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Taking Instantaneous values of signal
weeke
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06-04-2011 12:36 PM
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I want to take instantaneous values of my signal.
I want to measure the signal values at at different points in a period of a sine waveform.
How to configure a waveform chart to show Angle in (degrees and radians) and take measurements at those points.
Peter_W
NI Employee (retired)
06-06-2011 06:36 PM
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Hi weeke,
Are you measuring the value of a different signal and trying to trigger those measurements based on the angle of the sine waveform? You should be able to calculate the angle of the output using the frequency of the angle and take measurements that way, there isn't an explicit output of the angle that you can use to trigger a measurement though.
As for showing the Angle in the Waveform Chart, you can right-click on the chart and go to Properties where you can change the Display Format from absolute time to decimal and then use the Scales tab to scale the time value into an angular value. Another way to do this would be to build an array with the angular values and the amplitudes of the signals you are measuring and plot into an XY graph.
06-08-2011 04:10 AM
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Thanks for replying
Yes i want to trigger the signal at different points (Angle) and store the instantaneous values for the specified angles.
But i dont know if we can modify Waveform Chart to show Angular values on x-axis. I have tried it with Waveform Graph and its fine with it.
But my signals wouldnot be shown on waveform Graph.
06-08-2011 04:13 AM
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Any example related to this.
Where you can build a table for instantaneous values at specified angles
Peter_W
NI Employee (retired)
06-09-2011 10:55 AM
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Hi weeke,
As I mentioned in my previous reply, there isn't a way to explicitly time measurements from the angle of a signal, but using the frequency you can determine the time at which the waveform will be at the angle you wish, and then trigger a measurement based on that timing.
When it comes to showing the Angle on the Chart itself, the only way to change the axis is with the method I described of scaling the range. Since you are able to implement this on a Graph however, maybe the document below will help you use the Graph but have it act as a Chart.
Waveform Graph with Chart Functionality
http://zone.ni.com/devzone/cda/epd/p/id/4565
Regards,
Peter W.
