An Overview

A set-top box is a device that enables the television set to become a user interface to the Internet and also enables a television set to receive and decode digital television (DTV) broadcasts. In the current market space Set Top Box has become an integral part of TV viewing in many parts of the world.

​A set-top box (STB) or set-top unit (STU) (one type 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 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.

​​You can buy a standalone box, which are typically better-designed for this particular feature; everything from the remote to the interface is geared entirely around set-top and streaming features, and they’re usually a little simpler to figure out.

Operator are using of Set Top Box in cable television, satellite television, and over-the-air television systems. Price of the STB depend on feature and quality. A quality box has more life than a low price box. So it is very important to understand the math before buying STB.  A low end box may last 2-3 years where a middle and high end box has more life.


Type of Set-top Box (STB):

​High levels of technological innovations have led to the development of a wide range of STBs equipped with various features. Digital video recording is one of the most popular features as it enables viewers to watch and record their favorite shows.

01. Over-the-air DVR systems are a standalone set-top box that enables the viewers to broadcast and record TV programs. Apart from DVRs, subscription-based TV services providers offer STBs to customers. Moreover,  provider has introduced AI in their latest set-top boxes.

02. Moreover, government regulations mandating the digitization of cable networks in economies such as India and China have boosted the demand for STBs in these counties.

03. The latest trend witnessing momentum in the market is the availability of TVs integrated with STBs. These TVs provide access to online video streaming platforms and social media. Additionally, they deliver better storage options with capacities up to 2TB.

​​​Segment by Type:

A. Satellite STBs
B. Hybrid STBs
C. Cable / Digital TV STBs

Segment by Application
a. OTT (Over the Top)
b. DTT (Direct Terrestrial Transmission)

SET TOP BOX Features:

FAQ’s about Set-top BOX

Set Top Box or STB has become an integral part of TV viewing in many parts of the world. We commonly see this sleek looking device sitting on side of TVs. Though this device looks slim and simple but it is one of the most complex embedded systems today. STBs are increasing their feature set day by day. Few of the common features in current generation STBs are time shift mode viewing, recording, Internet based viewing, video on demand, Full High definition video output etc.

STB is very complex embedded system; it consists of 30+ hardware blocks and similar number of software drivers. STB has lot of computing power distributed across main processor and various co-processors.a digital headend. Aslo digital headend reduced the bandwidth use with better pitcher quality.


A typical STB would look similar to one shown in following image. This is picture of standard definition (SD) satellite based STB being used at my home. Number of components used is fairly less compared to complexity of this system. This credit goes to the main STB decoder chip which integrates a lot of hardware components required into a single chip. STB blocks
1. Power Supply
2. Smart Card Slot
3. RAM
4. STB Decoder
5. Flash
6. DVB-CI Slot
7. Satellite Front End
8. RF Modulator

Set Top Box Hardware Blocks

STB Decoder: This is heart of the whole system. In current generation STBs most of the features required by STB system are integrated in STB decoder chips. This level of integration is called System On Chip (SoC). STB SoCs contain a large number of blocks ranging from de-multiplexer to decoders and peripherals like USB, SATA etc.

Front End: Front End part of STB is responsible for receiving the broadcasted signal, demodulating the signal and outputting digital data output for STB decoder chip. Depending upon broadcasting environment terrestrial or satellite or cable front end will be used. Front end unit consist of 3 main blocks tuner to tune correct frequency, demodulator to demodulate as per standard and forward error correction (FEC) unit for data recovery.

Power Supply: This is the main power source for board. This unit generates different voltage required by various components on board. Input to this unit can be main line AC (220/110) or DC 12V via standalone power adapters.

Flash: This is used to store boot loader, main application and other user specific non volatile data. Different STBs uses different sizes of flash ranging from 8MB to 64MB.

RAM: RAM is used to store all intermediate data (such as decoded video/audio buffers) and application variables. In many cases main application is also copied to RAM and is executed from RAM to speed up the operation (as RAM is faster compared to Flash). RAM size ranges from 32MB in standard definition STBs to 256MB in some top end Full HD STBs.

Video Interfaces: STB decoder chip outputs video data in analog or digital format. To make these signals compatible with external devices, special circuitry like filter and physical connector are required. Current generation STBs provide many video output formats such as CVBS, S Video, Component video and HDMI.
Audio Interfaces: STB decoder chip outputs audio data in analog as well as digital format. In some cases high quality DACs are used to convert digital data into analog format. Digital data is also transmitted in digital format using SPDIF standard.

Storage: Few STBs also work as digital video recorders. To aid storage of programs some storage device (HDD) is added via any of the interfaces (SATA, eSATA, ATAPI or USB) provided by decoder chip.

Front Panel: This is STBs interface to external world. Front panels are different for different boxes. But most of them provide IR input/output, Status LEDs, 7 segments or LCD and few switches to configure set top box. These features are controlled by parallel IOs of main decoder chip. In some cases a dedicated microcontroller is added to front end to reduce processing load for main chip and also to reduce the number of wires going from front panel to main PCB.

DVB-CI Slot: This slot is provided to support various conditional access schemes. Conditional Access providers provide compatible DVB-CI cards to be used with STB. The DVB-CI card decrypts the channels encrypted by Conditional Access provider as per user’s subscription policies.

