Optimal estimation of the amplitude of signal with known frequency in the presence of thermal noise
Luo Jie1, Ke Jun1, Liu Yi-Chuan1, Zhang Xiang-Li1, Yin Wei-Ming1, Shao Cheng-Gang2, †
       

The variance of amplitude estimation with the correlation method as a function of m: (a) the variance of estimating the cosine component, (b) the variance of estimating the sine component. The line (circle) is fitting to the square of Eq. (16), the line (square) is to Eq. (12).