Method and apparatus for determining the altitude of a mobile device
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.
1. A method comprising:
directly detecting a change in pressure, a change in temperature, and movement by at least one environmental sensor of a mobile device;
determining whether a preliminary altitude measured by an altimeter is indicative of a change of an actual altitude of the mobile device or a detected environmental change based at least in part on the detected change in the pressure and a determination of whether the detected movement comprises a vertical movement component; and
adjusting a calibration of the at least one environmental sensor at least partially in response to the change in the pressure and the change in the temperature, and further in response to an absence of the vertical movement component.
2. The method of claim 1 further comprising storing sensor data from the at least one environmental sensor and the altimeter and determining a change in the sensor data over a predetermined period of time.
3. The method of claim 2 wherein the determining a change in the sensor data over a predetermined period of time comprises determining whether a rate of change of the pressure is caused by a rate of change in the temperature.
4. The method of claim 2 wherein the determining a change in the sensor data over a predetermined period of time comprises determining whether a rate of change of pressure is caused by a measured vertical movement.
5. The method of claim 2 further comprising storing predetermined sensor data profiles.
6. A mobile device comprising:
at least one environmental sensor disposed on the mobile device to directly detect a change in pressure and movement;
a processor to:
determine whether a preliminary altitude measured by an altimeter is indicative of a change of an actual altitude of the mobile device based at least in part on the detected change in the pressure and a determination of whether the detected movement comprises a vertical movement component, and
adjust a calibration of the altimeter at least partially in response to the change in the pressure and a change in temperature, and further in response to an absence of the vertical movement component.
7. The mobile device of claim 6 wherein the at least one environmental sensor comprises at least one motion sensor.
8. The mobile device of claim 6 wherein the at least one environmental sensor comprises at least one sensor type selected from the group consisting of: an accelerometer, a gyroscope, or a geomagnetic sensor.
9. The mobile device of claim 6 further comprising a memory for storing altimeter data and sensor data.
10. A method comprising:
detecting a change in pressure, by a pressure sensor;
detecting a change in movement, by a motion sensor;
detecting a change in temperature, by a temperature sensor;
determining whether a preliminary altitude detected by an altimeter is indicative of an change of an actual altitude or a detected environmental change based at least in part on the detected change in the pressure and a determination of whether the detected change in movement comprises a vertical movement component; and
adjusting a calibration of the temperature sensor at least partially in response to the change in the pressure and the change in the temperature, and further in response to an absence of the vertical movement component.
11. The method of claim 10 wherein the detecting a change in movement comprises measuring the vertical movement component.
12. The method of claim 10 further comprising comparing the detected change in pressure, detected change in movement or detected change in temperature with stored profiles.
13. The method of claim 10 further comprising 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.
14. The method of claim 13 wherein determining a change in the sensor data over a predetermined period of time comprises determining whether a rate of change of pressure is caused by a temperature change.
15. The method of claim 13 wherein determining a change in the sensor data over a predetermined period of time comprises determining whether a rate of change of pressure is caused by a measured vertical movement.
16. A device comprising:
a non-transitory computer readable medium comprising instructions executable by a processor to:
initiate measurement of a preliminary altitude of a mobile device, by an altimeter;
determine whether the preliminary altitude measured by the altimeter is indicative of a change of an actual altitude of the mobile device or a detected environmental change based at least in part on a detected change in pressure and a determination of whether detected movement comprises a vertical movement component, wherein the detected change in pressure and the detected change in movement are determined by at least one environmental sensor of the mobile device; and
adjust a calibration of the at least one environmental sensor at least partially in response to the change in the pressure and the change in the temperature, and further in response to an absence of the vertical movement component.
17. A device comprising:
a non-transitory computer readable medium comprising instructions executable by a processor to:
initiate measurement of a preliminary altitude of a mobile device, by an altimeter;
detect a change in pressure indicated at least partially by a pressure sensor;
detect a change in movement indicated at least partially by a motion sensor;
detect a change in temperature indicated at least partially by a temperature sensor;
determine whether the preliminary altitude determined by the altimeter is indicative of a change of an actual altitude of the mobile device or a detected environmental change based at least in part on the detected change in the pressure and in the temperature, and a determination of whether the detected change in movement comprises a vertical movement component; and
adjust a calibration of the temperature sensor at least partially in response to the change in the pressure and the change in the temperature, and further in response to an absence of the vertical movement component.
18. A mobile device comprising:
means for directly detecting a change in pressure and movement by at least one environmental sensor of the mobile device;
means for determining whether a preliminary altitude measured by an altimeter is indicative of a change of an actual altitude of the mobile device or a detected environmental change based at least in part on the detected change in the pressure and a determination of whether the detected movement comprises a vertical movement component; and
means for adjusting a calibration of the at least one environmental sensor at least partially in response to the change in the pressure and the change in temperature, and further in response to an absence of the vertical movement component.
19. The mobile device of claim 18 further comprising means for measuring a temperature of the mobile device.
20. The mobile device of claim 18 wherein the means for determining a change in the sensor data over a predetermined period of time comprises means for determining whether a rate of change of pressure is caused by a measured vertical movement.
21. The mobile device of claim 18 further comprising means for storing sensor data from the at least one environmental sensor and the altimeter and means for determining a change in the sensor data over a predetermined period of time.
22. The mobile device of claim 21 wherein the means for determining a change in the sensor data over a predetermined period of time comprises means for determining whether a rate of change of pressure is caused by a temperature change.