[USRP-users] b205mini - cannot get TX at 0-30dBm (with attenuator)

Marcus D. Leech patchvonbraun at gmail.com
Fri Feb 15 20:01:45 EST 2019

On 02/15/2019 06:01 PM, Varban Metodiev via USRP-users wrote:
> Dear all,
> This is my first post here and I would dare to ask you for help on the 
> following ridiculous situation. So... I am experiencing the following 
> issue on two USRP b205mini boards:
> 1) From the UHD Sink block in GnuRadio, configured to transmit from 0 
> to 30dBm gain, I cannot get any transmission on the spectral analyzer. 
> I am connecting the board via the -30dBm attenuator inbetween.
> 2) Same is observed not only from GnuRadio, but also from the USRP 
> examples (like tx_waveforms).
> 3) When setting  the board up for reception from GnuRadio - it works 
> great.
> Could you please advise what I could have done wrong?
> Thank you in advance.
> Regards,
> Varban
What frequency are you trying to transmit on?

The TX gain range on the B2xx series is 80dB or so--that means that 
setting it to 30 is 50dB below the maximum signal output power, which is
   about +5dBm.  So you may not see it at those very low levels.

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