Re: [Discuss-gnuradio] TX-POWER USRP N210 AND WBX DOUGHTERBOARD

[madengr]

As Martin said, it really helps to have a spectrum analyzer.  What I'll do is
generate a CW tone (sinusoid) of 0.707 Vp; that is 3 dB backed off from DAC
full scale power.  Then I'll increase the TX gain setting until the TX image
rejection starts to become poor.  This will typically be 15 dBm for low
frequencies (< 500 MHz), and will increase with frequency.  These settings
would be the maximum you want to transmit.  If linearity is a concern,
you'll want to do the same but generate two tones at 0.35 Vp and look at the
intermod levels, then back off TX gain to maybe -30 dBc intermod.

Once you have that max level set, it really depends on the statistics of you
signal; peak-average ratio or CCDF (see link).  If you stay 3 dB backed off
from both DAC full scale and TX chain P1dB, you should be OK for most
signals unless you are doing OFDM or other multi-carrier stuff.

http://www.emce.tuwien.ac.at/hfadmin/354059/download/Characterizing_Digitally_Modulated_Signals_width_CCDF_Curves__Agilent_Application_Note_5968-6875E_.pdf

Lou
KD4HSO
 

Simone Ciccia S210664 wrote
> - UHD USRP SINK block (in gnuradio) allows to set the tx_gain(dB)
> 
> Which is the relation between these parameters???
> If I want to set a specific transmitted power???





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