If you’ve watched television in the last few months, you’ve probably seen public service announcements about the big changeover to digital television. On February 17, 2009, TV as we’ve known it for the past three quarters of a century or so ends. If your TV set currently receives its signal over-the-air, after this date it will no longer be able to pick up a signal from an antenna.

Don’t panic! This doesn’t mean the end of television. You probably don’t even need to buy a new television set. What is happening is that the government is requiring all full-power television stations to stop broadcasting analog signals so that they can use them for emergency communication.

Trying to explain the difference between digital and analog television is difficult. Most people didn’t even realize their televisions were analog until the digital TV cutover became a news story.  Both digital and analog TVs broadcast on VHF and UHF frequencies. The difference is that analog television sends out a continuous stream of information, while digital TV sends it out in "data packets." So digital is not unlike an analog feed, but chopped up into many parts or "bits" and squeezed into a smaller space.

The problem is that analog television takes up too much bandwidth. We tend to not think about these kind of things, but there are only so many frequencies a signal can physically be broadcast on. Most people are familiar with an AM/FM radio interface that has a finite amount of numbers that all the stations broadcast within. Television is the same way, except TV signals are much larger because they must carry both audio and video information.

Pretend for a minute that the airwaves are like a highway. Television signals are like a convoy of 18-wheelers. There’s no way around them, which makes it difficult for vehicles like ambulances and fire trucks to edge past in case of emergency. But if the 18-wheelers are replaced by a fleet of fuel-efficient economy cars, it makes it easier for everyone to get around. Digital television is like the Prius of the airwaves -- digital TV signals take up a much smaller amount of bandwidth, so they don’t block the “lanes” as much. This analogy is particularly apt because one of the reasons for the digital cutover is precisely to make way for emergency broadcasts and public safety communications from police, fire departments, and rescue squads. And yet, because digital TV broadcasts have the capacity to maintain higher-fidelity signals, they can also often provide better picture and reception even while occupying less bandwidth than analog.

This only affects full-power television broadcasts. That means most of the major network and cable television stations people actually watch will broadcast only in digital. Smaller, low-powered stations such as local and community access channels will still be able to broadcast in analog. There's a search tool available to find out if there are any low-powered stations that can continue broadcasting in analog in your area.

The digital TV changeover will also have no effect on radio. Radio is broadcast on an analog signal, but it’s a much, much smaller signal because it contains only audio and no video data. If you have a radio that picks up the audio from television, you will no longer be able to hear those broadcasts after February 17, 2009 (or August 31, 2011 in Canada when the DTV cutover happens there) except from low-powered stations. Likewise, subscribers of cable, satellite and IPTV are fine, regardless of how old their television sets are -- because these technologies already deliver television broadcasts digitally. Cable and IPTV signals aren’t sent over the airwaves, so the only way their subscribers will notice the difference is if they plug in a set of bunny ears, just to see what happens.

The only people who have to worry about the digital changeover are people who get their television reception over an old-style aerial or antenna. If you don’t know how you get your television, there’s a good chance that’s you. Don’t worry though, you won’t necessarily have to start paying for television and you probably won’t have to spend a fortune to upgrade your TV. Fortunately, all you have to do to keep receiving free television is purchase an analog-to-digital convertor box, also known as a "set-top converter box" or "digital TV adaptor." Before freaking out at the word “purchase,” know that the government is giving out $40 coupons for these convertor boxes. Since the boxes cost somewhere between $40-$80, some or all of your convertor purchase will be subsidized.

There are a few catches, though (aren't there always?) -- each household is only eligible for two coupons, so if you have more than two TVs to convert the digital cutover will impact your pocketbook more significantly. The coupons are also only good for 90 days after the digital TV cutover occurs, so you'll have to act within 3 months to take advantage of them. Only one coupon can be used per box as well, so you can’t buy a really good convertor box by combining two coupons. To receive your coupon(s), visit https://www.dtv2009.gov/ or call 1-888-388-2009 (voice) or 1-877-530-2634 (TTY).

In other words, don’t panic. Yes, television as we know it is ending -- but the television of the future is about to arrive. As long as you pay attention and purchase an inexpensive digital convertor if you currently receive your TV by analog means, you should be able to keep watching “Seinfeld” repeats for a long time to come. If you have any other questions about the digital television changeover, the Federal Communications Commission has set up a Web site to answer them at http://www.dtv.gov.