What is Set-top box and How it works?

What is Set-top box and How it works?

Set-top Box - (STB) - May be known as set top, Set-tops, set-top box, set top box, STB, Receivers, Converters, Decoders, Intelligent Set-top Boxes, Set-top Decoders, Smart Encoder, Digital TV Converter, DTV Converter, Voice-enabled Set-top Boxes, Digital Decoder, DTV Tuner, Descrambler, Digital Set-top Box, Addressable Converter, Demodulator, Smart TV Set-top Box, ITV enabled Set-top Box, Internet-enabled Set-top Box, ITV enabled Set-top Cable Box, Satellite-enabled Set-top Box, Cable-enabled Set-top Box, Low-end Boxes, Thin Boxes, Thick Boxes, Smart TV Set-top Box, Super Box, All-in-one Set Top Box, Integrated Set Top Box, Hybrid Cable Box, Media Center. Associated with Digital Media Adapters, Digital Media Receivers, Windows Media Extender Set-top Boxes, Gaming Consoles, Multifunction Adapter.)

Its ancestor is often considered the Nintendo game box as those ancient 8-bit game boxes had data ports. (A data port is a physical interface on a device through which information travels.) A set-top box (STB) is a device that connects to an external signal source and decodes that signal into content that can be presented on a display unit such as a TV. 

Modern day set-top boxes generally are digital devices that communicate using computer language. In the past when the set-top box functions were built in to another device, such as a TV, it might have been referred to as a device with a“built-in”. Now-a-days the phrase “built-in” has been superceeded by the phrase "integrated". Now a TV with set-top box functionality built into it is more often called an "Integrated TV". If it's a digital TV, it would be known as an "Integrated Digital TV" (iDTV). Do note that just because a TV has set-top box functions built in to it, that doesn't mean it's a digital TV.  In that case it's just an analog TV with set-top box functions built into it. 

A set-top box is a computerized device that processes digital information. Set-top boxes (STB) come in many forms and can have a variety of functions. Digital Media Adapters, Digital Media Receivers, Windows Media Extender and most video game consoles are also examples of set-top boxes. Currently the type of TV set-top box most widely used is one which receives encoded/compressed digital signals from the signal source (perhaps your cable or telco TV provider's headend) and decodes/decompresses those signals, converting them into analog signals that your analog (SDTV) television can understand. The STB accepts commands from the user (often via the use of remote devices such as a remote control) and transmits these commands back to the network operator through some sort of return path. Most set-top boxes deployed today have return path capability for two-way communication.

STBs can make it possible to receive and display TV signals, connect to networks, play games via a game console, surf the  Internet, interact with Interactive Program Guides (IPGs), virtual channels, electronic storefronts, walled gardens, send e-mail, and videoconference. Many STBs are able to communicate in real time with devices such as camcorders, DVD and CD players, portable media devices and music keyboards. Some have huge hard-drives and smart card slots to put your smart card into for purchases and identification.

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Generally put, to provide interactive services, the set-top box might need some or all of the below:(1)  A network that offers the potential for interactivity.
(2) The network interface - This connects the STB to a network which makes it possible to communicate with the servers.
(3)  A tuner is electronics that 'catch' the incoming signal.(4) The decoder - In order to save storage space, disk bandwidth, and network bandwidth, programming is usually encoded (compressed) before being sent over the network to the STB. Thus, the end-user (subscriber) needs a decoder to decode (uncompress among other things) the incoming stream's data before it can be viewable on the TV. This is part of what a modem does. The decoding process may be known as (or include) Demodulation (Heavy Lifting.) It could include Demultiplexing. Also see Codec. H.264 (MPEG-4) compression technology utilizes up to 40 percent less network bandwidth than the MPEG-2 compression used in most systems to date.  
(5) The buffer - Due to delay jitters in the network, the exact arrival time of a video stream often cannot be determined. In order to guarantee continuous and consistent playback for the viewer, the video and/or data stream(s) may be received one or even a few seconds before it's actually seen by the end-user.  This way if there are fluctuations in the transport time of the streams to that receiver (aka set-top box, decoder), the viewer won't know the difference as their buffer has a bit of time to spare. 
(6) Synchronization software/hardware - Video and audio streams must be synchronized with each other before viewing. Other streams may be added including those related to enhancements (such as metadata.) 
(7) Middleware
(8) Platform
(9) Applications
(10) Any additional software and/or hardware.
(11) A return path (back channel).

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Set-top boxes may be associated with these major categories. (The below was originally written in 2002 and has some updates):  

(1) Broadcast TV Set-top Boxes - (a.k.a. Thin Boxes) - A more primitive set-top box with no back channel (return path.)  These might come with interface ports,some memory and some processing power.  

(2) Enhanced TV Set-top Boxes - (May be known as: Smart TV Set-top Box, Thick Boxes) - These have a back channel (return path), often through a phone line. These may be capable of Video on Demand, e-commerce, Internet browsing, e-mail communications, chat and more.

(3) Advanced Set-top Boxes - (a.k.a. Advanced digital Set-top boxes, Smart TV Set-top Box, Thick Boxes, All-in-one Set Top Box, Media Center) - A fully integrated set-top box.  These have good processors, memory, middleware, software applications and optional hard-drives.  They're often used with high-speed (broadband) connections. Features could include high-speed Internet access,Interactive TV, digital video recording & gaming. Instead of this, a "sidecar" (below) might be used in tandem with the set top box and/or TV. Advanced set-top boxes are more likely to be integrated with DVRs and high-definition TV. See Media Centers.

(4) Sidecar -  (Please note this 2007 update; as advanced set-top boxes now typically are integrated units, the sidecar is not often used.) - This type of set-top box provides an additional transport stream of data from the network operator to compliment the main stream.  With Charter Communications’, the BMC-8000 (Broadband Media Center) is/was a sidecar box that works in tandem with the Motorola DCT-2000. A fully integrated unit would not require a Sidecar. 

(5) Hybrid Digital Cable Box – A Hybrid Digital Cable Box is a specialized cable TV set-top box with high end functions. Motorola Broadband’s DCP501 home theater system is/was an example (depending on when you read this.) It has/had a DVD player and high-end stereo output. This term may be antiquated. See Home Media Centers.

(6) Over-the-top Boxes - Electronic device manufacturers are providing DVD players, video game consoles and TVs with built-in wireless connectivity. These devices piggy back on an existing wireless network and pull content from the Internet and deliver it to the TV set. Typically these devices need no additional wires, hardware or advanced knowledge in how to operate. Content suited for TV can be delivered via the Internet. These OTT applications include Facebook and YouTube. Also see Internet-connected TV.

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In the States, CableCARD can offer an alternative for cable TV users. The physical CableCARD is a PCMCIA type II PC card approximately the size of a thick credit card. These allows cable consumers in the States to view and record digital cable television channels on DVRs, PCs and TVs without the use of decoding equipment such as a set top box. CableCARDs unlock the channels and services that the cable customer has subscribed to. Some CableCARD technologies can even be used with devices that have no physical CableCARD slots.In the States, Motorola and Cisco's Scientific Atlanta supply most of the boxes cable operators provide to subscribers. 

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