The path to digital radio – a short history of our next big digital move

Why has digital radio taken so long to happen?

When we ask CEO of Commercial Radio Australia, Joan Warner, why digital radio has taken so long to get here, she actually responds that the process has been relatively quick.

“We’ve been working on this directly since 2003,” she says. “It’s not as simple as saying let’s do a new tech and then rolling it out.”

Warner explains that it’s important to Australia’s radio broadcasters that every possible standard and technology be examined and rated for suitability. There are also many behind-the-scenes questions that needed to be answered: who would control the transmission system? Would existing broadcasters get exclusive access to the new tech, and for how long?

And because the airwaves are public property, big decisions such as adding digital radio to the existing radio landscape have to be backed up by government legislation.

It’s hardly a glamorous start for a new tech: locked in committee rooms full of overhead projectors and whiteboards.

Still, all that’s behind us now, and it’s time to get the ball rolling on digital radio. But what exactly is digital radio?

Why we need digital radio

Current AM and FM broadcasts are analog. Your receiver converts the electrical signal directly into audio. You might have a radio that provides some kind of audio filtering or processing, but the signal is intrinsically degraded by the transmission process.

AM and FM suffer from all sorts of disadvantages. They take up a lot of bandwidth, so the number of channels that can be carried is limited. They’re vulnerable to ‘crosstalk’ – with stations overlapping each other. And of course we’ve all experienced static and loss of signal.

In fact, there are many similarities between the digital radio experience and digital television. Digital radio gives a solid signal, without any fuzz or static. You’ll also tune in to ‘named’ stations instead of esoteric numbers like 106.5 or 88.1 – just select ‘ABC Radio National’ from a list on your receiver.

The standard for digital radio – in Australia it’s called DAB+ – specifies that receivers must have a two-line text display. But this isn’t just for station names. Broadcasters can also add metadata to their transmissions, including playlist information, weather reports, anything really.

“Hearing is believing with digital radio,” says Warner. “Listeners are going to be really excited once they get the opportunity to actually experience digital.”

She says that with the ability to show text, and even images, digital radio has a natural “wow factor” built in. It will dramatically refresh our oldest and perhaps most undervalued broadcast medium.

In the beginning – a short history of digital radio

The Digital Audio Broadcasting standard, DAB, was developed in 1988 and formalised in 1993. Continental Europe and the UK started broadcasting in 2000, and it’s estimated that by 2006 around 500 million people lived in coverage areas for digital radio.

But the history of DAB is somewhat chequered, and that’s why we won’t be using it here in Australia. Instead, we’ll use the upgraded DAB+ standard. So what’s the difference?

DAB predates most compressed audio devices such as personal players and even affordable home PCs, so it uses MPEG-1 Audio Layer II compression (called MP2). This was good enough in the early ’90s, but it had a major drawback: digital stations had poorer audio quality than FM!

Yes, DAB eliminates crosstalk and static, but it sounds a lot worse than a CD. Adding insult to injury, some stations broadcast their music in mono to save on bandwidth. Analog radio gets a slice of the spectrum to use, and has a KHz ‘slot’ on the band. Digital radio does too, but since it’s digital, the amount of content is actually measured in kilobits per second (kbps), just like when you encode an MP3 at different quality settings.

Here in Australia, digital channels will be given a maximum of 192kbps per channel. It’s possible to split this bandwidth up, assign it to different sub-channels or use it for text, and that’s part of what’s so great about digital radio.

But in countries that use DAB, not DAB+ like Australia, any reduction in bandwidth has a massive effect on audio quality, because of the MP2 compression.

DAB+, on the other hand, uses AAC+ compression, just like iPod. It’s more efficient, and it means a 64kbps audio stream sounds fantastic, much better than FM. DAB+ also has better error correction, and when it comes to a digital signal, error correction makes all the difference between uninterrupted music and constant dropouts.

There’s more: in the UK for instance, initial digital broadcasts didn’t work indoors! It was only available in the car or on portable systems. And the way that ownership of the actual transmission system – the multiplexers that create the signal – was set up, meant broadcasters had to pay huge fees to access the technology, and that naturally impacted on the quality of programming.

World’s best for Oz

Australia aims to avoid all these problems, as Warner explains: “From day one we want to offer a complete system. We’ve learnt a lot from overseas.

“We have in-building coverage, we have very high coverage for Sydney, Melbourne, Brisbane, Adelaide and Perth, and the broadcasters hold the multiplex licenses.”

Warner also points to the relationship that the CRA has with DAB+ device retailers. “Our relationship is unique in the world, we work very closely with retailers and keep them in the loop. This means on launch you can hear about digital radio and then go into a store and buy a suitable device.”

She sums up the whole project as offering the broadcasting industry real freedom. “It’s a freedom to implement features and services to suit listeners. It’s all about listeners.”

Indeed, listeners are the whole point of digital radio, and Australia has no shortage of radio listeners. What’s more, we have an unusually high proportion of AM listeners: 48 percent. This makes us ideal candidates for a switch to digital radio, as the advantages over AM are in many ways even greater than over FM.

Further reading

Digital radio terminology: radiotext and UPnP – digital radio will see some new terms thrown our way, such as radiotext (or dynamic label segment) and UPnP – we look at what these terms mean.

Digital radio review round-up – 12 of Australia’s first – Digital radio begins broadcast in Australia on May 1… and GadgetGuy has gathered 12 of the first digital radios to go on sale.

Digital radio vs AM and FM radio – Digital radio is touted as being not only new, but demonstrably better than AM and FM radio in terms of audio quality and programming flexibility.

Digital radio FAQ – What is digital radio, and when is it launching? Where can I get it? Is is free? What’s different from AM and FM radio? These questions and more answered.