Spectral measurement

[maguine]

Good morning

I am working on an application with labview interface for arduino that uses Spectral measurements to plot a graph Frequency x Amplitude of a vibration system.  However, the graph is not showing the data it should. The input of the Spectral Measurement block is headed by a trigonometric function "20*tan((asin((X1-2.7)/-1.5))/2)". i 've realized that when I connect the block directly to the tension values, before the function, the plot works normally. Could someone help to demonstrate what is going wrong? The program is going togheter with the question.

Thanks,

Gabriel Machado

[TJWhit]

You're missing at least one control type definition needed to open the vi. Please attach it also.

[maguine]

Ok.

See if you can open now.

Thanks,

Gabriel Machado.

[johnsold]

What does your data look like?

When I feed the formula with a sum of two sines with a peak amplitude of about 1.5, the output of the Formula is mostly NaN (Not a Number). This often results from an input being out of range. The Spectral analysis VI produces no output when the input contains NaNs.

Lynn

[TJWhit]

There are still missing files so I can't run your vi. But I think johnsold has the answer. For example, if X1 is 0, the argument for the asin is 1.8, which gives NaN for the asin function. Are you sure your equation is correct for your values of X1? The range for X1 over which your function is defined is about 1.2 to 4.2 as shown below.