Device and method for calibrating and improving the accuracy of barometric altimeters with GPS-derived altitudes
First Claim
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1. An altitude determining apparatus comprising:
- an altimeter operable to determine an altitude of the apparatus;
a GPS unit for receiving satellite signals from a plurality of satellites and operable to determine an altitude of the apparatus;
a processor adapted to calibrate the altimeter accounting for changes in local atmospheric pressure when the altimeter and GPS unit are moved in tandem, wherein the processor calibrates the altimeter by subtracting the average difference between the altitude determined by the altimeter and the altitude determined by the GPS unit from the altitude as determined by the altimeter; and
a portable and handheld housing for housing the altimeter, the GPS unit, and the processor.
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Abstract
In a combined GPS/altimeter device, the calibration and hence the accuracy of barometric altimeter measurements are enhanced with the aid of derived altitudes from a GPS. The device determines the need for calibration and perform the subsequent computations necessary to facilitate the calibration. Furthermore, the device determines a correction quantity that should be applied to barometric altitude readings, thereby allowing the device to be calibrated while in motion. Both of these features ultimately result in a more accurate determination of altitude.
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Citations
13 Claims
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1. An altitude determining apparatus comprising:
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an altimeter operable to determine an altitude of the apparatus; a GPS unit for receiving satellite signals from a plurality of satellites and operable to determine an altitude of the apparatus; a processor adapted to calibrate the altimeter accounting for changes in local atmospheric pressure when the altimeter and GPS unit are moved in tandem, wherein the processor calibrates the altimeter by subtracting the average difference between the altitude determined by the altimeter and the altitude determined by the GPS unit from the altitude as determined by the altimeter; and a portable and handheld housing for housing the altimeter, the GPS unit, and the processor. - View Dependent Claims (2, 3, 4)
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5. An altitude determining apparatus comprising:
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an altimeter for determining a first altitude reading; a GPS receiver for receiving satellite signals from a plurality of satellites; and a processor coupled with the altimeter and the GPS receiver for calculating a second altitude reading as a function of the satellite signals, such that the processor is adapted to calibrate the altimeter while the apparatus is in motion by accounting for dynamic changes between the readings, wherein the processor determines an average altimeter drift for use in calibration. - View Dependent Claims (6, 7, 8, 9, 10)
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11. An altitude determining apparatus comprising:
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a barometric pressure sensor for determining a first altitude reading; a GPS receiver for receiving satellite signals from a plurality of satellites; and a processor coupled with the barometric pressure sensor and the GPS receiver for calculating a second altitude reading as a function of the satellite signals, such that the processor is adapted to calibrate the barometric pressure sensor accounting for changes in local atmospheric pressure while the apparatus is in motion using differences in the altitude readings, wherein the processor calibrates the barometric pressure sensor by subtracting the difference in the altitude readings from the first altitude. - View Dependent Claims (12, 13)
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Specification