Minimum Shift Keying (MSK) is a special form of Frequency Shift Keying (FSK) that is very bandwidth efficient, resulting in more efficient use of the available bandwidth
. In MSK
keying,the modulation index, which is determined from the ratio of the angular frequency of
deviationto the angular frequency of the modulation signal, is 0.5; in contrast, the modulation index of OrthogonalFrequency Sh
ift Keying(OFSK) is 1. Since a frequency change is associated with each bit period, Minimum Shift Keying (MSK) is also referred to as Fast Frequency Shift Keying
(FFSK). In the MSK process, frequency shift keying always takes place at the same phase position.