If you're familiar with the radio industry, you may be aware of discussions on IBOC. It's created a bit of a stir in many different countries. If you haven't, I will try and explain some more technical shite in simple terms.
IBOC stands for In-Band On-Channel, of which is its way of broadcasting data to a radio tuner. Oh, like RDS? Yes, and more - many say its the halfway house from AM/FM to Digital Radio.
You know when you tune a station into a clock radio, its fuzzy, then clear, then fuzzy as you tune across the frequency? You then go back and find the clearest place and settle there. IBOC works like a bracket around a frequency. It will help define the main frequency and adds redundant information on the edges. Kinda like putting soundproofing around it, making the main frequency "clearer".
IBOC also transmits a digital version of the analog broadcast simultaneously. These new digital signals are broadcast as "sideband" transmissions bracketing the top and bottom of the current "host" analog signal to help reception (think: driving under a bridge listening to AM - the digital will kick in and give you continuous reception). Heaps of US radio stations also face major interference from adjacent stations, so anything helps.
As for the RDS similarity mentioned above: IBOC leaves RDS behind in many respects, but so does Digital Radio (more on that later). RDS is only similar to IBOC in the respect of an 'extra signal' on a frequency, regardless how its done or what it does.
RDS displays scrolling or static text, along with "business card" info on an array of different services, and the RDS hat-trick is the ability to automatically locate your station if you go out of range, although rendered useless if theres no other freq to tune to. RDS is one-way, therefore not of this age.
With IBOC's digital inferface "HD Radio" (just launched in January at the US Consumer Electronics Show) you get interactive radio. "ID3" info is instantly available on the current song. If you use mp3 files, ID3 is used for adding Artist/Title/Album/Year information to the mp3, this info is available (that is to say if there IS a computer at one end rather than a turntable), as well as website integration. For example, while listening to your favourite morning show, you can read a bio of the host if your heart so desires. Plus theres breaking news, sport, traffic and the rest - blah blah.
With this, are a couple of interesting concepts. The ability to digitally record a radio broadcast and listen to it later. Thats On-Demand listening, which has nothing to do with the internet!. ~Radio evolves in its own medium! WOWEE!~
The other, is surround sound. So if your car just happens to be spec't to the max with da soundz bro, you can experience true surround sound. I await some shock-jock to play a DVD of the "101 Greatest Surround Sound Effects" during their show. SHIT! Was that the Enterprise flying over me?
So you'd think that this is a great thing? The theory is awesome really, but the real world effects are much different.
Because IBOC 'dampens' the edges, whilst trying to maximise the main frequency - the reality is that it still shrinks bandwidth (space where you can pick up the station). In Los Angeles, there are a ton of IBOC users of whom are unhappy with the outcome of installing this added feature. In their outer coverage areas where before IBOC, they could be heard they are heard no longer. Not only that, but you may know that AM signals have different properties at night, so radio engineers all over the country are ripping their hair out trying to re-engineer their station/s power (some not legally) to gain back that lost coverage. One disgruntled ethnic listener wrote in to her favourite station saying that she receives up to 5 different stations at once since this change! - A reverse effect?!?! That's unforseen.
The move to test and try IBOC all kinda stems at the base of digital radio. Sirius and XM over in the States are still signing up a shitload of users every week, and frankly I can't blame them due to the awful AM/FM climate in the US. I'd sign up if it were available here. These Digital Radio subscribers already get everything and more listed above. Just look at Digital TV. Compare Sky with regular VHF/UHF television... burp!
IBOC may help suck up the free range fat, but our dials are not (yet) that busy, and may only be useful to educate the NZ novice to grasp the beginning of radio's future. Time will tell, but signs so far seem to indicate that RDS is probably enough, and this hoop could possibly be skipped.