  The paper considers the phase retrieval problem in N-dimensional complex
vector spaces. It provides two sets of deterministic measurement vectors which
guarantee signal recovery for all signals, excluding only a specific subspace
and a union of subspaces, respectively. A stable analytic reconstruction
procedure of low complexity is given. Additionally it is proven that signal
recovery from these measurements can be solved exactly via a semidefinite
program. A practical implementation with 4 deterministic diffraction patterns
is provided and some numerical experiments with noisy measurements complement
the analytic approach.
