> > hi, > > How good or bad is the EC in Asterisk? > > Can anyone prove that it works at all and what it's limitations are? > > I ask cause I have some problems with this myself which variate from > call to call, and I see from others that Echo Cancel is a quite common > topic. > > Jan > >I have installed systems that had absolutely no echo and some with terrible echo. Whenever I sell or consult on an * system, I always make it clear that VoIP and * may suffer from echo. I also let them know that many times we can eliminate it but sometimes there will be a slight echo on some calls that may or may not go away. Echo is the number one complaint I get from customers so I like to be upfront about it. Thanks, Steve -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.375 / Virus Database: 267.15.2/251 - Release Date: 2/4/2006
> > virtually all software echo cancelers cannot get double echo removed > completly. It can get the first one but not the second one. Thereare> instances where you get a 2nd echo, so ... Asterisk is no exception > from this afaik nothing software only based is. > > If you really want good echo cancelation a hardware solution is theway> to go. >Just an enquiring mind wanting to know, but how is a hardware solution different to a software solution? The echo cancellers in the Digium hardware presumably just use the same sort of algorithms as the software versions, so it is just that they are dedicated and perform better, that they are closer to the source of the echo, or some other thing that I've overlooked? Thanks james
On Mon, 2006-02-06 at 04:01 -0800, asterisk@anime.net wrote:> On Mon, 6 Feb 2006, trixter aka Bret McDanel wrote: > > Again, I know Sangoma is a sore subject with some on this list, but the > > echo cancelation stuff I heard while presented by a Sangoma employee was > > not Sangoma specific, although it did include some research into > > different hardware/software based cancelers. > > digium licenses g729 codec, wonder if digium could license a good > G.168 echo canceller from someone.They can license anything that is on the market, the catch is whether it would be cost effective to do that. I also remember what the sangoma guy was talking about a little more now. It had to do with the ticks, hardware cancelers typically have a much higher amount becuase they are specialized to do that. As such they can do more processing. The second echo that he talked about was muted but present and out of the range of most software based echo cancelers. He said that their results were that software echo cancelation was about 30MHz per channel. Now he didnt quantify what cpu that was, 30MHz on a 486 is far different from 30MHz off a Xeon, as such I personally dont like such arbitrary numbers, but be that as it may be did say that intel rated the G.729 codec at about the same 30MHz per channel, which I would assume was based on the same series cpu. If that is true that gives you some scope of how much cpu you need, and why it may be better to do echo cancelation in hardware vs software. As I said earlier I missed the whole presentation, but do notthink he compared different vendors hardware echo cancelers, there are certainly good ones and bad ones, without some real data on each its hard to say ... -- Trixter http://www.0xdecafbad.com Bret McDanel UK +44 870 340 4605 Germany +49 801 777 555 3402 US +1 360 207 0479 or +1 516 687 5200 FreeWorldDialup: 635378 http://www.sacaug.org/ Sacramento Asterisk Users Group -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 189 bytes Desc: This is a digitally signed message part Url : http://lists.digium.com/pipermail/asterisk-users/attachments/20060206/bbb78e7b/attachment.pgp
asterisk@anime.net wrote:> On Mon, 6 Feb 2006, trixter aka Bret McDanel wrote: >> Again, I know Sangoma is a sore subject with some on this list, but the >> echo cancelation stuff I heard while presented by a Sangoma employee was >> not Sangoma specific, although it did include some research into >> different hardware/software based cancelers.I put a Tellabs 64ms echo canceller into my facility this weekend and am praying that it removes are echo problem. If it does, I plan on making it a standard on my Asterisk installs that have a channel bank or T1. Doug
Doug Lytle wrote:> asterisk@anime.net wrote: > > I put a Tellabs 64ms echo canceller into my facility this weekend and > am praying that it removes are echo problem. If it does, I plan on > making it a standard on my Asterisk installs that have a channel bank > or T1. >Well, the day is almost over here and not one echo reported today. Very impressive! I had 5 more cards delivered today. Doug
