Underwater Acoustic Communications

Award Information
Agency: Department of Defense
Branch: Navy
Contract: N00014-05-M-0221
Agency Tracking Number: N054-022-0142
Amount: $69,833.00
Phase: Phase I
Program: STTR
Awards Year: 2005
Solicitation Year: 2005
Solicitation Topic Code: N05-T022
Solicitation Number: N/A
Small Business Information
82 Technology Park Drive, East Falmouth, MA, 02536
DUNS: 050751346
HUBZone Owned: N
Woman Owned: N
Socially and Economically Disadvantaged: N
Principal Investigator
 Andrey Morozov
 Chief Scientist
 (508) 548-2077
Business Contact
 Daniel Webb
Title: President
Phone: (508) 548-2077
Email: dwebb@webbresearch.com
Research Institution
 James C Preisig
 A.O.P.E., Mail Stop 11, Water Street
Woods Hole,, MA, 02543
 (508) 289-2736
 Domestic nonprofit research organization
Webb Research Corporation (WRC) and Woods Hole Oceanographic Institution (WHOI) plan to develop on a modified Orthogonal Frequency Division Multiplexing (OFDM) modulation for mobile time-variable underwater acoustical channel. The OFDM and COFDM (coded OFDM) systems are well known as very attractive system for multi-path underwater acoustic communications channels. There were a few attempts to realize OFDM systems for underwater communications. The traditional approach expects the symbol duration of the transmitted signal to be larger then channel time spread and scattering shows as deep amplitude fading, which needs code protection from burst errors. Nevertheless there are no good examples of practical reliable working OFDM systems in the real ocean situations. All advantages of OFDM systems disappear in a time-variable channel, when channels begin to interfere due to Doppler frequency spread. Exploiting the main advantage of usual OFDM to simplify signal in a single frequency channel of broadband multi-channel system, a new approach suggests to use much shorter pulses partially spread in time and to apply more complicated soft decision multi-path decoders such as linear and decision feedback (DFE) equalizers and maximum-likelihood sequence detection (MLSD) algorithm. The expected result is a more robust and reliable system in time-variable or mobile channels. The proposal includes three stages: estimation of mobile channel statistical parameters using computer models of sound propagation; comparing different approaches for real time channel pulse response estimation; numerical simulation of proposed algorithms of signal receiving. The investigation will obtain and test innovative algorithms for an underwater acoustic communication modem, which can be used not only for high data rate communication at short range, but for long-range low data rate communication as well.

* information listed above is at the time of submission.

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