Quoting Marcus Leech <[EMAIL PROTECTED]>: > It would be useful to have a function that returned the as-aliased > frequency for > any given input frequency (up to the maximum input frequency of the A/D). > Trivial, I suppose, but less opportunity for brain farts that way.
A good idea. Anyway, to elaborate on what I said before, it is helpful to think in "normalized frequency" terms. The sampling rate is normalized to 1. The nyquist freq is 0.5. Thus, for real samples, the signal is from frequencies of 0 to 0.5. For complex samples, it is from -0.5 to +0.5. In the case we talked about before, 64 MHz => 1. 433 MHz = 6.765625. Drop the whole number part and you are left with 0.765625. Since that is over .5, you reflect it in 0.5. 1 - 0.765625 = .234375 .234375 * 64 MHz = 15 MHz Since we had to do that "reflection", the spectrum is reversed. This isn't a problem for FM, but needs to be taken into account for most modulations. Matt _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
