Let's write a trigonometric record of QAM:
If I=1 and Q=1, then the phase in the cosine will be equal to -pi/4, since the arctangent will be equal to pi/4. At the same time, this point is located in the first quarter on the constellation diagram, but its phase is pi/4 (without a minus). Why is that?
I looked, someone will write the point I=1; Q=1 as a cosine with amplitude sqrt(2) and phase pi/4, and someone as a cosine with amplitude sqrt(2) and phase -pi/4. Which option is more correct? Mathematically, it is more correct to write with a minus, it seems to me.