How to choose the correct passband frequency and stopband frequency of a low pass Equiriple Fir filter?

I design a low pass Equiriple Fir filter with 3 dB of ripple in the pass-band from 0 to 64 Hz and at least 60 dB of attenuation in the stop-band. I want to know the correct passband frequency and stopband frequency I choose here the passband frequency 0.45π and stopband frequency 0.5π

and with this the passband frequency 0.45π and stopband frequency 0.49π

and here the passband frequency 0.49π and stopband frequency 0.5π

Can anyone help me to choose the right one?

Answer 1

[Star Strider]

The ‘right’ filter is the design that does what you want it to do considering your data.

With FIR filters, the filter length increases significantly with shorter transition regions (steeper rolloffs). For example, if you have a short data vector, the third design (passband frequency 0.49π and stopband frequency 0.5π) may be too long to work with your data.

Shorter filters are more efficient, so if the filters you posted all give the same essential performance (as I expect they would), I would use the first design, with the passband frequency 0.45π and stopband frequency 0.5π.

[afef]

Ok,i understand. Thanks

[Star Strider]

My pleasure.