Hi,
> Andrew, echo is likly to be being caused by the complex impedance and
> E&M seperation.
yes yes - this is true - but what can be done about echo? Is there
anything you can do to ensure you are not causing echo in your skype
setup.
The telephone network has worked very hard to minimise the amount of wire
required to convey audio. Consequently, there are many places where just
two wires are used to convey the mic/speaker signals. Some phones use four
wires to convey these signals. If it is two wires, the mic/speaker signals
are separated by a combination of caps & inductors. Separation of the
signals reqires that both ends (and the wires between callee and caller)
have matching capacitance and inductance. Consequently, when connecting to
someone with a regular phone, you are at the mercy of a wired network
containing (potentially) unmatched inductors & capacitors.
1) If you are calling to a regular phone with skype, and are getting echo,
it is possible the remote endpoint has a mutant phone. They may be able to
change the phone, so that when you next call them, the echo will be gone.
(indeed, it can happen when you are calling regular phone to regular
phone that you get echo. Particularly when it is an international call
and/or cell phones are at either end.)
2)if you are calling to a remote skype user, and are getting echo, it is
a definate sound configuration issue. The simplest and most effetive
fix is to get a headset with a mic at both ends.
To test that your linux box is not causing echo, a simple test is:
-open two consoles
-in one, do arec file.wav
-in the other, do aplay some_valid_wav_file.wav
-end the test, and examine the the generated file.wav
-if any of the valid_wav_file is found in the recorded wav file, you
may well be causing echo.
Derek.
--
Derek Smithies Ph.D. Any fool can write code that
IndraNet Technologies Ltd. a computer can understand.
Email: [EMAIL PROTECTED] Good programmers write code
ph +64 3 365 6485 that humans can understand.
Web: http://www.indranet-technologies.com/ Martin Fowler
