FPGA Central

Hi everybody,

I'm trying to implement the MMSE algorithm for the Time Domain Equalize
used in the ADSL communication.
I receive real ADSL data from an AFE. I can decode without error the dat
used in the 994.1 ITU norm.
Now I'd like to equalize the upload channel with the training sequenc
used in the 992.1 norm.
Presently I use the LMS algorithm to comput the equalizer taps.
The training sequence is generated like that:
- IFFT the PRU, after getting the 33 to 63 datas with the conjugate of th
1 to 31 PRU data
- convolution of the training sequence with the TIR (target Impuls
Response)

The transmission channel delay is obtain by crosscorrelation between th
received datas and the training sequence. The place of the max value o
the Xcorrelation vector gives me the delay.

then the equalizer taps are computed with the LMS algorithm (I use 30 tap
and µ=0.01)

the error obtained fall sometimes under 0.01, but the symbol obtaine
after the FFT aren't the same of those obtained by making the FFT on th
training sequence

Could anyone tell me if I'm on the good way (if yes, what should I do t
make it work correctly) or if the equalization is made differently (I
yes, HOW???)

Thanks a lot!

Charly




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