Patent ID: 7228244

Claim:
A direction tracking method to track a direction-of-arrival of radio waves from a moving signal source by estimating directions-of-arrival of radio waves with an array antenna having a plurality of antenna elements arranged in different spatial locations along a straight line at identical adjacent spacing, the method comprising the steps of: calculating an instantaneous correlation between data received by the antenna elements at each sampling time; calculating an instantaneous correlation matrix from the instantaneous correlation; estimating a noise subspace through a linear operation using the instantaneous correlation matrix; predicting state vectors of directions-of-arrival at a current direction updating time with an observer by using state vectors of directions-of-arrival at a previous direction updating time; calculating provisional estimates of the directions-of-arrival at the current direction updating time based on predicted values of the directions-of-arrival obtained from the predicted state vectors and based on the noise subspace; calculating the state vectors at the current direction updating time based on the provisional estimates, the predicted state vectors, and the predicted values to calculate estimates of the directions-of-arrival; and outputting the estimates of the directions-of-arrival for instantaneous beamforming.