A Rapid Orbit Integration Algorithm for Multi-GNSS Satellites

A rapid and efficient orbit numerical integration algorithm with high accuracy is needed in multi-GNSS rapid precise orbit determination. In order to improve the compute efficiency, an adaptive step-changed Admas integration method and a synchronous integration algoritm for multi-GNSS satellites are developed in this paper. To validate the precision and efficiency of the proposed method, the multi-GNSS precise orbit products calculated by Wuhan University (WHU) and Center for Orbit Determination in Europe (CODE) are used for orbit fitting. Results show that, the average 3DRMS of GPS, GLONASS, BDS and Galileo satellites are all below 20 mm. Comparing with the traditional step-fixed orbit integraion method applied for each satellite separately, the computational efficiency of the proposed method is improved significantly: without damaging the accuracy, it takes only 0.09 s for a single satellite, which is 14 times faster than the traditional method. Besides, further improvement can be achieved when the number of satellites is increased.