Analog and digital television signals are broadcast using a portion of the electromagnetic spectrum that includes radio waves, known as the radio spectrum. The essential difference between analog and digital broadcasting is that the former transmits pictures and sound as a fluctuating wave, while digital broadcasting converts them to a string of binary digits or bits, which can have a value of "0" or "1," prior to transmission.
Digital Switchover
Digital television is more flexible than analog television because it can be received via digital terrestrial, digital cable, digital satellite and broadband. Full-power television stations in the United States have been broadcasting in digital format exclusively since June 12, 2009. By law, all new television sets must have digital tuners capable of picking up this signal. From the average television viewer's point of view, the main benefit of switching to digital television is that analog television is no longer available; however, you can still use your old analog television set to receive digital television programming by connecting it to a digital-to-analog converter box.
Picture and Sound Quality
Digital television allows broadcasters to offer improved picture and sound quality, including multi-channel digital surround sound, with less interference than analog television. Digital television also provides a range of interactive video and data services that are simply not possible with analog broadcasting. These enhanced features can include services for viewers with sight or hearing impairments, such as audio descriptions and subtitles.
Radio Spectrum
One of the main reasons for switching to digital television broadcasting was to create more space in the radio spectrum. The nature of a digital broadcast is that it can be compressed by computer processing and then occupies a fraction of the space in the radio spectrum required for an analog broadcast. In fact, up to eight digital television channels and associated services can be carried in the space required for a single analog television channel. The space vacated by the termination of analog broadcasting will now be used for emergency communications by police and fire departments, and some of it has been auctioned to companies providing wireless broadband and related services.
Multicasting
Digital broadcasting uses the radio spectrum more efficiently than analog broadcasting. This means that digital broadcasters can utilize a process known as multicasting to broadcast multiple standard-definition (SD) and high-definition (HD) programs rather than a single analog program. This creates a wider choice of programs and services for viewers. Switching to digital television upgraded the transmission network to the best available technology and eliminated the cost of broadcasting the same content simultaneously on analog and digital television.
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