Additional Information
When using this function, consider the following:
1. Output Datatype: The output of the function is an NIComplexNumber. You will have to calculate the magnitude of the signal at each frequency and then plot it in a graph. Here is an example that shows how to calculate and plot it:
2. Scaling the output: The
FFTEx works with raw data and can calculate the FFT without knowing the sample rate or the "dt" of the acquisition. This means the values in the X-axis of the graph do not have a specific unit, so they have to be scaled manually by multiplying by a factor of "df" or "1/dt" according to your acquisition, after calculating the FFT. For example:
Frequency of the signal measured: 10Hz.
Number of Samples = 1000 Samples.
Sample Rate = 20 Samples/s.
Output of the FFT: 500 units.
To get the frequency of the signal you will have to calculate the following:
1000 [Samp] / 20 [Samp/s] = 50s =dt.
df = 1/50s = 0.02Hz.
500 units * 0.02 = 10Hz.
You can use the following code as a guide to scale the X-axis:
