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A set-top box is a hardware device that allows a digital signal to be received, decoded and displayed on a television. The signal can be a television signal or Internet data and is received via cable or telephone connection.
In the past, set top boxes were mostly used for cable and satellite television. The STB could deliver more channels than a television's own channel numbering system. It received signals containing data for multiple channels and filtered out the channel a user wanted to view. The numerous channels were generally transmitted to an auxiliary channel on the television. Other features included a decoder for pay-per-view and premium channels.
Today, most STB systems have two-way communication, allowing for interactive features like adding premium channels directly from the device or incorporating Internet access.
A set-top box is also known as set-top unit.
The evolution of set-top boxes can be traced back to early 1980s, when a cable converter box was required to receive extra analog cable TV channels and convert them to content capable of being displayed on a regular television screen. The cable converter boxes came with a wired or wireless remote control, which helped to switch a channel to a low-VHF frequency for viewing on the TV. Some newer television receivers significantly reduced the need for external set-top boxes but they are still in wide use. Cable converter boxes are sometimes required to descramble premium cable channels and receive interactive services such as pay per view, video on demand and home shopping channels.
Set-top boxes can be divided into several categories ranging from simple boxes that receive and descramble incoming AV signals, to complex units delivering a slew of services such as videoconferencing, home networking, IP telephony, video on demand and satellite broadband TV services.
The set-top boxes can be broadly classified into the following types: