Shortwave radio

Call of the North

Anyone who wants to sail the Northwest Passage has to follow Greenland's west coast for many hundreds of nautical miles. Shortwave technology from Rohde & Schwarz ensures reliable radio contact even in high latitude areas.

Several years ago, the discovery of two ships caused a sensation and reminded people of a gruesome episode in the history of exploration. The wrecks of the HMS Erebus and HMS Terror ships from Franklin's infamous lost expedition were found in the Arctic ice fields of Canada within just two years of each other. They had set off in the middle of the 19th century to explore a Northwest Passage running from the Atlantic to the Pacific through the Polar Sea. Such a passage would shorten ship journeys between Europe and East Asia by about 5000 kilometers. Centuries of previous exploration attempts had failed, and this expedition also ended tragically. The entire expedition disappeared without a trace and remained undiscovered for a long time despite extensive searches. Only the more recent sustained efforts of Canada led to discovery of the ships and a probable clarification of the expedition's fate. The discovery sites and interviews with the native Inuit people suggest that at least some of the expedition members survived the initial disaster but didn't manage to reach the mainland.

Dwindling ice revitalizes ship traffic

The dream of an ice-free ship passage through the arctic waters lives on. And it may become reality in just a few decades, because the impacts of climate change are greater in high latitude areas due to leverage effects. In 2007, for example, the Canadian part of the Northwest Passage was completely ice-free for the first time since records have been kept. In 2016, the first cruise ship passed through the Passage.

But the southern section of the route, which runs for more than a thousand two hundred nautical miles along Greenland's west coast, will become increasingly interesting for shipping before regular transit traffic through the Arctic part of the route can even be considered. The decreasing ice density is attracting more and more cruise ships to the area, and intra-Arctic transport and supply traffic is also increasing. One problem is the region's still rudimentary infrastructure, especially for communications and rescue services. In maritime shipping, it is essential to be accessible at all times by radio, and this has been mandatory for professional ocean shipping since the Titanic disaster. However, this is only possible if a receiving station is always available. Satellite radio is the usual standard on the high seas, but it is not reliably available in Arctic waters. That is why only shortwave is permitted for maritime radio service beyond the 70th parallel, which applies to the northern half of the Greenland route.

Greenland operates a chain of radio stations along its west coast. Eleven of these stations are equipped with shortwave systems from Rohde & Schwarz.

Greenland is getting ready

Greenland, the largest country in the region, has long maintained a coastal radio service along its west coast. Aasiaat Radio is named after the city where the operations center is located. Its numerous unmanned stations are operated by the state-owned TELE-POST, the TELE Greenland subsidiary responsible for the island's telecommunications. All ships over 20 gross registered tons and the fishing boats that travel between Greenland's ports must register with the service and provide their departure and destination ports, route and an approximate timetable. For longer journeys, ships and boats have to report their current position at least once a day. If they do no report in as agreed, the rescue service will be informed.

Coastal radio usually operates on VHF frequencies. However, in order to cover the sea area up to the northern part of the island and to comply with maritime radio regulations, eleven stations are additionally equipped with shortwave radio systems. But the equipment was outdated and had to be replaced. Rohde & Schwarz was awarded the contract to supply the new equipment.

Digital fresh cell therapy for a proven medium

Before the introduction of satellite radio, shortwave radio was the only option for wireless long-distance communications. Although the spectrum of shortwave data applications is limited because the radio link's narrow useful bandwidth only allows low transmission rates, shortwave remains attractive as a voice communications platform for long distances since it does not require any infrastructure beyond the communication partners' radios.

Modern shortwave systems like the R&S®Series4100 systems procured for Greenland use all the communication and digital technology tricks of the trade to fit into a modern communications landscape. But only a fraction of the systems' capabilities are used for analog maritime radio services. On the naval vessels where these systems are mainly used, they are part of complex, fully digital and automatically managed communications networks. In these networks, the systems usually even operate digitally on the radio link. Radio processors dynamically optimize the connection and decide, for example, which frequencies are optimal for the distance to be covered and the current time (shortwaves are reflected at the ionosphere and the conditions there depend on time and location). But such optimization methods only work if the transmitter and receiver have matching equipment. In the maritime radio service, on the other hand, the coastal station communicates with a large number of different remote stations, so only a minimum of technical commonalities can be assumed. These commonalities are the internationally defined maritime radio frequencies and classic analog voice radio.

Not only does TELE-POST like using the highly developed options for the R&S®Series4100 radios, they were one of the reasons for the procurement decision. In the future, both remote control and voice input will take place over IP or voice over IP connections instead of analog lines, allowing standard network technology to be used. To ensure that the powerful 1 kW transmitters do not interfere with its own receivers, TELE-POST operates the shortwave stations in split site mode, where the transmitters and receivers are placed 500 to 1000 meters apart. The transmitters and receivers are prepared for this operating mode; from the operator's point of view they form a logical unit despite the physical separation.

With its new shortwave equipment, Greenland is prepared for all eventualities for decades to come. R&S®Series4100 systems are tested to MIL standards. These software defined radios are not only extremely robust and durable, they can be updated and upgraded over the long term. When needed, a new configuration can be quickly and easily installed.