Systems and methods for determining a reference pressure for use in estimating an altitude of a mobile device

One or more non-transitory machine-readable media embodying program instructions that, when executed by one or more machines, cause the one or more machines to implement a method for estimating an altitude of a device based on one or more monitored pressure conditions, wherein the method comprises:

• using a first reference pressure sensor at a first location to determine a pressure measurement;
• determining, using the pressure measurement, a reference pressure that specifies an estimated pressure for a reference altitude;
• determining a measurement of pressure using a pressure sensor of the device;
• determining, using one or more machines, if a pressure change condition is met by determining if a threshold change in measured pressure by the first reference pressure sensor is detected,
• determining, if the threshold change in measured pressure by the first reference pressure sensor is detected, that the pressure change condition is met, and
• determining, if the threshold change in measured pressure by the first reference pressure sensor is not detected, that the pressure change condition is not met;
• if the pressure change condition is met, determining a calibration value for the first reference pressure sensor using the one or more machines;
• if the pressure change condition is not met, identifying a previously-determined calibration value using the one or more machines;
• determining, using the one or more machines, an adjusted reference pressure,
• wherein if the pressure change condition is met, the adjusted reference pressure is determined using the reference pressure and the calibration value determined for the first reference pressure sensor, and
• wherein if the pressure change condition is not met, the adjusted reference pressure is determined using the reference pressure and the previously-determined calibration value;
• and
• determining, using the one or more machines, an estimate of the altitude of the device using the adjusted reference pressure and the measurement of pressure from the pressure sensor of the device.