Ask- amplitude shift keying modulation, which represents binary symbols 0 and 1 with different amplitudes respectively.

FSK- frequency shift keying modulation, that is, different frequencies represent different symbols. For example, 2KHz means 0 and 3KHz means 1.

PSK phase shift keying modulation, through the binary symbols 0 and 1 to judge the front and back phases of the signal. Such as 1 with π phase, 0 with 0 phase.

GFSK- Gaussian frequency shift keying, which limits the spectrum width of the signal through Gaussian low-pass filter before modulation.

GMSK- Gaussian filtering minimum shift keying modulation technology used in GSM system.

Orthogonal amplitude modulation.

DPSK differential phase shift keying modulation.

MQAM- multilevel quadrature amplitude modulation

MPSK polyphase phase shift keying

TCM trellis coded modulation

vestigial sideband

OFDM- OFDM modulation

Generally speaking, digital modulation is to convert digital baseband signals into digital bandpass signals.