Patent ID: 8121225

Claim:
A method of estimating the angle of arrival of a signal received by an array of commutated antenna elements, wherein there is a temporal boundary at the instant of commutation between antenna elements, comprising the steps of: (a) preprocessing samples of a signal received by an array of commutated antenna elements to construct estimates of the received signal for points in time that are immediately adjacent the temporal boundaries and thereby provide a preprocessed signal; and (b) estimating the angle of arrival of the received signal by processing the preprocessed signal; wherein step (b) comprises the step of: (c) for a low-band type of antenna, making a maximum-likelihood-estimation of the angle of arrival of the received signal; and wherein step (c) comprises the step of: (d) for a low-band type of antenna having a whip-antenna and a loop antenna as elements of the array, when the modulation of the received signal is known and the frequency offset of the received signal is unknown, making the maximum-likelihood-estimation of the angle of arrival φ of the received signal in accordance with the equation: φ=argmax φ ∥BΔy∥ 2 which is solved as a search for the values of φ and D that maximize ∥BΔy∥ 2 wherein B=W*A*, where (A*A) −1 =WW* for some W, which may be computed by Cholesky factorization or by LDU factorization, and where A = ( + cos ⁡ ( ϕ ) - ⅈ ⁢ ⁢ D + sin ⁡ ( ϕ ) - ⅈ ⁢ ⁢ D - cos ⁡ ( ϕ ) - ⅈ ⁢ ⁢ D - sin ⁡ ( ϕ ) - ⅈ ⁢ ⁢ D ) y is a vector of the constructed estimate components of the preprocessed signal; and D is some unknown constant relating the gains of the whip and loop antenna elements.