# 5.3 Frequency Shift Keying (FSK)

## FSK waveforms

#### Frequency Shift Keying (FSK) has until recent years been the most widely used form of digital modulation, being simple both to generate and to detect, and also being insensitive to amplitude fluctuations in the channel. FSK conveys the data using distinct carrier frequencies to represent symbol states. An important property of FSK is that the amplitude of the modulated wave is constant.

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Consider the case of unfiltered binary FSK shown here. This waveform can be viewed as two separate ASK symbol streams summed prior to transmission. |

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