Embodiments of the present invention are directed to a method and apparatus
for substituting temperature sensor data for a satellite signal in a GPS
receiver. In one embodiment of the present invention, a mathematical model
of a GPS receiver's clock's response to temperature change is maintained.
In one embodiment, the mathematical model is a third order polynomial. In
one embodiment, when a GPS receiver has contact with at least four GPS
satellites, the receiver collects data on changes in temperature and
resulting changes in the GPS receiver's clock frequency. The data is
incorporated into the GPS receiver's mathematical model. In one
embodiment, the data is incorporated by modifying one or more coefficients
in the mathematical model. In one embodiment, if a GPS receiver only has
contact with three GPS satellites, changes in temperature and the
mathematical model are used to estimate an adjustment to the signal
generated by the clock.
