  The spectrum of the spin particle in oscillatory potential subjected to
external parabolic magnetic field ${\bf B}=(B_0+Gx+\tilde G x^2){\bf \hat z}$
is obtained. The structure of energy levels of the considered system allows to
identify the frequency of the oscillator via the spectrum of spin sublevels
coming only from {\it one} oscillatory level. The effect is due to the gradient
terms in the form of the field.
