1) filter (not related); 2) Crystal (in progress); 3) IC; 4) Antenna. (not related)
The three most basic modulation methods (amplitude modulation, frequency modulation and phase modulation) of digital signal are ASK, FSK and PSK.MSK is an improvement of FSK.GMSK is an improvement of MSK. The gaussian low-pass premodulation filter is inserted before the MSK (minimum frequency shift keying) modulator to improve spectrum utilization and communication quality.OFDM can be regarded as a modulation method for multi-carrier.
frequency drift：