Doug, Can you provide any information on how you deployed that card into your setup? If it works for you we could put up a page on voip-info.org Richard On 2/6/06, Doug Lytle <Support@drdos.info> wrote:> > asterisk@anime.net wrote: > > On Mon, 6 Feb 2006, trixter aka Bret McDanel wrote: > >> Again, I know Sangoma is a sore subject with some on this list, but > the>> echo cancelation stuff I heard while presented by a Sangoma employee > was > >> not Sangoma specific, although it did include some research into > >> different hardware/software based cancelers. > > I put a Tellabs 64ms echo canceller into my facility this weekend and am > praying that it removes are echo problem. If it does, I plan on making > it a standard on my Asterisk installs that have a channel bank or T1. > > Doug > > _______________________________________________ > --Bandwidth and Colocation provided by Easynews.com -- > > Asterisk-Users mailing list > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-users >-------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.digium.com/pipermail/asterisk-users/attachments/20060206/06fe5011/attachment.htm
I had bad echo as well using the Te406 card. Swapped the card, swapped the box, nothing helped, until I got a Tellabs 2572 echo canceler, and echo is now gone. On 2/6/06, Doug Lytle <Support@drdos.info> wrote:> Doug Lytle wrote: > > asterisk@anime.net wrote: > > > > I put a Tellabs 64ms echo canceller into my facility this weekend and > > am praying that it removes are echo problem. If it does, I plan on > > making it a standard on my Asterisk installs that have a channel bank > > or T1. > > > > Well, the day is almost over here and not one echo reported today. Very > impressive! I had 5 more cards delivered today. > > Doug > > _______________________________________________ > --Bandwidth and Colocation provided by Easynews.com -- > > Asterisk-Users mailing list > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-users >
The echo canceller chip used in the Sangoma AFT "D" cards are fully compliant with all the G168 specifications. David Yat Sin Sangoma Technologies (905) 474-1990 x119 (800) 388-2475 x119 Fax: (905) 474 9223 MSN: david.ys1@hotmail.com Email: davidy@sangoma.com Website: www.sangoma.com> >Date: Mon, 06 Feb 2006 22:09:34 +0800 > > From: Steve Underwood <steveu@coppice.org> > > Subject: Re: [Asterisk-Users] BAD/GOOD Echo Cancel > > To: Asterisk Users Mailing List - Non-Commercial Discussion > > <asterisk-users@lists.digium.com> > > Message-ID: <43E7589E.4070200@coppice.org> > > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > > > James Harper wrote: > > > > >>virtually all software echo cancelers cannot get double echo removed > > >>completly. It can get the first one but not the second one. There > > >> > > >> > > >are > > > > > > > > >>instances where you get a 2nd echo, so ... Asterisk is no exception > > >>from this afaik nothing software only based is. > > >> > > >>If you really want good echo cancelation a hardware solution is the > > >> > > >> > > >way > > > > > > > > >>to go. > > >> > > >> > > >> > > > > > >Just an enquiring mind wanting to know, but how is a > > hardware solution > > >different to a software solution? The echo cancellers in the Digium > > >hardware presumably just use the same sort of algorithms as > > the software > > >versions, so it is just that they are dedicated and perform > > better, that > > >they are closer to the source of the echo, or some other > > thing that I've > > >overlooked? > > > > > > > > There isn't much difference, except for the amount of CPU > > taken, and the > > issue that software echo cancellation forces the device to use very > > short buffers. He's talking rubbish. Hardware echo cancellation > > certainly eases the timing constraints on the E1/T1 card to host > > processor interface. A lot more buffering can occur if the > > host does not > > do echo cancelling. A 20ms buffer on a PCI card will > > practically all the > > quirky timing issues people see go away. However 20ms of > > buffering would > > badly hurt an echo canceller's convergence. > > > > Most hardware cancellers, are actually software cancellers. > > The software > > just runs in a DSP (often a customised one) instead of the host > > processor. Some are a hybrid hardware/software design. Few are pure > > hardware. > > > > There are no standard algorithms for echo cancellation, and > > no standard > > level of performance. Few cancellers which claim G.168 compliance > > actually pass all the tests. If you look in the small print they > > generally say which tests they do pass. Echo cancellers vary a lot in > > performance, and making them truly robust and efficient is still a > > research topic. > > > > Regards, > > Steve > > \ > >