Conditions for multiple acquisition of echoes from stationary targets in successive transmissions of active sonars

In echolocation, the highest possible number of contacts with a detected target is clearly decisive on the possibilities of echo processing to optimise the estimation of distinctive characteristics of the observed target. In hydrolocation, the slow propagation of acoustic waves in water reduces the number of contacts of echosounders and sonars with detected targets. The article considers model conditions for acquiring multiple contacts with stationary targets detected by various sounding methods - with echosounders, classic active sonars and side looking sonars. Appropriate formulas explicitly linking the possible number of echo signals from the target in a specific geometry of the survey performed at the assumed speed are presented. These formulas are intuitively clear and not very complicated, but their value lies in the ability to instantly combine the vessel speed with the sounding effects, and may be a clear argument for imposing a low sounding speed, which make it difficult to steer the vessel.