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Iridium to join global safety system

Aug 28, 2017
As the Arctic opens up to increased commercial traffic due to melting ice, there will be an increased need for better high-latitude communications.

As the Arctic opens up to increased commercial traffic due to melting ice, there will be an increased need for better high-latitude communications.

NASA

It’s safe to say that most voyagers dream of tropical sailing. Yet the changing Arctic has made Greenland, the Northwest Passage and other northern destinations more cruiser-friendly and will likely draw more voyagers northward. As always, connectivity and communications are a consideration and one satcom firm, Iridium, is well positioned to garner more of this traffic as it heads to certification as an internationally approved communications service and as it updates its satellite constellation.

The Iridium satcom system starts out with an advantage for use in the Arctic: It is set up to operate there in a way that its competitors are not. Unlike other satellite systems that require an Earth station in view of the satellite in order for it to send and receive signals, Iridium satellites can receive signals from a user at the surface; if there is no Earth station in range, it can forward that message to other satellites in the constellation. The message bounces along until it gets to an Iridium spacecraft that has an Earth station in range. Then, that satellite will transmit the relayed message. This system is well suited for use at the poles because there are few Earth stations in the Arctic and Antarctic, which limits other systems but not Iridium.

Recreational voyagers are keen, of course, on having good, reliable communications and navigation tools. Their decisions about what to actually carry on their boats is ultimately up to them. Commercial mariners, on the other hand, must comply with regulations agreed upon by the International Maritime Organization (IMO) and other regulatory bodies. One of these international agreements is the Global Maritime Distress and Safety System (GMDSS). This is a “set of safety procedures, types of equipment and communication protocols used to increase safety and make it easier to rescue distressed ships, boats and aircraft.” The types of equipment that GMDSS-required ships (more than 300 gross tons) are required to carry include: EPIRBs, Navtex, HF and VHF DSC radios, search and rescue radar transponder (SART), and at least an Inmarsat C satcom unit.

When GMDSS got started in the early 1980s — and for a long time after that — the only company offering satellite communications to mariners was Inmarsat. So, naturally, Inmarsat was included in the provisions of GMDSS. Since that time, however, other satcom options have arisen, such as Iridium, Globalstar and Orbcomm. Like any international protocol devised by government agencies, changes to the GMDSS requirements haven’t happened quickly. In April 2013, Iridium made a request to become a recognized GMDSS satcom provider. According to Iridium, IMO will likely certify Iridium in 2018 and the company expects official GMDSS service to start in 2020.

Another way that Iridium is becoming a more attractive satcom choice for far northerly (and far southerly) voyagers is the upgrade of the 66-satellite constellation with new Iridium NEXT satellites. This latest generation of satellites will have increased bandwidth and higher data speeds. They are being launched by Elon Musk’s SpaceX company with two of eight launches already complete.

Iridium calls its new higher-bandwidth capability Iridium Certus. “With the availability of Iridium Certus and GMDSS recognition,” Wouter Deknopper, vice president and general manager of maritime at Iridium, wrote in an email, “we will be able to provide real choice to mariners when it comes to broadband communications and critical safety services all from one terminal.”

Another way GMDSS can be improved in the future is to expand the automatic identification system (AIS). AIS makes use of VHF DSC radio technology to exchange information about vessels in VHF signal range. With its robust ability to track vessels, AIS provides critical collision avoidance information like the name of the ship, its speed, course and the time and point of closest approach to your own vessel. AIS is a superb augmentation to radar and provides more information than radar alone.

Like the equipment mandated for GMDSS, AIS is required by the Safety Of Life At Sea (SOLAS) convention for commercial vessels greater than 300 gross tons. There are three classes of AIS: Class A devices that transmit at 12.5 Watts and are used on large commercial vessels; Class B with a less powerful 2-Watt signal and for use by smaller vessels; and AIS receivers that don’t transmit at all but can be used by smaller vessels like voyaging boats to monitor traffic for collision avoidance.

The benefits of AIS, along with the legal requirements, have made it a widely used system. One interesting development is satellite AIS, in which satellites are equipped to pick up AIS signals. This allows vessels to be tracked beyond normal line-of-sight VHF range.

AIS has become so omnipresent, however, that technical experts are concerned that the system will be overwhelmed by too many AIS transmitters. The result is a proposed new system called VHF Data Exchange System (VDES).

AIS makes use of two VHF radio channels to send short data messages to radios in range. VDES takes this technique and expands it by using a higher data modulation rate, more VHF channels and assigns specific channels for satellite use. This development will allow AIS to continue as an invaluable tool, even in crowded harbors and in remote areas like the Arctic and Antarctic.

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