No it points to Cell phone companies having better hardware echo cancellation on their lines, also cell phones themselves have a hardware echo can built in. ----- Original Message ----- From: "Mike Benoit" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, July 12, 2004 1:52 AM Subject: Re: [Asterisk-Users] UPDATE - Echo cancellation, when softwaredoesn't cut it. Whats next?
> Here's an update on my progress for all who are interested. > > After carrying out many more hours of testing, the only thing that made > a significant difference was changing the mainboard/CPU of my asterisk > server. > > My original Asterisk server was a Celeron 533 with 128mb ram. Now, keep > in mind, even with 5 channels in use at a time, the CPU usage was always > minimal, the load never went above 0.2 that I saw. > > First I upgraded to a brand new Celeron 2.4Ghz with 128mb ram, and > immediately noticed an improvement in the echo. > > Incoming calls now have virtually no echo. I have to really try to hear > it. Outgoing calls still have echo, but after about 30 seconds it mostly > goes away during normal conversation. Still not 100% acceptable though. > However it is a huge improvement. > > The weird part though is this. Outgoing calls to cell phone numbers > (tried 3 different ones) have virtually no echo. Outgoing calls to land > line numbers do seem to have echo. > > I then downgraded my asterisk server to a P3-800 with 128mb ram, and I > didn't notice any difference from the Celeron 2.4. So in my case just > upgrading a Celeron 533 to P3-800 made a noticeable difference, but > anything more than that did not. What I did notice is > in /proc/interrupts, the P3-800 displays: > > IO-APIC-level wcfxo > > Whereas I believe the older Celeron 533 displayed: > > XT-PIC wcfxo > > So my guess is its not the CPU speed at all, just the way interrupts are > handled. > > So the two questions remain. > > 1. Why do incoming calls have nearly no echo (sound great), and outgoing > calls are bad during the first 30 seconds, and okay (but not good) after > that. > > 2. Why do outgoing calls to cell phone numbers sound great? > > Seeing as an outgoing call to a land line has echo, but the same land > line calling in has virtually no echo, does this point the finger at > Asterisk code having issues? > > > On Wed, 2004-06-30 at 16:36 -0700, Mike Benoit wrote: > > Over the last couple weeks I've tried everything I could get my hands on > > in an attempt to get rid of my echo problems. Using a CVS checkout of > > just yesterday, I've tried every echo cancellation routine in zconfig.h > > (including Mark2 w/Aggressive) , as well as the echotraining=800 > > mentioned on this list just last week. > > > > While some things worked better then others, I would consider none > > acceptable solutions in my situation. Playing with rx/tx gain values > > just seemed to quiet the voice down and along with that the echo > > happened to be less noticeable. I could almost get the echo to disappear > > with a low enough rx/tx gain, but then the voice could barely be heard, > > or DTMF tones stopped working. > > > > So whats the next step? > > > > I only get echo when dialing over the PSTN. Using Nufone to dial a PSTN > > number results in absolutely zero echo. Do I put in a request for a > > Telco technician to come out and take a look at the lines? > > > > One page on the Wiki says: > > > > "Most of the telco's have technicians with the equipment necessary to > > help find the problem if the problem really is their outside plant. > > However, getting to that person can be a real challenge." > > > > Any suggestions on ways to overcome the challenge of getting the right > > technician on the phone? > > > > Thanks. > > > -- > Mike Benoit <[EMAIL PROTECTED]> > > _______________________________________________ > Asterisk-Users mailing list > [EMAIL PROTECTED] > http://lists.digium.com/mailman/listinfo/asterisk-users > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-users > _______________________________________________ Asterisk-Users mailing list [EMAIL PROTECTED] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
