Eco Canceling

 Hi people.
 I am trying to implement an eco canceling system using a DSP (ADSP -
21160M) and a LMS adaptive algorithm, but unfortunity it runs just at max
with 6 taps, beyond this value neither the sound unprocessed nor the
processed one can be heard. I think this is a problem releted with
processing rate of the the DSP, but I would Like to know if any body here
had a similar problem or have any possible solution.

 Best regards.

bruno-pb wrote:
> Hi people.
> I am trying to implement an eco canceling system using a DSP (ADSP -
> 21160M) and a LMS adaptive algorithm, but unfortunity it runs just at
> max with 6 taps, beyond this value neither the sound unprocessed nor
> the processed one can be heard. I think this is a problem releted with
> processing rate of the the DSP, but I would Like to know if any body
> here had a similar problem or have any possible solution.

I'm probably the least qualified to comment but since no one has:

It seems to me that a 6 tap FIR filter would be an easy load for just about 
any processor.  So that can't be the problem if the software is OK - which I 
highly suspect it may not be.

Adding the LMS load is likely important but I'm not sure how much.  At least 
a factor of 3 or 4 times I should think.

Have you counted up the critical operations in the loop?  How many adds and 
multiplies?  How does that compare with the processor throughput capability? 
Then, add a factor of 2 or 3 for overhead and room and you should have a 
quick guess at whether it's the processor limitations or a bug in the code.

Fred 

On Dec 18, 6:02&#4294967295;pm, "bruno-pb" <marcell....@gmail.com> wrote:
> &#4294967295;Hi people.
> &#4294967295;I am trying to implement an eco canceling system using a DSP (ADSP -
> 21160M) and a LMS adaptive algorithm, but unfortunity it runs just at max
> with 6 taps, beyond this value neither the sound unprocessed nor the
> processed one can be heard. I think this is a problem releted with
> processing rate of the the DSP, but I would Like to know if any body here
> had a similar problem or have any possible solution.
>
> &#4294967295;Best regards.

Well since the LMS algo is about as simple as it gets, the problem is
likely something else. An important detail which I don't see in your
post, is what is your sample rate. How many updates per second do you
need? Are you processing RF, video, audio?

Clay

On Dec 18, 5:02&#4294967295;pm, "bruno-pb" <marcell....@gmail.com> wrote:
> &#4294967295;Hi people.
> &#4294967295;I am trying to implement an eco canceling system using a DSP (ADSP -
> 21160M) and a LMS adaptive algorithm, but unfortunity it runs just at max
> with 6 taps, beyond this value neither the sound unprocessed nor the
> processed one can be heard. I think this is a problem releted with
> processing rate of the the DSP, but I would Like to know if any body here
> had a similar problem or have any possible solution.
>
> &#4294967295;Best regards.

At a sample rate of 8KHz, I have implemented NLMS algorithms on the
ADSP processor with 512 taps, embedded USB interface code, 4-channel A/
D, 2-channel DAC, 5-channel true RMS power meter, and "glue" code.
The processor was less than 25% loaded.  You have something else
wrong, or you have an extremely fast sample rate.


maurice Givens