Systems and methods for pressure-based estimation of a mobile device altitude or calibration of a pressure sensor

A method for pressure-based estimation of a mobile device altitude or calibration of a pressure sensor, the method comprising:

• determining if a reference-level pressure value based on one or more measurements of pressure from a network of weather stations should or should not be used to calibrate the pressure sensor of a mobile device or to estimate an altitude of the mobile device by:
• determining a period of time since an initial time when the reference-level pressure value was originally determined or since the one or more measurements of pressure on which the reference-level pressure value is based were measured;
• and
• determining if the period of time is less than a first threshold amount of time, wherein a first determination is made that the reference-level pressure value should be used when the period of time is less than the first threshold amount of time, and a second determination is made that the reference-level pressure value should not be used when the period of time is not less than the first threshold amount of time;
• if the first determination is made that the reference-level pressure value should be used, using the reference-level pressure value to calibrate the pressure sensor of the mobile device or to estimate the altitude of the mobile device;
• and
• if the second determination is made that the reference-level pressure value should not be used,
• (a) determining a trend in pressure, where the trend indicates a difference in the pressure in time,
• (b) at a first time, determining a first estimated reference-level pressure value based on the trend, and
• (c) using the first estimated reference-level pressure value to calibrate the pressure sensor of the mobile device or to estimate the altitude of the mobile device.