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Set-top box


A set-top box (STB), also colloquially known as a cable box is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of signal, turning the source signal into content in a form that can then be displayed on the television screen or other display device. They are used in cable television, satellite television, and over-the-air television systems, as well as other uses.

The signal source might be an Ethernet cable, a satellite dish, a coaxial cable (see cable television), a telephone line (including DSL connections), broadband over power lines (BPL), or even an ordinary VHF or UHF antenna. Content, in this context, could mean any or all of video, audio, Internet web pages, interactive video games, or other possibilities. Satellite and microwave-based services also require specific external receiver hardware, so the use of set-top boxes of various formats has never completely disappeared. Set-top boxes can also enhance source signal quality.

These frequencies corresponded to non-television services (such as two-way radio) over-the-air and were therefore not on standard TV receivers. Before cable-ready TV sets became common in the late 1980s, an electronic tuning device called a cable converter box was needed to receive the additional analog cable TV channels and transpose or convert the selected channel to analog radio frequency (RF) for viewing on a regular TV set on a single channel, usually VHF channel 3 or 4. The box allowed an analog non-cable-ready television set to receive analog encrypted cable channels and was a prototype topology for later date digital encryption devices. Newer televisions were then converted to be analog cypher cable-ready, with the standard converter built-in for selling premium television (aka pay per view). Several years later and slowly marketed, the advent of digital cable continued and increased the need for various forms of these devices. Block conversion of the entire affected frequency band onto UHF, while less common, was used by some models to provide full VCR compatibility and the ability to drive multiple TV sets, albeit with a somewhat nonstandard channel numbering scheme.

Professional set-top boxes are referred to as IRDs or integrated receiver/decoders in the professional broadcast audio/video industry. They are designed for more robust field handling and rack mounting environments. IRDs are capable of outputting uncompressed serial digital interface signals, unlike consumer STBs which usually don't, mostly because of copyright reasons.

Electronic program guides and interactive program guides provide users of television, radio, and other media applications with continuously updated menus displaying broadcast programming or scheduling information for current and upcoming programming. Some guides, such as ITV, also feature backward scrolling to promote their catch-up content.

Some remote controls can also control some basic functions of various brands of TVs. This allows the user to use just one remote to turn the TV on and off, adjust volume, or switch between digital and analog TV channels or between terrestrial and internet channels.

This SCART feature had been used for connection to analogue decoding equipment by pay TV operators in Europe, and in the past was used for connection to teletext equipment before the decoders became built-in. The outgoing signal could be of the same nature as the incoming signal, or RGB component video, or even an "insert" over the original signal, due to the "fast switching" feature of SCART.

In June 2011 a report from the American National Resources Defense Council brought attention to the energy efficiency of set-top boxes, and the US Department of Energy announced plans to consider the adoption of energy efficiency standards for set-top boxes. In November 2011, the National Cable & Telecommunications Association announced a new energy efficiency initiative that commits the largest American cable operators to the purchase of set-top boxes that meet Energy Star standards and the development of sleep modes that will use less energy when the set-top box is not being used to watch or record video.