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Zedboard FMCOMMS2 loopback issue

Question asked by LI1234 on Sep 23, 2016
Latest reply on Nov 18, 2016 by CsomI
Branched from an earlier discussion

Hi Csmol,

   I send data via DMA on the platform ZedBoard +AD-FMCOMMS2-EBZ. Now I want to use the iLA to get the data. I add the DMA data into the iLA. Except that, I don't change anything. Now I find the result is strange. When I don't connect Tx SMA with Rx SMA, I find the waveform of Rx chain is like Tx chain. And when I connect Tx1 with Rx1, I got the waveform:

From top to down, it is Rx1 I data,Rx1 Q data,Tx1 Q data,Tx1 I data,Tx2 Q data,Tx2 I data and Rx2 I data. you can find the Rx1 I data is reverse, and Rx2 I hava data when I don't  connect chain 2. I also find the result  will change when use diffrent length of SMA line, when I use shorter, the result is

you will find the I,Q data exchanged.

Could you have any idea for this?

Thanks!

David

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