Windowing techniques are used in FIR filter design to convert an infinite impulse response to a finite impulse response. The process involves choosing a desired frequency response, taking the inverse Fourier transform to get the impulse response, multiplying the impulse response by a window function, and realizing the filter. Common window functions include rectangular, Hanning, Hamming, and Blackman windows, which are selected based on the required stopband attenuation. The windowing technique allows designing FIR filters with a simple process but lacks flexibility compared to other design methods.

1. WINDOWING TECHNIQUES OF
FIR FILTER DESIGN
Presented by,
SoumilAgarwal (J001), Aayush Maheshwari (J015), Rohan Nagpal (J019),Vibhuti Maheshwari (J036)

2. WHAT IS AWINDOWING?
A window is a finite length sequence.
Windowing is a process of forming a finite length
sequence from an infinite length sequence by
multiplying an infinite length sequence with a window.

3. GENERAL PROCEDURE FORWINDOWING
1. Choose the desired frequency response of the filter Hd (ω)
2. Take inverse fourier transform of Hd (ω) to obtain the desired impulse response hd
(n)
3. Choose a window sequence W(n) and multiply hd (n) by Hd (n) to convert IIR to FIR
h(n)=W(n) x hd (n)
4. Taking ZT of h(n) we obtain a transfer function H(z)
5. Realize the filter using suitable filter method

4. TYPES OF WINDOWS
WINDOWS
Rectangular Hanning Hamming Blackman Bartlett
Depending on the stop band attenuation we will select a window. Stop band attenuation (As) are the
lower limits of attenuation.
For example, if As is 40 dB, we will choose HanningWindow

5. WINDOW EQUATIONS

6. EXAMPLE

7. STEP 1- CHOOSETHE DESIRED FREQUENCY

8. STEP 2 –TO FIND Hd (n)

9. STEP 3 – CONVERSION OF FINITETO
INFINITE SERIES

10. STEP 4–TO FIND H(z)

11. STEP 5 - LINEAR PHASE REALISATION

12. ADVANTAGES AND DISADVANTAGES
 Simple – involves minimum computation
 Maximum ripple amplitude in filter response is fixed regardless of how large the
filter order is
 Lack of flexibility
 When the expression for the desired filter response Hd(e^jw) is complicated or
cannot be put into a closed form mathematical expression, evaluation of Hd(n)
becomes difficult.

13. THANKYOU