FM demodulation

I am not sure of the exact nature of your signals, but I did something similar which may  be useful, in a old patent "Fiber-optic digital system for laser doppler vibrometers (LDVs)" US Patent 8,144,334 B2. The signal processing is described in the patent body. All calculations and analyses were done using IgorPro (I forget the version #) using basic code and analysis operations.

The patent has expired so you are free to use it. One thing that has been explained by many an attorney is that if a patent is still valid you cannot use it even in an R&D setting without a license from the patent holder.

Andy

https://patents.google.com/patent/US8144334B2/en?oq=US8144334B2+

You can use Igor's Hilbert Transform for demodulation.

This reference is using plain vanilla Matlab code; should be straightforward to convert to Igor-ese:

https://dsp.stackexchange.com/questions/44710/hilbert-transform-of-an-f…

Useful background info here:

https://www.gaussianwaves.com/2017/04/extract-envelope-instantaneous-ph…

and in Igor's HilbertTransform operation help.

Note: Igor 9 has an InstantFrequency operation which uses the Hilbert Transform "under the hood".

Thank you for these helpful hints s.r.chinn, hegedus, and Jim.