Abstract: Method and apparatus for providing accurately synchronised timing signals at mutually distant locations employs a GPS or similar receiver at each location. These receivers are interconnected by a communications network, and exchange data over the network to agree a common timing reference.

Abstract: A method of determining the position of a target comprising the steps of: providing a transmitter or a plurality of transmitters to transmit a signal to the target, providing a receiver or a plurality of receivers to receive signals reflected from said target. Determining the time of arrival information of said reflected signal at the or each receiver; using information pertaining to the position of the or each receiver and/or the or each transmitter and with the information obtained determining the target position. Preferably the signal includes a modulated or coded portion unique to the transmitter; and said signal portion is associated with the or each particular transmitter by virtue of said signal portion. The signal maybe a mobile phone transmission, DAB, digital TV, digital Radio or digital satellite transmissions.