multiple frequency shift keying (MFSK)
Multiple Frequency Shift Keying (MFSK) is a multi-frequency shift keying( FSK) technique that, in contrast to classical frequency shift ke ying, uses not only two but several frequencies for the transmission of the digitalsignals.
With multi-frequency shift keying, several signals can be modulated simultaneously or sequentially. The number of frequencies is calculated from the logarithm of 2 and can be between 2 and 64. The most commonly used is MFSK16. In multi-frequency keying, the ratio of the step rate( baud) to the data rate (bit/s) is lower than in binary transmission.
One of the best known MFSK methods is the two-tone method, which is used in telephone technology for dialing telephone numbers. Here, two tones are assigned to each symbol of the multi-frequency alphabet.