How to calculate the distance between communication constellations

Euclidean distance calculation between communication constellations. Those who have studied communication principles or digital communication should know, etc.). If it is closest to 00 o'clock, which signal to send is determined according to the distance between the received signal and the four points on the constellation diagram (generally called Euclidean distance), and the information content is twice that of sending one bit. At this time, you can choose QPSK (four-phase modulation, that is, 00) and not send modulation symbols.