One of the boats involved in the trials with the Norwegian
coastline in the background. Photo courtesy Gunnar Garfors
OSLO — Norway is famous for fjords and beautiful coastlines. The Scandinavian country has 25,148 kilometers of coastline, making Norway owner of the eighth largest coastline in the world.
Norway has a large fishing industry, and they, like everyone else, listen to the radio. Radio reception can be a matter of ensuring the safety of the crew: few small fishing boats have internet access, and public broadcaster NRK produces a weather radio station, NRK Vær, specifically made for those who work at sea.
However, early next year, Norway becomes the first country to start switching off FM transmissions in favor of terrestrial digital broadcasting via DAB+. Any switchoff of FM transmissions needs to consider all radio users — even those in fishing boats off the coast.
NRK Distribution Advisor Jørn Jensen tests DAB+ signal
distance on the water. Photo courtesy Gunnar Garfors
So, throughout the Norwegian summer, with temperatures hitting a balmy 50 degrees F (10 degrees C), three NRK engineers packed a variety of radio monitoring equipment, a few portable DAB+ sets and took to the waves.
“We wanted to see the how far from shore it’s possible to receive signals, and the quality of them: DAB reception offshore is not an official requirement for us, but we wanted to offer it anyway,” NRK’s Head of Distribution Øyvind Vasaasen told me via email. “We also wanted to test various receivers, and to test antenna solutions on boats.”
As long as a transmitter is well-situated and not shaded by buildings or mountains, a transmitted signal should travel quite far: though the curved surface of the Earth will eventually stop reception at 190–240 MHz, the frequencies being used for DAB. “We can’t find evidence that fog or rain have any practical negative effects on the reception,” Vasaasen told me, further highlighting the reliability of a good radio broadcast.
Michel Gascoin, NRK advisor for distribution, checks the
test gear on the boat. Photo courtesy Jørn Jensen
NRK Advisors Gunnar Garfors, Jørn Jensen and Michel Gascoin ran a set of tests from a number of different locations off the Norwegian coast — in a variety of search and rescue boats piloted by the Redningsselskapet sea rescue group.
As ever with digital reception, the quality of the antenna made all the difference — an antenna made for cars didn’t perform that well, nor did a split FM/DAB antenna. However, a specific marine antenna, made for DAB reception, performed excellently.
“The reception was even better than our calculations predicted,” said Vasaasen. “Our aim is to offer DAB reception 50 kilometers (30 miles) from the shore, and with the external, marine antenna this was always possible within this range corresponding to the coverage map and even much further.”
The hero, though, was a small, battery-powered consumer DAB+ radio with a telescopic antenna. In a trip from the working port and tourist town of Ålesund, the Sony XDR-P1DBP received signals a staggering 132 kilometers (82 miles) from land.
Gunnar Garfors, NRK advisor, tests DAB+ reception.
Photo courtesy Gunnar Garfors
One further discovery: Radio engineers don’t always cope well with bad weather. Seasickness isn’t fun at the best of times: but two of these trips, which lasted four and a half hours, were very stormy indeed.
However, for everyone working on what’s inevitably been dubbed “FMexit,” this was welcome validation of the coverage plan and reception characteristics of Norwegian’s DAB+ transmission network.
On Jan. 11 at 11:11 a.m., the first of many FM transmitters will go silent in Norway, appropriately in the coastal town of Bodø. Radio-loving Norwegians should relax, safe in the knowledge that even if they’re out fishing, they’ll still be able to tune in.
James Cridland reports on the industry for Radio World from Brisbane, Queensland.