Overview of Infrastructure
Ocean Networks Canada maintains several observatories installed in three different regions in the world's oceans. All three observatories are cabled systems that can provide power and high bandwidth communiction paths to sensors in the ocean. The infrastructure supports near real-time observations from multiple instruments and locations distributed across the Arctic, NEPTUNE and VENUS observatory networks. Major components of our network were designed, manufactured and installed under contracts with Global Marine Systems Ltd, OceanWorks International, and Alcatel-Lucent Submarine Networks. These include the:
- backbone cables
- branching units and spur cables
- major network nodes
- junction boxes and scientific instrument interface modules (SIIMs).
The infrastructure is broken down into two groups:
- primary infrastructure consisting of the shore stations, backbone cable, branching units, repeaters, network nodes and junction boxes/SIIMs
- land sensors comprise the secondary infrastructure
High-speed data lines connect our shore stations to Ocean Networks Canada's data management and archive facilities at the University of Victoria. The Oceans 3.0 data management system:
- acquires and archives incoming instrument data from the network
- provides access to archived data via the web
- allows technicians and scientists to control instruments and conduct experiments via the web
- continually monitors the subsea infrastructure and instruments, verifying data quality and detecting problems as they occur
- detect and trigger automated responses to network events
Each of the Ocean Networks Canada observatories has its own shore station which provides power to the observatories. Shore stations located in Port Alberni, Sidney, and Vancouver BC, are the places where power and communications connections are made between the land and subsea portions of the observatories.
Each shore station has power feed equipment that converts the utility AC power to high voltage DC. The backbone cables are run at 1,200 to 10,000 V DC depending on the length of the backbone cable. Network equipment in the shore stations handle routing, switching, optical multiplexing and precise time synchronization within the network.
The backbone cables carry both power and fibre optic communications across the network. In the NEPTUNE Observatory, the backbone cable is run in a large loop. Data is passed in both directions along the loop ensuring a communication path should the backbone cable be damaged or cut. The NEPTUNE backbone cable is approximately 800km long, VENUS Strait of Georgia is approximately 40km long and VENUS Saanich Inlet is 3km long. Different grades of armoured submarine cable are used for the various locations on the observatories, depending on depth and roughness of the seafloor. For example, where the seafloor is very rocky or jagged an armoured cable will be required.
The optical signal is degraded as it travels along the backbone cable. On the NEPTUNE observatory, repeaters (optical amplifiers) are used at regular intervals to boost the optical signal to prevent data loss.
On the NEPTUNE Observatory, branching units distribute power and communications (via optical couplers) from the backbone to spur cables which connect to the nodes.
Nodes serve as the link between the Primary and Secondary infrastructure. The nodes convert the high voltage used on the backbone cables down to the level needed by the junction boxes/SIIMs and instruments. The nodes monitor and control the power and bandwidth use of the secondary infrastructure through a number of science ports on each node. Each science port supports one or more junction boxes/SIIMs and associated instruments.
Each node consists of two sections, a removable node pod and a base. The removable node pod contains the power converters, network equipment and connectors. The node pod can be recovered to the surface by an ROV for mainteance or upgrade. The base is a trawl-resistant frame that protects the node pod from damage and supports the connection between the node pod and the backbone cable.
Photo caption: A spare node pod from the NEPTUNE observatory sits in the test tank (left). A node pod within its trawl-resistant frame on the seafloor, part of the NEPTUNE observatory (right).
Photo caption: A node pod from the VENUS observatory is lowered to the seafloor over the side of a ship.
Junction boxes and SIIMs form the first elements of the Secondary infrastructure. The junction boxes/SIIMs take the power and bandwith from the node science port and distribute it to various instruments. The junction boxes/SIIMs monitor and control the power and bandwidth use of the instruments through a number of ports on each junction box/SIIM. Junction boxes/SIIMs can be "daisy-chained" if more instruments are requried at a specific site. Some locations, such as Barkley Canyon, may have numerous platforms at different locations within a study area, "daisy-chained" together to a single node science port.
The junction boxes/SIIMs are secured to instrument platforms which provide a mounting structure for the instruments. Besides providing a place for the junction box/SIIM to rest clear of obstructions, the instrument platforms provide a place to attach instruments to best support the collection of data. The instrument platforms are periodically recovered for servicing of the junction boxes/SIIMs as well as any attached instruments.
Photo caption: A junction box (silver cylinder) is mounted on an instrument platform. The various cables connect the junction box to instruments and to the node. This platform is part of the NEPTUNE observatory.
Photo caption: An instrument platform, part of the VENUS observatory, with a SIIM and a variety of instruments attached is lowered over the side of a ship for installation on the seafloor.
Collecting the data from the ocean are the instruments. These instruments may be attached to an instrument platform or are connected to the instrument platform by extension cables. These "satellite" instruments can collect data far from a junction box or node in an undistrubed area of the ocean. The vast majority of the instruments connected to the observatory collect data in near realtime and transmit it back to shore, accessible via the Internet, for immediate analysis. There are some instruments, however, connected to the observatory that are not capable of sending near realtime data, but instead record the information in data loggers within the instrument. During installation and maintenance dives, the data loggers can be collected by the ROV and the data retrieved prior to returning the data loggers to continue collecting data. Other instruments, like the sediment traps, collect physical samples that are recovered during maintenance cruises offshore. The wide variety of instruments includes chemical sensors, temperature probes, current meters, seismometers, bottom pressure recorders, still and video cameras, and even remotely operated vehicles.
Photo caption: Examples of some of the oceanographic instruments used throughout Ocean Network Canada's observatories.