A Modular Gigabit Ethernet Backbone for NEPTUNE and Other Ocean Observatories

Andrew Maffei, J. Bailey, A. Bradley, A. Chave, X. Garcia, H. Gelman, S. Lerner, G. Massion and D. Yoerger

Abstract:

Cabled observatories such as MARS or NEPTUNE will consist of many deployed instruments which communicate with human operators and shore-side data repositories. In addition, these deployed devices may actually communicate with other, facilitating capabilities such as autonomous event response. These potentially complex interactions between multiple entities - human and machine - require that knowledge of the system configuration be available to participants. Users of instrument data require information - "metadata" - about the sensor that generated the data. Software which coordinates and controls instruments requires access to the software interfaces of those devices. "Manual configuration" has been used on small-scale systems, but in a network consisting of hundreds or thousands of instruments, the configuration challenge becomes critical. We propose to address the problem through automation of the configuration process, which will be achieved at several levels. Automated configuration will simplify the system operator's task of building and maintaining the observatory network. We describe a small, low-powered information storage device which we call a "sensor puck". When plugged into a suitable computer (lab workstation, deployed observing node), information can be written to or read from the puck. While an instrument is being prepared for initial integration into the observatory, a technician "loads" a puck with information necessary to configure the instrument within the observatory, and then physically attaches the puck to its instrument. Thereafter the attached puck always travels with its instrument, no matter where it is being installed in the observing network. The information loaded into the puck encompasses whatever is necessary to enable automatic configuration and system integration of the instrument when it is plugged into the observatory network, and any other information required by observatory policies. This information may include structured descriptions of the instrument's sensor and data characteristics (metadata). The information can also include actual software code that is retrieved from the puck and executed by an observatory node when the device is plugged in; this code could implement distributed instrument control and data retrieval interfaces, allowing network-wide access to the instrument functionality. We believe the puck concept to be a powerful one; a given instrument puck is configured just once, enabling automatic configuration of its instrument no matter where it is installed on the network thereafter. We also describe mechanisms by which an instrument and its puck can be "discovered" by the observatory network when the devices are plugged in. Several approaches are explored, with varying degrees of automation. We evaluate these approaches with special consideration to electrical and safety aspects of the undersea environment. Information and results from our prototyping efforts will also be presented.

Data transport system architecture for scientific submarine cable

Yukio Horiuchi and Masatoshi Suzuki

Abstract:

Recent evolution of optical submerged cable communication technology can provide possibility of many kinds of scientific observatory for earth observation thanks to its flexible and high capacity transport capability. Since the conventional optical submerged cable systems are usually used as point-to-point data transport topology, a novel methodology is necessary to realize a point-to-multipoint communication system for instance scientific submarine cable system. On the other hand, Ethernet technology offers scalable and simple network architecture, and is attractive for low-cost data communication backbones and wiring closets.
We present a scientific data transport system architecture based on recent optical communication and low-cost Ethernet networking technologies for next generation real-time seafloor globe monitoring cable network. The proposed data transport architecture provides a point-to-multipoint reconfigurable networking and protection functionality. The role of wideband optical fiber amplifier, optical add/drop multiplexing (OADM), Ethernet networking and network management technologies in the scientific submarine cable will be presented. In addition, a methodology for interconnection between a scientific backbone node and scientific sensors are also discussed.

Electrical and Electro-Optical Mooring Links for Buoy Based Ocean Observatories

Water Paul, D. Bentley, M. Chaffey and D. Frye

Abstract:

Both submarine cable-based and buoy mooring-based ocean observatories are rapidly advancing in concept and capabilities. Buoy observatories are designed to provide data from ocean areas beyond the reach of submarine cables, or to collect air and sea surface data for cabled observatories. In either application reliable conductor links are needed that span the water column and pass through the highly energized sea surface. This contribution will summarize recent designs for compliant mooring elements, which provide a durable electrical and electro-optical path for high bandwidth data streams between surface buoys and seafloor sensor packages or AUV docking stations.

Two different approaches will be described; all are based on the creation of stretch-neutral conductor "comfort zones", which allow significant stretch of the mooring member while keeping the conductor elongation near zero. Inclusion of more sensitive optical fiber assemblies will be addressed as well. The approaches are:

1.)Rubber mooring hoses with load elongation behavior controlled by nylon tire cord reinforcement. The hoses transfer the mooring tensions through built-in flange couplings directly into the surface buoy. Two different conductor paths for the mooring hoses are used:
a)Heavy rubber jacketed conductor cables, which are manufactured into coilcords, similar to telephone handset cords, are arranged inside the mooring hose cavity.
b) Helixed conductors are embedded in a stretch-neutral geometry in the hose wall itself.
The rubber mooring hoses allow designs with a maximum working stretch range of 20 to 140 percent, depending on the selected geometry and arrangement of the nylon tire cord reinforcement.

2.)Lightweight, compliant EM and EOM buoy mooring cables for deep-water moorings. These cables reverse the established construction method used in conventional armored cables by placing the strength member in the cable center. The conductors are spiraled in a stretch-neutral configuration around the strength member, and are protected by a thick plastic jacket. Depending on the strength member design and material up to 15 percent stretch at maximum cable working load can be realized.

The paper will describe details of the compliant conductor path development; including theoretical background, prototype constructions, termination techniques, laboratory and at sea testing, and highlighting a recently deployed observatory buoy mooring.

