[Discuss-gnuradio] Questions on the unit of Y-axis in usrp_oscope.py and usrp_fft.py

[Brook Lin]

Hi Eric and All,

I found one of replies sent by Eric said that:

>What are the units of the Y axis?

They are the output of the digital down converter.
They are not calibrated to any particular voltage level.
The levels depend on the gain setting too. 

My first question now is what the unit exactly is. Or is it just some number
coming from the output of DDC? Eric said that the levels depend on the gain
setting too. If the gain is 1, are Y-axis voltage?

My second question is what are the units of the Y-axis in FFT. I think
Y-axis should be referenced to some noise figure.  And 0dB in the plot is
not the exact 0dB, but relative to some noise figure, and how much the noise
figure is? Am I right?

Thanks,
Brook
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