DAB is digital radio. Instead of tuning to a frequency, you choose a station by name from a list, and the sound stays clean without the hiss of a weak FM signal. In the UK it carries far more stations than FM, including national stations that aren't on FM at all.
What DAB and DAB+ are
DAB stands for Digital Audio Broadcasting. Stations are grouped together in bundles called multiplexes, each sent out on one frequency, and the radio picks out the station you choose. The display shows the station name and often the song title, the programme or a news headline.
DAB+ is the newer version. It uses a more efficient audio format, so broadcasters can fit more stations into the same space, and it copes better with a weak signal. A growing number of UK stations broadcast only in DAB+, so a radio that handles both is the one to have.
Digital radio behaves differently from FM when the signal weakens. FM gets gradually noisier. DAB stays clear until the signal gets too weak, then it starts to bubble and drop out, or goes silent.
Stations in the UK
DAB in the UK has national, regional and local multiplexes.
- National: the BBC national stations, plus national commercial stations, many of which are only on digital radio.
- Regional and local: BBC local radio and local commercial stations, which change as you drive from one area to another.
- Small-scale DAB: community and specialist stations in some towns and cities.
The exact list depends on where you are. Do a full station scan when you first set up the radio, and again when you travel to a different region. Many radios can follow a station from DAB to FM when the DAB signal is lost, if the station is on both. This is often called service following.
The aerial a car needs
DAB needs an aerial that picks up the DAB band. Many older car aerials were made only for FM and AM, and pick up DAB poorly or not at all.
The usual options:
- A glass-mounted DAB aerial. A thin strip stuck to the inside of the windscreen, usually up one side near the windscreen pillar. It's the most common aftermarket choice. It needs a good earth to work properly, usually a bare metal point behind the pillar trim.
- A roof aerial with DAB. Some cars already have a combined FM and DAB aerial. Check whether yours does before buying another.
- A splitter. Some setups use the factory FM aerial with a splitter that adds DAB. Results vary from car to car.
Head units with DAB usually take the DAB aerial through its own socket, separate from the FM aerial, and some aerials need power to work. Check that the head unit's connections and the aerial's plug match before fitting.
Reception tips
- Earth the aerial properly. A poor earth is the most common cause of bad reception with glass-mounted DAB aerials. Scrape away any paint at the earth point so it touches bare metal.
- Keep the aerial clear of heated windscreen elements, metallic tint film and dash cams. These can block the signal or cause interference.
- Route the cable away from power cables behind the dashboard.
- Rescan after fitting, and when you move to a new area.
- Check coverage. DAB coverage is good on main roads and in towns, but some rural areas and valleys have a weaker signal. Online coverage checkers let you look up a postcode.
Common problems and fixes
No DAB stations found
Check the aerial is plugged into the DAB socket on the head unit, not the FM socket, and that it's earthed. If the aerial needs power, make sure it's getting it; some head units supply power through the aerial lead, others need a separate wire. Then run a full scan.
Stations keep dropping out
That usually means the signal is borderline. Improve the earth, move the aerial away from metal and electrical devices, and turn on service following so the radio switches to FM when DAB drops.
Interference when a phone charger or dash cam is plugged in
Cheap USB chargers and some dash cams give off electrical noise that affects DAB. Try a different charger, or move the dash cam's power cable away from the aerial.
The station list shows stations that won't play
These are often stations from another region, or ones that have stopped broadcasting. Clear the list and do a fresh scan.
FM is fine but DAB is poor
The FM and DAB aerials are separate, so good FM doesn't mean the DAB aerial is working. Check the DAB aerial's earth and plug first.