Orthogonal cascade realization of real multiport digital filters
E. Deprettere, P. Dewilde · International Journal of Circuit Theory and Applications · 1980
Abstract A generally applicable theory for multiport orthogonal digital filter synthesis is discussed, using a direct algebraic method. Standard (complex) degree 1 and irreducible (real) degree 2 chain scattering matrices are derived and the computability problem which normally occurs in such filters is discussed and solved for the general case. It is shown that any finite causal and lossless real multivariate system can be realized as a computationally compatible cascade of real degree 1 and degree 2 factors consisting of an orthogonal constant interconnecting part and a lossless dynamic portion. In order to increase the practical interest of the paper, realizations of these sections are explicitly given. The known scalar wave digital filter ‘adaptors’ emerge as a special case of the theory presented in this paper. The general results are of interest in multiport digital signal processing, in multivariate interpolation theory and in multichannel prediction and modelling theory and techniques.