hi Rehan, Thanks for your reply.
My current test-bed is : IP Phone A <------> Asterisk IP PBX <---ISDN ---> Phone B I called IP Phone A using Phone B. IP Phone A is answered by someone else using its speaker. Both phones are in different rooms. I tried 2 scenarios for vISDN, viz, one with echo cancellation enabled and echo taps set to 256, and the second scenario with echo cancellation disabled. In both scenarios, I could hear my own voice, i.e. echo in Phone B. I then tried to conduct the echo tests using zaptel driver using the following setup. IP Phone A <------> Asterisk IP PBX <---> Analog Phone B I used the echo canceller MG2 in zaptel. In both scenarios, i.e. with and without echo cancellation in zaptel, I heard echo. It seems like echo cancellation cannot eradicate the echos. I was wondering if the delay caused by traversing the one-hop IP segment of the network too large for the echo canceller in both vISDN and zaptel to handle ? Have you conducted the echo tests using the same test-setup and also obtained the same results as mine ? Does anyone know if this test-setup is an appropriate setup to test the performance of echo cancellation in vISDN ? or are there any other ways of testing ? Thank you. Best Regards, Kwang Mien > Not too knowledgeable about this topic. However: > > a) Yes echo cancelling in on for vISDN. As I understand the echo > canceller is the zaptel echo canceller. There was some talk of this not > being quite good enough and a new echo canceller being built into vISDN > at some point in the future. Haven't heard whether this has happened yet > or not. So to change parameters for the echo canceller you need to try > and change the zaptel echo canceller parameters. > > b) The test I believe is not a fair test. The phone should be in another > room answered by another person. However when this is done there is > still some echo (in my tests with default echo cancellation settings) on > Phone A's side but not on phone B's side. In your scenario there will > always be echo because the audio is going from the speaker at phone A > into both microphones. You may have to make the echo canceller settings > to max (256 taps?) to fix echo in this situation. > > R > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Chan Kwang Mien > Sent: 13 July 2006 08:31 > To: [email protected] > Subject: [Visdn-hackers] Queries regarding Echo Cancellation in vISDN > > Hi, > > I have a few questions regarding Echo Cancellation in vISDN. > > a) When I run "visdn_configurator", i noticed the visdn_ec is loaded. > Does it mean that Echo Cancellation is activated for vISDN ? > > b) With visdn_ec loaded, I tested the following scenario : > > Phone A <------> Asterisk IP PBX <---ISDN ---> Phone B. > > I called Phone A using Phone B. The call at Phone A is answered by > turning on the speaker at Phone A. This is to create echo back to Phone > B. > > I realized that I can hear my voice after a slight delay, i.e. echo when > i spoke into Phone B. Does anyone have any idea why I am still getting > echo when I have enabled Echo Cancellation in vISDN ? > > Thank you. > > > Regards, > Kwang Mien > > _______________________________________________ > Visdn-hackers mailing list > [email protected] > https://mailman.uli.it/mailman/listinfo/visdn-hackers > > > _______________________________________________ Visdn-hackers mailing list [email protected] https://mailman.uli.it/mailman/listinfo/visdn-hackers
