Revised single‐spacecraft method for determining wave vector k and resolving space‐time ambiguity

A practical method is proposed for determining the wave vector of waves from single‐spacecraft measurements. This wave vector knowledge can then be used to remove the space‐time ambiguity produced by frequency Doppler shift associated with spacecraft motion. The method involves applying the Wiener‐Khinchin theorem to cross correlations of the current and magnetic field oscillations and to autocorrelations of the magnetic field oscillations. The method requires that each wave frequency component map to a unique wave vector, a condition presumed true in many spacecraft measurement situations. Examples validating the method are presented.