Using the FFT Values from

Dear all,

I am a new user to GNU Radio, as well as signal processing. I am
currently working on my final year (UG) project which involves both of
these components however:
To implement a wideband spectrum analyzer 50 - 2400MHz range using the
USRP and GNU Radio.

I am trying to use the code but am still unsure
as to what to do with the output: fft values.
From the code documentation:

    # are the mag_squared of the fft output (they are in the
    # standard order.  I.e., bin 0 == DC.)

In trying to determine how to use the data, I have come across several
varying responses in a number of posts on this forum:

One user has taken the average of the values in the vector and
plot this versus center frequency as the “mean power”. - S. Ortega

Another suggestion was to get power, take the square root of the output.

  • Firas A.

And finally, I saw the use of the log function in:

      for bin in
                signalPower += bin
      signalPower = 10*math.log10(signalPower) -

10math.log10(tb.fft_size) - 20math.log10(tb.power) - tb.gain

Can someone please guide me as to which of these I should use, or what
other options and calculations I need to perform?
I would like to show signal strength vs. frequency somehow.



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