Re: [Discuss-gnuradio] GRC FFT Plot

[madengr]

1) Send in a CW tone from a signal generator of known power (dBm)
2) Read the level from GR FFT (dB)
3) Figure out the amount you need to offset (dB) 
4) Multiply your samples by a constant value of 10**(offset_dB/20.0)
5) The GR FFT will now be calibrated to an absolute power (dBm).

Note if you change any settings, technically you would have to go through
this again.

Lou

 

Jan wrote
> Hi guys,
> 
> I transmitted this -30 dB signal (Image 1) using a usrp: The spectrum
> analyzer displays -50 dBm (Image 2) as its reading. My receiver end picked
> up the signal with the same peak power at -30 dB (Image 3). I'm confused.
> How
> do I convert the dB power in the GRC to the received signal of the
> spectrum
> analyzer in dBm? How do I convert the Power (dB) of the FFT to dBW or dBm?
> 
> Best,
> 
> *Gerome Jan M. Llames *





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