RE: Re: LEC and NEC

Started by Huo Jiaquan in Echo Cancellation15 years ago

The papers i read gave me the impression that the hybrids at the central offices are equipped with ECs. So they are not? Or those...

The papers i read gave me the impression that the hybrids at the central offices are equipped with ECs. So they are not? Or those ECs do not provide sufficient suppression? --- "Shaw, David G (David)" <> wrote: > I will discuss V.32, sinc


RE: Re: LEC and NEC

Started by Huo Jiaquan in Echo Cancellation15 years ago

Sorry, i have been working with acoustic echoes, not very familiar with modem designs. Could u explain 'determined through an...

Sorry, i have been working with acoustic echoes, not very familiar with modem designs. Could u explain 'determined through an exchange between the end-points during startup' in a bit more details? Or sugguest some good ref.? thx --- "Shaw, David G (Davi


acoustic echo cacellation performance?

Started by andrew_xiang in Echo Cancellation15 years ago 1 reply

Anyone implemented a system that get you 30dB of reduction for AEC? In my system, I only get 4X for voice signal. I will give it...

Anyone implemented a system that get you 30dB of reduction for AEC? In my system, I only get 4X for voice signal. I will give it a try with white noise. But seems 30X is far away. But I don't expect users to utter white noise when they speak. My calculation:


RE: acoustic echo cancellation performance?

Started by Shaw, David G David in Echo Cancellation15 years ago 1 reply

From experience you should not count on echo cancellation like you expect from the LEC numbers you may be familiar with. Measure...

From experience you should not count on echo cancellation like you expect from the LEC numbers you may be familiar with. Measure the microphone noise floor and make sure that your residual error is not dominated by it. It is VERY, VERY hard to reach 30dB from just the AEC. Issu


complex NLMS update?

Started by Chandrasekaran C in Echo Cancellation16 years ago 1 reply

Hi all, I am using NLMS complex Adaptive filter. In the coefficient update part, error is normalized with input signal power...

Hi all, I am using NLMS complex Adaptive filter. In the coefficient update part, error is normalized with input signal power and is multiplied with gain and reference signal. Input power is X X* (* complex conjugate). This includes addition of square of two numbers. My problem


details about the test vector

Started by Ravi Revankar in Echo Cancellation16 years ago 2 replies

Hi, I need some information about the css (composite source signal) required for echo canceller testing. Can I get it free in...

Hi, I need some information about the css (composite source signal) required for echo canceller testing. Can I get it free in some URL. If someone has generated it on his, please give me some information for generation of the signal. RAvi _____________


Subband technique

Started by ondal95 in Echo Cancellation16 years ago 1 reply

I am a student in South Korea. My concern is about the echo cancellation using the subband technique. During my study, I found...

I am a student in South Korea. My concern is about the echo cancellation using the subband technique. During my study, I found that the faster convergence in subband technique is caused by the reduction of spectral dynamic range in each subband. But I don't understand this word


ERLE definition

Started by Mukul Bhatnagar in Echo Cancellation16 years ago 5 replies

Hi All I am not sure where to post a question on acoustic echo cancellation. I am just a little confused on the defintion of...

Hi All I am not sure where to post a question on acoustic echo cancellation. I am just a little confused on the defintion of ERLE (Echo return Loss Enhancement). I came across a definition : ERLEmax(N)= 60(N/Nr), where N is the number to taps for a tra


Can you give some information about howling control?

Started by ondal95 in Echo Cancellation16 years ago 1 reply

I am a MSc student in South Korea. And my research topic is Howling Control. But there is no one to help me even my professor. ...

I am a MSc student in South Korea. And my research topic is Howling Control. But there is no one to help me even my professor. There are many theses about howling control. But I can't find fundamental theory of experimental method for basic case. ex) How to detect


noise suppression + echo cancellation

Started by Mukul Bhatnagar in Echo Cancellation16 years ago 2 replies

Hi All I had another question, in order to make an echo cancellers performance more robust in noise, if we integrate it with a...

Hi All I had another question, in order to make an echo cancellers performance more robust in noise, if we integrate it with a noise suppression algorithm- for instance Spectral Subtraction. What is more advisable "theoritically" 1) To put the Noise suppre


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