  The Ramsey fringes formation during the excitation of topological coherent
modes of a Bose-Einstein condensate by an external modulating field is
considered. The Ramsey fringes appear when a series of pulses of the excitation
field is applied. In both Rabi and Ramsey interrogations, there is a shift of
the population maximum transfer due to the strong non-linearity present in the
system. It is found that the Ramsey pattern itself retains information about
the accumulated relative phase between both ground and excited coherent modes.
