Estimating the Location of a Wireless Terminal Based on Dissimilar Barometric Pressure References

A method comprising:

• receiving, from a first barometer, a first measurement of absolute barometric pressure p1 at a first moment-in-time t1;
• receiving, from a second barometer, an indication of a change in barometric pressure Δp at the second barometer during a time-interval Δt;
• receiving, from a wireless terminal, a second measurement of absolute barometric pressure p2 at a second moment-in-time t2, wherein the second measurement of absolute barometric pressure p2 is measured by a third barometer in the wireless terminal;
• generating an estimate of the altitude of the wireless terminal at the second moment-in-time t2, based on:
• (i) the second measurement of absolute barometric pressure p2, and
• (ii) a reference barometric pressure p0 that is based on:
• (1) the sum of p1+Δp, and
• (2) an estimate of the altitude of the first barometer;
• and
• transmitting, to a location-based-application server, the estimate of the altitude of the wireless terminal.

A method comprising:

• receiving, from a first barometer, a first measurement of absolute barometric pressure p1 at a first moment-in-time t1;
• receiving, from a second barometer, an indication of a change in barometric pressure Δp at the second barometer during a time-interval Δt;
• generating a second measurement of absolute barometric pressure p2 at a second moment-in-time t2, wherein the second measurement of absolute barometric pressure p2 is measured by a third barometer in a wireless terminal;
• generating an estimate of the altitude of the wireless terminal at the second moment-in-time t2, based on:
• (i) the second measurement of absolute barometric pressure p2, and
• (ii) a reference barometric pressure p0 that is based on:
• (1) the sum of p1+Δp, and
• (2) an estimate of the altitude of the first barometer;
• and
• transmitting, to a location-based-application server, the estimate of the altitude of the wireless terminal.