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	Communications

	Overiew Surface-Habitat Intra-Habitat Habitat-Vehicles The Cable References

Communication from the Habitat to the Surface

A multimode fiber optic link from the main server of the underground lab to a satellite antenna at the land base on Rodriguez Island (part of the Mauritius Islands ), 570 km Northwest NW of the vent system, will be used for all communication from the habitat to the rest of the world. This link will be used for all data transmissions and email / internet requirements of the laboratory.

Companies who specialize in underwater fiber optic systems take care of the specific equipment and other general requirements of the system. Our studies told us that it is possible to lay a cable system in the harsh environment our mission focuses on.

The regular bandwidth of 1.544 Mbps for the connection was considered sufficient to cover all possible requirements in communication. Fiber optic cables were found to be the optimum solution for requirements.

We considered a number of other alternatives. Initially, wireless transmission was our primary choice. We looked into transmission using electromagnetic waves. However, due to the density of water, most of the EM spectrum gets highly attenuated giving rise to very small bandwidth in underwater communication, hence wireless signal transmission was deemed unsuitable.

Another option we seriously researched on, for habitat to base communication were acoustic systems. Acoustic systems have speeds of data transmission that are not high enough to satisfy our requirements.

Due to the inability to use wireless communication, we looked into fiber optic, coaxial cable and other means of wired communication. The low attenuation and superior signal integrity found in optical systems allow much longer intervals of signal transmission than metallic-based systems. While single-line, voice-grade copper systems longer than a couple of kilometers (1.2 miles) require in-line signal repeaters for satisfactory performance, it is not unusual for optical systems to go over 100 kilometers (about 62 miles), with no active or passive processing.

Optical fiber systems have many more advantages, such as a large bandwidth, a small diameter, and long lengths. The relatively small diameter and lightweight of optical cables makes installations easy and practical. Long, continuous lengths also provide advantages for installers and end-users. Small diameters make it practical to manufacture and install much longer lengths than for metallic cables: twelve-kilometer continuous optical cable lengths are common.

Easy Installation, Maintenance and Upgrades

Long lengths make optical cable installation much easier and less expensive. Optical fiber cables can be installed with the same equipment that is used to install copper and coaxial cables, with some modifications due to the small size and limited pull tension and bend radius of optical cables.

Security

Unlike metallic-based systems, the dielectric nature of optical fiber makes it impossible to remotely detect the signal being transmitted within the cable. The only way to do so is by actually accessing the optical fiber itself. Accessing the fiber requires intervention that is easily detectable by security surveillance.

Resistance to Harsh Environmental Conditions and Non-Conductivity Another advantage of optical fibers is their dielectric nature. Since optical fiber has no metallic components, it can be installed in areas with electromagnetic interference (EMI), including utility lines and power-carrying lines. This is particularly suited to for our design plan, as the power cable supplying all the energy needs of the habitat will be laid simultaneously, alongside the fiber optic cable, possibly by the same contractor. More details can be found in the Habitat section of the Mission Report.

Temperature and Pressure Resistance

Fiber optic cables are also extremely temperature and pressure resistant, making it a perfect solution for communication needs in an underwater laboratory in a hydrothermal vent system. As the habitat will not be situated within the vent system and because the cable will run northwest away from the volcanic area of the sea floor, the cable will have little, if any, exposure to extreme temperatures. Fiber optic cable can withstand temperatures of around 300-400 degrees Celsius comfortably.

Contractor for System Development

Several companies were studied. Possibilities include AT&T cable systems, Alcatec Communication Systems and Williams Communications and several others. Different companies have different benefits and the best company for this particular project can be established by calling in tenders.

Cost

Generally fiber solutions are less dear than other systems with comparable performance. Costs range from $6-10 per meter of cable. The running costs are minimal and due to the durability and reliability of fiber optic systems, maintenance will also be a manageable cost.

Estimated Initial Cost (for the complete layout of the communication link): $ 5,700,000
Hence we conclude that fiber optic communication systems is the optimum solution considering factors such as efficiency, practicality and cost.

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