A first set of coordinates (100) of a device and an estimated positional
error ("EPE") radius (102) is measured. An EPE circle (104) is derived, in
which the device is approximately located, from the first set of
coordinates (100) and the EPE radius (102). When it is determined that the
EPE radius (102) exceeds a predetermined threshold, a first range (106)
between the device and a ranging site (108) is measured, and a locus of
points (110) on and within the EPE circle (104) is determined, wherein a
distance between the ranging site (108) and each point in the locus of
points (110) approximately equals the first range (106).
