Norway is set to begin switching off its FM radio network this week, although 66% of Norwegians oppose the move, according to Reuters. One concern is that 2 million cars on Norway’s roads are not equipped with the Digital Audio Broadcasting (DAB) receivers that will replace FM radios, and drivers may miss broadcast emergency warnings.
Norway’s parliament approved the move because DAB can carry many more channels than FM. However, The Washington Post reports that 7.9 million radio sets will be affected by the switch, and an adapter to convert an FM car radio to DAB costs about $175.
According to a Q4 2015 survey conducted by TNS Gallup, 60% of Norwegians use digital radio on a daily basis, and 26% of Norwegians have DAB in their car, up from 20% in Q4 2014 and 10% in 2013. A status report says it will be up to broadcasters to choose between DAB and DAB+ (the 2006 upgrade), although most DAB transmissions going forward will probably employ DAB+, which employs the HE-AAC v2 audio codec and MPEG Surround audio format. (The status report and survey are in Norwegian, but you can find a brief English summary here.)
Reuters adds that Switzerland will similarly shift to DAB in 2020, and Britain and Denmark are considering such a shift. Britain plans to review the need for a switchover once DAB listening reaches 50%, possibly by the end of this year. (UK residents in the market for a DAB radio can check out this review.)
Norway was the first country to deploy DAB; the Norwegian Broadcasting Corp. (NRK) launched the first DAB channel in the world on June 1, 1995.
The move is not without critics. In an article titled “Norway’s controversial radio switch-off,” The BBC quotes digital media expert Jan Thoresen as writing, “Norwegian politicians have decided to make 15 million FM radios in Norway completely useless. That’s a bad idea.”
Nevertheless, as reported at Radio.no, Ole Jørgen Torvmark, CEO of Digitalradio Norway, says, “Radio needs modernization and renewal. FM technology was introduced in the 1950s and is very limited in relation to current needs. One of the main challenges is the lack of capacity. There is no room for more national FM channels in a country like Norway, where the challenging terrain and sparse population place great demands on the broadcasting networks. DAB provides the capacity we need to generate more content for listeners.”
FM broadcasting was invented in 1933 by Edwin Armstrong. Stereo FM was approved in the United States in 1961. To maintain compatibility, FM stereo broadcasts transmit a left- plus right-channel signal in the baseband, which a mono receiver can demodulate directly. The transmitted stereo signal also includes a left- minus right-channel signal modulated onto a 38-kHz subcarrier, occupying a 23- to 53-kHz range in the baseband. A stereo receiver can algebraically derive left and right channel signals from the L+R and L-R signals.
Obviously, there is no similar upgrade path from FM to DAB. DAB has its own compatibility problems, as older DAB receivers cannot receive DAB+ broadcasts.
The digital radio technology of choice in the United States is HD Radio (a trademarked term for iBiquity’s in-band on-channel digital radio technology), which is compatible with AM and FM analog transmissions and offers the possibility of a seamless fallback to analog should the digital signal fail.