Frequency shift keying(FSK)

Modulation scheme often used for wireless transmission is frequency shift keying(FSK).The simplest form of FSK ,also called binary fsk(BFSK),assigns one frequency f1 to binary 1 and another to frequency f2 to binary 0.A very simple way to implement FSK is to switch between oscillators ,one with the frequency f1 and other with frequency f2,depending on the input.To avoid sudden changes in phase ,special frequency modulation with continous pahse modulations (cpm) can be used .Sudden changes in phase cause high frequencies ,which is an undesired side - effect.
A simple way to implement demodulation is by using two bandpass filters ,one for f1and the other for f2.A comparator can then compare the signal evels of the filter outputs to decide which of them is stronger.FSK needs a larger band-width compared to ASK but is much less suscepilble to errors.
It has a wide sinusoidal graph in it....