Radio frequency measurements on a SBX daughter board using GNU radio and USRP N-210

In this paper we report Radio Frequency (RF) measurements performed on a GNU Radio/Universal Software Radio Peripheral (USRP) testbed. The USRP hardware is connected to SBX daughter board, both designed by Ettus Research. We can confirm the bandwidth stated by the designer, nonetheless the output power was found to be constantly decreasing with increasing the output frequency. USRP Hardware Driver (UHD) gain is a supplementary amplification parameter available to the user, nonetheless its manipulation has to be done with care. For the lower part of the SBX frequency band (400–1500 MHz), simply increasing the UHD gain above some value has the effect to increase the Total Harmonic Distortion (THD) without any increase in the desired carrier frequency power but with a significant increase in the out-of-band emission.