The theory of linear systems is applied to simulate and describe signals and synchronous noise registered by seismic sensors. An algorithm is proposed to reduce the effect of the inhomogeneous upper layer and of regular interference associated with the low velocity zone. Mathematical models of synchronous noise are given with consideration for their randomly changing parameters. The materials from this paper can be helpful in developing algorithms to process data acquired primarily by nonexplosive pulsed and vibrational seismic survey technologies.