An augmented smoothed rank profile algorithm for determination of source coherency structure

This correspondence deals with the problem of determining the source coherency structure and estimation of directions of arrival in the presence of coherent signals. The method is closely related to the smoothed rank profile (SRP) algorithm presented in [3], which Manuscript received July 20, 1987; revised October 3, 1988. This work was supported by the Naval Physical and Oceanographic Laboratory (N.P.O.L.) and the Department of Electronics (D.O.E.), Government of India. S. Prasad is with the Department of Electrical Engineering, Indian Institute of Technology, New Delhi 110 016, India. B. Chandna is with the Centre for Applied Research in Electronics, Indian Institute of Technology, New Delhi 110 016. India. IEEE Log Number 8928133. shows that for determining the source coherency structure, the number of elements required is greater than or equal to the total number of sources plus the highest degree of signal coherency present. In the modified approach suggested here, we show how the SRP method can be augmented by the incorporation of "forward-backward" averaged covariance to increase the likelihood of successful determination of source coherency structure (SCS) with a limited number of sensors. We would like to caution, however, that for some situations, the modified approach may not yield the desired increase in the array aperture.