The Accuracy of Barometric Altimeters With Respect to Geometric Altitude

John Dobyne

Abstract:	This paper presents estimates of the accuracy of barometric altimeters with respect to the geometric altitude above mean sea level. These estimates can be used in simulations of the performance of GPS User Equipment that incorporate barometric altimeter aiding. The primary source of altimeter error was found to be the conversion from atmospheric pressure to altitude. This conversion is based on a theoretical standard relationship- between pressure and altitude (the U.S. Standard Atmosphere). In actuality, the real atmosphere varies widely from the theoretical standard. The ability of the altimeter to measure air pressure and perform the conversion (altimeter system error) is quite good in comparison, and generally a much smaller source of error. Global extremes of altimeter error due to variations of atmospheric pressure and worst-case error gradients with vertical and horizontal motion were investigated. Supplementary investigations were also conducted to determine the effectiveness of compensation for local surface pressure and ambient air temperature, and to estimate the magnitude of the altimeter system error.
Published in:	Proceedings of the International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1988) September 19 - 23, 1988 The Broadmoor Hotel Colorado Spring, CO
Pages:	451 - 459
Cite this article:	Dobyne, John, "The Accuracy of Barometric Altimeters With Respect to Geometric Altitude," Proceedings of the International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1988), Colorado Spring, CO, September 1988, pp. 451-459.
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