Demodulating FSK audio in Python

1. What is demodulation of FSK?
2. What is the most commonly used demodulation technique for FSK?
3. Which IC is used for FSK demodulation?

What is demodulation of FSK?

An FSK demodulator is provided comprising means for receiving and digitizing an FSK signal (such as a signal comprising two frequencies f1 and f2 in which first and second logic states are represented by first and second periods of different durations).

What is the most commonly used demodulation technique for FSK?

The most used demodulation technique is the one using a PLL circuit (fig. 2). The FSK signal across the PLL input takes two frequency values. The error voltage supplied by the phase comparator follows such variations, and so, it constitutes the NRZ binary representation (high and low level) of the FSK input signal.

Which IC is used for FSK demodulation?

... FSK modulation, the task is to detect mark and space frequencies of the received signal and converts it back to digital 1 or 0. The IC used to make the demodulator circuit is IC XR2211 which has a special function as an FSK demodulator.