Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

Sound amplitude

Hi, I'm trying to write noise gate in vhdl. I use DE2 board and I wonder how can I compare sound amplitude and threshold in noise gate. How can I check sound amplitude value?
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

In order to estimate the sound amplitude, you can use a modified moving average filter like this:

y[n]=1/N*sum(k=0,k=N-1,|x[n-k]|)

This resembles a full wave rectifier.

if N=2^m you don't need any multiplier. So, you need N registers, N-1 sub/add circuits ("sub" if x[n-k]<0 and "add" if x[n-k]>=0) and a hardwired arithmetic shifter.