A Novel Method for Precise Onboard Real-Time Orbit Determination with a Standalone GPS Receiver

Area of Science:

• Satellite geodesy
• Spacecraft navigation
• Remote sensing technology

Background:

• Accurate real-time orbit determination (RTOD) is crucial for satellite remote sensing.
• Onboard Global Positioning System (GPS) is commonly used for RTOD.
• China's HY2A and ZY3 missions require decimeter-level precision for RTOD.

Purpose of the Study:

• To present a novel RTOD method achieving decimeter precision using GPS carrier phases.
• To introduce and validate the 'pseudo-ambiguity' parameter for improved orbit determination.
• To assess the method's performance for HY2A and ZY3 satellite missions.

Main Methods:

• Developed a novel RTOD algorithm incorporating a 'pseudo-ambiguity' parameter.
• Modeled pseudo-ambiguity as a random walk and estimated it using an extended Kalman filter.
• Processed real data from HY2A and ZY3 missions using the SATODS software.

Main Results:

• Achieved position accuracy of 0.2-0.4 m and velocity accuracy of 0.2-0.4 mm/s (3D RMS) for HY2A using dual-frequency GPS carrier phases.
• Demonstrated feasible orbit accuracy of 3-5 decimeters for position and 0.3-0.5 mm/s for velocity.
• Slightly lower accuracy was observed for the ZY3 mission.

Conclusions:

• The novel RTOD method with pseudo-ambiguity is effective for achieving decimeter-level precision.
• The method is feasible for onboard operational scenarios of missions like HY2A and ZY3.
• This approach enhances the accuracy of satellite geo-referencing and data quality.