Patent ID: 6141293
Filing Date: 2000-10-31
Classification: G01S,Y10S

Abstract:
A method of tracking an object within a surveillance area having a predetermined linear extent, comprising:fixing one or more ultrasound transducers to the object;placing a plurality of background units at known positions in the area, each unit comprising an ultrasound transducer;transmitting one or more ultrasound waves between the object and the plurality of background units;receiving those of the ultrasound waves that propagate between the object and the background units within a time window of a duration such that the product of the duration and the speed of sound is substantially less than the linear extent of the detection area;determining a characteristic of the received ultrasound waves;calculating coordinates of the object responsive to the characteristic; andwherein placing a plurality of background units in the area comprises placing the background units such that for at least one or more of the background units, there are at least some points in the area to which ultrasound waves cannot propagate from the at least one or more background units within the time window.