  This paper presents the analytical and numerical analysis of fluctuational
dynamics of ac hysteretic SQUID. It has been demonstrated, that the most
important parameter for the improvement of the hysteretic SQUID sensitivity is
the ratio between the pump and the characteristic frequencies but not their
absolute values. The resonant behavior of signal-to-noise ratio as function of
the pump frequency has been observed and the narrow area for the optimal pump
frequency range is indicated.
