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Discussion Groups | Analog Devices DSPs | noise from fft() in VDSP library
Technical discussions related to Analog Devices DSPs (including Blackfin, TigerSHARC, SHARC and ADSP-21xx DSPs).
noise from fft() in VDSP library - prasanth rajagopal - Dec 8 12:40:00 2005
hi,
the fft() and ifft() in library of the VDSP gives values which are 4 times scaled..Now if I want to use this for an audio algorithm, I am getting large noises.. Is there a remedy? Do everyone get it same? Then where do I get an error free 16 bit implementation of FFT in blackfin?
the fft() and ifft() in library of the VDSP gives values which are 4 times scaled..Now if I want to use this for an audio algorithm, I am getting large noises.. Is there a remedy? Do everyone get it same? Then where do I get an error free 16 bit implementation of FFT in blackfin?
with regards,
prasanth
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Re: noise from fft() in VDSP library - Mike Rosing - Dec 8 23:36:00 2005
On Fri, 9 Dec 2005, prasanth rajagopal wrote:
> hi,
> the fft() and ifft() in library of the VDSP gives values which are 4
>times scaled..Now if I want to use this for an audio algorithm, I am
>getting large noises.. Is there a remedy? Do everyone get it same? Then
>where do I get an error free 16 bit implementation of FFT in blackfin?
What are you doing in between? If you just run fft and then ifft I'd
expect a difference in output, and that could be called noise. If you try
to filter with an fft and ifft, you need to be careful.
The best remedy is to write your own software that does exactly what you
want.
Patience, persistence, truth,
Dr. mike
(You need to be a member of adsp -- send a blank email to adsp-subscribe@yahoogroups.com )
> hi,
> the fft() and ifft() in library of the VDSP gives values which are 4
>times scaled..Now if I want to use this for an audio algorithm, I am
>getting large noises.. Is there a remedy? Do everyone get it same? Then
>where do I get an error free 16 bit implementation of FFT in blackfin?
What are you doing in between? If you just run fft and then ifft I'd
expect a difference in output, and that could be called noise. If you try
to filter with an fft and ifft, you need to be careful.
The best remedy is to write your own software that does exactly what you
want.
Patience, persistence, truth,
Dr. mike
(You need to be a member of adsp -- send a blank email to adsp-subscribe@yahoogroups.com )