One question, at my understanding if I use a filter to decimate I'm ,in a certain way, adding all the samples using the filter for the decimation, like averaging with the appropriate weights for one frequency range. So the decimation filter should interpret the same role as the accumulation you mention.
Aside from that, I have a throughput requirement so I can't add a lot of samples... The dithering you mention only works with a proper accumulation right? because I tried to add noise to my system and didn't see a difference. El mié., 4 sept. 2019 a las 14:14, Dan Werthimer (<d...@ssl.berkeley.edu>) escribió: > > you can get extremely high SNR if you add noise to your sine wave signal. > and then integrate many spectra together to beat down the noise. > to get rid of ADC quantization noise and other spurs, > you should have noise at least at the one LSB level, better if you have > two LSB's of noise. > then you can get 150 dB SNR if you add enough spectra together. > > dan > > > Dan Werthimer > Marilyn and Watson Alberts Chair > Astronomy Dept and Space Sciences Lab > University of California, Berkeley > > > On Wed, Sep 4, 2019 at 10:39 AM Sebastian Antonio Jorquera Tapia < > sebastian.jorqu...@ug.uchile.cl> wrote: > >> Hi casperites, >> I have been working in project that needs a high SNR In order to achieve >> that I made a model with 3 decimation steps with factors 16, 8 and 4, to >> zooming the frequency range [50.625, 52.730]MHz and then put the PFB-FFT >> combo. >> The system achieve 100dB of SNR for inputs with the same frequencies of >> the FFT twiddle factors, but outside those frequencies the noise floor goes >> up 50dB in the worst cases, which is when the signal is between two bins. >> I am using the 8 bit aasia ADC, so the SNR without any further processing >> should de 48 dB approx, so in the bad cases we loose the improvement due >> decimation. >> I attached the pictures of the response in the best and in the worst case. >> >> There is a limitation in the amount of decimation that one could make tho >> improve the SNR?? Or I am missing some assumption of the improvement due >> decimation that I am not meeting? >> Has anybody faced a similar problem? >> >> >> Cheers! >> >> [image: worst_response.png] >> >> >> [image: best_response.png] >> >> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "casper@lists.berkeley.edu" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to casper+unsubscr...@lists.berkeley.edu. >> To view this discussion on the web visit >> https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/93a6ec1c-7a2e-46de-9d6d-2ea460c9570a%40lists.berkeley.edu >> <https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/93a6ec1c-7a2e-46de-9d6d-2ea460c9570a%40lists.berkeley.edu?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups " > casper@lists.berkeley.edu" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to casper+unsubscr...@lists.berkeley.edu. > To view this discussion on the web visit > https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CAGHS_vFFKY2Xysw-B1A0eA9vhvXDvLkn9FEByUPVaMjb33EMOQ%40mail.gmail.com > <https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CAGHS_vFFKY2Xysw-B1A0eA9vhvXDvLkn9FEByUPVaMjb33EMOQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "casper@lists.berkeley.edu" group. To unsubscribe from this group and stop receiving emails from it, send an email to casper+unsubscr...@lists.berkeley.edu. To view this discussion on the web visit https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CAASoV%3DMTXOV11tYDZwRG23c%2BNcBiTYCPPZ9Rzoy8z0t93WupvA%40mail.gmail.com.
