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How to Specify TailLen

Started by Suryadi August 26, 2002
I read about echo cancell that it can can cancell echo between 30 ms and
62 ms.
These number get from the delay in Hybrid 30 ms (240 samples) and the
tailLen 32 ms.

tailLen is defined as "The length of the echo spread in the number of
samples. Echo spread is also sometimes referred to as the dispersed
signal"

If using LMS, how to apply tailLen ?

thank you very muach

suryadi



Suryadi,
Your use of a echo-path (tail) length of 30 ms to 62 ms is very restricted, and
far less than the accepted. To see how to apply the echo length, I suggest you
look at texts on adaptive signal processing, and the ITU Recommendation G.168.
More directly, the length of your adaptive system must be able to estimate an
impulse response that is as long as the echo-path length. Maurice Givens

---------- Suryadi <> writes:

From: Suryadi <>
To: <>
Subject: [echocancel] How to Specify TailLen
Date: Mon, 26 Aug 2002 14:08:40 +0700 (JAVT)

I read about echo cancell that it can can cancell echo between 30 ms and
62 ms.
These number get from the delay in Hybrid 30 ms (240 samples) and the
tailLen 32 ms.

tailLen is defined as "The length of the echo spread in the number of
samples. Echo spread is also sometimes referred to as the dispersed
signal"

If using LMS, how to apply tailLen ?

thank you very muach

suryadi

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Echotail is the the path delay of the "echo" !
i.e. the delay between the original signal and its echo .
if you have a 8KHz sampling system then a 24ms delay means 192 taps ,
(24E-3 * 8000 ),
that is the transversal filter model to represent the echo tail must have
192 taps
if the system is sampled at 8000Hz. i.e. there must be 192 tap(24ms) delay
before the signal reappears(as echo) at the echo canceller to be cancelled. ----- Original Message -----
From: "Suryadi" <>
To: <>
Sent: Monday, August 26, 2002 12:38 PM
Subject: [echocancel] How to Specify TailLen >
>
> I read about echo cancell that it can can cancell echo between 30 ms and
> 62 ms.
> These number get from the delay in Hybrid 30 ms (240 samples) and the
> tailLen 32 ms.
>
> tailLen is defined as "The length of the echo spread in the number of
> samples. Echo spread is also sometimes referred to as the dispersed
> signal"
>
> If using LMS, how to apply tailLen ?
>
> thank you very muach
>
> suryadi >
>
> _____________________________________
> Note: If you do a simple "reply" with your email client, only the author
of
> this message will receive your answer. You need to do a "reply all" if
you
> want your answer to be distributed to the entire group.
>
> _____________________________________
> About this discussion group:
>
> To Join:
>
> To Post:
>
> To Leave:
>
> Archives: http://www.yahoogroups.com/group/echocancel
>
> Other DSP-Related Groups: http://www.dsprelated.com > ">http://docs.yahoo.com/info/terms/ >