Cambridge Positioning Systems Limited

Simon David Hern

Robert Willem Rowe

Peter James Duffett-Smith

Murray Robert Jarvis

Ben J Tarlow

Nicolas Guy Albert Graube

Christopher R Drane

A method of determining the location of a mobile receiver is provided. The method works within a radio system in one or more dimensions, the radio system includes a network of transmitters the positions of which are known. The method comprises the steps of: compiling a list of the signals detected by the receiver, sending said list to a calculation device; constructing a position function which relates to the probability that the receiver is at a given location, which position function has components corresponding to each member of the list, each component including a predetermined probability function that depends on mobile receiver position; and evaluating said position function to determine a position that corresponds to the highest probability of location, and defining that position to be the location of the mobile receiver.

Method and system for locating a mobile radio receiver in a radio system with multiple transmitters

In a terminalhaving a receiverfor receiving the signals from plural transmission sources-whose positions and transmission time offsets are unknown within the terminal, a method is provided for determining the change in the time (elapsed time) at the terminal between two instants. At a first position of the terminal a first set of measurements, aligned to a first instant, of a signal parameter representative of the time or phase of receipt of said signals from said plural transmission sources relative to one or more of them, or to a reference, or to a terminal clock is obtained. Then at a second position of the terminal a corresponding second set of measurements, aligned to a second instant, of a signal parameter representative of the time or phase of receipt of said signals from said plural transmission sources relative to one or more of them, or to the reference, or to the terminal clock is also obtained. The aligned measurements of the first and second sets are combined, and the time elapsed between the first and second instants is calculated from the change in the combined aligned measurements of the first and second sets.

Determining the change in time at a mobile terminal

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Cambridge, United Kingdom

Simon David Hern