Re: [Discuss-gnuradio] FFT of one OFDM symbol

[Marcus Müller]

Dear Alice,

the reason you're seeing all the active carriers at once is that, since
the human eye is bandwidth-limited, the Qt frequency sink averages
multiple FFTs.

If you want to have a real-time visualization, go for gr-fosphor, or use
the Qt vector or time raster sinks; if you need offline analysis, I
recommend writing the data to a file using the file sink, loading the
data into python with numpy's fromfile(...., dtype=numpy.complex64), and
writing your own visualization or using the specgram() tool with 0 overlap.

Best regards,

Marcus

On 09/20/2017 01:41 PM, Alice Lo Valvo wrote:
> Hi,
> I'm working with the tx_ofdm.grc in the gr-digital example. I saw that
> I can choose a set of
> subcarriers for each OFDM symbol. Is there a way (FFT plot, for
> example) to display these active subcarriers?
> I tried, but FFT plot shows every active subcarriers for ALL OFDM
> symbols simultaneously and not one by one in sequence.
> Thanks in advance,
>
> Alice
>
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