Thanks to a mandate by FCC commissioner Jonathan Adelstein, a number of networks in metropolitan areas across the US will turn off their analog broadcasts, for a full two minutes tonight. The goal is to test the networks' preparedness for the February 17 switch over to digital TV.

During that time, an on-screen message will inform users whether they are digitally connected. If viewers are not fully prepared, text will direct them to the government's conversion site, www.dtv.goc.

Stations including ION Media Networks, NBC Universal, and Telemundo will be participating in New York, Los Angeles, Washington, D.C. and Hartford, Conn. The shutdown will occur between 5:59 and 6:01 PM.