This is the third installment in a continuing series, discussing the transition of many common services from analog to digital. Here’s the scoop on HD Radio.
As more over-the-air transmissions make the move to digital, broadcast radio has begun to jump on the bandwagon. While many countries are promoting DAB (Digital Audio Broadcast) technology, the United States is putting its money into HD-Radio. Here’s the rundown on this emerging technology.What is HD Radio? HD Radio, a technology designed and licensed by iBiquity, is the up-and-coming digital broadcast mode in the USA. Unlike DAB, which can be in any part of the spectrum that the country of origin decides to use (such as 1.2Ghz in Canada, 400Mhz in many parts of Eurpoe, and so on), HD Radio operates within the current AM and FM broadcast spectrum. HD Radio is designed to do two things: First, it allows the listener to hear existing programming in a better audio quality. Second, it allows FM broadcasters to offer multiple programs within their existing licensed bandwidth, offering the opportunity to provide radio formats that were previously unable in the limited spectrum.
HD Receivers are capable of receiving both analog and HD modes. The HD user will notice that he is actually receiving the HD signal for the first few seconds after tuning to the station. After those few seconds, during which the radio is buffering and sync-ing the HD signal, digital (HD) mode kicks in. While it is a subtle difference on FM broadcasts, which turns the signal into CD-quality audio, the difference is far more dramatic on AM. Here, an AM signal transforms into an FM quality station, with a natural audio range and true stereo sound. This fact may make AM radio usable for modern music once again.
FM broadcasters have room for up the three different programs on their current bandwidth. HD-1 is the digital rebroadcast of the standard analog signal. HD-2 and HD-3 (where available) are alternate programming options that are available on HD receivers only. Because of the limited bandwidth on AM, there is only room to rebroadcast the analog signal.
HD Radio is still, for the most part, classified as “experimental” by the FCC. This status comes with some restrictions: First, the HD-2 and HD-3 channels must be commercial-free. Second, the output power of an HD signal is limited to one percent of the station’s total power output. So the 50kW blow-torch is limited to a mere 500 watts of digital output. Recent rulings by the FCC may allow broadcasters to double that to two percent. Still, it means that the digital footprint is much smaller than its analog counterpart, since the uninterrupted reception of HD radio requires a very favorable signal-to-noise ratio. In fringe areas, an outdoor FM antenna may be required.
HD Radio vs. Satellite Radio: Despite being similar to satellite radio in that both modes are digital, there are three distinct differences between satellite radio and HD Radio: First, HD broadcasters cannot charge for the service, since it is still virtually experimental. Future developments in HD Radio may change that, but for now, it’s free-to-air just like conventional analog. Second, unlike satellite radio, HD radio is still considered a terrestrial broadcast, and is subject to the same FCC content rules. So while Howard Stern can now drop the “F-Bomb” all he wants on satellite, he is still prohibited from doing that, even on HD radio. But unlike satellite, which offers the same programming selection nationwide, HD radio signals, being terrestrial, are local to a single metropolitan area.
Availability: HD Radio is available in the majority of broadcast markets nationwide. In many areas, the technology has ben put in place by even the lowest-budget of stations, including community radio and NPR affiliates. Since it works in their existing licensed bandwidth, it requires a simple retrofit of their existing transmitter–a comparably small expense when the price of an all-new transmitter on a new frequency is considered.
To find HD radio stations broadcasting nationwide, go to www.hdradio.com, where you will find an updated list of stations on both AM and FM, complete with a list of the formats offered on each station.
Is Analog Radio Going Away? In a word, no. In two words, not yet. HD Radio is still being implemented in most of the country…some markets have 100% of their stations on the air, some markets have only a portion of the stations up and running, and many markets are still without a single HD station. Until more stations go on-air with HD Radio, and until more listeners adopt the technology, analog broadcast radio will remain on the air. At the present time, the FCC has not started to discuss any sort of timetable for a full conversion to digital. Such a decision would likely be years away.
If you’re an avid broadcast radio listener, and you have the budget for a new radio (typically starting arouond $150), you will appreciate the benefits of HD Radio. But for the vintage radio owner, those antique radios will still receive programming for more years to come. Keep buying the new caps and tubes…you’ll still need ’em for a while.
