GNSS多通道级联群时延特性对零值叠加的影响

The Influence of Group Delay under GNSS Multichannel Cascade on Superposition of Zero Value

导航信号从卫星发射到用户接收处理,中间可能存在多级通道,通道的群时延特性会对时延估计零值产生影响。目前较为普遍的做法是将各通道零值进行简单叠加得到级联通道的零值,针对级联通道的零值结果是否简单等于各通道零值之和还尚未有研究。本文定量分析了级联通道群时延特性对时延估计零值的影响,研究了级联通道时延估计零值的叠加特性,并在软件接收机上对分析结果进行了仿真验证。结果表明,零阶群时延通道与其他通道级联时,零值满足叠加特性;奇数阶群时延通道的零值为零,所以奇数阶群时延通道间级联时零值满足叠加特性;其他群时延通道相互级联时,零值不满足叠加特性,若对群时延系数进行约束,可使零值近似满足叠加特性。

There may be several channels for the navigation signal to propagate from the satellite to the user,of which the group delay characteristics influence the zero value of time delay estimation.It is common practice to simply add the zero value of each channel to obtain zero value of cascaded channel,whether the sum of the zero values of each channel is simply equal to the zero value of the cascade channel has not been studied yet.In this paper,the influence of the group delay characteristics on the zero value is analyzed quantitatively.And the superposition characteristic of the zero value of time delay estimation under the cascade channel is estimated.The result of the simulation is verified on the software receiver.The results show that when the zero-order group delay channel and other channels are cascaded,the zero value satisfies the superposition characteristic.Since the zero value of the first-order group delay channel is equal to zero,it satisfies the superposition characteristic too.For other situations,the zero value does not satisfy the superposition characteristic,while the zero value can be approximately to satisfy it when the group delay coefficient is constrained.