Implementation of an advanced ocean transponder and deckset utilizing complex waveforms

Phase-coded pingers, which came into practical application in the 1970s on fixed undersea tracking ranges, were one of the early uses of a complex waveform in undersea tracking applications. Prior to this, gated continuous-wave (CW) pings utilizing peak detection algorithms were used on undersea tracking ranges and for other navigation and tracking applications. Today´s tracking and navigation applications require much higher accuracy, higher probability of detection, portability (which includes low power), and high system availability. An advanced ocean transponder (AOT) and deckset system has been developed which meets these challenges. Utilizing advanced complex digital waveform signaling techniques and high-performance commercial off-the-shelf (COTS) components, the new AOT/deckset system meets today´s tracking and navigation requirements. The complex waveforms used by this system provide enhanced processing gain, narrow correlation peaks, and robust communication in highly reverberant environments. The need for portable systems has also added the challenge of extensive in-water processing requirements. New COTS, low-powered field-programmable gate-arrays, digital signal processors, and micro-controllers provide the necessary processing bandwidth to adequately detect, classify, and process the complex waveforms. These functions are provided as part of the portable in-water AOT. The low power characteristics and operational scenarios incorporated provide for long battery life. This paper describes the commercially available AOT/Deckset system, which utilizes these advanced complex waveform techniques. It includes a discussion of the signaling scheme, the processing architecture, and the detection algorithm, as well as results from recent field tests