DESIGN OF LOW PASS FIR DIGITAL FILTER USING COMBINATION OF HAMMING & BOXCAR WINDOW FUNCTION

摘要

We are aimed to design a low pass FIR digital filter using new window function. This is nothing but combination of Hamming window function and Boxcar window function. Digital filter is a digital system that can be used to filter discrete time signals. Digital filters are classified either as finite duration unit impulse response (FIR) filters or infinite duration unit pulse response (IIR). In this paper we proposed low pass FIR filter designing. There are numerous methods available for designing of Low pass FIR filters, window techniques is one of them. There are mostly six types of window technique i.e. Rectangular (Boxcar) window function, Hamming window function, Hanning window function, Blackman window function, Bartlett window function, Kaiser-Bessel window function. We designing FIR filter using MATLAB Software. One of the main characteristics of MATLAB is the availability of a set of toolboxes almost ready to be used in the design of filters. MFILTERS is organized around the MATLAB signals toolbox. The idea behind MFILTERS is to take advantage of the expertise already available in this toolbox. The advantage of designing filters in this way is twofold: first, we do not have to program each and every equation. That could take a considerable length of time to do and second, by using this well proven toolbox, we guarantee that there are new errors introduced by programming everything ourselves. It is observed that there is increase in the pass band width of low pass FIR filter using the new window function. In this paper the characteristics of fixed window function Hamming and Boxcar, are compared with new proposed window function i.e. combination of Hamming and Boxcar. Thus it is concluded that this new window function will have a better response in the pass band edge, and also the ripple are less.