Cambridge Positioning Systems Limited

John Christopher Clarke

Peter James Duffett-Smith

Robert Willem Rowe

Malcolm David MacNaughtan

James Brice

Malcolm David Macnaughtan

The present invention sets out to overcome the hearability problem in CDMA communications networks in which positioning services are provided, by using a separate sampling devicefor each transmitter, which sends to the computing devicea representation of the signals transmitted only by that transmitter. A cross-correlation of the representation sent back by the mobile terminalwith the representation sent back by the sampling device in the brightest transmitter is performed in the computing device, and a blurred estimate of that brightest signal is subtracted from a blurred version of the representation sent back by the mobile terminalin order to reduce its effect on the remaining signals as far as possible. The cross-correlation and subtraction steps are iterated until no useful signals remain to be extracted.

Radio positioning systems

A location measurement unitfor a radio location measuring system has two or more coupling devicesfor picking up the signals from a plurality of base transceiver stations (BTSs) of a cellular radio communication system. A switching device, is connected to the coupling devices, for switching between the signals picked up by the coupling devices and/or one/two or more receivers-are connected to respective coupling devices, for receiving the signals picked up by the coupling devices. A processoris connected to the or each receiver, for processing the signals output by the receiver. A communications linkis connected to the processor, for transferring the processed signals to a calculation node

Radio location system measurement unit

The present invention sets out to overcome the hearability problem in CDMA communications networks in which positioning services are provided, by using a separate sampling device () for each transmitter (), which sends to the computing device () a representation of the signals transmitted only by that transmitter. A cross-correlation of the representation sent back by the mobile terminal () with the representation sent back by the sampling device in the brightest transmitter is performed in the computing device (), and an estimate of that brightest signal is subtracted from the representation sent back by the mobile terminal () in order to reduce its effect on the remaining signals as far as possible. The cross-correlation and subtraction steps are iterated until no useful signals remain to be extracted.

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Cambridge, United Kingdom

John Christopher Clarke