Technology & Engineering

HD Radio

HD Radio: The digital revolution you didn’t know about.

There’s a quiet digital revolution going on around us, and I don’t mean televisions or blu-ray disc players. I mean something much more mundane: radio. I bet you didn’t know it, but your favorite FM radio station is probably also broadcasting one or two digital radio stations in the same FM bandwidth. You can’t hear them unless you have a radio capable of tuning in these new digital stations. It’s called HD Radio, and because we think it’s one of the neato-keeno-ist technological advances of the last few years we’ve included an HD Radio tuner in the I-Sonic Entertainment System. Best of all, HD Radio is free; no subscription needed, no satellite linkup required. Plug in your I-Sonic Entertainment System, and discover the new realms of radio!

Who Doesn’t Want Something for Nothing?

When you’re finished reading this, you’ll know something that you didn’t know before; one of the best kept secrets of plain old radio. You know, radio. The original broadcast medium. Pre-television. What you probably didn’t know was that your favorite FM radio stations have slowly been making the government-mandated digital switchover, too. It turns out that the digital signal can be broadcast right alongside the analog signal in the radio. So when the switchover comes, radio stations will already be digital.

HD Radio is not satellite radio. HD Radio originates from your local Earth-based radio station, and it doesn’t require a satellite or a subscription. And while satellite radio may be commercial free, you still pay a subscription fee. HD Radio, on the other hand, is still commercial radio (or, noncommercial if you’re listening to a public radio digital station), and there’s no subscription fee. These digital radio stations broadcast near CD-quality digital signals right alongside the old fashioned, scratchy, staticy FM signal you’re familiar with. They’re free. When you have an HD radio tuner in your home or in your car, you’ll have access to these shadow digital stations broadcasting cleaner, crisper, clearer signal. Free, superior-quality radio broadcasts. All you need is an HD Radio tuner. Lucky for you, Polk has one.

The Next Generation of Radio Broadcasting: Digital HD Radio

How could this possibly be? There are secret radio stations broadcasting digitally on the FM bandwidth? It must be a conspiracy!

Actually, it’s an evolutionary step forward in radio broadcasting technology. It’s called IBOC, which stands for In-Band On-Channel, and it’s a technology that’s been developed by the iBiquity Corporation, which owns the name HD Radio. Technology makes it possible to broadcast digital signals directly alongside analog signals in the FM spectrum by adding what are called digital carrier signals to a radio station’s analog signal. The radio station begins to broadcast digital radio stations, sometimes multiple stations (called Multicasting, see diagram) within that bandwidth. Not only are these digital stations broadcasting in clear, near CD-quality, they are also broadcasting data! HD Radio stations, like satellite radio stations, broadcast metadata, such as artist name, song title, and even special messages about events, traffic and weather. You’ll see all this metadata information on the LCD screen of your I-Sonic Entertainment System!

Metadata and Multicasting: More than Just the Hits

When I was a little kid, I would listen to my little transistor radio in the wee hours of the morning. I turned the tuning dial slowly, and listened to the static in my little earpiece. Sometimes, on clear cold nights, I’d hear strange signals and weird broadcasts: a woman’s voice counting slowly or Morse code, in between the more powerful local AM or FM stations. It was strange to think that people were out there in the ether broadcasting in-between the radio stations. Digital HD Radio is a lot like that; digital technology allows multiple data streams to be broadcast within the same frequency range. In Digital HD Radio parlance, this is called multicasting.

Multicasting technology enables radio stations to broadcast multiple streams of data on separate supplemental or sub-channels of their main frequency. If you have an HD Radio tuner, you’ll be able to hear these supplemental sub-channels.

Say your favorite FM radio station is a jazz station broadcasting at 94.1. To make the digital switchover easy later, 94.1 probably has a digital mirror at 94.1HD. If you have an HD Radio tuner, you'll find that 94.1HD broadcasts a far superior audio signal, and you’ll probably start listening to your jazz station in HD Radio. The station may also have additional digital HD Radio streams at secondary channels 94.1-2, 94.1-3, etc.. Each of these secondary stations is able to broadcast an entirely different kind of programming! How do you get to swim in this glorious pool of digital beneficence? All you need is an HD Radio tuner. Did I mention: Polk has one.

Analog Dial 94.1 Familiar analog channel
HD Dial 94.1 94.1 HD Same channel, broadcast in Digital High Definition
HD Dial w/Supplemental Channels 94.1-1,
Digital sub-channels, often offering completely different programming!


The Sky’s the Limit, Digitally.

Currently, there are over 500 stations broadcasting in Digital HD, with another 2000+ expected to be on the air in the next two years. Over 90% of the US will be able to receive HD Radio signals in the next year, and with the government-mandated digital switchover in the not too distant future, you can be sure that HD Radio is not a fad (as many people continue to think of satellite radio). Soon, all digital HD Radio broadcasting, along with its increased data services and digital capabilities, will be your radio reality.

HD Radio is Not a Fad. It’s the Future.

You can find your local stations that are already broadcasting in HD radio here.

HD Radio is in the I-Sonic

We grew up listening to radio, and we remember when radio was really innovative. We’ve included an HD Radio tuner in the I-Sonic Entertainment System because we believe in radio’s future. But digital HD Radio is just one of the benefits of the Polk I-Sonic Entertainment System. The I-Sonic is the tabletop radio that produces big, lifelike sound in a compact, stylish package. Because it delivers classic room-filling Polk sound, along with exclusive Polk technologies, the I-Sonic could even be your primary home entertainment system! By integrating digital technology, along with iPod and iPhone docking technology and video pass-throughs, the I-Sonic System is much more than just a tabletop radio. Hear it today!

This article was last modified on Mar 26, 2013

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