Abstract

The Haiyang 2B (HY-2B) satellite requires precise orbit determination (POD) products for geodetic remote sensing techniques. An improved set of reduced-dynamic (RD) orbit solutions was generated from the onboard Global Positioning System (GPS) measurements over a 14-month period using refined strategies and processing techniques. The key POD strategies include a refined empirical acceleration model, in-flight calibration of the GPS antenna, and the resolution of single-receiver carrier-phase ambiguities. In this study, the potential periodicity of empirical acceleration in the HY-2B POD was identified by spectral analysis. In the along-track direction, a noticeable signal with four cycles per revolution (CPR) was significant. A mixed spectrum was observed for the cross-track direction. To better understand the real in-flight environment, a refined empirical acceleration model was used to cope with the time variability of empirical accelerations in HY-2B POD. Three POD strategies were used for the reprocessing for superior orbit quality. Validation using over one year of satellite laser ranging (SLR) measurements demonstrated a 5.2% improvement in the orbit solution of the refined model. Reliable correction for the GPS antenna phase center was obtained from an over-420-day dataset, and a trend in radial offset change was observed. After application of the in-flight calibration of the GPS antenna, a 26% reduction in the RMS SLR residuals was achieved for the RD orbit solution, and the carrier phase residuals were clearly reduced. The integer ambiguity resolution of HY-2B led to strong geometric constraints for the estimated parameters, and a 15% improvement in the SLR residuals could be inferred compared with the float solution.

Highlights

  • HaiYang-2B (HY-2B) is the second marine dynamic environment satellite of China [1].It was launched on 25 October 2018, with an altitude and inclination of about 973 km and99.3◦, respectively

  • Noticeable signals were identified in the along-track and radial directions, and a mixed spectrum was observed for the cross-track direction

  • The GRG provided by the CNES/CLS analysis center was used to support the implementation of HY-2B ambiguity-fixed precise orbit determination (POD) solutions, which resulted in a 15% improvement of satellite laser ranging (SLR) residuals compared to the float solution

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Summary

Introduction

HaiYang-2B (HY-2B) is the second marine dynamic environment satellite of China [1]. It was launched on 25 October 2018, with an altitude and inclination of about 973 km and. Along with the initial state vector of LEO satellites and the scaling factors for individual force model constituents, empirical acceleration parameters are estimated in reduced-dynamic POD The performance of this technique in high-precision orbit determination has been widely investigated by the LEO POD community [21,22,23]. The accurate known location of the GPS receiver antenna relative to the center of mass (CoM) is the premise of precise orbit determination [25,26] This location is typically provided by the spacecraft manufacturer, with a nominal accuracy of millimeters or better, but the experience of past geodetic missions has shown that there may be inconsistencies at the level of 2–3 cm [16,27,28].

Spectral Analysis of HY-2B Empirical Accelerations
POD Processing and Models
Frequency Characteristics
The along-track direction and directions is shown in Figure
Amplitude
Refined
Improvements in HY-2B POD
Performance Analysis of the Refined PEA Model
Statistics
GPS Antenna Offset Calibration
Single-Receiver Ambiguity Resolution
Findings
Discussion
Conclusions

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