ARPA's Ocean Monitoring Program continues to explore new 

 techniques to improve our ability to conduct military operations in 

 the ocean. This includes extending the monitoring and detection 

 capabilities of deep submersibles by adapting and developing 

 advanced submarine detection concepts, by investigating new 

 methods for conducting submerged communications, and by 

 developing new techniques to use sonar signals for detection of 

 objects on the ocean floor. A suite of acoustic transmitting, receiving, 

 and recording equipment is being developed for deep submersibles. 

 The equipment will allow measurement of acoustic parameters of 

 midwater scatterers, small bottom features, and detailed area 

 surveys. Experiments and data analysis are underway to determine 

 the design parameters for a submarine-to-submarine acoustic 

 communications system that can adapt to changes in the 

 transmission properties of the ocean. Results of yet another program 

 that will define dynamic and physical characteristics of deep ocean 

 breaking waves are expected to have ASW applications and improve 

 our capability to interpret radar and satellite observations. Under 

 ARPA sponsorship low-frequency sound sources have been 

 developed and are being tested to determine feasibility of developing 

 high-power sources capable of providing significantly improved 

 detection capability. Also under development is a large aperture 

 array sonar that uses advanced beam forming and signal-processing 

 techniques. This system will be used to study the limitations 

 imposed on sonar performance by the oceanic noise field. 



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