https://www.mathworks.com/help/comm/ref/fskdemod.html
fskdemod - Frequency shift keying demodulation - MATLAB
This MATLAB function noncoherently demodulates the complex envelope y of a signal using the frequency shift key method.
frequency shift keyingdemodulationmatlab
https://en.wikipedia.org/wiki/Gaussian_frequency-shift_keying
Frequency-shift keying - Wikipedia
frequency shift keyingwikipedia
https://www.mathworks.com/help/phased/ref/mfskwaveform.html
MFSK Waveform - Multiple frequency shift keying (MFSK) continuous waveform - Simulink
The MFSK Waveform block generates a multiple frequency-shift keying (MFSK) continuous waveform with a specified step time, sweep bandwidth, frequency offset,...
frequency shift keyingmfskwaveformmultiplecontinuous