On May 21, a giant television will roll through the streets of Watertown and down Route 3 to a stop in the Wal-Mart parking lot.

Called the DTV Trekker, the mammoth screen is part of a 16-month campaign by the National Association of Broadcasters designed to raise awareness of the upcoming transition to digital television next year.

On Feb. 17, television stations across the United States must stop broadcasting analog signals and convert to a digital format.

The transition means that people who watch television on their analog sets, estimated to be about 10 percent of New Yorkers, must take certain steps to maintain their broadcast programming.

Residents must either purchase a new television with a digital tuner, buy a converter box to translate the new signal or subscribe to cable or satellite service.

Although many people already have heard about the transition, Latrice A. Griffin, a spokeswoman for DTVanswers.com, said many misconceptions continue to float around.

Ms. Griffin, who travels with the DTV Trekker, said 60 percent to 70 percent of the people she meets have heard about the shift, but many don't understand how they might be affected. Another 30 percent to 40 percent have never heard about the change at all.

"The major misconception of people I talk to is that you have to go out and purchase a brand new digital television," she said. "You can use an older television set, it can be 20 years old, if you connect to a converter box."

For those worried about the cost of the transition, Ms. Griffin said, she directs people to a coupon program run by the Department of Commerce. Under the program, each household is eligible to receive two $40 coupons toward the purchase of a converter box, which generally costs $40 to $70.

"It allows you to convert two television sets to digital without paying a lot of money," Ms. Griffin said.

The awareness campaign,began Nov. 1 and will continue until the month of the transition, Ms. Griffin said.

At each stop, information about the transition plays across the sides of the DTV Trekker truck. Two televisions demonstrate the difference between digital and analog-quality televisions.

The road show also features games where visitors can spin a wheel to receive prizes such as pens, hats and Post-It pads.

Residents can obtain more information about the converter box coupon program by calling 1 (888) DTV-2009.