POSITION DETERMINING SYSTEM

The invention relates to a position determining system, for receiving digital telephone signals transmitted by a number of transmission sources BTS. In particular there is described a method of estimating the offset in time of receipt of a broadcast signal received at two locations (CBU,CRU), where the signal received at the one location (CRU) may have been subject to corruption by multipath effects. To overcome this problem, the signals received at the one location are auto-correlated and the signals received at the other location are auto-correlated. The signals received at the two locations are cross-correlated and a template comprising that portion of the auto-correlation of the signals received at the other location corresponding to the negative time axis, and that portion of the auto-correlation of the signals received at the one location corresponding to the positive time axis is constructed. The offset at which the template best fits the measured cross-correlation of the signals received at the two locations is measured as an estimate of the time offset between the signals received at the two locations.