Mapping of soil contours in development planning is necessary. Soil contour mapping is also called topography. While mapping the contours of the seabed is called bathymetry.

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In the seafloor mapping or Bathymetry instruments we commonly use include echosounder or fishfinder. Both instruments are working principles using underwater acoustics.

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An echosounder is a device for measuring water depth by sending wave pressure from the surface to the bottom of the water and recorded the time until echo returns from the bottom of the water.

The basic utility of echosounder is to determine the depth of a waters by sending wave pressure from the surface to the bottom of the water and recorded the time until echo returns from the bottom of the water. Display data can also be combined with global coordinates based on signals from existing GPS satellites by installing a GPS antenna (if the GPS feature on echosounder exists).

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The principle works are: the transmitter there is a transducer that serves to convert electrical energy into sound. Then the resulting sound is emitted with a certain frequency. This sound is transmitted through a water medium having a velocity of, v = 1500 m / s. When the sound is about an object, such as a fish, this sound will be reflected. In accordance with the wave nature of the wave when a barrier can be reflected, absorbed and refracted, the same thing happens in this wave.

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When the wave is about the object, some of its energies are reflected, refracted or absorbed. For the reflected wave the energy will be received by the receiver. The amount of energy received will be processed with a program, then will be obtained output (output) of the program. The received results are derived from data processing obtained from the determination of the time interval between the transmitted pulse and the received pulse. From this result can be known the distance of a detection object.