HELP - Echo Cancellation

Started by Marcin J. Manowiecki in comp.dsp14 years ago 1 reply

Hello, I received the task to built up an Line Echo Canceller (LEC) with the TMS320C6211. I am equipped with tha TMS320C6211 DSK. Is there...

Hello, I received the task to built up an Line Echo Canceller (LEC) with the TMS320C6211. I am equipped with tha TMS320C6211 DSK. Is there anybody who has experiences with the implementation of an echo canceller on a DSP ? Is there some source code in C++ available which deals with this problem and probably gives examples for the realization? Many thanks in advance, MJM -- S...


Narrow band energy and echo cancellation

Started by Steve Underwood in comp.dsp14 years ago 6 replies

Hi, I am trying to implement a G.168 compliant echo canceller. I'm conversant with most aspects of cancellation, including the problems of...

Hi, I am trying to implement a G.168 compliant echo canceller. I'm conversant with most aspects of cancellation, including the problems of mis-training on signal with strong continuous spectral lines. However, I have never been forced to cure this problem before. :-) It seems clear there is no way to get a canceller through the G.168 tests unless it freezes its adaption when the sign...


Narrow band energy and echo cancellation

Started by Maurice Givens in comp.dsp14 years ago

Steve, I can tell you a bit about the origin of CSS use in G.168. CSS was introduced to us in ITU SG-15/Q7 by Dr. Hans Gerlich of Germany. ...

Steve, I can tell you a bit about the origin of CSS use in G.168. CSS was introduced to us in ITU SG-15/Q7 by Dr. Hans Gerlich of Germany. It is 44.1KHz because it was used with the artificial head and work done on perception. This should not be a big problem. You can build the signnal at 44.1KHz and then resample to 8KHz. Your first question is a bit more sticky. The solution is clos...


Acoustic Echo Cancellation source

Started by john in comp.dsp14 years ago 5 replies

Hello , We are 2 students writing a VideoConference application on linux; We want to use microphones for recording and loudspeakers for...

Hello , We are 2 students writing a VideoConference application on linux; We want to use microphones for recording and loudspeakers for hearing. Now , test we made so far show that there is acoustic echo even if there is a reasonable distance between micropone and loudspeakers. Is there open source for Acoustic Echo Cancellation anywhere ? I mean not a chip-level (assemble...


Audio engineer

Started by John in comp.dsp14 years ago 7 replies

I am a software DSP engineer. I would like to consider a job as a DSP audio engineer. What type of algorithms I need to know ? I did some work in...

I am a software DSP engineer. I would like to consider a job as a DSP audio engineer. What type of algorithms I need to know ? I did some work in echo cancellation, and voice compression does this make me an audio engineer ? John


Cancellation

Started by Michael in comp.dsp14 years ago 2 replies

Hi all, I have read up on using echo cancellation and training FIR filter coefficients with various algorithms. All these systems rely on...

Hi all, I have read up on using echo cancellation and training FIR filter coefficients with various algorithms. All these systems rely on two uncorrelated signals to find echo paths. Does anyone know if methods exist to allow echo paths to be found using a single frequency turned on an off or a frequency sweep(chirp) to allow delays to be determined? Could a FIR filter be trained using suc...


Is there an Open Source Echo Cancellation module available?

Started by Robert Oschler in comp.dsp12 years ago 21 replies

Hello, I am the lead programmer for the SourceForge based Robosapien Dance Machine project, released under the GPL...

Hello, I am the lead programmer for the SourceForge based Robosapien Dance Machine project, released under the GPL license: http://sourceforge.net/projects/robodance I just added voice recognition capability to the program using another SourceForge open source project, the Sphinx 3.5 speech recognition engine: http://sourceforge.net/projects/cmusphinx The Robosapien robot is a ver...


Preventing feedback by delay?

Started by Ronny Nilsson in comp.dsp12 years ago 8 replies

Hi I'm having a question about echo cancellation and feedback reduction. --------- ----- | Speaker | ...

Hi I'm having a question about echo cancellation and feedback reduction. --------- ----- | Speaker | --------air------> | Mic | --------- ----- ^ | | ------- ----- | +- | Delay |


Echo Cancellation

Started by Jacky_42 in comp.dsp12 years ago 6 replies

Hi, I have a problem where I send a signal and listen for reflections of different surfaces but I dont want to listen for signals that...

Hi, I have a problem where I send a signal and listen for reflections of different surfaces but I dont want to listen for signals that are reflected of two or more surfaces. How can I use an adaptive filter to remove these kind of reflections? Any help on this topic will be greatly appreciated. Thanks, Jack This message was sent using the Comp.DSP web interface on www.DSPRelated...


Echo Cancellation on PC platform

Started by qfu72 in comp.dsp12 years ago 13 replies

we want to implement an acoustic echo canceller on a windows PC platform for chatting tools like MSN/skype. A serious problem we found in this...

we want to implement an acoustic echo canceller on a windows PC platform for chatting tools like MSN/skype. A serious problem we found in this kind of platform is the time delay (sound card play+speaker+air+mic.+ sound card record) between Ref. signal and Echo signal is not consist in every session 1)how could we esimate the time dealy? 2) why the AEC is so sensitive to time delay setting? ...


