Hi Dirk, On Sat, 2018-03-10 at 22:22 +0000, Dirk Gorissen wrote: …snippety snip… > My assumption was that the center frequency is at the middle bin > (Shift = True) and that if I want +/- 500Hz (for example) I can just > take the bins (middle bin index - 500) -> (middle bin index + 500)
Think about how wide your bins are! An FFT transforms "input vector length" =: N samples from time domain into frequency domain. Thus, every bin represents Nyquis bandwidth / N of bandwidth. Since Nyquist bandwidth is sampling rate, you get f_sample/N*1000 of bandwidth. > The python block should be trivial in that it just snips out a subset > of the FFT bins (around the center frequency). Now, to act a bit like Clippy: > It looks like you're building a decimating low pass filter. Do you want help with that? Generally, cutting out spectrum from the DFT of your signal *might* lead to a distorted view at your signal; see [1]. It might be OK (correct, even), however, for specific purposes. What's the bigger thing you're planning to do? Best regards, Marcus [1] https://dsp.stackexchange.com/questions/6220/why-is-it-a-bad-idea-t o-filter-by-zeroing-out-fft-bins
smime.p7s
Description: S/MIME cryptographic signature
_______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
