초록 ▼

Real time correction to ground generated satellite ephemeris implements a reference trajectory management module (334), an error estimation module (336), an parameter calculation module (338) and a position information management module (340). The reference trajectory management module (334) accesse

Real time correction to ground generated satellite ephemeris implements a reference trajectory management module (334), an error estimation module (336), an parameter calculation module (338) and a position information management module (340). The reference trajectory management module (334) accesses reference trajectory data such as ground generated ephemeris data which is uplinked to a spacecraft through a communications unit (312). The position information management module (340) accesses and interprets position information such as Global Positioning System (GPS) measurement data to provide measured spacecraft positions. The parameter calculation module (338) calculates spacecraft position and velocity from the reference trajectory data. The error estimation module (336) compares the measured and calculated positions to provide a position difference, smoothes the position difference to filter anomalous data, and provides a correction term for the determination of corrected spacecraft orbital parameters such as position and velocity. The time rate of change of the correction term may be used to provide additional correction to the orbital parameters.

대표청구항 ▼

[ We claim:] [1.] In a system including a processor and a memory a method for real time on-board determination of corrected spacecraft orbital parameters, said method comprising:obtaining a reference trajectory for the spacecraft based upon reference trajectory data provided from a source external t

[ We claim:] [1.] In a system including a processor and a memory a method for real time on-board determination of corrected spacecraft orbital parameters, said method comprising:obtaining a reference trajectory for the spacecraft based upon reference trajectory data provided from a source external to the spacecraft:obtaining a measured position of the spacecraft corresponding to a first time:calculating a position of the spacecraft along the reference trajectory which corresponds to the first time:comparing the measured position and the calculated position corresponding to the first time:determining a position error as a result of the camparison between the measured position and the calculated position corresponding to the first time;determining an in-track component of the position error as a portion of the position error that is parallel to the reference trajectory;determining a time correction term based upon the in-track component of the position error; andcalculating corrected orbital parameters on-board the spacecraft using the determined time correction term.