Baro-inertial Altitude Accuracy Improvement for GPS Monitoring and Integration

Daniel O. Molnar

Abstract:	ABSTRACT Herein is shown that GPS integrity monitoring can be improved by non-standard baro-altitude aiding. When a Barometric Altimeter measures pressure altitude relative to the srandurd sea level datum, 29.92 in of Hg, local changes in pressure will cause the pressure altitude to shift relative to the geocentric altitude - 500 m or more. However non-standard Buro altitude processing can reduce the error relative to geoid to about -250 ft (a military technology conversion). The improved barometric pressure altitude accuracy results in improved GPS integrity coverage. The non-standard Buro altitude is obtained by the on-line integration of the atmosphere hydrostatic equation, rather than the currently used solution based on a standard day lapse rate. Horizontal pressure gradient estimates can be included by employing cross track wind and ground velocity from the INS. Most of the remaining uncertainty in altitude is due to errors in pressure and temperature sensors and some small residual atmospheric errors. The continuous calibration of barometric pressure bias by using a Kalman filter running in parallel with the baro- inertial complementary filter could support improved GPS integrity monitoring, positioning and may also contribute to energy management applications.
Published in:	Proceedings of the 50th Annual Meeting of The Institute of Navigation (1994) June 6 - 8, 1994 Antlers Doubletree Hotel Colorado Springs, CO
Pages:	129 - 138
Cite this article:	Molnar, Daniel O., "Baro-inertial Altitude Accuracy Improvement for GPS Monitoring and Integration," Proceedings of the 50th Annual Meeting of The Institute of Navigation (1994), Colorado Springs, CO, June 1994, pp. 129-138.
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