Digital Nonrecursive FIR Filter Design Using Exponential Window

Recently it has been found that the Exponential window gives better side-lobe roll-off ratio compared with Kaiser window. That difference is important for some applications like beam forming, filter design, and speech processing. In this thesis, the design of digital non-recursive finite impulse response (FIR) filter by using Exponential window is proposed. One of the most effective variables is the far-end stopband attenuation especially when the signal needed to be filtered has a great concentration of spectral energy. In a sub-band coding, the filter is intended to separate out various frequency bands for independent processing. When it is applied on speech, the far-end rejection of the energy in the stopband needs to be as higher as possible to make leakage of the energy from one band to another as lower as possible. Therefore, the designed filter should have special specifications which should provide better far-end stopband attenuation (amplitude of last ripple in stopband). Finding a digital filter that has a higher performance far-end stopband attenuation than Kaiser window is very valuable when the FIR filter constructed by the use of Kaiser window far-end stopband attenuation becomes better than the one constructed by the well-known adjustable windows, for instance, the special cases of Ultraspherical windows, Dolph-Chebyshev and Saramaki. In this thesis, the construction of non-recursive digital FIR filter has been presented through applying Exponential window. After applying the Exponential window, it is found that the far-end stopband attenuation becomes better than the filter constructed by Kaiser window, and that is one of the advantages of filter building by using Exponential window over Kaiser window. The proposed scheme is simulated by MATLAB. All the simulation results show a good agreement with the proposed theory. Keywords: Digital FIR Filter, Side-lobe Roll-off Ratio, Far-end Stopband Attenuation, Window Technique, Kaiser Window, Exponential Window