This is very true, you must use hardware echo cancel and voice processing. we use sangoma 104d hardware echo cancel card, it eliminates all echoes we had.
Best Regards Matt ----- Original Message ----- From: "Steve Underwood" <[EMAIL PROTECTED]> To: "Asterisk Users Mailing List - Non-Commercial Discussion" <asterisk-users@lists.digium.com> Sent: Monday, February 06, 2006 6:09 AM Subject: Re: [Asterisk-Users] BAD/GOOD Echo Cancel > 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 > \ > _______________________________________________ > --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 > _______________________________________________ --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
