Advanced Television Systems Committee (ATSC) 3.0

ATSC 3.0 is an new video transmission standard for terrestrial television broadcasting that is aimed at enhancing viewer experience.

HISTORY OF VIDEO TRANSMISSION STANDARDS

NTSC STANDARDS 

For the first 50+ years of terrestrial television broadcasting, the standards for video transmission in North and Central America, parts of South America, and a handful of African and Asian nations were governed by the National Television System Committee, or NTSC. 

The NTSC standard provided for 6MHz of bandwidth for each channel and was limited to 525 lines of interlaced video (480 active) at 30 frames per second. With the exception of the addition of stereo audio in the mid 1980’s, the NTSC standard remained largely unchanged in between 1953 and June 12, 2009, the day that broadcasters were forced to switch off their analog transmitters and begin digital-only transmission.    

INTRODUCTION OF ATSC STANDARDS (ATSC 1.0)

The initial iteration of the ATSC (Advanced Television Systems Committee) standard provided the groundwork for digital television transmission by:

  • Defining MPEG-2 as the compression method for transmission.
  • Specifyinga transport stream bitrate of 19.39Mbps.
  • Establishing 1920x1080 interlaced, 1280x720 progressive, and 640x480 interlaced as acceptable video resolutions.
  • Providing for audio coding using Dolby AC-3. 
  • Producing the criteria for the insertion of PSIP, a series of data tables necessary to identify the transmission source of a stream.
  • Providing receivers with virtual channel tuning information, guide data, system time, and other metadata.

After much debate, ATSC 1.0 also established 8-VSB as the modulation scheme for terrestrial broadcasting. This modulation scheme was selected primarily due to its lower transmission power requirements. However, 8-VSB proved to perform poorly in multi-path situations, making it a sub-par choice for densely developed cities and mobile applications.   

ATSC 3.0

CODEC EFFICIENCY

By the time full-power analog television transmission ceased in 2009, the MPEG-2 codec used for ATSC was already 14 years old. While the quality of available encoding hardware and algorithms has improved over the years, the MPEG-2 codec itself had not changed substantially since its inception. 

The more efficient MPEG-4 codec was already in use for contribution and was being rolled out for distribution on cable and satellite, once again putting terrestrial broadcast at a competitive disadvantage. With 4K video on the horizon, the desire for a more efficient codec drove the push toward a revised ATSC standard. This codec would facilitate the transmission of higher resolution video, additional audio tracks, and data services outside of real time video and include HEVC as its standard for video encoding. With the move to HEVC, broadcasters will have the ability to distribute 4K, 8K, and HDR content. The more efficient use of bandwidth will also allow broadcasters to include additional subchannels, metadata, and non-real-time data and will allow for incentivized spectrum sharing among multiple licensees within a given market. 

    ENHANCING VIEWER EXPERIENCE

    Beyond improved video encoding efficiency, ATSC 3.0 enables several additional enhancements to the viewer experience. With ATSC 3.0 being built on IP standards that mirror the 7-layer OSI data distribution model and including HTML5 protocols, it behaves much like a web page with the television running an embedded browser to display content rather than the it being a passive device used to decode and display a video and audio stream. The result is a user experience that is tailored to the individual viewer. 

    Some of the enhancements enabled by the ATSC 3.0 standard include: 

    • Non-real-time data and statistics delivered over the air.
    • Non-video program companion data such as instructional files and historical documents. 
    • Advanced loading of VOD content to a viewer’s devices. 
    • Advanced emergency alerting including hyperlocalization, evacuation route maps, and “wake up” function for powered-off receivers in emergency situations. 
    • Improved reception. 
    • Single-frequency networks enhance on-channel signal penetration into RF “dead zones” and eliminate the need for translators. 
    • Mobile device reception enabled. 
    • Improved signal penetration into densely developed areas previously susceptible to interference from high rise structures. 

    For broadcasters, the ATSC 3.0 specification enables new and enhanced revenue opportunities as well.   

    • The use of Physical Layer Pipes (PLP’s) allows broadcasters to balance the quality of their various services against the distances of their transmissions. 
    • An IP return channel from the receivers will enhance the accuracy of viewership data (ratings). 
    • Viewer demographics will be available to the programmer, enabling targeted advertising opportunities. 

    The redundant IP-based content origination infrastructure and managed service from Comcast Technology Solutions easily scales to facilitate terrestrial, satellite, and online distribution.