Error Analysis of an Integrated Inertial/Doppler-Satellite System with Continuous and Multiple Satellite Coverage.
IOWA STATE UNIV AMES ENGINEERING RESEARCH INST
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The study investigates the accuracy of an integrated navigation system in which a modest quality airborne inertial navigation system is coupled with an extensive system of Doppler navigation satellite. The two systems are integrated in an optimal fashion by using the delayed-state Kalman filter. The performance of the integrated system was evaluated by conducting variance analyses on a number of computer-simulated flights in which an aircraft was assumed to be equipped with both navigation systems. Three hypothetical Doppler-satellite configurations were considered in these studies all of these configurations provided sufficient satellite coverage to enable continuous Doppler measurements from two satellites to be used for the Kalman filter input. A Doppler satellite generally provides better navigation information in its along-track direction than its crosstrack direction, and this is reflected in the integrated system by an imbalance in the quality of the estimates of the two level channel errors. Three satellite altitudes were considered and it was found that the accuracy of the integrated system degrades with increased satellite altitude. The variation of the quality of the inertial system was found to have a lesser effect on the resultant performance than did the quality of satellite coverage. Author
- Navigation and Guidance