Figure 9. Lab test of the real-time optical mapping system. 



The demonstration hardware provides a swath width of 400 feet (122 meters) 

 when operated at an altitude 120 feet (37 meters) above the seafloor, with a resolution 

 element size of 3 inches (8 centimeters). Higher resolutions, but smaller swath widths, 

 are obtained by lowering the operating altitude. A 5-knot (2.6 meters per second) speed of 

 advance provides a search rate of 0.2 square nautical mile per hour. 



MINISONAR 



To provide an acoustic navigation capability for very small vehicles, a sonar device 

 of minimal size is required. The goal of a current development effort at NOSC is an elec- 

 tronics "scan-within-pulse" sonar with an underwater head not larger than 3 by 6 by 6 

 inches (8 by 15 by 15 centimeters) that will have a range of 100 to 300 feet (30 to 90 

 meters) and a resolution of 3 inches (8 centimeters). The prototype demonstration model 

 is currently under test. 



PRESSURE TOLERANT ELECTRONICS (PTE) 



With the advent of solid-state electronic components, a major improvement in the 

 packaging of undersea electronic systems is possible. The primary characteristic of PTE, 

 i.e., the electronics are not protected from the pressure, describes its real advantages. It 

 frees the designer from constraints imposed by pressure vessels, and it provides almost un- 

 limited freedom in the choice of container size, shape, and materials. Since there is no 

 pressure difference between the inside and outside of the container, there is no need for 

 heavy containers or high-pressure penetrators and seals. At the present time, all known 

 PTE systems use liquid- filled, pressure-equalized containers. In addition to offering the 

 advantages of few container constraints, such systems can or will be able to allow control of 

 package buoyancy, eliminate the potential for catastrophic pressure seal and penetrator 

 failures, provide a low thermal resistance path to the ocean, and permit the design of 

 flexible, inexpensive electronic systems capable of operation at any depth. There are 

 currently a large number of electronic devices and components that have been tested and 

 found adequate for PTE application. Many amplifiers, signal processing devices, and sonar 



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