some evidences to show how patient QPSK is:
https://bbs.gter.net/thread-1007982-1-1.html 11楼
https://bbs.gter.net/thread-1007791-1-2.html 10楼
https://bbs.gter.net/thread-1007627-1-3.html
https://bbs.gter.net/thread-1007561-1-3.html
https://bbs.gter.net/thread-1007991-1-2.html