What is MSK?

Minimum shift keying MSK (Minimum Shift Keying) is a modulation technique that changes the carrier frequency to transmit information, that is, special continuous phase shift keying (CPFSK). The maximum frequency shift is 1/4 of the bit rate, that is, MSK is FSK with continuous phase and the modulation coefficient is 0.5.

In digital modulation, minimum shift keying is a frequency shift keying method with continuous phase, which came into being in the late 1950s and 1960s.

Similar to offset quadrature phase shift keying (OQPSK), MSK also delays the quadrature subgrade signal by half a symbol interval relative to the in-phase subgrade signal, thus eliminating the 180 phase mutation phenomenon in the modulated signal.

Extended data:

MSK is an attractive digital modulation method in wireless mobile communication, which has the following two main characteristics:

1, 99.5% of the signal energy is limited within the bandwidth of 1.5 times the data transmission rate. The spectral density decreases with the fourth power of the reciprocal frequency (away from the center of the signal bandwidth), while the spectral density of the usual discrete-phase FSK signal decreases with the square of the reciprocal frequency.

Therefore, the out-of-band interference of MSK signal is very small. This is a valuable feature that we hope to have in the case of band-limited work.

2. The signal envelope is constant, and the system can use cheap and efficient nonlinear devices.

References:

Baidu encyclopedia-? MSK