Six television stations that serve Vermont and the surrounding region will be testing the switch to all digital broadcasting.
For two minutes beginning at 7:58 p.m. Tuesday, some of the stations viewable in much of the state will switch to a digital signal.
Viewers who see a number flashing on their screens will be encouraged to phone a panel of experts to get advice on how to adapt their over-the-air reception to the new format.
Jim Condon of the Vermont Association of Broadcasters says about 15-thousand Vermonters get their television signal over the air.
Condon says some viewers might need to upgrade their equipment to view digital television.
The permanent switch will come February 17th.