Sea Technology

MAY 2018

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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Page 21 of 44 May 2018 | ST 21 Waltham, Massachusetts, Septem- ber 2016 using the analog feed-for- ward technique for sonar and communications. The goal was to demonstrate sufficient active ana- log cancellation to enable full-du- plex acoustic communications and continuous active sonar. The DOL- PHIN Comms POC system was able to demonstrate 65+ dB of analog cancellation in a highly reverber- ant laboratory tank. This exceeded the goal of 40 dB and validated the concept of adaptive cancellation for full bandwidth. Full-duty continu- ous active sonar and communica- tions using CDMA, OFDMA and FSK (frequency-shift keying) were all successfully demonstrated. Following tank trials, the devel- opment program moved on to open water to evaluate potential to scale up in real water conditions using commercial equipment. This test included open water, omnidirec- tional transducers, realistic frequen- cy ranges and bandwidth, useful range distances, and highly rever- berant conditions. The goal was to demonstrate DOLPHIN Comms technology at 100-m range and maintain full-duplex acoustic capa- bility providing data communica- tions in challenging environments. The testing was performed in a very challenging shallow-water environ- ment with many obstructions (pil- ings, floating docks and cables) in a marina in Boston, Massachusetts, March 2017. The maximum water depth was 5 m at high tide. This condition was chosen to test common issues that often degrade acoustic communica- tions, such as multipath and Dop- pler impacts. Stations A and B were 100 m apart, transmitting between and under docks with cables and pilings. This environment is among the most challenging for typical acoustic transmissions, but testing was successful using the DOLPHIN Comms cancellation technology. The test demonstrated 80 dB of analog cancellation in a dynamic environment and the ability to scale to useful distances using commer- cial equipment, while maintaining robust, reliable full-duplex commu- nications. The test was performed at 6 percent power (60 mW or 160 dB) and demonstrated its expected 1.6 Kbits/sec data rate, full duplex, us- ing binary FSK modulation. Following the initial laboratory and open-water testing, the DOL- PHIN Comms technology was demonstrated at the Annual Navy Test and Experimentation (ANTX) event in August 2017 and the Spe- cial Operations Command (SO- COM) Diver Comms demonstra- tion in November 2017. DOLPHIN Comms successfully demonstrated an additional capability: clandes- tine, full-duplex communications in a network environment. DOLPHIN performed in less than 5 m of wa- ter and successfully delivered clan- destine text messages in full-duplex mode. Practical Applications The DOLPHIN Comms technol- ogy can be applied anywhere there is a demand for ad hoc networks, high throughput, long range/high reliability and clandestine com- munications. This could include: homogenous networks of similar undersea nodes; heterogeneous networks of diverse undersea nodes (divers, UUVs, fixed stations); ad hoc networks of surface and un- dersea nodes, especially USV plus UUV system of systems; submarine communications systems; and diver communications. Such features will be of interest to divers. Military operations will bene- www. 25 rue Michel Marion 56850 Caudan - France +33 (0)297 898 580 - UNDERWATER LISTENING SYSTEMS New Noise Processing Features Versatile Acoustic Recorders Real-Time Listening Remote Buoys 26-28 June 2018 SEC, Glasgow Find us at stand E42 "The DOLPHIN Comms technology can be applied anywhere there is a demand for ad hoc networks, high throughput, long range/high reliability and clandestine communications."

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