than the direct phase difference method by two orders of magnitude.The measured data shows that in the band 270～ 370 MHz,the traditional direct phase difference method and linear fitting measurement method have failed,but the method proposed for the group delay measurement precision is better than that of 0.1 ns,it is verified that the nonlinear fitting method can carry out additional phase and group delay characteristics measurement with high precision.%针对VLBI(Very Long Baseline Interferometry,甚长基线干涉测量)系统直接相位差分法的群时延测量精度与分辨率存在矛盾,以及线性最小二乘拟合法不适用于群时延失真链路的问题,采用一种基于非线性拟合的宽带信道群时延测量方法,对出现的问题进行分析与仿真,同时进行了实验验证并获取到实测数据.仿真表明,基于非线性拟合的宽带信道群时延测量方法适用于非线性相位系统,而且群时延的测量精度优于直接相位差分法2个量级.实测数据表明,在270～370 MHz频段内,传统的直接相位差分法和线性拟合测量法已失效,而该方法群时延的测量精度优于0.1 ns,由此验证非线性拟合法能够以较高精度进行附加相位和群时延特性测量.