Digital TV Conversion Factsby Shawn McClain
On June 13, 2009, all full power TV stations in the United States were required by law to shut down their analog signals and broadcast only in digital. Anyone whose TV only accepted an analog signal would have to either purchase a new TV or buy a converter box that would convert the digital signal into an analog one.
Less Spectrum Use
Television stations work by sending out electromagnetic waves at a given frequency. The entire range of available broadcast frequency is called the broadcast spectrum and is controlled by the FCC for uses such as television, radio, wireless telephony, wireless Internet and public safety communications. Digital television uses less of the spectrum then analog television does, thus freeing up parts of the spectrum for other uses.
Digital television is transmitted as a series of ones and zeros that a computer in your TV can process and output as a picture. Since the data is in binary format, it is able to take advantage of compression technology that reduces the amount of information that has to be transmitted. Compression encoders like MPEG-2 will look at the picture transmission frame by frame and only transmit the parts that change allowing a much higher quality picture to be transmitted with far less bandwidth use.
As of June 13, 2009, all full-power television stations in the United States were required to turn off their analog signals and broadcast in digital only. The United States Department of Commerce offered each U.S. household two $40 coupons that could be used to purchase converter boxes that would allow analog televisions to be able to view the digital broadcasts. The coupon program ended on July 31, 2009.
Television signals get weaker the farther from the transmitter that you get. On an analog television, this weak signal will show up as static or as ghost images from another channel. Since digital television comes through as a series of zeros and ones, these ghost images and static no longer exist. A digital image will remain nearly perfect the farther from the transmitter you get, until the signal becomes too weak for anything to show up on the television.
Digital television is received on the same antenna that analog signals were. The only antennae that will not work correctly are those that are not able to receive signals in the ultra-high-frequency range, which is channels 14 and above. In this case, the antenna would either need to be replaced or have a UHF section added to it.
Digital and Analog Televisions
As of March 1, 2007, all televisions shipped or imported in the United States were required to have a digital tuner. As of May 25, 2007, retailers were required to notify customers of the impending digital TV conversion if they were purchasing an analog television. Anyone who is unsure about a television purchased before May 25, 2007, should consult their television manual or contact their television manufacturer to find out if that television contains a digital receiver.
- photo_camera tv tower image by Alexey Chesnokov from Fotolia.com