I am working on wideband direction finding algorithms for passive sensors.
I started with Music algorithm. For practical reasons, the spacing can not be maintained lambda/2. For greater antenna spacing, grating lobes appear.
I found some algorithms for ambiguity resolving. However, I only found algorithms for resolving ambiguity in presence of only one source signal (eg. one transmit signal). Most of the algorithms (multiple baseline algorithms) take phase difference value for multiple baseline and determines/resolves the angle of arrival value (for one source).
For my application, I am looking at resolving ambiguity for multiple sources with one baseline consisting of 4 to 8 elements (receivers).As for Music algorithm, with 4 sensors its possible to determine 3 sources (maximum) unless any rank enhancement algorithm is applied.
Is there any algorithm which resolves such ambiguity issue?