Elimination of ambiguity in estimates of the arrival directions of broadband signals in multisignal bearing mode

Direction finding of wideband signals overlapping in the spectral domain by a fixed antenna array requires the correction of steering vector ambiguity and phase differences corresponding to different spectral components. The spectral components of the same signal correspond to unequal values of the distance in wavelengths between the antennas in the array. A method of steering vector ambiguity correction suitable for subspace methods such as MUSIC and ESPRIT is proposed. The ambiguity in the presence of multiple signals is resolved by correcting phase diffe-rences between antennas for each spectral component, with preliminary correlation of the ambiguous steering vector with unambiguous ones obtained for the low-frequency range of the spectrum using maximum correlation. The corrected steering vector for each spectral component is obtained from the adjusted phase differences between the antennas and is used in the direction finding correlation algorithm to obtain unambiguous estimates of the directions of arrival of the wideband signals. Simulation results for direction finding of five sound wideband signals using a square internally filled antenna array consisting of 16 antennas, based on ESPRIT with the proposed method of ambiguity correction, are presented. The proposed method for correcting the steering vector ambiguity caused by different spectral components of wideband signals in the antenna array allows estimation of their directions of arrival, as is done for narrowband radio signals.