Measuring Amplitudes of 3 Mixed/Staggered Phase Square Waves

[BadScientist]

I'm writing a vi intended to measure the amplitudes of three mixed signals.  These signals are generated by the DAQ already to drive 3 LEDs at 9kHz/ 50% DC combined. 

I was able to modify an existing example vi to create the LED drive.  I was hoping to find a similar example for the data capture and analysis.  I haven't been successful thus far. 

Could someone please suggest a good example to get me started?  Please forgive my inexperience as I have been teaching myself Lab View and thus have a very ignorant instructor.

-Thanks in advance.

[johnsold]

Bad,

Have you tried the analog data acquisition examples? The sample rate would need to be >18 kHz to meet the Nyquist criterion, but that assumes sinusoidal signals. Since you are talking square waves, you will need to sample quite a bit faster to recover the waveforms. 100 kHz or 250 kHz are probably good starting points if your device will sample that fast.

Tell us what you have tried and specifically what does not work. Do you get error messages? Does the result look wrong?

Posting you code with the data you have collected is very useful.

Lynn

[Ipshita_C]

Hi,

It depends on what kind of analysis you want to do. Data capture can be done in two ways, streaming or by writing to a file. There are specific examples dealing with both methods in Example Finder, Harware Input and Output<DAQmx. There is a Statistics Express VI available for statistical analysis of DAQ data. I would start with using that first. Hope this helps.

Ipshita C.

[BadScientist]

Thanks for the help.  I forgot to put the differential input on ch. 8.  I'm seeing waveforms now. I'm going to have to generate a sync pulse or I can't tell one square wave from the next.  Wish me luck.  I'll be back for more good advice for sure.