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
Is Assembly code/linear assembly code necessary?
Started by ●March 30, 2009
Reply by ●April 25, 20092009-04-25
Reply by ●April 27, 20092009-04-27
Why don't you cascade 2 filters?
Are you sure you have enough dynamic to achieve more than 90dB after computation?
To: c...
From: r...@lntemsys.com
Date: Sat, 25 Apr 2009 17:18:17 +0530
Subject: [c6x] Fir filter with high stop band attenuation
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
_____________________________________
Are you sure you have enough dynamic to achieve more than 90dB after computation?
To: c...
From: r...@lntemsys.com
Date: Sat, 25 Apr 2009 17:18:17 +0530
Subject: [c6x] Fir filter with high stop band attenuation
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
_____________________________________
