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PXI-5402 Burst generation

Hello everyone, 

 

I'm attempting to generate Burst sinewave at 1M-1.5Mhz with a specific number of cycles (eg 2-20) with a specified interval (eg 100ms) on a PXI-5402. The vi I created is able to do that task but by using frequency lists. I have just two frequencies in the list: one at 1.1Mhz and the other at zero for specified times. The way I do this is calculate the what duration is for say 3 period at 1.1Mhz and use the remaining time to determine 0hz. 

 

The Problem is that I think due to rounding, the cycle doesn't complete at 0Volts in all cases. In the case of 1.1Mhz and 4 cycles with a 100ms the last cycle comes below 0V. Is there a better solution to this VI? I've tried creating a "nudge" variable to attempt to make the cycle complete but that is a failure. Any ideas would be appreciated. 

 

thanks, 


Mark Khemmani

University of Hawaii

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Hi mkhemmani,

 

The PXI-5402 is an arbitrary function generator as opposed to an arbitrary waveform generator. As a result, using your PXI-5402 in List Mode is the right solution for outputting sine waves at different frequencies. More information about the Frequency List Mode can be found here

 

In your case, you would like the waveforms to end at 0 volts, when outputting N cycles of a sine wave. Since you are using an arbitrary function generator you need to specify the correct duration time that ends the waveform at 0 volts.

 

The Frequency List Output specs for the PXI-5402 can be found here. This page tells us what the minimum step duration is and the step duration quantum. For the PXI-5402, this page lists the step duration quantum as 80 ns, but I recommend using the “Frequency List Duration Quantum” property node to confirm this. Try multiplying your pulse nudge with the step duration quantum as opposed to 1E-9. 

Tunde S.
Applications Engineer
National Instruments
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