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 "[email protected]" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. 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.
