Time Domain Implementations Of The Coherent Signal-subspace Transformations

The Coherent Signal-Subspace method for wideband high- resolution direction finding is basically frequency domain based in that, it involves the alignment of signal subspaces at various frequencies by a focusing operation (preprocessing) via transformations. In this paper, we introduce two approaches to implementing the focusing in the time domain based on the principles of Taylor series expansion and least squared error. The time domain preprocessor is realized by a multichannel digital FIR filter thus rendering real-time application. For diagonal transformations, the problem reduces to implementing different delays at each sensor by suitable tapped delay lines. Various tapped delay line filters are proposed and an error analysis is detailed.