Howdy Ramaraju,
An FIR can get that good if you have enough taps. So it depends on how
much delay you can live with. If you need faster response time, then an
IIR might be a better choice - the trade off is more ripple and non-linear
phase shifting. If you use a 1000 tap filter you have almost 1/2 second
delay, but you'll get almost a brick wall filter. What can your system
response live with?
Patience, persistence, truth,
Dr. mike
On Sat, 25 Apr 2009, rama raju wrote:
>
Hi ,
I am facing some problem with filter implementation.
Sampling frequency of my ADC %60hz . ADC will give data
which have frequency range from 0-5120hz. Because of hardware limitation I
cannot
down sample below 2560hz. But signal of interest is 0-to 5 0hz. So after
acquiring
data from adc I am implementing fir filter whose sampling frequency is
10240hz,
and cutoff frequency 50hz. After that I am decimating filtered data by 20
times. I mean to say that actually I am
over sampling the signal 20 times.
Fs= 2560
FcPhz
Decimation factor ;
So effective sampling frequency is = 2560/20= 128hz
My fft spectrum show
frequencies range from 0-64hz.
According my system requirement anything above -80db will be
considered to the signal. In order to achieve this, I should select my filter
stop band attenuation >90db.
But conventional FIR filter cannot give this much attenuation.
Can anyone suggest some technique to achieve this..
Thanks in advance,
Regards,
Ramaraju
