  We have studied the precession mode, the rotational excitation built on the
high-$K$ isomeric state, in comparison with the recently identified wobbling
mode. The random-phase-approximation (RPA) formalism, which has been developed
for the nuclear wobbling motion, is invoked and the precession phonon is
obtained by the non-collective axially-symmetric limit of the formalism. The
excitation energies and the electromagnetic properties of the precession bands
in $^{178}$W are calculated, and it is found that the results of RPA
calculations well correspond to those of the rotor model; the correspondence
can be understood by an adiabatic approximation to the RPA phonon. As a
by-product, it is also found that the problem of too small out-of-band $B(E2)$
in our previous RPA wobbling calculations can be solved by a suitable choice of
the triaxial deformation which corresponds to the one used in the rotor model.
