AnsweredAssumed Answered

PSG received modulation continuously rotates

Question asked by oscar.monerris on May 31, 2012
Latest reply on Jun 1, 2012 by oscar.monerris
Hello, 

I'm trying to capture IQ samples from a PXA using Labview (I can download them with Labview). My source is a PSG generating a digital modulation (4QAM or BPSK). 

The point is that, if I set the PXA using Basic->IQ Waveform->Display->I/Q Waveform I'm able to distinguish the samples. I'm using an scope to monitor de Q samples form the BNC output in the  PSG. So I can actually see the bits. 

Nevertheless, the blue and yellow lines in the PXA representing I and Q are not still. They should the same be from trigger to trigger as happens in the scope given that the PN23 sequence repeats all the time. 

When I download the samples to labview and plot the IQ samples I see that the constellation spins all the time. It's never still.

Any explanation on this?

Thank you!

Òscar

Edited by: oscar.monerris on May 31, 2012 8:06 AM  

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