Say there is a wave of sines and cosines. (<- one can think of Fourier theory.)
A) There is a wave that has the same frequency all the time. However, amplitude (- shape) of each period differs. Is it possible to separate this wave into combinations of waves that have the same amplitude for each wave?
B) Say there is a added combination of two waves that are same in frequency but different in amplitude. The amplitude of each wave is equal all the time. Can the signal be decomposed into two signals that were combined?