Orthonormal bandlimited Kautz sequences for global system modeling from piecewise rational models

Frequency-domain rational macromodeling techniques have to be limited to relatively small frequency ranges or to a limited number of poles, mostly due to numerical issues. A pertinent problem in system modeling is therefore to come up with a global broad-band macromodel, given a number of piecewise rational, possibly disjoint, small-band models. We describe an effective implementation procedure, based on orthonormal bandlimited Kautz sequences. As a first step, we show how a truncated Kautz basis can be obtained directly from a judiciously chosen state-space description. Next, having incorporated the bandlimitedness requirement, we obtain imbeddable orthonormal bandlimited Kautz sequences. A numerical procedure for calculating the underlying bandlimited scalar products and Grammians, as applied to piecewise bandlimited state-space data, is implemented and tested