Method And Apparatus For Determining The Altitude Of A Mobile Device

Abstract

A method and apparatus for combining pressure information from pressure sensors, motion information from dead reckoning or other motion sensors, such as accelerometers, gyroscopes, and geomagnetic sensors, and temperature information from temperature sensors, to separate a change in altitude from a change in environmental pressure or temperature. A change in measured pressure without any motion or change in temperature must be a weather-related barometric pressure change. If there is an associated temperature change, but no motion, and the rate of change is too fast for a normal weather change, the measured change represents a change in sensitivity of the pressure sensor with temperature, and the sensor calibration can be adjusted. A rapid change in pressure, associated with horizontal motion, but no measurable vertical motion represents a movement into a different pressure environment. Only changes in pressure that are associated with measurable vertical motion are true changes in altitude.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a part of the specification, illustrate several embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating a preferred embodiment of the invention and are not to be construed as limiting the invention. In the drawings:

FIG. 1 is a block diagram depicting the components for the preferred embodiment.

FIG. 2 is a flow chart showing the steps involved for determining the actual change in altitude of a typical portable device.

Claims

1. A method of determining an actual altitude of a mobile device, a preliminary altitude of the mobile device having been determined by an altimeter, the method comprising the steps of: providing at least one environmental sensor to the mobile device;determining whether the preliminary altitude is a result of an altitude change or an environmental change from an output from the at least one environmental sensor; andadjusting the preliminary altitude to the actual altitude based on the step of determining.

2. The method of claim 1 further comprising measuring a temperature and a movement of the mobile device.

3. The method of claim 2 wherein the step of measuring a movement comprises measuring a vertical movement.

4. The method of claim 1 wherein the step of providing at least one sensor comprises providing a motion sensor and a temperature sensor.

5. The method of claim 1 further comprising the step of storing data from the at least one sensor and the altimeter and determining a change in the sensor data over a predetermined period of time.

6. The method of claim 5 wherein the step of determining a change in the sensor data over a predetermined period of time comprises corresponding a temperature change to a rate of change of pressure.

7. The method of claim 5 wherein the step of determining a change in the sensor data over a predetermined period of time comprises corresponding a measured vertical movement to a rate of change of pressure.

8. The method of claim 5 further comprising the step of storing predetermined sensor data profiles.

9. A system for determining an actual altitude of a mobile device, a preliminary altitude having been measured by an altimeter, the system comprising: at least one environmental sensor disposed on the mobile device;a processor for comparing an output from the at least one environmental sensor to the preliminary altitude measurement; andsaid processor adjusting the preliminary altitude to the actual altitude.

10. The system of claim 9 wherein the at least one environmental sensor comprises at least one motion sensor.

11. The system of claim 9 wherein the at least one sensor comprises at least one member from the group consisting of an accelerometer, a gyroscope, a geomagnetic sensor, a motion sensor and a temperature sensor.

12. The system of claim 9 wherein the at least one sensor comprises a motion sensor and a temperature sensor.

13. The system of claim 9 further comprising a memory for storing altimeter data and sensor data.

14. A method of determining an actual altitude of a mobile device, a preliminary altitude of the mobile device having been determined by an altimeter, the method comprising the steps of: providing a temperature sensor and a motion sensor to the mobile device;detecting a change in pressure by the pressure sensor;detecting a change in movement by the motion sensor;detecting a change in temperature by the temperature sensor;determining whether the preliminary altitude is a result of an altitude change or an environmental change from the detected change of the motion sensor and temperature sensor; andadjusting the preliminary altitude to the actual altitude based on the step of determining.

15. The method of claim 14 wherein the step of detecting a change in movement comprises measuring a vertical movement.

16. The method of claim 14 further comprising the step of storing data from the motion sensor, the temperature sensor and the pressure sensor and determining a change in sensor data over a predetermined period of time.

17. The method of claim 16 wherein the step of determining a change in the sensor data over a predetermined period of time comprises corresponding a temperature change to a rate of change of pressure.

18. The method of claim 16 wherein the step of determining a change in the sensor data over a predetermined period of time comprises corresponding a measured vertical movement to a rate of change of pressure.

19. The method of claim 14 further comprising the step of comparing the detected change in pressure, detected change in movement and detected change in temperature to stored profiles.

20. A computer program product, comprising: computer readable medium comprising:instructions to cause at least one computer to measure a preliminary altitude of a mobile device from an altimeter;instructions to cause at least one computer to determine whether the preliminary altitude is a result of an altitude change or an environmental change from an output from at least one environmental sensor disposed on the mobile device; andinstructions to cause at least one computer to adjust the preliminary altitude to the actual altitude based on a result from the code to determine whether the preliminary altitude is a result of an altitude change or an environmental change.

21. A computer program product, comprising: computer readable medium comprising:instructions to cause at least one computer to measure a preliminary altitude of a mobile device from an altimeter;instructions to cause at least one computer to detect a change in pressure by a pressure sensor;instructions to cause at least one computer to detect a change in movement by a motion sensor;instructions to cause at least one computer to detect a change in temperature by a temperature sensor;instructions to cause at least one computer to determine whether the preliminary altitude is a result of an altitude change or an environmental change from the detected change of the motion sensor, the pressure sensor and the temperature sensor; andinstructions to cause at least one computer to adjust the preliminary altitude to the actual altitude based on a result from the instructions to determine whether the preliminary altitude is a result of an altitude change or an environmental change.