How to separate a low amplitude signal of same frequency but different phase I have a signal consisting of two sine waves of same frequency but have different phase (and also a lot of HF noise). Their amplitudes differ by about $120\textrm{ dB}$. How to I go about separating them? SNR is about $130\textrm{ db}$ but its frequency is far higher than my signal, i.e. $f(\textrm{noise}) \gg  f(\textrm{signal})$.

Any special technique? Also I am really just a beginner, so extra points for those who give a detailed explanation.
Two exact sine waves of the same frequency but different phases sum to another exact sine wave.  That resultant sine wave can be decomposed into an infinite numbers of pairs (or any other greater number) of sine waves of the same frequency, not just the two original ones.  Thus more information is required to reduce the possible solution space below infinite.