Re: [Discuss-gnuradio] TX characterisation of USRPN210 with SBX daughterboard

[Martin Braun]

Ron,

thanks for the input!

On 03/25/2014 12:02 PM, Ron Economos wrote:
> I took a look at the SBX schematic. The final output
> uses a Mini-Circuits PHA-1+ MMIC amplifier that's
> rated at +22 dBm output power at 1 dB compression.
> 
> It would seem that the gain distribution of the SBX
> is arranged so that the PHA-1+ cannot be overdriven,
> even at DAC full-scale and 0 dB attenuation. That is,
> you cannot saturate the SBX.
> 
> So your measurements are showing that the SBX is
> quite linear over it's operating range.
> 
> BTW, I'm not really familiar with the USRP (I'm a bladeRF
> user), but the amplitude value in tx_waveforms is most
> likely just a relative amplitude (with 1 equal to DAC
> full-scale), and not an actual voltage.

That is correct. If you were using GNU Radio, and connected that to a
USRP, this would be amplitude of the digital signal going into the USRP
sink.

Martin