 Until the transition was completed, most U.S. broadcasters transmitted their signals in both analog and digital formats, though a few were already digital-only.Digital stations transmitted on another channel, which was assigned to each full-power broadcaster in a three-round digital channel election.The transition from the analog NTSC format to the digital ATSC format was originally required to be completed on February 17, 2009, as set by Congress in the Digital Transition and Public Safety Act of 2005.