Patent ID: 6894644
Filing Date: 2005-05-17
Classification: G01S

Abstract:
1. A method of finding the position or state of motion of a terminal in a communications network having a plurality of transmitters, the terminal having a radio receiver, the method comprising the steps of (a) creating at the terminal a section of a representation of the signals from the transmitters received by the radio receiver; (b) creating a first section of a representation of the signal transmitted by a first of said transmitters, and creating a second section of a representation of the signals transmitted by a second of said transmitters, each of which sections overlaps in time with the section created at the terminal; (c) calculating an estimate of the signal received at the terminal from said first transmitter using said first section, and subtracting said estimate from the section created at the terminal, to produce a residual representation; (d) performing a calculation using said residual representation and said second section, and estimating the time offset between them; and (e) calculating the position of the terminal using said time offset.