  The one-dimensional phase retrieval problem consists in the recovery of a
complex-valued signal from its Fourier intensity. Due to the well-known
ambiguousness of this problem, the determination of the original signal within
the extensive solution set is challenging and can only be done under suitable a
priori assumption or additional information about the unknown signal. Depending
on the application, one has sometimes access to further interference
measurements between the unknown signal and a reference signal. Beginning with
the reconstruction in the discrete-time setting, we show that each signal can
be uniquely recovered from its Fourier intensity and two further interference
measurements between the unknown signal and a modulation of the signal itself.
Afterwards, we consider the continuous-time problem, where we obtain an
equivalent result. Moreover, the unique recovery of a continuous-time signal
can also be ensured by using interference measurements with a known or an
unknown reference which is unrelated to the unknown signal.
