Patent ID: 8217827
Filing Date: 2012-07-10
Classification: G01S

Abstract:
1. A method of detecting a moving object or objects in a region of interest, the region including a multipath rich environment, comprising the steps of: i. arranging at least three transducers about the region in known locations, each transducer being a transmit antenna or a receive antenna, and there being at least one transmit antenna and at least one receive antenna; ii. for a given transmit and receive antenna pair, transmitting a first signal from the at least one transmit antenna, and receiving it at the at least one receive antenna, the signal at the receive antenna being a composite signal made up of signals received from multiple propagation paths; iii, processing the first composite signal to produce a first power delay profile response (alternatively known as an impulse response) representative of the transit time or times of the transmitted signal at the receive antenna; iv. repeating steps ii and iii as necessary for each other transmit antenna and receive antenna pair to produce, for N transmit and M receive antennas, a first set of N×M responses each comprising a power delay profile response, and being representative of the region at a first time; v. repeating steps ii. to iv. to produce a second N×M set of power delay profile responses representative of the transit time or times of arrival of the transmitted signal(s) at the receive antenna(s) and being representative of the region at a second time; vi. calculating a difference between the first and second set of responses, the difference containing values representative of signal strength received for different signal propagation times, and including information relating to object movement between the first and second time; vii. using the transmitter and receiver antenna location information, and the timing information in the power delay profile difference to localise the moving object, the localisation being carried out with the aid of an image, each pixel of which corresponds to a part of the region of interest, and the image comprising information representative of the power delay profile difference, wherein the value of each pixel is based upon an accumulation of the values from each difference corresponding to the propagation delay of a signal passing between each transmit antenna to each receive antenna via that part of the region represented by the pixel.