Re: [Discuss-gnuradio] fm modulation

[Alexandru Csete]

If you fix your sampling rates to be consistent in all blocks (e.g.
64k on audio side, 320k on the other side) and decrease the signal
frequency to be strictly less than half the audio rate, say 31 kHz
you'll see the peaks.

Note that the NBFM block is for narrow band FM, which usually means
less than 5kHz. If you want to send higher frequency signal you may
want to switch to the WBFM block.

Alex


On 13 July 2010 15:33, EsserIHF <address@hidden> wrote:
>
> Thank you,
> I tried to use the NBFM transmit block.
> I generated a signal with a frequency of 32k. This I connected with the
> NBFM-Block. The quadrature Rate of this block is 320k. This output i
> connected with the USRP an a FFT-Plot. I expected to see a line
> at 320k and two lines at (320k- 32k) = 288k and (320k+32k) = 352k. But on
> the FFT-Plot and on the Spectrum Analzer which is connected to the USRP, I
> only see a line at 320k.
> Here the grc-file:
>  http://old.nabble.com/file/p29150442/myFM.grc myFM.grc
> --
> View this message in context: 
> http://old.nabble.com/fm-modulation-tp29149390p29150442.html
> Sent from the GnuRadio mailing list archive at Nabble.com.