Book Description

Information from field tests, literature, and published data was gathered to establish the operating principles, capabilities and limitations, environmental restrictions, and availability of acoustic systems from the standpoint of conditions in the Lower Mississippi Valley. The acoustic systems are commonly classified according to the method by which the sound energy is produced, such as boomers, sparkers, and gas guns. Different degrees of resolution and penetration are achieved, largely because of differences in the frequency spectrum of the generated energy. However, because of inherent limitations, it is impossible to achieve both high resolution and deep penetration with any acoustic system. Either transducers or hydrophones of various designs are used to detect signals reflecting from subbottom horizons. Graphic recorders of various types are used with most acoustic profiling systems; however, magnetic-tape recording and signal processing is being accomplished with increasing frequency. Proper interpretation of acoustic subbottom profiles required an awareness of and possible corrections for scale variations caused by several factors, recognition of multiple reflections, an understanding of why reflections occur, and recognition of characteristic signatures. System selection for a particular survey requires a consideration of operational factors such as size and weight of equipment as well as environmental factors such a(Author).