  In recent years, progress in improving the bias stability of NMR gyroscopes
has been hindered. Taking inspiration from the core idea of rotation modulation
in the strapdown inertial navigation system, we propose a general approach to
enhancing the bias stability of NMR gyroscopes that does not require
consideration of the actual physical sources. The method operates on the fact
that the sign of the bias does not follow that of the sensing direction of the
NMR gyroscope, which is much easier to modulate than with other types of
gyroscopes. We conducted simulations to validate the method's feasibility.
