Accession Number : ADA313254

Title :   Precise Orbit Determination with GPS.

Corporate Author : NATIONAL AIR INTELLIGENCE CENTER WRIGHT-PATTERSON AFB OH

Personal Author(s) : Rim, H. ; Powell, G. E. ; Tapley, B. D.

PDF Url : ADA313254

Report Date : 19 AUG 1996

Pagination or Media Count : 23

Abstract : The Global Positioning System (GPS) is likely to become a powerful means in precise orbit determination (POD) of low-orbiting Earth satellites as long as it can fully cover the satellites. With its continuous tracking and coverage capabilities, this system can realize not only conventional dynamic precise orbit determination, but kinematic orbit determination as well. Technically, by smoothing the pseudo-range measurement values derived from at least four GPS satellites by using the carrier wave measurement values, the geocentric position at the phase center of the antenna and the clock correction values of the user satellites can be determined. Therefore, the foregoing technology does not require a dynamic model to impose a force on a user satellite. The kinematic method is extremely sensitive to the effects from measurement models, such as the GPS sidereal error (either as a given or to be solved), signal multipath, receiver noise, etc. On the other hand, however, the dynamic method also suffers from effects caused by parameter errors and/or imperfections of the force model. With this scenario, a hybred arrangement was proposed designed for weighting the kinematic and dynamic algorithms by compensating for the process noise. Our project was focused on the investigating these orbit determination methods through a simulation and covariance analysis with several dynamic and measurement error models. The orbital uncertainty generated by these models was found to be roughly equivalent to the sidereal error estimated in processing actual GPS data. In this case, the covariance analysis, when adjusted, was able to reflect these errors and to reveal the characteristics of various filtering techniques.

Descriptors :   *GLOBAL POSITIONING SYSTEM, KINEMATICS, ALGORITHMS, SIMULATION, ORBITS, MEASUREMENT, POSITION(LOCATION), UNCERTAINTY, CLOCKS, DYNAMICS, PARAMETERS, TRACKING, RECEIVERS, ERRORS, PRECISION, ARTIFICIAL SATELLITES, USER NEEDS, COVARIANCE, NOISE, GEODESY, WAVES, CHINA, CORRECTIONS, CHINESE LANGUAGE.

Subject Categories : Navigation and Guidance

Distribution Statement : APPROVED FOR PUBLIC RELEASE