  The theory of spin fluctuations is developed for an ensemble of localized
electrons taking into account both hyperfine interaction of electron and
nuclear spins and electron hopping between the sites. The analytical expression
for the spin noise spectrum is derived for arbitrary relation between the
electron spin precession frequency in the field of the nuclear fluctuation and
the hopping rate. An increase in the hopping rate results in the drastic change
of the spin noise spectrum. The effect of an external magnetic field is briefly
addressed.
