Channel

Television stations are sent through channels, which is a selection of frequencies with enough bandwidth to transmit the data. Terrestrial television frequencies and bandwidth are set by the nation's spectrum regulation body. In North America, television channels are located in the VHF and UHF spectrums, which stand for Very High Frequency and Ultra High Frequency respectively. Cable television channels are transmitted through the frequencies that the cable will allow, while satellite television channels are transmitted over the airwaves through licensed Ka-band and Ku-band spectrums.

Analog

Analog television was the standard television format up until 2009. There are three forms of analog television: NTSC, PAL, and SECAM, which are all interlaced. They are transmitted using 6 MHz of bandwidth, with the audio on the upper most frequency. Channel 6's audio is located on 87.75 MHz, meaning that certain FM radios that can tune to that frequency will allow motorists to listen to channel 6 audio in their cars.

Digital

Digital television is the newer television format which the FCC converted to in 2009, after several delays. Digital television uses the same frequencies as analog, but because digital data requires less bits of information than analog data, the amount of bandwidth requires is more along the lines of 2 MHz for television with similar properties as analog. Digital television in the US, also known as ATSC, is transmitted using 8-level vestigial sideband modulation. The FCC requires all digital channels to broadcast at 19.39 Mbps, regardless of HDTV standard. Stations can also compress the digital data stream further, in order to split their frequencies into several channels, or sub-channels, which show up on a digital tuner using numbers such as 18.2, or 7.4. Depending on the amount of subchannels vs. the HDTV standard used by the station, more subchannels could end up compromising the quality of the primary channel. The digital spectrum currently ends at channel 51; the FCC plans to end it at channel 36 sometime within the next couple of years. Any station transmitting above 36 will be relocated below it and will be compensated as per the spectrum auction.

Television Frequencies in the US

• VHF
  • Channel 2 - 54 MHz
  • Channel 3 - 60 MHz
  • Channel 4 - 66 MHz
  • Channel 5 - 75.5 MHz
  • Channel 6 - 81.5 MHz
  • Channel 7 - 174 MHz
  • Channel 8 - 180 MHz
  • Channel 9 - 186 MHz
  • Channel 10 - 192 MHz
  • Channel 11 - 198 MHz
  • Channel 12 - 204 MHz
  • Channel 13 - 210 MHz
• UHF
  • Channel 14 - 470 MHz
  • Channel 15 - 476 MHz
  • Channel 16 - 482 MHz
  • Channel 17 - 488 MHz
  • Channel 18 - 494 MHz
  • Channel 19 - 500 MHz
  • Channel 20 - 506 MHz
  • Channel 21 - 512 MHz
  • Channel 22 - 518 MHz
  • Channel 23 - 524 MHz
  • Channel 24 - 530 MHz
  • Channel 25 - 536 MHz
  • Channel 26 - 542 MHz
  • Channel 27 - 548 MHz
  • Channel 28 - 554 MHz
  • Channel 29 - 560 MHz
  • Channel 30 - 566 MHz
  • Channel 31 - 572 MHz
  • Channel 32 - 578 MHz
  • Channel 33 - 584 MHz
  • Channel 34 - 590 MHz
  • Channel 35 - 596 MHz
  • Channel 36 - 602 MHz
  • Channel 37 - Section 73.603(c) of the FCC regs states that Channel 37 (608-614 MHz) is for the exclusive use of the Radio Astronomy service.

The following channels will be discontinued as TV frequencies and will be used for radio and cellular purposes as part of the spectrum auction:

• • Channel 38 - 614 Mhz
  • Channel 39 - 620 MHz
  • Channel 40 - 626 MHz
  • Channel 41 - 632 MHz
  • Channel 42 - 638 MHz
  • Channel 43 - 644 MHz
  • Channel 44 - 650 MHz
  • Channel 45 - 656 MHz
  • Channel 46 - 662 MHz
  • Channel 47 - 668 MHz
  • Channel 48 - 674 MHz
  • Channel 49 - 680 MHz
  • Channel 50 - 686 MHz
  • Channel 51 - 692 MHz

See also

2009 digital television bandplan