Oceanus.

v. 26, no. 4 (1983

Oceanus.

v. 17, summer (1973

Oceanus.

v. 15, no. 2 (1969

Oceanographic and underwater acoustics research : conducted during the period 1 November 1960 - 30 April 1961

Digital computing techniques have been used in special computing applications in underwater acoustics at WHOI for many years, but recently we have commenced intensive application of digital data handling and computing facilities to a variety of computing, data storage, and data handling problems. Progress in these applications is described under Acoustic Instrumentation below. Some bathymetric studies carried out recently under another contract have shown that even very narrow-beam, single-beam echo sounders simply cannot provide reliable depth sounding information where the topography is complex. In this work we have been experimenting with the inverted echo sounder, discussed below, originally developed to measure depth of the sound velocimeter. The inverted echo sounder is lowered to a position within a few feet of the bottom. The total acoustic travel time from surface to bottom may be read as the sum of the travel times from the instrument to the bottom and surface . True depth is then computed in the usual way with appropriate s cnmd velocity data. In its present form the inverted echo sounder is suitable for mapping ~mall areas~ a few square miles, provided there is a suitable means of positioning the instrument. We have experimented with radio-acoustic navigation, and intend to experiment with vertical triangulation from the suspending ship as well. Steady demands for new, modified, and improved instrumentation have been responded to in echo sounding, seismic profiling, and spectrum analysis, as detailed below.Undersea Warfare Branch Office of Naval Research Under Contracts Nonr-1367(00)NR261-102 and Nonr-2129(00)NR261-10

Sonar research conducted during the period 1 January - 31 March 1961

This is a report of activities supported under Contract NObsr-72521 for the period 1 January through 31 March 1961. It also contains mention of other reports, papers, and undertakings of the submarine geophysics group (listed under "Personnel") which are believed to be of interest to the Bureau of Ships. During this period no cruises have been supported directly under this contract. Eight members of the group under the leadership of Dr. Voorhis have participated in a cruise of CHAIN to the Romanche Trench. Their principal objective was to determine the sill depth which controls the exchange of deep, cold water ,between the western and eastern sides of the Atlantic Ocean. This sill was previously identified from hydrographic evidence to lie somewhat east of the Romanche Trench. A second objective was to continue the observations of temperature structure near the sea's surface with the thermistor chain. Another group, under Mr. Baxter's leadership, continued a sound transmission study in the Bermuda area in support of Project ARTEMIS. A third group, under Dr. Hays's direction, commenced a finely detailed bathymetric survey of an area of special interest to Project ARTEMIS. In all three of these studies we are making use of one or more experimental techniques in the use of sonobuoys, underwater acoustic navigation for submerged instruments, and sound coherence studies which are planned for use eventually in sound transmission and bottom reflection research under this contract.Bureau of Ships Under Contract NObsr-7252

Oceanus.

v. 13, no. 1 (1966

Oceanus.

v. 17, winter (1973-1974

Oceanus.

v. 45, no. 3 (2007

Sonar research conducted during the period 1 October - 31 December 1961

Research at sea during this three month period, supported by Contract NObsr-72521, was carried out mostly during the latter portion of the CHAIN Cruise 21 to the eastern Mediterranean. Near-surface sound transmission runs were made with the aid of two foreign ships in the eastern Mediterranean and Tyrrhenian Sea. Sound velocity measurements were made there also. Reverberation and back-scatter measurements using half pound explosives as sound sources were recorded on magnetic tape for future analysis. Further, at several places during the cruise acoustic reflectivity of the sea-floor was measured by means of a semi-automatic system employing the Precision Graphic Recorder and the Edo UQN Echo Sounder. Research other than that on CHAIN Cruise 21, included ambient noise studies of recorded signals from finback whales, and analysis of data from previous observations at sea.The Bureau of Ships Under Contract NObsr - 7252

Oceanus.

v. 16 (1972