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Shallow Water Investigations at the Naval Underwater Systems Center.
NAVAL UNDERWATER SYSTEMS CENTER NEWPORT R I
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The objective of these efforts is to formulate a model suitable for sonar performance prediction in shallow water. For this purpose, the BIFI range, which is 18.6 miles long and 110 ft deep, was established with bottom-mounted acoustic sources and receivers and moored oceanographic telemetering buoys. Measurements of propagation loss, time smear, frequency smear, and, in addition, temperature profiles and salinity provided a data bank for average values and fluctuations of a number of shallow water acoustic and oceanographic parameters. These oceanographic data were supplemented by others obtained from hydrographic and aerial radiometer surveys and from geoological studies. Evidence from tests using explosives as sound sources indicated that the lowest of the normal modes was predominant in the received signal. This led to the design and emplantment of a normal mode source consisting of 25 hydrophones capable of transmitting any desired low mode in the frequency range 1 to 4.5 kHz. Author
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