Digital radio was launched with much hooplah this week -- or to be precise, launched in Sydney. Turns out the other major capital cities have had it for a few months now -- who'd have known?
Now that Sydney, Melbourne, Brisbane, Adelaide and Perth have DAB+ digital radio blitzing its way through the airwaves, retailers finally have the green light to start selling digital radios full-steam ahead, rather than just having the odd display model that nobody in the shop quite knows how to use and can't be tuned in to anything.
But first… what is DAB+ digital radio?
Digital radio is to radio what digital TV is to TV -- at the most basic level, it's the same thing at much higher quality. You can forget the hiss, buzz and crosstalk of analogue radio, as well as the muffled sound of AM radio stations. With digital radio, you get somewhere between optimal FM and CD quality sound.
We hesitate at calling it "CD quality" because if you listen to it with headphones, it sounds more like an 128Kbit/s MP3 -- on some songs you do hear the audio compression artefacts. But it's much better than listening to analogue FM, and it's a vast improvement on muffled old AM radio.
Naturally, because it's digital, a range of different sound problems can occur -- just like suboptimal digital TV reception, you can get unpleasant squealy audio glitches or sound dropping in and out like a GSM mobile phone with bad reception. However, many digital radios come with a big extendable antenna (about twice as long as an average FM radio) that gives them better reception.
Digital radio is about more than just nicer quality sound though -- it has some other major benefits, the most important of which is that there's no longer the need to remember frequencies of your favourite stations. The DAB+ radio system hides frequencies from you -- DAB+ radios auto-tune a list of stations and you simply scroll down a list of stations ordered alphabetically and select the one you want. (Let's hope this doesn't have the unfortunate effect of encouraging unscrupulous radio broadcasters to start moving towards station names like AAA Aardvark.)
You can also receive a lot more channels than on a regular radio. Each broadcaster gets a 128Kbit slice of spectrum allocated to them, however, most are slicing that up into smaller chunks in order to broadcast multiple stations. For example, the Triple M network got 128Kbit/s, but is actually broadcasting two stations using 48Kbit/s each, and using the remaining 32Kbit/s data transmission to go along with the channels.
The 48Kbit/s sound quality really is quite incredible -- especially if you think how crap music on your PC would sound if it was encoded at 48Kbit/s, rather than 192 or 256Kbit/s. While DAB radio marketing executives are at pains to point out that they don't claim it's CD quality, it's very satisfying to listen to. Although you can occasionally hear the sound compression, the lack of analogue hiss, interference and so on tricks the mind into thinking it's listening to a CD or iPod.
The remaining 32Kbit/s of bandwidth is used for data transmission, and when you're listening to the audio, your digital radio displays album cover art, song name, weather/traffic information for your area, web addresses for the music you're listening to, program name, and so on. Of course, not all digital radios will have a colour screen capable of displaying cover art.