The U.S. Congress is deciding on a new kind of television signal that will change your viewing habits forever.

KIRO 7 Eyewitness News Consumer Investigator Wayne Havrelly tells what's on the way, and what it will mean to you.

Since the dawn of television, we broadcasters have been sending our programs to you over the air by what's called an "analog" signal.

But we now live in a largely digital world, and that will soon include television signals -- creating some concern and a lot of confusion.

Walk into any Costco store and you can't help but stop and stare at the huge television screens with brilliant pictures.

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Some of the best feature HDTV, or high-definition television.

"It is so different today what we have on our floor than what we had on our floor even three years ago," said Geoff Shavey of Costco. "It's completely different and the sales have just gone off the charts."

Those sales are likely to continue to climb, in part because of the higher quality and lower cost of these TVs over the past decade and in part because of a coming revolution in the way viewers receive television signals.

Congress is debating a fixed date when all television transmissions will be converted from analog to digital, a necessary step to transmit high definition programs.

But what will it mean to you? We found a lot of confusion among viewers.

"I don't know anything about how our TV now works," said one viewer.

"Whatever they do to it will be fine with me as long as I get my TV," said another viewer.

Alysson Harkin adjusts the rabbit ears of her television in the Capitol Hill apartment she shares with her husband, Barry.

The Seattle couple is among 21 million Americans who still receive their TV signals over the air, for free.

Their apartment is close to television broadcast towers. They don't see any reason for satellite, cable or digital TV. They don't need it, they say, and they don't want it.

"We just are frugal. I like to keep the bills at a low minimum," Alysson Harkin said.

But when the digital conversion comes, if they still have their current analog television, these rabbit ears will be useless. They'll need a special digital converter box or their TV screen will go blank.

Congress promises to pay a large portion of the cost of those boxes.

But Barry Harkin, who comes from Northern Ireland where the boxes are provided free by the government, is outraged.

"Being compelled to buy anything in order to watch TV in this day and age is ridiculous," said Barry Harkin.

The kids and friends of Kris Peterson watch a DVD on the Peterson's state-of-the-art high definition television at their Queen Anne home. Unlike the Harkins, Peterson can't wait for all digital, high definition TV broadcasts.

"You just have a much brighter, clearer, more vibrant color picture," Peterson said. "So I'm all for it!"

Remember, you can buy a new TV with a digital tuner built in. And if you subscribe to cable or satellite services, they'll make the conversion for you.

But for viewers like the Harkins, the days of old-fashioned, completely free TV are numbered.

"How many things are they going to take away from us that were free for my parents, his parents?" Allyson Harkin said.

One reason for the change is to provide better picture and sound quality. But the government is also eager to free up the current TV signals so police, fire and other first responders can use them to improve emergency communications.

The exact date must still be worked out in Congress, but it looks like TV digital conversion will happen by the spring of 2009.