Very long baseline interferometry (VLBI) plays a crucial role in geodesy and astrometry, and it is also being successfully used in spacecraft tracking. Phase referencing VLBI is a technique that uses phase information rather than the traditional VLBI group time delay to achieve higher measurement accuracy. The newly developed source-frequency phase referencing (SFPR) VLBI has been proven to be a powerful method to eliminate errors, but for positioning purposes, only “core shifts” are left in SFPR. Therefore, in this paper, an in-beam SFPR (IB-SFPR) VLBI method based on SFPR is proposed to overcome the positioning deficiency in SFPR, and to achieve high positioning accuracy. The proposed IB-SFPR method is further researched in more detail and shown to have the ability to achieve high positioning accuracy. For the first Martian rover of China, the IB-SFPR is first applied in its positioning. The positioning results of the rover have shown that the 1σ formal position error is hundreds of meters, with a formal error of post-fitted phase time delay of about 1.3 ps. However, the position discrepancies among the results of IB-SFPR, the guidance, navigation and control system, and the visual localization are at kilometer level, which are mainly affected by the orbit error of the orbiter. Therefore, considering the external reference’s (the obiter) orbit error, the final positioning accuracy of the Martian rover is at the kilometer level.

中文翻译：

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我国首次火星车波束内源频相位参考VLBI定位方法

甚长基线干涉测量（VLBI）在大地测量学和天体测量学中发挥着至关重要的作用，并且也成功应用于航天器跟踪。相位参考VLBI是一种利用相位信息而不是传统的VLBI群时延来实现更高测量精度的技术。新开发的源频率相位参考（SFPR）VLBI已被证明是消除误差的有力方法，但出于定位目的，SFPR中仅留下“核心移位”。因此，本文提出一种基于SFPR的波束内SFPR（IB-SFPR）VLBI方法，以克服SFPR的定位缺陷，实现较高的定位精度。对所提出的 IB-SFPR 方法进行了更详细的进一步研究，并证明其能够实现高定位精度。我国首台火星车首次采用IB-SFPR进行定位。漫游车的定位结果表明，1σ形式位置误差为数百米，安装后相位延迟的形式误差约为1.3 ps。但IB-SFPR结果与制导导航控制系统、目视定位之间的位置误差都在千米级，主要受轨道飞行器轨道误差的影响。因此，考虑到外部参考（跟踪者）的轨道误差，火星车最终的定位精度为公里级。