Multiple frequency-shift keying
| Passband modulation | 
|---|
| Analog modulation | 
| Digital modulation | 
| Hierarchical modulation | 
| Spread spectrum | 
| See also | 
| 
 | 
Multiple frequency-shift keying (MFSK) is a variation of frequency-shift keying (FSK) that uses more than two frequencies. MFSK is a form of M-ary orthogonal modulation, where each symbol consists of one element from an alphabet of orthogonal waveforms. M, the size of the alphabet, is usually a power of two so that each symbol represents log2 M bits.
- M is usually between 4 and 64
- Error correction is generally also used