# Which FIR filter window to choose?

I need to design a high pass FIR filter based on parameters given. However I'm stuck at which window i should select. How do I calculate the parameter M?

• In the previous article you can see that the transition band ($\omega_s- \omega_p$) can be used as an estimate of the required main lobe width and therefore find the window length from the given table. e.g. Hann window with transition band of $0.2\pi$ $$\frac{8\pi}{M}=\omega_s- \omega_p$$ $$\frac{8\pi}{M}=0.2\pi$$ $$M=40$$ – Crypted_39 Apr 9 '18 at 14:15