fast frequency shift keying (FFSK)

Fast Frequency Shift Keying (FFSK) is a variant of Frequency Shift Keying (FSK). As with frequency shift keying, each logical state is assigned its own frequency in the FFSK process. The shift keying from one frequency to the other frequency always takes place at the zero crossing of the modulation oscillation. Fast Frequency Shift Keying (FFSK) is also referred to as Minimum Shift Keying ( MSK).