Communication technologies are important for underwater vehicles and underwater systems. Communication links are used to interconnect vehicles, both manned and unmanned, with the surface and with remote control stations. Communication links are also used to interconnect benthic and midwater instrumentation to the remote control and data acquisition systems.
Acoustic communication, fiber optic communication and, over short ranges, optical transmission techniques are generally available in the FSU, Western Europe, and the United States. Extending the range and bandwidth of the communication links seems to be the primary focus of current research. Making systems that are capable of working in multipath environments is also an area of interest. There seems to be interest in Russia and Ukraine in participating in the follow-on projects to the Heard Island Experiment of 1991. This test demonstrated the ability to communicate sound very long distances around the world through the sound channel.
Since many of the communication projects that were being worked on are still classified, hosts were not able to provide in-depth information on the current state of their research.
. Several organizations are working on acoustic communication systems. Andreev Institute is working on communication from a drill head to the surface control vessel. Scientists at the institute would like to be able to track and monitor data from the drill head as it operates beneath the ocean's bottom. They are also interested in technology for long range (2,000 to 3,000 km) communication (see Andreev Institute site report). Communication between submersibles and surface vehicles is also an area of research. In addition to data and control, Oceanpribor is working on sending compressed video over acoustic communication links (see Oceanpribor site report).
There is a general feeling in the institutes that the team visited that they have a strength in the development of algorithms for communication systems. Scientists at the institute feel that they have been limited in their access to fast computers, so they have compensated for this by developing very efficient algorithms. Also, many researchers seem to be involved in the development and theory of algorithms (see Table 8.2).
Fiber optic communication systems seem to be an available technology (see Dubna/TECHNOPOLE and Energia site reports - Appendix B). These systems are used to link offshore surveillance systems to the land. The team did not see any fiber optic communication tethered to remotely operated vehicles.
In the General Physics Institute, a unique communication system was described (see General Physics Institute site report - Appendix B). This system is designed to communicate between submarines and aircraft. The aerial platform would use a very high power, modulated laser directed at a very small area of the sea surface. The power output of the laser would be high enough to create mechanical surface roughness variations that could be picked up by a sonar, decoding the signal by using signature analysis techniques. The submarine would use an upward directed, very high frequency sound source to create similar roughness on the sea surface. This surface roughness variation would be detected by a high frequency cross-polarized radar (Figure 8.2).
France. IFREMER has developed the TIVA acoustic modem system and operated it for the last five years (see IFREMER site report). TIVA is a 20 kbaud communication link that passes both data and compressed video between a submersible and a support vessel. This system has been transferred to a commercial company and is now available for sale.
Figure 8.2. Atmosphere - Ocean Laser Communications
United Kingdom. EEVMAC is a European Community supported project to develop underwater communication technology. One of the goals is the development of high data rate communication systems for AUVs. EEVMAC is developing a very large acoustic communications test range in the Firth of Forth. This range will be fully instrumented so that the data can be evaluated in real time in the laboratories (see Heriot-Watt University site report - Appendix E).
Communications technologies and research programs are generally consistent across Russia and Ukraine, Western Europe, and the United States. The main focus seems to have been on communication with submarines, which has provided spin-off technology that is now being made available to the nonmilitary community. Communication tools are generally available to research and development programs in each of the countries. The current push is for longer range, higher speed, and more robustness.
Communication is an area where the focus on simple efficient algorithms, which we have seen in Russia and Ukraine, may pay off. Researchers in the FSU have focused on algorithm development and less computationally intensive solutions. Techniques using these algorithms could have advantages over other techniques used in Western countries.