Superresolution DoA Estimation With Circular Arrays Using Signal Segregation Algorithm in Conjunction With a Nulls-Synthesis Method

A method for superresolution direction-of-arrival (DoA) estimation of correlated signals using a circular array is presented. This is accomplished in two steps: 1) the directions of arrival and amplitudes of signals with angular spacing larger than the array beamwidth are detected using the array signal segregation using an iterative approach (ASSIA) and 2) signals with angular proximity smaller than the array beamwidth are separated using a novel closely spaced nulls-synthesis method (CNSM). It is demonstrated that the proposed ASSIA-CNSM is superior to the other superresolution DoA estimation techniques such as maximum-likelihood method. The experimental results indicate that ASSIA-CNSM can be effectively used to distinguish the DoAs of the signals with angular spacing as small as 0.15 BW (where BW is the array half-power beamwidth) and with signal-to-noise ratio as low as 5 dB.