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Registered Member #1143
Joined: Sun Nov 25 2007, 04:55PM
Location: Vilnius, Lithuania
Posts: 721
DerAlbi wrote ...
I am also not sure why they think that a frequency shift solves the problem. It does not matter if the mic picks up a 10Hz shifted signal or is by itself shifted by 10Hz. The other person does not want to hear him self speaking at the other end. The 10Hz shifting would still feedback a 10Hz shifted version just because its picked up by the mic.. i dont see a solution there. You guys are currently mixing up an echo with an oscillation. You just call everything a "feedback" so canceling the "feedback" is the solution for you. Its not. 10Hz-Shifting chancels oscillation, not feedback (there is still feedback, it just forced out of phase so it cant amplify in phase = oscillate.). Please keep it apart. Linas, did you read about the LMS-FIR-Filter? That there is an echo present, can be checked by the Cepstrum ( ).
Same thinking here, shift does not solves problem, i just need filter mic signal that has all the noise as well as older version of talk, that must be delayed and summed with audio path.
Yes, i was reading LMS-FIR filter, it looks difficult, but stm32f4 does have this filter written by some one, so will try to use it.
Registered Member #2906
Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 727
Yes, its difficult.. thats why you choose a thread name like this "the older version of the talk" will be implemented within the FIR-Structure itself. I dont really understand the code you linked. imho there is missing a function that should be minimized. I am not sure how you would formulate this... as said, the Cepstrum is an indicator for the echo... (you can check if the echo cancelation works with that) I am really sorry that i only know the bzzwords for that topic.. i cant help you with more specific stuff
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Very Hard DSP Problem (audio echo cancelation inside car)
