Fir

Forger it, I did a adc/ dac circuit with a
connections mistake...
Now I tried example bandpass, fine, but I
need steeper slopes and low ripple over
3khz, I increased to 200 taps with result not very good
I wonder if floating point and full 16 bit
(4.0 + i2s board)
could give better performance
 
In addition I'll need explaination about the
mention in the design tool :
The impulse response must be given in
reverse order
(I am quite a noob in DSP)
 
Using the technical terms you'll find in DSP books, convolution (FIR filtering) is the same as cross-correlation with a time-reversed finite impulse response, so it is often implemented by cross-correlation as you only need one index variable.

Steeper slopes or lower frequency poles/zeroes mean more taps are required - IIR filters can be significantly more efficient, note.

If you do need a high tap count then FIR filters are best implemented using FFT techniques. You'll find a few threads about such things on these forums if you delve about.
 
Thank you, I understand more or less thèse
basics but I focus on actual implementation
I did a quick and dirty with a 3.2 (fixed point
math), adc (13 bit) dac (12 bit), no special signal conditioning
The online calculator promised a nice -45db
on slopes and a "roof" ripple less than 1 dB.
Tested and obtained too much ripple and
less out band atténuation
Then I wonder if is worth spend 50 euro for
4.0 + Audio Shield.
 
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