Hi
My project is dealing with Tx/Rx Characterization. I wanted to know if anyone has tried finding the IIP3 and OIP3 for the USRP N210 with WBX and SBX daughter-boards.
I did an experiment on Tx side ( USRP behaving as a TX, with the GRC on host generating the two tones & output from USRP goes to an attenuator of 10 db before going to a spectrum analyzer) and got the following results. (as in the excel sheet attached.)
I am planning to do this for the RX side using Two signal generators instead of the GRC flow graph. However I had a few questions:
1. I found the IIP3 for SBX to be given as 0 dBm & for WBX as 50 ~ 100 dBm on receive, What is it for Tx?
2. Usually IIP3 and OIP3 are said to have more importance on the RX side, to measure non-linearity. Do IIP3 and OIP3 hold same significance on TX side? if not, what could be judged as a good measure of non linearity for TX side.
3. In this test, When I increase the amplitude of the signals, o/p varies. But for SBX the Inter-mods appear at 250mV while for WBX it is ard 550mv, and here the plot is very unsteady, and the NF is seen as curving.
however if I do the test with attenuation as 30 dB before the spectrum analyzer, The plot has a steady NF. Also after a certain point, I see a lot of spurious signals. Is there a specific amplitude range I should constraint myself to, to get the IIP3 and OIP3 points.
Thanks
Gayathri
IIP3_test.xlsx