  Ramsey fringes observed in an atomic fountain are formed by the superposition
of the individual atomic signals. Due to the atomic beam residual temperature,
the atoms have slightly different trajectories and thus are exposed to a
different average magnetic field, and a velocity dependent Ramsey interaction
time. As a consequence, both the velocity distribution and magnetic field
profile are imprinted in the Ramsey fringes observed on Zeeman sensitive
microwave transitions. In this work, we perform a Fourier analysis of the
measured Ramsey signals to retrieve both the time averaged magnetic field
associated with different trajectories and the velocity distribution of the
atomic beam. We use this information to reconstruct Ramsey fringes and
establish an analytical expression for the position of the overall observed
Ramsey pattern.
