Extending the reach of cabled ocean observatories

Industry publications indicate that most cabled ocean observatory systems are based on the same general architecture: primary and secondary infrastructure and nodes, junction-boxes, low voltage nodes and then extension cables to instrumentation and experiments. Non-repeatered datacom technology often limits such transmission to less than 100km reach without optical-electrical-optical regeneration. Undersea telecom repeaters (optical amplifiers) can be used to extend the reach of these systems by thousands of kilometers, opening up new and significant areas to observatory exploration. Undersea telecom amplifier designs have been tailored for use with existing low-cost transceiver technology already in use in these observatories. Another technological advancement, dual conductor cable (DCC), is available for use in fiber optic scientific networks and is currently in-service. It provides two independent electrical powering paths which, in combination with compatible repeaters, branching units, and joints, may be used to power branches and undersea devices from diverse power sources. One conductor may be used to power repeaters, while a second conductor can provide observatory power. In addition to powering nodes from shore, DCC can be used for multi-conductor subsea connectivity between observatory primary and secondary nodes. With industry standard armor packages available, DCC can be deployed and plow-buried between observatory elements in hazardous subsea environments. This cable can be terminated with wet-mate connectors to facilitate subsea connection by remotely operated vehicles. This paper provides an introduction to data transmission and powering architectures associated with cabled ocean observatories, and describes the elements needed to extend observatory exploration reach with undersea repeaters. Subsea connectivity beyond primary nodes using flying lead deployment pallets and direct connection devices is also discussed.