Hello! Thanks for the help. Now the frequency is correct. But the amplitudo is wrong. I messauring in the real life a triangle signal and it's not similar.
Attached picture: http://img7.imageshack.us/img7/8049/messung9.png The second peak have to be: Frequency: 3kHz Amplitudo: -45dB The amplitudo of the first peak also not correct. Best regreads 2009/10/22 Josh Blum <[email protected]>: > > > Kóczián Gergely wrote: >> >> Hi all! >> >> A have a little probleme with FFT. >> >> I use the GRC without USRP. I would like to messeaure a triangle >> signal, but i never becam the right effect. I attached the picture >> about the measuring. >> >> The problem are the followed: >> >> I don't why but, i have allways a peak at 0Hz. - Independent from the >> type of signal > > The imaginary part of your signal has a dc offset. > >> On the picture i messaure a triangle, but the next peak in the FFT >> failed at 12kHz. >> > > Try making it a real signal (float outputs, not complex outputs). > >> Attached picture: >> http://img8.imageshack.us/img8/5620/messung5.png >> >> Have you any Idea? >> >> Thank: Gergely >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> [email protected] >> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > -- ---------------------------------------------------------- Kóczián Gergely Neptun kód: XCK220 Telefon: 06-70-637-19-85 skype: koczian.gergely Műszertechnikai és automatizálási intézet Automata gyártórendszere modul - F4 _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
