Multiprocessor implementation of algorithms for multisatellite orbit determination

Previous studies of parallel processing methods for use with satellite related, many parameter estimation problems indicate the need for faster numerical integration methods. Parallel numerical integration methods for use in satellite orbit determination were studied and tested. Several methods such as parallel Runge-Kutta schemes showed improvement over serial methods when tested on the two body problem. Existing orbit determination routines were modified for use on a Cray T3E parallel supercomputer. These routines were used to test a selected set of the parallel integration routines, including Parallel Extrapolation and Parallel Iterated Runge-Kutta methods, for the case of the GPS satellite constellation orbits with nominal force models. None of the methods showed significant improvement over the fastest serial method, a Class II predictor-corrector scheme.; A combined parallel observation processing and parallel least squares orbit determination program was compared to a serial orbit determination program. The fastest parallel orbit determination scheme, a 16 processor version, was not superior to the fastest time of the serial orbit determination scheme, but was just as fast as the average time of the serial scheme. Use of the fastest serial integration method in the parallel scheme revealed that the numerical integration contributed almost one quarter of the fastest overall processing time. The primary hindrance to the performance of the parallel scheme was caused by delays associated with synchronization of the processors.; Improved force model algorithms for use in GPS orbit determination were implemented. Pseudo-stochastic velocity changes and the updated solar radiation pressure model developed by the CODE Analysis Center of the IGS were tested using 30 hour and 3 day orbit arc lengths. Use of these models resulted in an improvement of the orbit overlap statistics but a degradation of the differences of the orbits with respect to IGS orbits.