Short Transient IIR Multinotch Filter With Time-Varying Parameters and Nonzero Initial Conditions

In this article, an analytical concept and hardware verification of the time-varying infinite impulse response narrow multiband-stop filter with nonzero initial conditions are presented. The time variability of the filter parameters and nonzero initial conditions are introduced to the filter structure in order to reduce its transient response. Such a filter can be very useful in various measurement systems. In particular, short transient filters are very desirable for processing signals whose initial part is of great importance. In this article, the algorithm for finding the length of the initial conditions vector is presented. As an example, the proposed IIR multinotch filter is used for removing power-line interferences from the ECG signal. Computer simulations, hardware verification, and performance indices demonstrate that the proposed time-varying IIR multinotch filter with nonzero initial conditions possesses much better properties than the traditional time-invariant filter with zero initial conditions.