Smart Card Slot: This slot is provided to use smart card for Conditional Access implementation. Unique subscriber ID is stored on each card. Smart card is also used in decrypting the channels.

RF Modulator: This is used to modulate Audio and video into RF signal. This is mainly to be used with older TVs which have only RF input and no composite (CVBS) input.

Set Top Box Decoder blocks

Main CPU: This is the main CPU executing the STB application. It is a general purpose CPU with lot of development tools available. Its speed range from 200MHz on standard definition devices to near 1GHz on High Definition devices. The main CPU is generally based on industry standard core such Super H or ARM to improve ease of tools and reusable stack availability.

Demux: Demux is a dedicated co-processor to de-multiplex the digital transport stream into audio, video and other data. Demux checks the input stream for errors and protocol compliance and filters the required data into desired buffers (Audio, video)

Video Decoder: This co-processor is responsible for converting compressed video (MPEG) data into basic video format. Current generation decoders have programmable video decoders, so video decoders can support a variety of formats such as MPEG2, H264, VC1 etc.

Graphics Engine: This co-processor is dedicated to graphics acceleration. Its main task is to draw pictures and menus for user interface (UI). This unit is becoming more powerful these days with introduction of 3D menus.

Mixer: This block is responsible for mixing the video output and graphics output and producing a final single image. This is also responsible for ordering of video and graphics plane and transparency settings. As shown is image there are two planes one video in background on video plane and other is rectangular window showing program information on graphics plane. These two planes are mixed by mixer to generate a single image.

Video Output: Final result after mixing video decoder and graphics accelerator outputs is provided to video output block. This block is responsible for outputting data as per required standards (PAL, NTSC, SECAM, HDMI). This block generates output in analog format using DACs. This block also generates output in digital format using HDMI convertors.

Audio Decoder: Audio decoder converts the compressed audio data into basic audio data. Audio decoders are also programmable these days. They can be programmed to support any audio standard. Audio decoder generally supports MPEG, AAC, Dolby formats.

Audio Output: Audio output is fed to audio output block. This block provides audio output in analog format using internal DACs and in digital format using SPDIF convertor.

Peripherals: Other than main decoders and CPU a lot of peripheral devices are supported by STB SoCs for providing various features.
USB: For record/playback on external storage
SATA: used to connect HDD for providing digital video recording facility.
Ethernet: Input source for IP based STBs
UART: Debug port. Sometimes also used for software upgrade in field
I2C: Used by main STB SoC to communicate with external peripheral devices such as front end, SCART controller, HDMI controller etc.
SPI : Used for connecting to non-volatile storage on serial flash devices.


STB Software is organized as layered architecture as shown in block diagram below. RTOS is generally STB company proprietary or some industry standard OS such as Linux. Software drivers are written for all hardware blocks and some software components. A typical STB has 30-40 different drivers. Middleware is generally used to standardize the interfaces from drivers to application so that device independence can be provided. Final application is on top of middleware and it usually remains same for one service provider across different STBs.

Set-top box – A device that enables a TV set to receive and decode digital television (DTV) broadcasts. A set-top box is necessary for viewers who want to use their analog television sets to receive digital broadcasts.

Few of the common features in current generation STBs are time shift mode viewing, recording, Internet based viewing, video on demand, Full High definition video output etc.

he label “STB” means “set top box” (e.g., your cable or satellite box) , and is so labelled mostly for your convenience; this should be a standard HDMI input, and may be identified by default as the “STBinput in your source selection menu.satellite dishes that receive the signals from the satellite and redistribute them to the house hold.

What are the advantages of using STB?
  • The quantity of channels extends to a great amount.
  • View all channels and packages. …
  • A large enhancement in picture quality when utilizing the set-top box.
  • All kinds of troubles in watching channels will be reduced.
  • IPTV providers will be able to offer HD quality which is one of the most important uses of the set-top box.
  • The big switch on the small screen with the use of a set top box. It will bring on the digital revolution.
  • Add Basic Plus or HD Essentials, sports packages and premium channels.
  • Have access to On Demand content including movies, TV shows, events and more. …
  • Purchase pay-per-view events and specials.
  • Take advantage of parental controls and the on-screen program guide.
Choosing STB, We need to Consider the following:

Considering the above, operators should take quality set top box (standard set top box (SD/MPEG 4), HD set top box, HD Recorder etc ) of a same brand, so while looking out for a set top box you need to look at the different features that you are interested in to make a correct choice of a digital set top box that suits your need. You should consider Timer, Live TV recording,   Universal Remote Controls, Parental Locks feature. We should consider the following when we buy STB:

    • EASY TO USE: STB should be user friendly. Universal Remote control for TV & STB.
    • FEATURE: Standard feature – along with recording, Timer, Parental lock etc.
    • QUALITY: We should go for standard & high quality STB which is long lasting.
    • WARRANTY / GUARANTY: One year replacement & 2 years warranty


Based on the above, In southeast Asia, we may consider three type of STB:
  • 01. High-end STB including IOT feature- for high income people

    02. Middle range quality STB – for Middle income people

  • 03. Low cost STB – for people under poverty level

    Operator should use 2/3 CAS and 4/5 types of STB in their network to serve all spectrum mention above.

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