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djaram ·
Could someone help me to figure out how to write a simple code for cutoff?
I looked at the State variable Filter code, but couldn't really understand the procedure.
Is there a good DSP source so I can see what should be done on the stream?
Regards,
Shifrin ·
You might want to take a look at these :-
http://www.dsptutor.freeuk.com/dfilt1.htm http://www.biochem.oulu.fi/~oniemita/dsp/dspstuff.txt http://www.dspguide.com/
Then come back with any questions 😉 (Which I'm sure someone can help answer - probably not me though I only know enough to fiddle around with filters!).
Shif.
djaram ·
TYVM for the links Shiff,
They are really useful and what I was looking for.
Regards,
djaram ·
Ok I read some part of those but still I can't figure out what really Cutoff means in samples. I mean i know what is does but i don't know how it does it.
Is it a recursive function? Could someone put a very very simple code with comments?
Regards,
skOre ·
I have still got to really understand this, but AFAIK filters are actually the same signal copied, phase shifted and added again. Due to cancellations, parts of the signal are deleted.
A simple code would look like this:
streamin in; streamin cutoff; streamout LP; float out1; LP=LP+((in-out1)*cutoff); out1=LP;
But somebody else has to explain this 😀
stefan ·
In an IIR filter it can be viewed as recursive, since it relies on it's own previous calculations.
Basicly, the above example from sk0re is a function needing itself as input: f[x] = a * x + b * f[x-1], which indeed makes it recursive.
For FIR filters this doesn't apply though.
djaram ·
Thanks a lot, Stefan and Skore.
I'm gonna do some experiments based on this issue.
Regards,
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