DAB Digital radio is supposed to be the future of radio broadcasting as we know it.
A far cry from old-fashioned crystal radio sets, digital radios can pick up and decode radio stations using digital transmissions.
A good question. The problem with AM radio is that it's not very good quality. In the US, you can have stereo AM radio, but even that's not too good, and after dark, AM radio can be very difficult to listen to.
FM radio's better, and doesn't suffer as badly from atmospherics overnight. But it is difficult to tune into, and needs a good aerial and good strong signal to get rid of "hiss".
And with both the current normal broadcast formats (and even shortwave), listeners need to know the frequency that a station broadcasts on to find it. Without that frequency, you're lost. Enter digital radio.
What it does
It's actually quite clever. By allocating space on a "multiplex" (a transmitter broadcasting more than one station at a time on the same frequency) each station can have enough space as it needs. So a talk station can get away with a mono, 48K data stream, whereas a classical music station could get a decent stereo 160K data stream or even higher.
Cleverer still, stations can use the space they've been allocated to split themselves in two. BBC Radio 5-Live, a sports station in England, currently broadcasts a football commentary on Saturday afternoon on medium-wave, but broadcasts TWO seperate commentaries on digital radio, just splitting the station in two. At the end of the commentary, the stations just join together again as one data stream. And you never even noticed.
The coding is specially made for people on the move, so that you can listen under bridges and all the dodgy areas you've never got decent radio before.
And finally, it's capable of lots more, including text, pictures and even video.
Digital radio is currently broadcasting across the UK.
So where can I get the receivers from?
This is where you need to be clever. A "digital radio" according to the spotty youth in electrical shops is one with numbers on the front instead of a dial. This is not a digital radio. We want one that probably says "DAB Digital Radio" on the front of it, and costs around £300. Yes, £300. New technology doesn't come cheap - although there are plans to bring out cheaper digital radios soon.
You can also get things you can stick onto your PC to enable you to listen to digital radio. I use one occasionally, when I can get it to work.