초록 ▼

Methods and apparatus for determining altitude, specifically altitude in an aircraft, and an estimated error of the altitude. The altitude determination preferably uses a first altitude based on hydrostatic calculations, including local pressure and temperature, as well as a second altitude which is

Methods and apparatus for determining altitude, specifically altitude in an aircraft, and an estimated error of the altitude. The altitude determination preferably uses a first altitude based on hydrostatic calculations, including local pressure and temperature, as well as a second altitude which is preferably a GPS altitude. A radio altimetry can also be used instead of or to complement the GPS altitude. Other sources of altitude determination can be used in the equation for the calculation of the final altitude. Each of the sources of altitude determination is provided with a complementary estimated error. In the final determination of the probable altitude, each source of altitude information is preferably accorded a weighting according to the estimated error of the altitude source. For global positioning altitude, the final combination of the altitude sources uses a complementary filter which takes into account the selective availability of the GPS altitude. This accounts for the long-term accuracy but short-term inaccuracy of GPS altitude. Corrections are provided to account for horizontal changes in pressure gradient as the aircraft moves from an origin to a destination. The invention further provides for the altitude to be corrected based on non-standard atmospheric temperature (ISA) variations. The apparatus includes a computer processor and memory configured to receive the altitude information and make the necessary calculations to result in an estimate of the current altitude which is then displayed on an output display. The apparatus includes inputs to receive sources of altitude information.

대표청구항 ▼

[ What is claimed is:] [1.]1. A method for determining a modified aircraft altitude signal, said method comprising:a. receiving an air temperature signal, a pressure altitude signal, a first validity signal associated with the pressure altitude signal, aircraft altitude and position signals, and an

[ What is claimed is:] [1.]1. A method for determining a modified aircraft altitude signal, said method comprising:a. receiving an air temperature signal, a pressure altitude signal, a first validity signal associated with the pressure altitude signal, aircraft altitude and position signals, and an error signal and a second validity signal associated with the aircraft altitude and position signals;b. if the aircraft is below a predefined altitude, receiving a radio altimeter generated altitude signal and a third validity signal associated with the radio altimeter altitude signal;c. generating a hydrostatic altitude signal based on the received pressure altitude signal and the air temperature signal;d. correcting the received barometric altimeter signal based on the received air temperature signal and a flight crew setting;e. initializing the hydrostatic altitude signal;f. calculating an error signal for the corrected barometric altimeter signal based on a predefined basic error factor, a predefined atmosphere instability factor and a predefined airport database;g. calculating an error signal for the received hydrostatic altitude signal based the initialization of the hydrostatic altitude signal;h. calibrating the hydrostatic altitude signal based on the received aircraft altitude signal, the at least one error signal associated with the aircraft altitude signal and the calculated error signal for the hydrostatic altitude signal;i. if the aircraft is below a predefined altitude, calibrating the hydrostatic altitude signal based on the received radio altimeter generated altitude signal and a predefined terrain elevation database;j. calculating an error signal for the aircraft altitude calibrated hydrostatic altitude signal based on the most recent calibration of the hydrostatic altitude signal and calculating an error signal for the radio altimeter calibrated hydrostatic altitude signal based on the most recent radio altimeter calibration of the hydrostatic altitude signal;k. determining a fourth validity of the aircraft altitude calibrated hydrostatic altitude signal based on said first received validity signal of the received pressure altitude signal and said second validity signal associated with the received aircraft altitude signal and determining a fifth validity of the radio altimeter calibrated hydrostatic altitude signal based on said first validity signal of the received pressure altitude signal;l. determining reasonableness of the generated hydrostatic altitude signal, the aircraft altitude calibrated hydrostatic altitude signal, the radio altimeter calibrated hydrostatic altitude signal and the corrected barometric altimeter signal; andm. generating a modified aircraft altitude signal based on the reasonableness determinations, the fourth and fifth validity determinations, the first, second, and third received validity signals, the aircraft altitude signal, the calculated and received error signals, the generated hydrostatic altitude signal, the aircraft altitude calibrated hydrostatic altitude signal, the radio altimeter calibrated hydrostatic altitude signal and the corrected barometric altimeter signal.