Alright. Here is a module that is only partially finished but does have a way to plot the Frequency Spectrum for a given point. Only Numerical points are allowed, and Mango Core Version 2.1 or higher is required.
To use it just go to the control toolbox icon and navigate to the Signal Processing Tab. Then select your point and select the number of previous samples to use for the DFT. Press Generate and you should see 2 graphs. The top chart is just the signal plotted against time, the lower chart is the DFT and the peaks are in Hz.
The DFT will calculate your sample rate based on the data, so if you have changed poll periods recently then you should wait because the sample period won't be stable and the results will be skewed. Also note that all DSP Theory applies here so you have to sample at least 2x as fast as the highest frequency you want to detect. So if you are looking for a 2Hz signal you will need to sample at 4Hz (250ms poll Period). Realistically you will need to sample much faster to get quality results. Remember that Frequency = 1/Sample Period in seconds.
Another note on sample numbers, you will need at least enough samples to reproduce one full cycle of the signal you are searching for. So low frequency signals will take more sample time to detect as higher frequency signals will take less. For example a 2Hz signal has a period of 500ms, so as above you will need to sample at at least 250ms for a duration of 500ms. But for quality results you would sample for longer faster.
I am successfully detecting a pure 10Hz signal by sampling at 5ms as you can see in the attached image.
Mango's fastest sample rate is 1ms so you won't be able to detect signals faster than 500Hz reliably, unless modifications are made the Core code.
The code for the module is here:
https://github.com/terrypacker/mango-modules
Attachment: download link
