A SYNTHETIC BANDWIDTH MEASUREMENT SYSTEM FOR ACOUSTIC REMOTE-SENSING OF GEOACOUSTIC PROPERTIES OF BOTTOM SEDIMENTS

A series of narrowband acoustic transmissions may be combined into an equivalent broadband signal-with a corresponding increase in resolutio n in the time domain. This procedure is called synthetic bandwidth pro cessing. If ray methods are used in combination with inverse theory to determine the otacoustic properties of bottom sediments, the increase d time resolution aids in the identification of arrivals which are clo sely spaced in time. This, in turn, permits improved estimates of the spatial distribution of properties and more accurate otacoustic models . Signal processing techniques and guidelines for synthesizing multioc tave broadband pulse-like signals are presented here. Also described i s the instrumentation used to implement the technique in real ocean en vironments.