[asterisk-dev] Zaptel Echo Cancellation

[Andrew Kohlsmith]

On Thursday 03 August 2006 11:09, Eric "ManxPower" Wieling wrote:
> > Is there not an inherient delay of several ms due to CPU and encoding
> > overhead etc or is this not a factor in the calculations? I'm just
> > wondering what kinds of delays play into this or is the only thing that
> > matters the delay on the PSTN before the signal hits the card?

> The PSTN delay is what matters.  Echo must be removed at the PSTN
> interface.

When the echo cancellation is being done in software on the PC (i.e. in 
zaptel), you need to account for the PCI delay and processing delays as well, 
do you not?  That is the advantage of the hardware echo cans; they work on 
the echo "closer" to the source.

-A.