Digital radio broadcasts, after years of dreaming and development, are finally arriving on the air. And at first, this technology might not seem terribly enticing: The hardware needed to tune in these new signals is laughably expensive and few stations transmit in digital anyway.

But its sharper, clearer sound is an improvement for what it leaves out: Digital FM eliminates analog FM's scratches and pops and much of its background hiss. The results are not quite CD quality -- the way a song is compressed for broadcast makes digital FM's sonic fidelity closer to that of an MP3 file. With jazz or classical, the greater clarity is easy to notice; voices and heavily produced pop music can sound almost the same in digital and analog.

On AM, there's no mistaking digital for analog. The routine buzzing static is gone, replaced by a clear, crisp, if sometimes brassy sound that sounds not too different from high-quality Web radio. It makes these frequencies good for something besides traffic reports and baseball games -- you can actually enjoying listen to music on AM.

More fascinating yet, digital radio -- which its developer, Columbia-based iBiquity Digital Corp., is marketing as "HD Radio" -- can deliver data as well as music and voices. It can carry a brief description of each station, the title and artist of the current song and, someday, text alerts about news or traffic updates.

And this technology is being deployed in an impressively elegant manner: A station's digital broadcast seamlessly shares the same frequency as its analog signal, allowing a receiver, like a cell phone, to hop from one to the other as needed. This is unlike digital TV -- where a massively awkward transition from one set of analog frequencies to a new batch of digital channels is underway.

It's also unlike satellite radio, where a new broadcast technology brings you a much wider range of programming for a monthly fee. HD Radio is free, but it doesn't put any more stations on the air.

I gave this technology a listen over three long days of driving earlier this week, both around the District and up Interstate 95 to Philadelphia -- the closest city where I could tune into digital AM music programming.

One major impression was boredom: In the Washington area, only WAMU (88.5 FM), WETA (90.9 FM) and WHUR (96.3 FM) offer digital broadcasts, I found a single digital FM station in Baltimore, and the Panasonic radio in the car loaned by iBiquity picked up one FM and AM station each in Philadelphia.

The Federal Communications Commission's Web site lists only 117 stations across the entire country conducting any digital broadcasts. IBiquity maintains its own database of stations with digital plans (for some reason, readable only in the Internet Explorer and Opera browsers) at www.hd-radio.com.

I also couldn't help noticing how digital FM's increased quality is paid for with decreased range. On a drive northwest along interstates 270 and 70, WHUR's digital signal first started to drop back into analog in the northernmost reaches of Montgomery County, becoming increasingly unreliable until it disappeared around Hagerstown. But the station could still be heard in analog -- if not well -- 20 miles farther up the road.

The downside of this surfaced on the trip back, when I tried tuning into WETA's digital broadcasts. Because its digital and analog signals were a few seconds out of sync, the evening news broadcasts kept skipping forward and back each time the radio jumped from digital to analog and back.

That's the paradox of digital FM: In general, it functions only where analog broadcasts already work fine.

Digital AM, on the other hand, was a revelation. Hearing an old swing band tune on Philadelphia's WPEN (950 AM) had me rolling down the window to crank up the volume, something I can't remember ever doing before with AM.

But digital AM's reception was even shakier than digital FM's. Driving underneath a cluster of electrical wires or a sufficiently long overpass -- or simply going through some intersections in the center of Philadelphia -- routinely cut out the crisp stereo sound and dumped me back into scratchy old AM.

I couldn't help wondering how much better HD Radio might sound at home, where none of those factors applies. But the only digital-radio receiver on the market is a $1,000 Panasonic car stereo. Other car and home receivers are due later this year; iBiquity says that HD Radio compatibility should add $100 to $150 to a radio's manufacturing costs, a sum that it expects to drop by half every year in the years to come.

Like a lot of new consumer-electronics technologies, HD Radio feels like a project more than a product. Many of its capabilities have yet to be deployed -- for instance, I didn't find any stations that sent out song-title data. It may take years for stations to upgrade their transmissions (an expense iBiquity spokesman Gil Chorbajian estimated at $75,000 to $100,000 a pop), and some may never bother. HD Radio's basic workings are still being tweaked; next year's receivers may perform significantly better than this year's models.

Then again, they might not: The Recording Industry Association of America is making a belated, misguided attempt to persuade the Federal Communications Commission to mandate copy controls in HD Radio receivers.

That's a lot of uncertainty to hang on HD Radio. But if things go right, this could well earn a spot on non-audiophiles' shopping lists -- next year.

Living with technology, or trying to? E-mail Rob Pegoraro at rob@twp.com.