Tracking of bandpass signals using center-frequency adaptive filters

A class of constrained adaptive filters, called recursive center-frequency adaptive filters, is applied to the tracking of bandpass signals. For this application, these filters form a class of completely digital tracking filters which are shown to have several advantages over existing analog and semidigital tracking filters. A procedure of analyzing the tracking behavior of these filters using the ordinary differential equation approach is presented. The tracking performance of two examples of these filters is analyzed for step, ramp, and sinusoidal variations of the input signal center frequency, and these are shown to track the signals very effectively. The dependency of the performance on the parameters of the algorithm, transfer function of the filter, and the input signal is studied