矢量延迟锁定环码跟踪偏差产生机理研究

矢量延迟锁定环（VDLL,Vector Delay Lock Loop）是一种直接估计接收机状态（位置,速度和钟差等）进而实现对各路可见卫星信号PRN序列的跟踪的方法.不同卫星信号到接收机的传输时延由接收机和卫星的位置决定,它们满足特定的几何关系,VDLL通过对各路卫星信号传输时延之间相关信息的提取,达到降低跟踪门限的目的.目前国内外对VDLL算法的研究均默认了VDLL跟踪的无偏性,给出了VDLL算法的理论计算结果,发现VDLL算法会导致码跟踪偏差,并通过理论计算和实验仿真验证了该问题,该码跟踪偏差会导致定位解算出现较大的偏差,因此必须加以修正.

The study of code tracking bias in vector delay lock loop

The Vector Delay Lock Loop （VDLL） is used in GNSS receivers to track the PRN sequences received from satellites by estimating directly the receiver’s navigation states （position, velocity , clock bias and so on）. For a given receiver, the transmission delays of the signals from different satellites vary with the 3-D coordinates of both the receiver and the satellites, so they are geometrically correlated. Then the VDLL can reduce the tracking threshold by extracting the interrelated information from the transmission delays. The tracking bias caused by the VDLL is seldom mentioned in recent researches. This paper presents the theoretical results of the VDLL algorithms, and derives the tracking bias introduced by VDLL. To validate the results, both theoretical calculation and simulation are carried out. The tracking bias which can bring about position deviation must be corrected.