Is there anyone that could explain to me the phenomenon of Echo or at least point me where I can learn more? Why is this affecting the VoIP world so much and not the regular PSTN analog world? What does the PSTN industry have that they can handle such high volume of calls and there is "no" echo problem? Thanks, Daniel
Daniel Salama wrote:> Is there anyone that could explain to me the phenomenon of Echo or at > least point me where I can learn more? Why is this affecting the VoIP > world so much and not the regular PSTN analog world? What does the > PSTN industry have that they can handle such high volume of calls and > there is "no" echo problem? >Search the list archives, there is more then enough information there. http://lists.digium.com/pipermail/asterisk-users/ Doug -- Ben Franklin quote: "Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety."
On 6/19/06, Daniel Salama <lists@infoway.net> wrote:> Is there anyone that could explain to me the phenomenon of Echo or at > least point me where I can learn more?This paper by Cisco is a great start: "Echo Analysis for Voice over IP" http://www.cisco.com/en/US/tech/tk652/tk701/technologies_white_paper09186a00800d6b68.shtml (it's the first result I get when I google for "echo in voip")> Why is this affecting the VoIP world so much and not the regular PSTN analog world?That's a misconception -- echo is always there, just not perceivable. (I actually think that if absoluteley all echo were removed, conversations would sound strange, similar to being in an anechoic chamber.)> What does the PSTN industry have that they can handle such high volume of calls and > there is "no" echo problem?Expensive equipment with built-in echo-cancellers? Extensive planning and testing before deployment? Decades of experience dealing with such problems?
In the context of Asterisk and TDM cards, I think this article is pretty good. Very light on the technical but David points out some of the unique challenges. http://www.linuxjournal.com/article/8424> -----Original Message----- > From: Doug Lytle [mailto:support@drdos.info] > Sent: Monday, June 19, 2006 3:43 PM > To: Asterisk Users Mailing List - Non-Commercial Discussion > Subject: Re: [Asterisk-Users] ECHO Tutorial > > Daniel Salama wrote: > > Is there anyone that could explain to me the phenomenon of > Echo or at > > least point me where I can learn more? Why is this > affecting the VoIP > > world so much and not the regular PSTN analog world? What does the > > PSTN industry have that they can handle such high volume of > calls and > > there is "no" echo problem? > > > > Search the list archives, there is more then enough information there. > > http://lists.digium.com/pipermail/asterisk-users/ > > > Doug > > > -- Ben Franklin quote: "Those who would give up Essential > Liberty to purchase a little Temporary Safety, deserve > neither Liberty nor Safety." > > >