A method for estimating the location of a
beacon from an ensemble of measurements associated with said
beacon, where, contained in each measurement, are
GPS data from which surfaces of location may be extracted, together with the ID's of beacons detectable at the point of measurement, is disclosed. The method comprises extracting the canonical set of surfaces of location implicit in each of the associated measurements, and determining the estimate of the location of the
beacon as the point for which a weighted sum of the squares of the distances to each of the surfaces so extracted is minimized. A
system for the compilation of a
database of beacon locations from measurements containing a time-stamped recording of the composite GPS
signal (which recording is referred to as a
datagram), together with the ID's and associated
signal strengths of beacons detectable at the point of measurement, is also disclosed. The
system comprises GPS
signal processing means for extracting, from each time-stamped
datagram, the canonic set of surfaces of location, and beacon location
estimation means for estimating the location of a beacon from an ensemble of surfaces of location associated with said beacon.