Monday, December 10, 2012

Set Top Box Overview


A set-top box is a device that enables a television set to become a user interface to the Internet and also enables a television set to receive and decode digital television (DTV)
broadcasts. DTV set-top boxes are sometimes called receivers. A set-top box is necessary to television viewers who wish to use their current analog television sets to receive digital broadcasts.
Before Digital TV was invented, TV’s decoded broadcast analogue channels, initial STB’s simply converted one type of analogue TV channel signal to one the TV could understand.
Initial STBs had very little security and the ownership of a STB and the feed (Cable ,Satellite or Terrestrial  meant a consumer could have access to the video content.
As multi-channel TV started to expand the move to Digital TV allowed some major changes:

  • Basic features of the STB are to Receive Demodulate, Demultiplexer, and decode the incoming Digital signal and convert it into the Analog format
  • Input digital stream to STB may be from satellite ,cable or terrestrial medium.
  • It can also de-scramble the received signal and thus provide conditional access to the STB.
  • Conditional access is the key feature for Pay TV system
  • If STB is used for satellite applications then input frequency range is 950 to 2150 MHZ and modulation technique used is QPSK
  • If STB is used for cable applications then input frequency range is 110 to 862 MHZ and modulation technique used is QAM
  • If STB is used for Terrestrial applications then input frequency range is  47 to 860 MHZ and modulation technique used is COFDM

STB’s were constantly evolving, as the battle between the satellite and cable broadcasters heated in any given region.
Many new features were add to the STB since then:

  • nVOD – Near Video on Demand, a broadcaster plays out a video many time starting every 15 mins
  • VOD (Video on Demand – the broadcaster just plays a video when a customer wants to watch it)
  • Internet Access on TV
  • PVR/DVR – secure video recording on internal hard disks
  • High Definition TV – more pixels better quality TV
  • 3D TV
  • Personalize-able ‘Apps’ similar to smart-phones 
etc. etc

The STB has now become a highly complex software based system requiring years of development effort for each new feature.
The consumer is quite happy for his mobile smart phone to crash every now and then, or his PC to slow down and need fixing,
but historically they expect their TV  to work all the time or they will call the broadcaster and complain.
However the next technology development is to the Connected TV, this moves into the arena of the PC, smart phone and games console.
Content will be obtainable from many sources and not just the traditional broadcaster Also the software running on these devices will be obtained from many developers.

Most of the content is known to all of us and used from some of the major provider and vendors in the industry
Stay tuned for more updates on the STB Middleware and other STB stuff.

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