High Reliability Submarine Optical Cables and Their Use in Scientific Applications

Gary Waterworth and Mark Fullenbaum

Abstract:

This paper describes optical submarine cables specifically developed for the telecomm industry and their application to scientific projects. Hundreds of years of development have resulted in highly reliable Commercially Off The Shelf (COTS) products. These field-proven cables are now readily available for use in challenging non-telecomm underwater projects. The paper details the design requirements for high reliability cable and some of the key considerations made in the selection of a product for submarine use. These include the stability under load and pressure, protection from environmental effects such as hydrogen through to the choice of the optical fiber itself. A typical range of fully proven cable types and armor packages are described with advice on the selection process for different seabed conditions. Connectivity between various types of cable and submerged equipment is also a by-product that is well established. Some examples of telecomm cables already chosen and installed for offshore observatory work are given.

Re-use of Retired Fiber Optic Telecommunications Cables for Ocean Observatories

Duennebier, Fred K, Rhett Butler, David Harris and David Gunderson

Abstract:

The retirement of the oldest electro-optical telecommunications cables, installed in the late 1980's and early 1990's presents an important opportunity for ocean observatory science. These cables and associated shore connections represent more than $500M and 25,000 km in installed submarine cable infrastructure that can be made available for scientific use. These systems are no longer of value to the telecommunications industry because more recent cables have hundreds to thousands of times more bandwidth than the older fiber cables. Even so, the older cables are capable of transmitting data rates of hundreds of megabits per second, orders of magnitude higher than can be transmitted by coaxial cables or by satellite transmission from buoys. They can also deliver kilowatts of continuous electrical power to ocean observatories.
Use of these cables for ocean observatories, while likely to be considerably more cost effective than other fixed observatory systems, will have significant costs that will depend on how the cables are used. In the simplest and least expensive use, observatory nodes will be attached to cut-ends of cables far from shore, and data transmitted back to existing shore stations, as was done with a retired coaxial cable at the Hawaii-2 Observatory. Alternatively, the cut ends can be reeled onto cable ships and moved to new sites while still utilizing the existing shore stations, or whole cable sections, possibly thousands of km long, can be moved to remote parts of the ocean where they can be re-installed with new shore connections.
Re-use of these cables will involve design of new data interfaces that will convert signals at the observatories to PDH (plesiosynchronous digital hierarchy) or SONET (depending on the cable system), required by the cable repeaters, and to more useful formats, such as internet protocol, at the shore stations for distribution of data to users.

Synchronous Data Transmission and Sea Water Power Return Cable System

Steve Meehan

Abstract:

A wide range of modern in-water scientific systems requires data transport over optical fiber and power over copper conductors. These systems often utilize building blocks from the Telecommunications industry. As a standardized approach, a data backbone using Synchronous Transfer Mode (STM) has been utilized for a wide range of applications. The transfer of data from the digitized sensor input to the synchronous backbone is by means of the Asynchronous Transfer Mode (ATM). Power for these systems is over a standard elecommunications single conductor cable requiring a return over a seawater path. Experience with this combination of technologies has lead to an increased level of understanding in the interactions between the data, power and sensor elements. Switching rates in the conversion of analog sensor outputs to digital are usually synchronized to the STM frame rate eliminating noise at the sampling rate. However, the ATM cell loading rates present in the seawater return path create harmonic and intermodulation products that appear back at the analog input. These conditions contaminate the data and need to be minimized in the design of the sensor and power elements. Examples of these conditions are presented along with approaches to their substantial reduction.

The Data Transmission System for the Real-time Seafloor Monitoring Cable Network

Minoru Yoshida and Yoshiharu Hirayama

Abstract:

The ARENA (Advanced Real-Time Earth monitoring Network in the Area) project has been proposed by Japan Marine Science & Technology Center (JAMSTEC). The data transmission system for seafloor monitoring cable network has been discussed in the transmission sub-workgroup of ARENA project. This presentation is on behalf of this workgroup. In the ARENA project, the total length of cable is more than 1000km, and observation nodes are set at about 50km intervals, with various sensors installed in these nodes. The objective is to construct the data transmission system from the sensors in the seafloor to the landing stations.Various conditions should be considered such as transmission range, time accuracy, extendibility,cost, affinity with IP, power consumption. In the ARENA project, the total amount of data transmitted from the observation apparatus installed on the seafloor is estimated to be about 2Gbit/s. Most of them are due to high-definition television (HDTV) signals, while the total amount of the data from other sensors is only about 4.5Mbit/s. The data transmission system should be flexible so it can handle these data with various bit rates. As this cable network system is based on Internet Protocol (IP), the time synchronization method is Network Time Protocol (NTP). However, the time accuracy of NTP is about 10 milliseconds.Some sensors need the time accuracy of 1 microsecond, therefore, an exclusive line for the time synchronization signal should be also prepared to provide the accurate signal. This signal is based on the PPS signal, which is synchronized by the GPS. Users can select those time synchronization signal as required for each sensor.
In order to transmit such a large amount of data, it is planed to use an optical cable. Optical cables will be used for the science layer to transmit the observed data, while a backbone layer will be used to transmit the data between a landing station and data server for the reduction of cost. Moreover, this system must have redundancy for data transmission and extendibility so it can be extend with new observing point easily. The ring network architecture is adopted to solve these problems. Any observation node on the network can be accessed from two landing stations, and the two routes are secured for robustness and redundancy. This method makes also possible to extend the network easily. Moreover, data format and sensor interface are also important in the system. In order to realize an open and scalable system, suitable ones should be adopted, which can easily extend the system.