Patent ID: 7508883

Claim:
A method of finding the time offset between signals transmitted by at least one of a plurality of transmitters (A, B, C) of a communications network and received by a receiver attached to a terminal, the method comprising the steps of (a) creating at the terminal a terminal section (r(t)) of a representation of the signals from the transmitters received by the receiver; (b) creating a first section (S A (t)) of a representation of the signal transmitted by a first (A) of said transmitters, and creating a second section (S B (t)) of a representation of the signal transmitted by a second (B) of said transmitters, each of which sections overlaps in time with the terminal section (r(t)); (c) creating a first function (â(τ)) dependent on the first section (S A (t)) and the terminal section (r(t)), and convolving the first section with the first function to form a blurred estimate (b(t)) of the signal received at the terminal from the first transmitter (A); (d) creating a second function (p A (τ) dependent on the first section (S A (t)), and convolving the terminal section with the second function to form a blurred terminal section (r(t)*p A (τ)); (e) subtracting the blurred estimate (b(t)) from the blurred terminal section (r(t)*p A (τ)) to produce a blurred residual representation (r′(t)=r(t)*p A (τ)−b(t)); and (f) estimating the time offset between the blurred residual representation (r′(t)) and the second section (S B (t)).