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AD9371 Questions 6

Question asked by Shay.L on Mar 23, 2017
Latest reply on Mar 31, 2017 by sripad

Hello,

 

I am testing the AD9371 Rx path using the ADRV9371-W/PCBZ EVB.

I am using the Xilinx, HW-Z7-ZC706 Rev: B evaluation platform and the TES software to control the EVB.

Rx Profile:  100MHz, IQRate=153.6MHz, Dec5
The Rx PLL frequency is 3410MHz. The input signal is a CW signal at 3415MHz Pin = -30dBm connected directly to Rx2 SMA connector.
Rx2 gain Index = 241, It means that the AD9371 Rx Gain = 10dB in this frequency. 
In file TES_Rx2_Plot_Index=241_Pin=-30dBm.JPEG we can see the TES plot of this signal.

When I capture the IQ samples to Matlab and perform FFT I get the following results as shown in file Matlab_Rx2_Plot_Index=241_Pin=-30dBm.JPEG

Notes:

1.  The measured signal in Matlab is -19.77dBm, it relate to the 10.23dB gain of the Rx path.

2.  At low power levels (No RF, Noise test) the Matlab plot is identical to the TES Rx plot.
     Files:  TES_Rx2_Plot_Index=241_Pin=NO_RF.JPEG and Matlab_Rx2_Plot_Index=241_Pin=NO_RF.JPEG

 

My questions are:

1.  Why the IQ samples in the Matlab plot looks like the Rx path is in compression ?

2.  Why there is a difference between the TES Rx plot to the IQ samples Matlab plot ?

3.  Why I don't see this difference in the noise test ?

 

Thanks,

Shay.

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