Acoustic Towed Array Position Measurement System for Nuclear Submarines

DDL OMNI Engineering proposes to design a secure system for the continuous, real time acoustic measurement of towed array position relative to the host submarine. By using focused transmit and receive assemblies, pseudo- random spread broadband signals, and relatively high carrier frequency, the transmission level will be minimized so as to be virtually undetectable by a non-dedicated system. Uncorrelated broadband signals from two separate transmit modules will be received by a specially designed linear hydrophone group imbedded in the towed array. The receive assembly will have a single, preformed beam focused at the host submarine, with its base-banded output inserted into the towed array telemetry stream. Each transmit module will be a horizontal line of transducers mounted under the stern plane end caps, supported by electronics that will steer the signals toward the towed array. Array location will be based on acoustic travel time from each transmit module to the receive module. The primary concern of the DDL OMNI engineers in this project is to generate a minimum source level that, under operational conditions, is detectable only at the towed array, but is sufficient to yield array localization within 0.5 degrees (lateral) and 50 microseconds (axial).