[asterisk-users] The High Performance Echo Canceller (HPEC)

[Matthew Fredrickson]

On Feb 14, 2007, at 3:12 PM, shadowym wrote:

> The algorithms may be similar but EC is an infinitely variable
> non-linear(analog) process.  A CPU cannot do that.  You can fake it by
> performing cpu intensive rapid calculations one after another but it is
> fundamentally not an analog processor.  HWEC is designed to deal with 
> the
> analog process on an instant by instant basis performing parallel
> computations.  A CPU cannot do that at ANY clock speed.

I don't think you are seeing this clearly.  The octasic is a processor. 
  It has firmware that loads.  Though it maybe a specialized processor 
with instructions that help with echo cancellation, by the time that a 
HW echo canceller sees the data it is very much not analog anymore.  It 
has already gone through an analog to digital converter and the 
algorithms and math that are used to cancel echo are done in the 
digital domain.  Modern echo cancellation is not done in continuous 
time, it is done in the digital, discrete time.  That means sampled, 
and coming in through a TDM bus of some sort.  Not analog.

Matthew Fredrickson