How Does DAB Radio Work?

Digital audio broadcasting (DAB) was initiated in the 1980s, launched in the UK in 1995 and is becoming increasingly popular.

DAB radio offers a bigger choice of stations as the technology allows for more radio services in the same amount of bandwidth.

How Does DAB Radio Work?

The principle behind radio is that a device transmits a form of electrical energy that is picked up wirelessly by a receiver using an aerial.

The transmitted energy spreads out as radio waves that are characterised by their frequency, which can range from 30 hertz (Hz) to 300 gigahertz (GHz).

Rather than sending signals based on the length or frequency of the carrier wave (as in analogue radio), digital radio (including the DAB format) works digitally by sending a series of numbers, coded in digital format as a string of zeroes and ones.

The signals for radio programme are split into fragments and given coded digits, which are then compressed and transmitted many times so at least some are more likely to be received.

The DAB radio receiver collects the unique radio signals, expands and reassembles the fragments then recreates the programme being broadcast.

Because it has to do so much processing, what you hear on a DAB radio will lag slightly behind an analogue version.

DAB stations broadcast using the MP2 audio codec, whereas the newer DAB+ standard uses the more efficient HE-AAC v2 codec.

It’s worth clarifying that digital radio doesn’t use the internet—it’s different to internet radio. DAB radio is free to listen to as long as you have the right equipment.

How Analogue Radio Works

To understand DAB radio better, here’s a brief explanation of analogue (AM/FM) radio, so you can compare how it works to how digital radio works.

Each analogue radio station transmission is at a different frequency, enabling a radio receiver to tune into and identify a particular station.

A process known as modulation attaches a radio programme to a carrier radio wave.

This can be by one of two processes:

  • Amplitude modulation (AM) – Also known as medium wave or MW, amplitude modulation is where the size (or amplitude) of the carrier wave’s peak is adjusted
  • Frequency modulation (FM) – This is where the carrier wave’s frequency is adjusted.

 

How Does DAB Radio Work in a Car?

In technical terms, DAB radio in the car works the same way as a DAB radio in the home.

The radio picks up digital signals, processes them and outputs them as audio.

There are a few things to be aware of if you want to listen to DAB radio in the car:

  • Most new cars come with DAB as standard. See a list of cars that have DAB radio here.
  • DAB radio requires a special aerial. A regular AM/FM radio aerial usually won’t offer good enough reception.
  • If your car didn’t come with DAB when you bought it, you can install a DAB adapter to receive digital radio stations. These adapters come with an aerial, and are usually easy to install yourself.

 

Advantages of DAB Radio

Each digital radio signal is transmitted across an extremely wide band, which has several advantages:

  • More data can be carried – The width of the band enables different streams of data to be carried on one digital signal, a process known as multiplexing.
    Typically, a signal might contain a music track and text information about it (the radio station, current programme, name of the track and artists) which can be displayed on the radio.
  • Less interruptions – Because the signal is so wide, it can bypass obstacles and still get through to the radio receiver.
    This means you should get better reproduction of the sound and won’t lose service in the same way as for analogue if your car goes under a bridge or enters a tunnel, for example.
    However, there are still problems with the DAB radio signal in lots of places, so things aren’t always better in practice.

Being a more modern technology, DAB delivers a purer signal with less noise.

The signal also degrades quickly as the signal fades when the transmitter becomes out of range rather than becoming poorer in quality, like analogue.

However, the sound quality isn’t always great as it’s often highly compressed. If you want to enjoy the best sound quality, internet radio is usually better—read our comparison of internet and DAB radio sound quality here.

Another advantage of digital radio is that since it doesn’t use frequencies in the way that analogue does, you don’t get interference from neighbouring stations.

It also discards sounds that cannot be heard and so only broadcasts the essential information. The signal carries an in-built protection system to prevent transmission errors.

However, this can result in an irritating gurgling sound if the reception is less than perfect—see some tips for improving your DAB signal here.

 

Do You Need a DAB Radio?

Although DAB radio is becoming more popular, there’s no immediate need to replace your old set.

AM and FM are both still broadcasting in the UK, and are likely to remain for at least the next few years.

If you want to buy a DAB radio, see our recommendations here. Most DAB radios also offer FM, so you can choose to keep listening on FM if you prefer.

That gives you the chance to compare the relative quality of the two methods, with digital radio from FM stations reckoned to be the equivalent of CD quality while AM stations have the superior FM quality when received digitally.

It also lets you experience the time lag that the additional digital processing creates.

 

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