Hello,

I'm programming the Fast Affine Projection for echo cancellation,I see this
article "Steven.L. Gay,

and S. Tavathia, “Fast affine projection algorithm,” in Proc. of the
ICASSP,

vol. V, pp. 3023-3026,1995"to do it.

for the white noise (as input signal), it

converges but for the speech signal it does not, the answer is in

paragraph below but I did not understand exactly what to do.

5. NUMERICAL CONSIDERATIONS

FAP uses the sliding window technique to update and

downdate data in its implicit regularized sample correlation matrix

and cross correlation vector. Errors introduced by finite arithmetic

in practical implementations of the algorithm therefore cause the

correlation matrix and cross correlation vector to take random

walks with respect to their infinite precision counterparts. A

stablized sliding windowed FRLS algorithm[11] has been

introduced, with complexity 14N multiplications per sample period

(rather than 10N for non-stablized versions). However, even this

algorithm is stable only for stationary signals, a class of signals

which certainly does not include speech. Another approach, which

is very straightforward and rather elegant for FAP, is to

periodically start a new sliding window in parallel with the old

sliding window, and when the data is the same in both processes,

replace the old sliding window based parameters with the new

ones. Although this increases the sliding window based parameter

calculations by about 50% on average (assuming the restarting is

done every L+N sample periods), the overall cost is small since

only those parameters with computational complexity proportional

to N are affected. The overall complexity is only 2L+21N for FAP

without relaxation and 2L+30N for FAP with relaxation. Since

this approach is basically a periodic restart, it is numerically stable

for all signals.

Thank You

in advance and I wait for your response,

Best

regards,

_____________________________________

# Question about the convergence of Fast Affine projection Algorithm

Started by ●April 30, 2009