Adaptive parameter estimation for a constrained low-pass system

A novel algorithm is presented for adaptive parameter estimation for a constrained low-pass Butterworth system model. The algorithm will estimate the system cutoff frequency and gain online. When it is known that the true system has a low-pass Butterworth structure or some transfer function similar to it and its true order is used, the algorithm will lead to a substantial savings in computation and more accurate results than unconstrained algorithms. Potential applications include filter design and adaptive decision on Nyquist rate for systems