Application of CTLS for estimating the direction of arrival of cyclostationary signals

The cyclic constrained total least squares (CCTLS) is developed as an alternative to W.A. Gardner´s cyclic MUSIC (1988) and to the technique of G. Xu and T. Kailath (1989) for estimating the direction of arrival of cyclostationary signals impinging on the elements of an antenna array. CCTLS exploits the fact that a narrowband cyclostationary feature of a signal has the same delay at the various array elements as the signal itself. By extracting the narrowband feature at each antenna element, traditional CTLS can be applied. Whereas most direction finding techniques rely on the narrowband assumption, CCTLS is most appropriate for wideband signals in which estimates of the carrier frequency and symbol rate are available or can be derived. CCTLS is shown to be more interference-tolerant than cyclic MUSIC and to be able to separate signals from the same direction with the same symbol rates but with different carrier frequencies