| Resumo: |
The side looking sonars have been developed for greater swath coverage, digital processing of the signals has improved the quality of the images and interferometric techniques have been used to determine the depth of the bottom features. A review of the systems existing today is presented. Documents such as graphs, block diagrams, images, maps, sections, created from data acquired at sea level suffer from a filtering or smoothing effect that restricts the representativity of the measured parameters and therefore limits their interpretation. The greater the depth of the seafloor, the greater the filtering. It is due not only to the nature of the measured phenomenon but also the characteristics of the sensors, to their operation and to the data processing. As far as the measurement is concerned, moving the sensors on vehicles cruising at limited elevation above seafloor would allow detection of shorter wavelengths and production of documents more representative of the true nature of the seafloor morphology and structure. A better knowledge of the distribution of all the wavelengths of the seafloor morphology particularly lacking in the meter to kilometer range, is necessary in order to understand seafloor processes and to develop models of the seafloor.
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