# Translations:Water reverberations - book/3/en

Let the integer *N* represent the two-way traveltime parameter in the water layer (Figure 7). A unit source impulse is generated at the surface at time zero. The impulse travels downward in the water and is reflected at the water bottom. Thus, an upgoing pulse of size is generated, and it arrives at the water surface at discrete time parameter *N*. There it is reflected downward and becomes a secondary source. The water surface has a reflection coefficient of –1 as seen from below, so the secondary impulse has the value and occurs at time parameter *N*. This secondary impulse travels the same path as did the initial impulse, thereby producing another secondary source with its impulse occurring at time parameter 2*N*. This repeats again and again. The total result is the one-pass *minimum-delay* reverberation train