float32 application: FFT
reimay
Posts: 5
Hello all,
I use the float32 library to perform a Fast Fourier Transform on Propeller.
To take a step forward, i implement the algo in spin.
In next step i want to alter to native assembler.
Also I would like to process real world input signal.
Currently the program calculate several input signals, run the fft and display
the result on vga screen.
The input signals from left to right are a linear ramp, a dirac impuls, a sine
and a sin/cos mix.
Under the inputs the corresponding fft results are displayed.
My roadmap is:
·change to assembler
·use real signals ( e.g. microphone sample )
·very interesting experiments:
··make it sense split the fft in several cogs
··e.g. one cog run the sin multiplication, another run the cos multiplication ... ( like a vector processor )
· ...
· ...
·· HAVE FUN WITH THE PROPELLER
Best Regards
p.s.: please excuse for my broken english
I use the float32 library to perform a Fast Fourier Transform on Propeller.
To take a step forward, i implement the algo in spin.
In next step i want to alter to native assembler.
Also I would like to process real world input signal.
Currently the program calculate several input signals, run the fft and display
the result on vga screen.
The input signals from left to right are a linear ramp, a dirac impuls, a sine
and a sin/cos mix.
Under the inputs the corresponding fft results are displayed.
My roadmap is:
·change to assembler
·use real signals ( e.g. microphone sample )
·very interesting experiments:
··make it sense split the fft in several cogs
··e.g. one cog run the sin multiplication, another run the cos multiplication ... ( like a vector processor )
· ...
· ...
·· HAVE FUN WITH THE PROPELLER
Best Regards
p.s.: please excuse for my broken english
Comments
I would love to see someone from parallax get involved and produce
code objects for real and complex ffts for different fft algorithms.
Can you parallax guys do that ?
Good job !!
Really could be great, get a reverb effect in real time....would be possible in assembler with the PChip ?
Regards.
Alberto.
This is excellent. A great way to learn about FFT's.
Is there any chance you have done a similar program to calculate the inverse FFT?
Thanks,
Jim C
I will do the IFFT in next time.
Here is a link for a intuitive FFT entry:
http://sepwww.stanford.edu/oldsep/hale/FftLab.html
This was very helpfull for myself.
Best Regard, reimay
I am trying to do something very similar.· I would like the prop to be able to read the levels of certain frequencies within an audio signal.· Do you think your work is capable of doing this?· If so, do you think you could help me make it work?
Thanks!
Dave
[noparse]:)[/noparse]
Since I work on this application only after my work, this is very slow in progress.
I found several items:
The Floating point engine is too slow for real time application.
I measured 160 ms for this 64 point FFT. (fast enough to analyse earthquakes, but not audio
Off Course this algo is not optimized, but I think the better way is to use a fixed point calculation,
instead the floating point.
So I have to learn about fixed point stuff, and I can not guess when finished.
Best Regards, reimay
If I say : this algo is not optimized
I mean my FFT- Algorithm, not the Float32- Object !!!!!!!!!
Best Regards, reimay