Not that most Angelenos would know it, but many local TV stations are already sending digital signals through the airwaves. They just don’t have anything much to put on them.

As TV stations around the country make the transition from analog to digital broadcasting, they are confronted with an embarrassment of riches. Digital signals can be compressed into a very narrow bandwidth, narrow enough to squeeze up to five channels of programming into the same segment of spectrum occupied by a single analog channel.

What do you do with all those extra channels? A Los Angeles company called iBlast thinks it has the answer.

IBlast is creating a television network for the 21st century, a kind of interactive ABC that will use digital TV signals to send data that users can unscramble with their personal computers. Ultimately, the aim of the technology is to allow people to choose what they want to watch, when they want to watch it allowing super-fast downloads of software and other entertainment content, like movies, TV shows, music and games.

IBlast is setting up a network-affiliate type of relationship with television stations across the country, to help participating stations offer multimedia content in addition to their own broadcasts by using their excess digital channels.

IBlast was founded earlier this year by several media giants, including Tribune Co., E.W. Scripps Co., Post-Newsweek Stations, Gannett Co. and the New York Times Co., which were looking to pool their resources and make good use of the portion of the digital airwaves allocated to them by the Federal Communications Commission.

“The magic of iBlast is that it melds new media and traditional broadcasting,” said company President Ken Solomon.

Like traditional broadcasting, some digital programming will be free for consumers but extras like on-demand movies, games, music and software will carry a fee. Users will be able to order content and download it directly onto their PC hard drives, but that content will come through the airwaves, not through the Internet.

TVs aren’t yet PCs

All of this, of course, will have to be done using computers rather than television sets. But that won’t last forever.

“You’re going to have a smart television at some point in the future,” said Mark O’Brien, executive vice president at media consulting firm BIA Financial Network.

Such “smart televisions” will be very unlike those sitting in living rooms today. Televisions of the future will likely combine digital television and radio broadcasts with the interactivity and vast variety of the Internet. But such a device is a long way off.

“Analog television can only do one thing, and that is receive analog television signals,” O’Brien said. “As television goes digital, and until you get this converged device, the computer is the closest thing to that right now.”

Digital signals can carry television broadcasts along with other kinds of data, such as software coding. Users will navigate digital channels with a digital tuner, a feature already included in some new computers currently on the market. External digital receivers that users can attach to older computers are also arriving in stores.

In addition to putting in this hardware, iBlast users will need to install special software that can interpret the data sent over iBlast’s digital waves.

Users will have to pay to purchase games, music and other content and will need Internet access to conduct those transactions, at least for now. But delivery of the content can come through the air, via iBlast’s digital transmission. When ordering a piece of software through a company’s Web site, for example, one delivery option would be iBlast.

“It is a safe assumption that anyone doing that kind of stuff (online buying) probably already has an Internet connection,” O’Brien said.

Ordering through the air

How is it possible to get a custom software order over a universal digital broadcast? The system will send a constantly changing stream of data containing thousands of different items. The most popular items will be transmitted the most frequently.

So, for example, if you want to get the latest version of Microsoft Word, that program might be beamed out on the digital spectrum once every two minutes. Ordering the software means your computer would be able to unscramble that particular signal and pull down the program.

But let’s say you want to download the latest musical release by the band Insane Clown Posse. That might hit the airwaves only every hour or so.

“The less popular something is, the longer you’ll have to wait, in theory,” Solomon explained. “What we’ve found is, people want to be able to order immediately, but don’t really need to use it immediately. You may not be able to get Adobe Photoshop the second you order it; you may have to wait 15 minutes.”

Delivery of content through iBlast will still be extremely fast quick enough to enable about 100 MP3 music recordings to be downloaded in four minutes or less.

A digital distribution system such as iBlast would help entertainment companies offering digital music, games or software to substantially reduce their distribution costs.

“Instead of having to produce the CD-ROM, put it in a box, wrap the box, put it on a truck, ship it to the store and advertise for people to go to the store and buy it, all the costs, every one of them, becomes consolidated into a one-megabyte-per-second delivery cost,” Solomon explained.

The fee that content providers will pay to transmit their programming via iBlast will be shared between iBlast and its participating stations, giving stations a new revenue stream in addition to their traditional advertising revenue.

Each station participating in iBlast has agreed to give the company a portion of the station’s digital spectrum allotment, a cash investment and a marketing agreement, in exchange for equity in iBlast and revenue sharing.

IBlast will manage and distribute the content with widespread popularity, like the top video games and software. The company will leave the airing of extremely local content, like Little League games and PTA meetings, to the local stations themselves.

Channel 5 goes digital

Because the digital spectrum of each station can accommodate multiple broadcasts simultaneously, the system will be very flexible to suit the local market.

KTLA-TV Channel 5, owned by Tribune Co., is the only local television station currently working with iBlast.

“(IBlast) might download news video clips, clips from the ‘KTLA Morning News,’ and since we’re merging with Times Mirror, they may decide to download large portions of the L.A. Times Web site,” said Michael A. Silver, vice president of new media for Tribune. All of Tribune’s 22 television stations are participating in iBlast.

“It’s great if there’s a local basketball game and there’s a big movie running over the network and there’s a flood,” Solomon said. That’s because all of that content could be transmitted over iBlast at once.

IBlast is one of four companies currently helping stations across the country band together and develop strategies to gain new revenue streams as digital broadcasting phases out the longstanding standard of analog.

Geocast Network Systems Inc. in Menlo Park, Calif., has signed deals with some local stations to be a multimedia content provider. Granite Broadcasting Corp. in New York City and BIA Data Management in Chantilly, Va. are working with broadcasters to pool their digital spectrum allocation and sell access to businesses that want to use it for business-to-business transactions.

IBlast sits somewhere in the middle, allowing content providers to rent digital space from iBlast-affiliated stations.

IBlast is currently testing its service in three markets: San Jose and two other markets the company declined to identify. Users in L.A. can expect to see a test version of iBlast’s services through KTLA before the end of the year. The company plans to begin its national rollout early next year.