C Source for VoIP Echo Cancellation

Started by MMHafezi in comp.dsp12 years ago 6 replies

Hi everybody, Does anybody know any C source code for Echo Cancellation on a voice over ip system? Regards, M. Hafezi

Hi everybody, Does anybody know any C source code for Echo Cancellation on a voice over ip system? Regards, M. Hafezi


matlab & ccs interfacing

Started by vasu in comp.dsp12 years ago 2 replies

we are currently working on echo cancellation using adaptive filtering on dsk 6713. we have implemented fir low pass and high pass filters on...

we are currently working on echo cancellation using adaptive filtering on dsk 6713. we have implemented fir low pass and high pass filters on the board using CCS. we have developed L.M.S algorithm in Matlab(Not the Blockset provided in Help. A new one). we want to download that m file on the board(Portability between Matlab and Code Composer Studio). How ?


Unstability in NLMS algorithm for Echo Cancellation

Started by MMHafezi in comp.dsp11 years ago 9 replies

Hi every body, I have implemented a line echo canceller based on NLMS algorithm (TI app. note SPRA129) but sometimes the coeficient...

Hi every body, I have implemented a line echo canceller based on NLMS algorithm (TI app. note SPRA129) but sometimes the coeficient updatation falls into a bad state and echo will amplify. I changed the algorithm in a way that when I find this situation has happend I reset the coeficients to zero so it takes time again for the coeficients to converge and during this time you will hear echo. B...


Echo Cancellation - non acoustic application

Started by martini in comp.dsp11 years ago 8 replies

all: I dont know if this will work or not, but from what I read it sounds like acoustic echo cancellation is fundamentally the same problem I...

all: I dont know if this will work or not, but from what I read it sounds like acoustic echo cancellation is fundamentally the same problem I have. I am recording pitch measurments with a single sensor located at the center of gravity of a vehicle. I would like to extract the road profile from this measurement through a suspension model for the front and rear suspension. For the time b...


Explanation of LMS algorithm using samples

Started by Anonymous in comp.dsp11 years ago 2 replies

Hai All, I am a beginner in the DSP domain . And now I am working on the Acoustic Echo Cancellation. I have gone through the...

Hai All, I am a beginner in the DSP domain . And now I am working on the Acoustic Echo Cancellation. I have gone through the theoretical details of LMS algorithm and I have analysed that and I understood that why we are getting each step. But when I go for sample by sample analysation I am having several doubts.Please help me that how to analyse that .Can any one give explanat...


How to calculate the error signal in the LMS algorithm

Started by Anonymous in comp.dsp11 years ago 1 reply

Hai All, I am working with Acoustic Echo Cancellation using LMS adaptive algorithm.In that I have understood each and every...

Hai All, I am working with Acoustic Echo Cancellation using LMS adaptive algorithm.In that I have understood each and every step.But I am facing the problem with error calculation.If d[n] is the desired signal that is captured by the microphone and x[n] be the filtered far end signal (that is echo replicated signal) and e[n] be the error signal that is obtained by subtracting ...


Acoustic Echo Cancellation using LMS algorithm with C++ coding

Started by Anonymous in comp.dsp11 years ago 6 replies

Hai all, I am working on Acoustic Echo Cancellation using LMS algorithm . Theoretically I went through that thorougly and now I...

Hai all, I am working on Acoustic Echo Cancellation using LMS algorithm . Theoretically I went through that thorougly and now I am implementing that using C++. I am considering the 16 bit mono with 8KHz sampling frequency.As it is considered of 16 bits amplitude(intensity) of each sample should be within the range -32768 to 32767.As we know the computational equation...


Regarding acoustic echo cancellation using frequency domain LMS algorithm and subband LMS algorithm

Started by Aparna Ram in comp.dsp11 years ago 12 replies

Dear all, I am working on the acoustic echo cancellation.I have implemented the time domain LMS algorithm for acoustic...

Dear all, I am working on the acoustic echo cancellation.I have implemented the time domain LMS algorithm for acoustic echo cancellation and it is working fine only for some audio files and not working for some other audio files which has the large eigen value spread.So to avoid this eigen value spread now I am working on the subband LMS algorithm in frequency domain for aco...


Regarding polyphase IIR filter.

Started by venkat in comp.dsp11 years ago

Dear All, Iam working subband acoustic echo cancellation.In that for subbanding the input signal i used polyphase IIR filter.I...

Dear All, Iam working subband acoustic echo cancellation.In that for subbanding the input signal i used polyphase IIR filter.I searched in net for polyphase IIr filter design.I got some techinical documents related to polyphase IIr filter, I mentioned important links related to documents below. 1 http://users.cscs.wmin.ac.uk/~krukowa/pdf/Paper27.pdf 2http://ieeexplore.ieee.org...


regarding polyphase IIR filter.

Started by ch.venkat in comp.dsp11 years ago 6 replies

Dear All, This is the my first mail to post our group.Iam working on subband acoustic echo cancellation.In that for subbanding the...

Dear All, This is the my first mail to post our group.Iam working on subband acoustic echo cancellation.In that for subbanding the input signal 2 path polyphase IIR filter is used.I searched for polyphase IIR filter design in net I got some techginical documents.In those documents one documents for 2 path polyphase IIR filter design related to acoustic echgo cancellation, The filter coe...