Patent ID: 7053818
Filing Date: 2006-05-30
Classification: G01S

Abstract:
1. A method for determining the distance of a movable object from an immobile object and determining the speed of the movable object with respect to the immobile object comprising the steps of, (a) generating a pulse train at an immobile object at first location for a first fixed-period-of-time, wherein said pulse train is composed of a predetermined number of pulses having a known width and period; (b) modulating the pulse train with a high frequency carrier radio wave during said first fixed-period-of-time; (c) transmitting said high frequency carrier radio wave to a movable object at a second location during said first fixed-period-of-time; (d) receiving said high frequency carrier radio wave at said movable object during said first fixed-period-of-time; (e) demodulating said pulse train at said movable object while generating said pulse train during said first fixed-period-of-time; (f) remodulating said pulse train at said movable object with a second high frequency carrier radio wave during said first fixed-period-of-time; (g) transmitting said second high frequency carrier radio wave from said movable object to said immobile object during said first fixed-period-of-time, wherein said pulse train remains unchanged as to the number of pulses, pulse width and period; (h) receiving at said immobile object that portion of said second high frequency carrier radio wave that can be received during said first fixed-period-of-time; (i) demodulating the pulse train received at the immobile object in that portion of said second high frequency carrier radio wave; (j) counting the number of pulses in the pulse train in that portion of said second high frequency carrier radio wave; (k) determining the number of missing pulses from that portion of the pulse train in relation to the number of pulses generated in the first fixed-period-of time; (l) dividing the number of missing pulses by two to obtain an average number of pulses traveling between the immobile object and the movable object; (m) calculating the delay time by dividing said first fixed-period-of-time by the predetermined number of pulses and multiplying the result by said average number of pulses; (n) determining a first distance between said immobile object and said movable object by multiplying said delay time by the radio wave propagation velocity; (o) repeating steps (a) through (n) for a second fixed-period-of-time equal to the first fixed period of time to determine a second distance; and, (p) determining the speed of the movable object with respect to the immobile object by taking the difference between the first distance and the second distance and dividing the result by the time between the termination of the first fixed-period-of-time and the start of the second fixed-period-of-time.