Why do have to ‘rescan’ my TV channels?

Across the country, viewers are seeing commercials telling them to “rescan” TV frequencies on certain dates — but what does this mean and why do you need to do it?

  • Mostly importantly, note that if you watch TV via a cable or satellite box or a streaming provider there’s nothing you need to do.
  • The so called “rescan” only affects viewers who watch TV using an antenna. The changeovers happen at 2 a.m. on designated dates, so most viewers will want to do it when they wake up that morning.
  • The need to rescan is triggered by “repacking” that, in turn, is part of the “spectrum reallocation.”

Both concepts are super complicated and highly technical, so we’re just going to give a broad, simplified overview here.

  • In simple terms, when TV was first invented, TV stations started out sending out signals over the air using wave frequencies — just like the earlier radio technology, though obviously with pictures as well.
  • Each frequency is assigned a corresponding number — for TV stations in the U.S. it is a number.
  • It’s worth noting that the numbers are somewhat arbitrary in the U.S. in that they don’t necessarily align with any wavelength measurement.
  • For the early years of TV, almost everyone got their TV over the air like that — often relying on those “rabbit ears” to help catch the signals out of thin air.
  • However, with the invention of cable and satellite television (and, eventually, the web), more and more viewers began receiving the same signals that TV stations air via cable wires, satellite signal or internet connections.
  • During all this time, however, TV stations still broadcast over the air — though the number of people viewing that signal via antennas has decreased dramatically.
  • With less and less viewers watching on over the air waves, there is more demand for the space the radio wave spectrum for use in other wireless communications, especially mobile devices.
  • Hence, after a lot of wrangling, TV stations have been allowed to sell off their parts of the wave spectrum — often to the tune of hundreds of billions of dollars.
  • In short, the lure of a windfall cashflow was simply too lucrative to ignore — even despite the hopefully minimal confusion with over the air viewers.
  • Since they are selling off over the air channel frequencies and will no longer be able to send signals over them, the stations have a few options: Switch to a different channel, use a channel sharing arrangement or simply just down over the air broadcasting.
  • For stations switching channel numbers or moving to a subchannel, rescanning should make them viewable over the air for free.
  • However, in the case of TV stations shutting down their over the air signals, then a cable, satellite or other subscription will be needed that includes that channel in its lineup.