Frequency shift keying (FSK) is a relatively simple, low-performance form of digital modulation. Binary FSK is a form of FSK where the input signal can have only two different values (hence the name binary). Binary FSK is a constant-envelope form of angle modulation similar to conventional frequency modulation except that the modulating signal varies between two discrete voltage levels (i.e., 1’s and 0’s) rather than with a continuously changing value, such as a sine wave.
Binary FSK is the most common form of FSK. With binary FSK, the center or carrier frequency is shifted by the binary input signal. Consequently, the output from an FSK modulator is a step function in the frequency domain. As the binary input signal changes from a logic 0 to logic 1 and vice versa, the FSK output signal shifts between two frequencies; a mark or logic 1 frequency and a space or logic 0 frequency. Users can see the binary input and the varying output frequency through the GUI.