Editing Set-top box (section)

==TV signal sources==
[[File:Sat-Receiver Palcom DSL-350.jpg|200px|thumb|A consumer Palcom DSL-350 satellite-receiver; the [[Intermediate frequency|IF]] [[demodulation]] tuner is on the bottom left, and a [[Fujitsu]] [[Moving Picture Experts Group|MPEG]] decoder [[Central processing unit|CPU]] is in the center of the board. The [[power supply]] is on the right.]]
[[File:Sky Q Silver.jpg|thumb|A [[Sky Q]] digital satellite receiver set-top box]]The signal source might be an [[Ethernet]] cable, a [[satellite dish]], a [[coaxial cable]] (see [[cable television]]), a [[telephone]] line (including [[Digital subscriber line|DSL]] connections), [[broadband over power lines]] (BPL), or even an ordinary [[Very high frequency|VHF]] or [[Ultra high frequency|UHF]] [[antenna (radio)|antenna]]. Content, in this context, could mean any or all of [[video]], [[Sound|audio]], [[Internet]] [[web page]]s, [[interactivity|interactive]] [[video game]]s, 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.

===UHF converter===
Before the [[All-Channel Receiver Act]] of 1962 required US [[television set|television receiver]]s to be able to tune the entire [[very high frequency|VHF]] and [[ultra high frequency|UHF]] range (which in [[North America]] was [[NTSC#NTSC-M|NTSC-M]] channels [[Pan-American television frequencies|2 through 83]] on 54 to 890{{spaces}}[[hertz|MHz]]), a set-top box known as a UHF converter would be installed at the receiver to shift a portion of the UHF-TV spectrum onto low-VHF channels for viewing. As some 1960s-era 12-channel TV sets remained in use for many years, and [[Canada]] and [[Mexico]] were slower than the US to require UHF tuners to be factory-installed in new TVs, a market for these converters continued to exist for much of the 1970s.

===Cable converter===
{{main|Cable converter box}}
[[File:HK Cable TV Settop Box 2002.jpg|left|thumb|An older digital cable TV set-top box]]
[[Cable television]] represented a possible alternative to deployment of UHF converters as broadcasts could be frequency-shifted to VHF channels at the cable head-end instead of the final viewing location. However, most cable systems could not accommodate the full 54-to-890&nbsp;MHz VHF/UHF frequency range and the twelve channels of VHF space were quickly exhausted on most systems. Adding any additional channels therefore needed to be done by inserting the extra signals into cable systems on nonstandard frequencies, typically either below VHF [[Pan-American television frequencies|channel 7]] (midband) or directly above VHF channel 13 (superband).

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 television|analogue]] [[Cable television|cable]] [[television channel|TV channels]] and transpose or convert the selected channel to analogue [[radio frequency]] (RF) for viewing on a regular TV set on a single channel, usually [[very high frequency|VHF]] channel 3 or 4. The box allowed an analogue non–cable-ready [[television]] set to receive analogue encrypted cable channels and was a prototype topology for later date digital encryption devices. Newer televisions were then converted to be analogue cypher cable-ready, with the standard converter built-in for selling [[pay television|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. [[Low-noise block downconverter|Block conversion]] of the entire affected frequency band onto [[ultra high frequency|UHF]], while less common, was used by some models to provide full [[videocassette recorder|VCR]] compatibility and the ability to drive multiple TV sets, albeit with a somewhat nonstandard channel numbering scheme.

Newer television receivers greatly reduced the need for external set-top boxes, although [[cable converter box]]es continue to be used to [[scrambler|descramble]] premium cable channels according to carrier-controlled access restrictions, and to receive digital cable channels, along with using interactive services like [[video on demand]], pay per view, and [[home shopping]] through television.

===Closed captioning box===
Set-top boxes were also made to enable [[closed captioning]] on older sets in North America, before this became a mandated inclusion in new [[television set]]s. Some have also been produced to mute the [[Sound recording and reproduction|audio]] (or replace it with noise) when [[profanity]] is detected in the captioning, where the offensive word is also blocked. Some also include a [[V-chip]] that allows only programs of some [[television content rating system]]s. A function that limits children's time watching TV or playing [[video game]]s may also be built in, though some work on main electricity rather than the video signal.

===Digital television adapter===
{{main|Digital television adapter}}
The [[digital television transition|transition]] to [[digital terrestrial television]] after the turn of the millennium left many existing [[television set|television receiver]]s unable to tune and display the new signal directly. In the United States, where the [[Digital television transition in the United States|analogue shutdown]] was completed in 2009 for full-service broadcasters, a federal subsidy was offered for [[coupon-eligible converter box]]es with deliberately limited capability which would restore signals lost to digital transition.

===Professional set-top box===
{{main|Integrated receiver/decoder}}
Professional set-top boxes are referred to as IRDs or [[integrated receiver/decoder]]s in the professional broadcast audio/video industry. They are designed for more robust field handling and [[19-inch rack|rack mounting]] environments. IRDs are capable of outputting uncompressed [[serial digital interface]] signals, unlike consumer STBs which usually do not, mostly because of copyright reasons.

