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

[Martin Braun]

On 03/24/2014 05:56 AM, Gayathri Ramasubramanian wrote:
> I am trying to characterize the TX and RX characteristics of USRPN210
> with a SBX board. I have tried one test : Amplitude Variation
> effects, by varying the amplitude in steps and finding out the o/p
> power through spectrum analyser. The foll are the readings I got.
> Amplitude level       921.25 MHz      2.45625 GHz 0.0625      -49.18  -60.97 
> 0.125
> -43.2 -55.05 0.25     -37.25  -49.09 0.5      -31.24  -43.05 1        -25.38 
> -37.13
> Amplitude change      921MHz  2.456GHz 1 to 0.5       5.86    5.92 0.5 to 
> 0.25        6.01
> 6.04 0.25 to 0.125    5.95    5.96 0.125 to 0.0625    5.98    5.92

Gayathri,

how did you measure? Did you use an antenna, or cable connection to the
spectrum analyzer?
Also, what were your gain settings? And your tx signal?

Martin

> when i ploted the graph in excel, (O/p power Vs amplitude), i got two
> almost linear curves, but their was a big difference in the 2 lines @
> 921.25 MHz and 2.45625 GHz (as seen above) at the start and if
> extrapolated could converge at a higher ampl and o/p power. I was not
> sure about my results and was looking to see if some one could let me
> know if these values look within the normal expected behaviour? if
> not, please let me know what is the normal expected behaviour. I am
> new to USRP and GRC programming and doing this for a project.