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Hi, My name is Mirza. I am still new in LabView. Currently, i came with an idea to generate a test program. The program is to check the amplitude of an signal. How i want to make an indicator will light up if the amplitude of the signal is equal to 5 ? Please someone help me

 

mija96_0-1595099622429.png

 

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It would help if you could attach the actual VI. We cannot really debug pictures with express VIs, because there is no way to tell how it's configured (noise? simulate timing? etc.). Also, if you want to change one of the controls during the run, the terminals need to be inside the loop.

 

It is unlikely that an amplitude is exactly 5 at any given time, so maybe you want to light up if it is greater or equal 5, for example. Have you looked at the content of the cluster?

 

Please attach your VI. Thanks!

 

 

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Hi, here i attached my VI. I able to light up the indicator if the amplitude is equal to 5. But there is certain frequency that set, the indicator is not light up although the amplitude is 5.

 

 

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Solution
Accepted by topic author mija96

As I already said, "equal" comparisons of DBLs are very dangerous and you should never do them. Replace the " equal to 5" comparison with e.g. an "larger than 4.99" or similar. real signals also have noise, so adjust accordingly. You might also want to tune the width input of the peak detector.

 

(Set your amplitude display to show 16 decimal digits and you'll see what I am talking about. For a frequency=11 and amplitude=5, the calculated amplitude from the peak detector is 4.9999994547609026) and ymax=4.9996052210190793)

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