There is a need to develop a high power, high data-rate, extremely low frequency (ELF) communications system that will allow faster, deeper communications with submerged submarines and other undersea systems.
The only electromagnetic waves able to penetrate deep into the ocean are those that are generated at extremely low frequencies. The rate that data can be transmitted at these extremely low frequencies is a function of the effective radiated power of the generated signals. The current U.S. ELF system for communicating with submerged submarines is located in Wisconsin and Michigan. Because the system radiates at very low power (2-5 watts) its ability to communicate with submarines is severely limited — it only serves as a “bell ringer” to direct submarines to come to shallow depths and deploy their antennas to receive messages at a higher frequency. While the current U.S. system accomplishes its necessarily limited mission, it has the obvious disadvantages of lack of timeliness and increased submarine vulnerability — submarines lose time in ascent and are more susceptible to detection at shallow depths.
In the past decade, research at several institutes and universities has demonstrated a practical, new method for generating ELF waves. ARCO Power Technologies, Inc. has extended this research and formulated a concept for a higher power ELF communication facility of significant military value. While the facility’s operation would initially be focused on proof of concept, it would have operational utility for the U.S. Navy the minute it begins transmitting. And it would be built in such a way as to permit its rapid expansion into a full operational facility that would complement the current Wisconsin/Michigan ELF site by providing up to 100 watts of radiated power, allowing deeply submerged submarines to receive data at depth, in quantity, and in real time.
This new system would enhance the deterrent value of the U.S. strategic submarine fleet and would also enable the U.S. Navy to take on new strategic and tactical missions due to:
• Enhanced communications with deeply submerged submarines;
• Real time control of command activated mines, mobile mines, and unmanned undersea vehicles;
• Real time targeting/retargeting of SLCMs;
• Enhanced C3 for ASW; and
• Capability to jam enemy ELF systems.
How the New ELF Communications System would work
High Frequency waves that have been modulated at extremely low frequencies are radiated into the lower ionosphere. These ELF-modulated high frequency signals create disturbances in the earth’s electrojet – a naturallyoccurring current that flows in the lower ionosphere in the earth’s polar and equatorial regions. These disturbances create a large antenna that radiates signals at extremely low frequency, corresponding to the modulation of the high frequency signal.
The resulting ELF signals can be received anywhere in the world and are capable of penetrating deep into all the oceans. The high strength of the created signals is attained by scanning the high frequency transmitted beam across the lower ionosphere to increase the size of the ionospheric antenna.
The new ELF system would require a 2000 ft2 control facility which could be trailer-mounted, plus a one quarter square mile antenna farm that is sparsely populated with simple antennas raised approximately 50 feet off the ground. (This compares to the current Wisconsin/Michigan site that includes 148 miles of buried cables, transmission facilities, and a 28-mile above-ground cable antenna.)
The new system should be located in the U.S. as far north as possible to take maximum advantage of the polar etectrojet phenomenon. This argues for a site on the north slope of Alaska. Several options are available that would permit integration into the existing North Slope industrial infrastructure.
Special features comprise:
• Up to 50 times faster message transmission;
• Worldwide ELF coverage from a single transmitter site;
• The system is jam resistant as result of frequency agility;
• It uses a relatively small, relocatable transmitter.