3rd order intercept point NI USRP 2920

[sab432]

Hi,

I need to know about how to calculate the Third order intercept point for NI USRP 2920 theoratically. So far, I have searched up this formula from NI website.

SFDR_TOI = 2/3(OIP₃ – Noise Floor)

from http://zone.ni.com/reference/en-XX/help/372058H-01/nirfsa/dynamic_range/

Can we plugin values of Noise Floor and SFDR from USRP data sheet for receivers and get OIP(3) 
http://sine.ni.com/ds/app/doc/p/id/ds-355/lang/de

Or do I have to use any other approach. Because I just came across this topic recently so I am not sure about how to approach this problem.

Regards,

[Anthony_F]

hi sab432,

If you take a look at ni.com/rf-academy  there is a great collection of RF measurement application notes, specifically the Super Heaterodyne Signal Analyzers PDF which you should find useful starting at page 75 for information on TOI

[sab432]

^ That link is quite beneficial. I will study it. But a question that I have is that can Third order intercept point be measured theoratically by using the data sheet of USRP ?

[Sarah_Y]

Hey sab432,

Attached is a pdf with various measurements for the 2920.  I'm not sure if you are trying to calculate the IP3 yourself, or if you just wanted to know it, but either way these should help.  The plots contain IP3, IP2, NF, receive magnitude, IQ imbalance, and DC offset.  When I measured the IP3, I held the input power of my 2 tones constant.  This results in some of the higher gain settings becoming saturated, making the IP2/IP3 data incorrect.  A gain setting of 22 is about where the saturation begins.

[sab432]

Actually I needed to know if there is a way to get 3rd intercept point(calculate) by applying some kind of formula using the USRP receiver specifications.

Here http://zone.ni.com/reference/en-XX/help/373380A-01/usrphelp/specifications/