Performance Analysis of Beidou-2/Beidou-3e Combined Solution with Emphasis on Precise Orbit Determination and Precise Point Positioning

AbstractThe first pair of satellites belonging to the European Global Navigation Satellite System (GNSS)—Galileo—has been accidentally launched into highly eccentric, instead of circular, orbits. The final height of these two satellites varies between 17,180 and 26,020 km, making these satellites very suitable for the verification of the effects emerging from general relativity. We employ the post-Newtonian parameterization (PPN) for describing the perturbations acting on Keplerian orbit parameters of artificial Earth satellites caused by the Schwarzschild, Lense–Thirring, and de Sitter general relativity effects. The values emerging from PPN numerical simulations are compared with the approximations based on the Gaussian perturbations for the temporal variations of the Keplerian elements of Galileo satellites in nominal, near-circular orbits, as well as in the highly elliptical orbits. We discuss what kinds of perturbations are detectable using the current accuracy of precise orbit determination of artificial Earth satellites, including the expected secular and periodic variations, as well as the constant offsets of Keplerian parameters. We found that not only secular but also periodic variations of orbit parameters caused by general relativity effects exceed the value of 1 cm within 24 h; thus, they should be fully detectable using the current GNSS precise orbit determination methods. Many of the 1-PPN effects are detectable using the Galileo satellite system, but the Lense–Thirring effect is not.

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A Second-Order Time-Difference Position Constrained Reduced-Dynamic Technique for the Precise Orbit Determination of LEOs Using GPS

Remote Sensing ◽

10.3390/rs13153033 ◽

2021 ◽

Vol 13 (15) ◽

pp. 3033

Author(s):

Hui Wei ◽

Jiancheng Li ◽

Xinyu Xu ◽

Shoujian Zhang ◽

Kaifa Kuang

Keyword(s):

Orbit Determination ◽

Dynamic Models ◽

Precise Orbit Determination ◽

Second Order ◽

Time Difference ◽

Error Sources ◽

Precise Orbit ◽

Unmodeled Dynamic ◽

Reduced Dynamic

In this paper, we propose a new reduced-dynamic (RD) method by introducing the second-order time-difference position (STP) as additional pseudo-observations (named the RD_STP method) for the precise orbit determination (POD) of low Earth orbiters (LEOs) from GPS observations. Theoretical and numerical analyses show that the accuracies of integrating the STPs of LEOs at 30 s intervals are better than 0.01 m when the forces (<10−5 ms−2) acting on the LEOs are ignored. Therefore, only using the Earth’s gravity model is good enough for the proposed RD_STP method. All unmodeled dynamic models (e.g., luni-solar gravitation, tide forces) are treated as the error sources of the STP pseudo-observation. In addition, there are no pseudo-stochastic orbit parameters to be estimated in the RD_STP method. Finally, we use the RD_STP method to process 15 days of GPS data from the GOCE mission. The results show that the accuracy of the RD_STP solution is more accurate and smoother than the kinematic solution in nearly polar and equatorial regions, and consistent with the RD solution. The 3D RMS of the differences between the RD_STP and RD solutions is 1.93 cm for 1 s sampling. This indicates that the proposed method has a performance comparable to the RD method, and could be an alternative for the POD of LEOs.

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Inter-satellite link augmented BeiDou-3 orbit determination for precise point positioning

Chinese Journal of Aeronautics ◽

10.1016/j.cja.2021.05.002 ◽

2021 ◽

Author(s):

Liqian Zhao ◽

Xiaogong Hu ◽

Chengpan Tang ◽

Shanshi Zhou ◽

Yueling Cao ◽

...

Keyword(s):

Orbit Determination ◽

Precise Point Positioning ◽

Satellite Link ◽

Point Positioning

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Assessment of single-difference and track-to-track ambiguity resolution in LEO precise orbit determination

GPS Solutions ◽

10.1007/s10291-021-01103-4 ◽

2021 ◽

Vol 25 (2) ◽

Author(s):

Xingyu Zhou ◽

Hua Chen ◽

Wenlan Fan ◽

Xiaohui Zhou ◽

Qusen Chen ◽

...

Keyword(s):

Ambiguity Resolution ◽

Orbit Determination ◽

Precise Orbit Determination ◽

Precise Orbit ◽

Single Difference

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A More Reliable Orbit Initialization Method for LEO Precise Orbit Determination Using GNSS

Remote Sensing ◽

10.3390/rs12213646 ◽

2020 ◽

Vol 12 (21) ◽

pp. 3646

Author(s):

Xuewen Gong ◽

Jizhang Sang ◽

Fuhong Wang ◽

Xingxing Li

Keyword(s):

Parameter Estimation ◽

Orbit Determination ◽

High Reliability ◽

Precise Orbit Determination ◽

Direct Approach ◽

Design Matrix ◽

Reference Orbit ◽

Stability Analyses ◽

Precise Orbit ◽

Orbit Parameter

Precise orbit determination (POD) using GNSS has been rapidly developed and is the mainstream technology for the navigation of low Earth orbit (LEO) satellites. The initialization of orbit parameters is a key prerequisite for LEO POD processing. For a LEO satellite equipped with a GNSS receiver, sufficient discrete kinematic positions can be obtained easily by processing space-borne GNSS data, and its orbit parameters can thus be estimated directly in iterative manner. This method of direct iterative estimation is called as the direct approach, which is generally considered highly reliable, but in practical applications it has risk of failure. Stability analyses demonstrate that the direct approach is sensitive to oversized errors in the starting velocity vector at the reference time, which may lead to large errors in design matrix because the reference orbit may be significantly distorted, and eventually cause the divergence of the orbit parameter estimation. In view of this, a more reliable method, termed the progressive approach, is presented in this paper. Instead of estimating the orbit parameters directly, it first fits the discrete kinematic positions to a reference ephemeris in the form of the GNSS broadcast ephemeris, which construct a reference orbit that is smooth and close to the true orbit. Based on the reference orbit, the starting orbit parameters are computed in sufficient accuracy, and then the final orbit parameters are estimated with a high accuracy by using discrete kinematic positions as measurements. The stability analyses show that the design matrix errors are reduced in the progressive approach, which would assure more robust orbit parameter estimation than the direct estimation approach. Various orbit initialization experiments are performed on the KOMPSAT-5 and FY3C satellites. The results have fully verified the high reliability of the proposed progressive approach.

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