===Hybrid box===
[[File:Lenovo A30 Internet TV Set Top Box - Front with Remote (6639767915).jpg|thumbnail|Lenovo A30 set-top box]]
Hybrid set-top boxes, such as those used for [[Smart TV]] programming, enable viewers to access multiple TV delivery methods (including terrestrial, cable, internet, and satellite);<ref>[https://iptv-abonne.fr/smart-iptv-guide-complet-installation-et-activation/ SMART IPTV]</ref> like IPTV boxes, they include [[video on demand]], [[time shifting|time-shifting]] TV, Internet applications, [[videotelephony]], surveillance, gaming, shopping, TV-centric [[electronic program guide]]s, and e-government. By integrating varying delivery streams, hybrids (sometimes known as "TV-centric"<ref>{{cite web
 |url         = http://inview.tv
 |title       = Welcome to Inview
 |publisher   = [[Inview Technology]]
 |date        = 2013-07-26
 |ref         = Website
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20130801212130/http://inview.tv/
 |archive-date = 2013-08-01
}}</ref>) enable pay-TV operators more flexible application deployment, which decreases the cost of launching new services, increases speed to market, and limits disruption for consumers.<ref>{{cite web |url=http://www.v-net.tv/Webcast.aspx?id=5 |title=Webcasts |access-date=2010-06-02 |url-status=dead |archive-url=https://web.archive.org/web/20100405064453/http://www.v-net.tv/Webcast.aspx?id=5 |archive-date=2010-04-05 }}</ref>

As examples, [[Hybrid Broadcast Broadband TV]] (HbbTV) set-top boxes allow traditional TV broadcasts, whether from [[digital terrestrial television|terrestrial]] (DTT), satellite, or cable providers, to be brought together with video delivered over the Internet and personal multimedia content. [[Advanced Digital Broadcast]] (ADB) launched its first hybrid DTT/IPTV set-top box in 2005,<ref>{{cite web|url=http://www.dvb.org/about_dvb/dvb_worldwide/spain/index.xml|title=About – DVB|website=dvb.org|access-date=28 April 2018|url-status=live|archive-url=https://web.archive.org/web/20130606075928/http://www.dvb.org/about_dvb/dvb_worldwide/spain/index.xml|archive-date=6 June 2013}}</ref> which provided [[Telefónica]] with the digital TV platform for its [[Movistar TV]] service by the end of that year.<ref>{{cite web |date=September 11, 2006 |title=ADB Delivers World's First Hybrid, Single-Chip, Advanced Video Coding, High Definition IPTV Set-Top Boxes To Telefónica |url=http://www.digitaltvnews.net/items/060911adb_spain.htm |url-status=dead |archive-url=https://web.archive.org/web/20120227141252/http://www.digitaltvnews.net/items/060911adb_spain.htm |archive-date=2012-02-27 |access-date=2013-06-15 |website=digitaltvnews.net}}</ref> In 2009, ADB provided Europe's first [[three-way hybrid]] digital TV platform to Polish digital satellite operator [[n (Poland)|n]], which enables subscribers to view integrated content whether delivered via satellite, terrestrial, or internet.<ref>{{cite web|url=http://www.broadbandtvnews.com/2009/09/12/adb-takes-%E2%80%98n%E2%80%99-hybrid-ibc09/|title=ADB takes 'n' hybrid|date=12 September 2009|website=broadbandtvnews.com|access-date=28 April 2018|url-status=live|archive-url=https://web.archive.org/web/20170704130208/http://www.broadbandtvnews.com/2009/09/12/adb-takes-%e2%80%98n%e2%80%99-hybrid-ibc09/|archive-date=4 July 2017}}</ref>

UK-based [[Inview Technology]] has over 8{{spaces}}million STBs deployed in the UK for [[teletext]] and an original push [[video on demand|VOD]] service for Top Up TV.

===IPTV receiver===
[[File:Motorola IPTV.jpg|thumb|An older model IPTV receiver set-top box built by [[Motorola]]]]
In [[Internet Protocol television|IPTV]] networks, the set-top box is a small computer providing two-way communications on an [[Internet Protocol|IP]] [[computer network|network]] and decoding the video [[streaming media]]. IP set-top boxes have a built-in [[home network]] interface that can be [[Ethernet]], Wireless (802.11{{spaces}}g,n,ac), or one of the existing wire home networking technologies such as [[HomePNA]] or the [[ITU-T]] [[G.hn]] standard, which provides a way to create a high-speed (up to 1&nbsp;Gbit/s) [[local area network]] using existing home wiring ([[Power-line communication|power lines]], phone lines, and [[ethernet over coax|coaxial cables]]).<ref>[http://www.itu.int/ITU-T/newslog/New+Global+Standard+For+Fully+Networked+Home.aspx New global standard for fully networked home] {{webarchive|url=https://web.archive.org/web/20090221090736/http://www.itu.int/ITU-T/newslog/New+Global+Standard+For+Fully+Networked+Home.aspx |date=2009-02-21 }}, ITU-T Press Release</ref>

In the US and Europe, telephone companies use IPTV (often on [[ADSL]] or [[optical fiber|optical fibre]] networks) as a means to compete with traditional local [[cable television]] monopolies.

This type of service is distinct from [[streaming television]], which involves third-party content over the public Internet not controlled by the local system operator.