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

[shadowym]

I gotta take issue with your comments that a HWEC is just software running
on a DSP.  In the case of Octasic, it's an ASIC.  How it does EC is VERY
different because.....it's done completely in hardware, not firmware loaded
into memory and run on a specialized CPU!  Yes, the ASIC does contain an DSP
but it is customized for EC.  You cannot think of it as a CPU. 

-----Original Message-----
From: Nic Bellamy [mailto:nicb-lists at vadacom.co.nz] 
Sent: Tuesday, February 13, 2007 5:43 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [asterisk-users] The High Performance Echo Canceller (HPEC)

shadowym wrote:
> Interesting,
>
> Is this just a more advanced software echo canceller or software with 
> hardware hooks or software with hardware assisted processing?
>   
A more advanced software canceller (there's no magical thing that makes
"hardware" echo cancellers better, it's still software, but it's running on
a DSP so it has more grunt available to it).

It's licensed from Adaptive Digital Technologies - G.168 compliant, and
supports up to 1024 taps (128ms) of tail coverage. Comes as a binary blob,
but such is life.
> How would it compare to a true hardware echo canceller like the one 
> Sangoma uses.  Besides the extra CPU cycles required.
>   
Quite comparable - not sure if Octasic (as used by Sangoma and the latest
Digium cards) or ADT would win in a shootout, but they're both in the same
quality class.

The main issue is going to be CPU usage - getting this going at 1024 taps on
a full T1/E1 span would likely require two fast CPUs with the interrupts
distributed evenly between them... and even then, *shrug*

Cheers,
    Nic.
> -----Original Message-----
> From: Nic Bellamy [mailto:nicb-lists at vadacom.co.nz]
> Sent: Tuesday, February 13, 2007 12:41 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [asterisk-users] The High Performance Echo Canceller 
> (HPEC)
>
> Larry Shields wrote:
>   
>> I recently read about the following new technologies from Digium.  
>> Has anyone tried the new HPEC or knows when it will be available?
>>     
> It's out now, and I've tried it - the difference between HPEC and MG2 
> from trunk is stunning - in situations with bad echo where MG2 can 
> take ten or more seconds to converge to a reasonable degree, HPEC does 
> it in perhaps 300ms - converging on my intake of breath before I say 
> "hello", and absolutely no echo after that unless I purposefully go 
> out of my way to screw it up (whistling/blowing into the handpiece for 
> instance - even then, the malfunction is minimal).
>
> You can now buy it from the Digium website (US$10 per channel), or if 
> you have an in-warranty Digium card, email through the serial numbers 
> to Digium support and they'll give you a key (this is what I did).
>
> You'll need Zaptel 1.2.13 to make it go.
>
> It does take quite a bit of CPU though - perhaps 70% more compared to 
> MG2-trunk for the same number of taps from my rough measurements.
>
> Cheers,
>     Nic.
>
> --
> Nic Bellamy,
> Head Of Engineering, Vadacom Ltd - http://www.vadacom.co.nz/
>
>
>
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--
Nic Bellamy,
Head Of Engineering, Vadacom Ltd - http://www.vadacom.co.nz/