Page 46 - 2016Fall

History of Underwater Sound
on passive listening sonar for US submarines and quieting of their radiated noise or ship signature (Lasky, 1977). An example of their work was the JP directional hydrophone system, shown in Figure 7, mounted on a submarine. This enabled submerged US submarines as well as patrol boats to get bearings on surface ships from their signatures in the audio band (NDRC, 1946b). This system provided much needed sensing in the audio band, enabling US submarines to sense and measure the direction of enemy ships. CUDWR NLL became the US Navy Underwater Sound Laboratory af- ter the war (Knobles et al., 2015)
In 1942, CUDWR was also tasked to operate an Underwater Sound Reference Laboratory (USRL), under the direction of Robert S. Shankland, to be in charge of developing and providing an inventory of wideband underwater acoustic standard transducers (NDRC, 1946c; Brown and Paolero, 2015). A test facility was established in Orlando, FL, while
Figure 7. JP directional hydrophone, the fleet’s first wideband surveil- lance system in the audio band.
the engineering work was done at CUDWR headquarters in New York. These transducers were calibrated by first prin- ciple means (i.e., reciprocity) and were utilized by a variety of clients working on the war effort.
The Harvard Underwater Sound Laboratory (HUSL) was es- tablished in June 1941 with Frederick V. (Ted) Hunt (Figure 8) as its director. Hunt went on to become an ASA President (1951-1952). He received the ASA Pioneers of Underwater Acoustics Medal (1965) and the Gold Medal (1969). HUSL operated for four years, making important contributions on
Figure 8. Frederick (Ted) Hunt and Mk 24 torpedo “Fido.”
using sound to detect submarines by (1) improving current equipment, (2) developing new devices, and (3) develop- ing acoustic homing torpedoes (Hunt, 1946; Pestorius and Blackstock, 2015).
Improvements to the existing fleet ASW sonar included (1) a system to determine target bearing with a single, split so- nar beam, called the bearing deviation indicator (BDI), (2) a time-varying Gain (TVG) system to compensate for trans- mission losses, and (3) an own-ship Doppler nullification (ODN) system to increase the detection of Doppler shift in target signals. These were incorporated in an improved so- nar display console. The new sonar architecture HUSL de- veloped (cylindrical array of transducer elements, electrical capacitive, and electronic modulation scanning) set the pace for modern sonars (Pestorius and Blackstock, 2015).
A classic HUSL development was the Mk 24 torpedo (for secrecy purposes, designated a mine called “Fido”) that was developed by this laboratory in record time. It was an air- dropped, battery-electric propulsion device, guided by an autonomous sonar system installed ahead of the warhead (Figure 8) and was developed and tested in December 1942, put in production by Western Electric, and successfully uti- lized in 1944 operations in the Atlantic.
The University of California Division of War Research (UCDWR) was established by the NDRC in April 1941 to capitalize on the scientific expertise of the University of California system, the Scripps Institute of Oceanography (SIO), and to provide a research and development presence on the West Coast. The Navy Radio and Sound Laboratory (NRSL) was already in existence at San Diego’s Point Loma. The UCDWR was contracted to administer the NSRL for the Navy and provided most of the scientists, engineers, and technical staff while the NSRL provided the facilities and support. The first director (1941) was Vernon Knudsen, a cofounder of the ASA, a former ASA president (1933-1935), and later an ASA Gold Medalist (1967). Knudsen was suc- ceeded in 1942 by Gaylord Harnwell, who received the Medal
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