Direction of arrival estimation using quadratic time frequency distributions

The paper introduces a novel time-frequency linearly constrained minimum variance (LCMV), also known as Capon method, for the direction of arrival (DOA) estimation of nonstationary signals impinging on a multisensor array receiver. The results are compared with the conventional Capon method of DOA estimation technique. In Capon method, the weights are chosen to minimize the weighted array power output subject to the unity gain constraint in the desired look direction. Time-frequency distributions localize the signal power in the time-frequency domain and as such enhance effective Signal to noise ratio (SNR), leading to improved DOA estimates. Time-frequency distributions result in signal separation in the time-frequancy domain and hence fewer signals can be selected for processing. Therefore, the interference signals are eliminated by selecting proper time frequency regions. This paper focuses on the class of frequency modulated (FM) signals because of their clear representation in time-frequency plane.