What he said^^ https://en.wikipedia.org/wiki/Nyquist_frequency
On Sun, Jan 21, 2018 at 12:18 PM, Jeff Long <willco...@gmail.com> wrote: > Try reducing the RX filter bandwidth, the gain of the receiver and/or > transmitter, or moving the TX and RX apart, and see what happens. This is > aliasing, and probably has nothing to do with software. > > On Sun, Jan 21, 2018 at 12:56 PM, Yang Liu <lyangbigt...@gmail.com> wrote: > >> Dear all, >> >> In this application, I am trying to send a sine wave at a specific >> frequency to usrp x310: >> sine wave generator ---> usrpx310 >> >> For the sine wave generator, I use blocks.sig_source_c from gnuradio. The >> parameters at the transmitter are in the following: >> center frequency: 1e9 (usrp tuning frequency) >> sampling_rate: 5e6 >> waveform frequency: -2.4193125e6 (at the boundary of this frequency >> band). >> >> At the receiver side, I tuned the usrp to 1e9, and used 10e6 to sample >> the received data. According to the spectrum I observed, there are two >> frequency components, one is at -2.4193125e6, another one is around at >> -2.4193125e6 + 5e6 (not very sure if they are exactly symmetric). Actually, >> this happens when the sine wave is very close to the boundary (near -2.5e6 >> or 2.5e6). As I moved the waveform frequency to the center (1e9), the >> second frequency disappeared. Firstly, I thought that it is the power >> issue, however, after I decreased power level, the second component is >> still there. >> >> According to the function (blocks.sig_source_c), what it generates is a >> exp(j*2*pi*f_waveform/f_s). Therefore, there should not exist any second >> frequency component. I feel very confused about why this can happen. >> >> Any thoughts about this will be greatly appreciated! >> >> Best, >> Yang >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
_______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
