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About NI 5783 PLL problem

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Hello everyone, now I am using NI 5783 (adapter of NI 7972 flexrio) to generate signal, the clock I choose is phase lock to REF IN. I also have a NI 5651 RF signal generator, it use its own on board clock and I use its REF Out as the input of REF IN of NI 5783.


The weird thing is when I connect both signals to an oscilloscope, it shows the two signals are not synchronize, I attached the photo:IMG_7148.jpg

So do I need to do any further programming for that?



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By the way, the two signals on oscilloscope are the output of NI 5783 and the NI 5651.



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One more thing, the way I generate signal from NI 5783 is using the DDS method. In the getting started example of NI 5783, it used another way to generate the signal: generate data from the host and stream that data to the FPGA, and using this way, two signal can be synchronized.

However, now due to my project requirement, I have to use the DDS to generate the signal, is there any modification needed for the code?



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hey guys,


I think maybe there is a problem for my oscilloscope, when 1MHZ signal and 10 MHZ signal connect to the scope the same time, using 10MHZ signal as trigger, the waveform shown is messed up. If we use 1MHZ signal as trigger, the waveform is barely good, but you can still see there is a slow phase drift as time goes by.


I think this is not normal, because oscilloscope shown should be the same either you use 1MHZ or 10MHZ as trigger

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I think the REF Out must be configured to output the clock signal.  Did you probe what is coming out of that pin?

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Accepted by topic author zyb1003

Hello Terry, 


Yes, I probed the REF out, it's a 10MHZ signal. 

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