modify the AD9361 simulink model to look at LNA output?

I'd like to be able to look at the output of the LNA in the AD9361 Simulink model. I've been able to modify the model to get the output from the IQ demod, but no further back towards the receive antenna. The issue is that when I take the output from the LNA, I still get the spectrum from roughly -5.5 to +5.5MHz. I'm not sure how to set the spectral display. It seems that the issue is with the inherited sample rate in the spectral display, but I don't see how to adjust that.

One other question. In the LNA, I see that NF (noise figure) is used as a variable to set the noise contribution of the LNA, but I don't see where in the model where NF is actually defined/quantified.



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  • 0
    •  Analog Employees 
    on Apr 25, 2019 6:29 PM over 1 year ago in reply to SrikanthPagadarai

    Condition 2 works fine for me, not a problem, I get 2 MHz on the output. Condition 1 is where I am seeing the offset. I do have the carrier frequency in the outport block set to 2 GHz. I'm still struggling with how to set variable types in Simulink. How would I set the data type in one of the outport blocks? I have a sneaking suspicion that my problem is due to a data type somewhere not having enough resolution, so that when it calculates the RF frequency of 2MHz, based on the LO of 2GHz, it doesn;t come up with an accurate enough number. Does that make sense. Can you help me understand how to set the data type in the outport block? 

  • 0
    •  Analog Employees 
    on Apr 25, 2019 6:52 PM over 1 year ago in reply to stevereine

    When you drop the Outport block on the canvas, the default output is Complex Baseband. So, nothing else other than Center Frequency needs to be set for this block for (1). Similarly, nothing else needs to be changed in the model out-of-the-box. You should be able to see the correct spectrum plot.