Patent ID: RE42546

Claim:
A method of estimating a minimum range from an ownship to a target at a closest point of approach (CPA) between the target and the ownship , comprising: a. a bearing detector obtaining at least three bearing data points of the target with respect to an the ownship , wherein each of said bearing data points includes a bearing angle and a corresponding time of acquisition ; b. using the three bearing data points to determine a speed contribution V os of a first point of interest to a distance from a relative velocity vector over a time frame comprising an initial time t o to a predetermined time t i ; c. a computer system determining an angle θ β as defined as , where θ β is the bearing relative to the ownship's heading at the point in time (t β ) of the closest point of approach to a second point of interest ; and d. the computer system calculating a minimum range Min R CPA using the formula : Min R CPA =V OS (t β −t i )cos(θ β −θ i ) θ i |=0 ; using the calculated minimum range for at least one of: targeting a weapon with respect to the target, navigating the ownship; e. wherein t β is the time at which θ β was mreaured and θ i is a bearing angle to the target relative to the ownship corresponding to a first of said at least three bearing data points obtained at time t i , and V os is the speed of the ownship during said obtaining said at least three bearing data points .