SPECIAL REPORT: ‘Re-Imagining’ Emergency Alerting with ATSC 3.0

In its just-released final report entitled “Comprehensive Re-imagining of Emergency Alerting,” the Communications Security, Reliability and Interoperability Council’s Working Group 2 highlights the advanced emergency alerting capabilities of Next Gen TV powered by ATSC 3.0. 

CSRIC’s mission is to provide recommendations to the Federal Communications Commission to ensure, among other things, optimal security and reliability of communications systems, including telecommunications, media, and public safety. Working Group 2 is charged with exploring all aspects of next-generation alerting and developing recommendations regarding actions the FCC should take to promote deployment of next generation alerting systems. Excerpts from the 68-page report follow.


The CSRIC VI Working Group 2 Report on a Comprehensive Re-imagining of Emergency Alerting examines the various current and future methods for disseminating emergency alert information to the public.  The subject encompasses a wide range of emergency information sources, many techniques of disseminating alerts through networks, a growing number of presentation methods, and a disparate user population with different language needs and abilities to perceive audio and visual media.  The committee explores the common threads and makes recommendations on moving forward…

The committee makes recommendations in the areas of improved geotargeting, multimedia, increased resiliency, redundancy, and accessibility.  It also recommends extending outreach to encourage better integration of emergency warning systems to consumer electronics for personal, home and in-vehicle use.

Advanced Television Systems Committee (ATSC 3.0)

The ATSC 3.0 (aka “Next Gen TV”) standard holds the potential to not only vastly improve the broadcast television viewing experience and expand programming opportunities, but also enhance emergency communications capabilities and create new operational capabilities for broadcast stations. Advanced Emergency Alerting (AEA) is one such capability that could be of relevance to broadcasters, their audiences, and emergency managers.

Enhanced emergency information distribution is one of the major enhanced capabilities and potential benefits of Next-Gen TV. ATSC 3.0 can support emergency information distribution in three distinct potential services:

  • EAS support, through onscreen and aural transmission of emergency alerts,
  • Advanced emergency information services, via ATSC 3.0 AEA, and
  • CAP relay, through ATSC 3.0’s native IP transport capability.

Transmission of conventional EAS messages can be supported under ATSC 3.0. Advanced emergency information services in ATSC 3.0 AEA also can support a broader range of information than the current EAS in place, beyond “emergency alerting – providing a powerful tool to provide targeted emergency information of any type to TV audiences.    This is an informational service capable of conveying a broad range of urgent information bulletins and updates to targeted audiences.

Support of IP-based CAP relay may provide a very robust and secure manner of transporting Federal, state and local CAP alerts from station to station.

ATSC 3.0 Support for EAS
For conventional EAS, the EAS audio would likely remain as an embedded textual display in the video, and part of the main audio Track as defined in the ATSC A/342 standard.   A/342 also provides for alternative audio Tracks (e.g., assistive audio services, other language dialog, special commentary, music and effects) with the main audio Track or other audio Tracks.  In this sense, visual and aural display of EAS by ATSC 3.0 stations would remain substantially similar to current methods of receiving, processing and displaying EAS.

ATSC 3.0 Support for “Emergency Information”

For non-EAS emergency information displayed by the broadcaster, ATSC A/331 specifies the signaling of audio (speech) that provides an aural representation of emergency information provided by broadcasters in on-screen text display.    Further, for “Accessible Emergency Information”, the ATSC 3.0 audio system supports the inclusion and signaling of audio (speech). 

ATSC 3.0 Support for “Advanced Emergency Alerting” Services
ATSC 3.0 AEA is one of numerous services supported in this IP-based broadcast system.  ATSC 3.0 AEA is an open, non-proprietary specification and incorporated in the ATSC A/331 standard, with support for other ATSC 3.0 standards.   The ATSC 3.0 AEA service includes an XML-based messaging format intended for flexible communications of any manner of urgent information to the consumer receiver.  In the most extreme circumstances, this service can also activate the bootstrap “wake-up” capability for enabled ATSC 3.0 receivers.  

ATSC 3.0 AEA supports a broad range of urgent and emergency information.  ATSC 3.0 AEA differs from the current emergency alert system in a number of key areas.  ATSC 3.0 AEA can provide the ability to target audiences with emergency information about a school lockdown, school district closures, traffic emergencies or other local disturbances— exactly the type of local urgent information that audiences can use, but is also the kind of information that is NOT part of an EAS message.

ATSC 3.0 AEA can also serve to repurpose a less-critical EAS message to an ATSC 3.0 AEA bulletin, which in turn may serve to motivate the transmission of greater amounts of urgent information, via this alternative channel.  An EAS event can be intrusive because it would interrupt audio programming and impose a crawl on screen.  An ATSC 3.0 AEA message can be less intrusive to the viewer, because it does not interrupt programming, and allows the viewer to choose what information they want to see. Furthermore, ATSC 3.0 AEA messages can support much narrower geotargeting of emergency information, supplemented with graphics, video, and a station’s live stream of coverage of an event.  

ATSC 3.0 AEA emergency information capability provides the potential for a range of capabilities offered by television broadcasters to fixed, mobile and portable consumer devices that support these features, including:

  • Audience targeting, ranging from the general public to non-public restricted messaging to specific groups (such as first responders or other organizations).
  • Flexible alert messaging capability, sufficient to handle virtually any form of emergency information, ranging from all hazards public alerting to narrowly targeted urgent messaging for a smaller defined audience, and even to specific messaging for first responder functions.
  • Location targeting that will allow compatible receivers to monitor alerts that can be addressed to specific geocodes, polygons or circles, essentially meaning that an alert can be targeted as widely as the entire broadcast area, or as narrowly as receivers in a very specific set of coordinates.
  • Multimedia capabilities, allowing ATSC 3.0-enabled receivers to receive and display graphics, photos, maps, video, and other assets as part of the emergency information.
  • Alert update and cancellation features;
  • Alert priority settings;
  • Wake-up signaling, to awaken compatible receivers when in standby or sleep mode, and
  • Multilingual support, providing the prospect for broadcast viewers to select their language of choice for receiving emergency information.

The alerting capability in Next-Gen TV is intended to provide enhanced next-gen emergency information capabilities for TV stations to reach the public.

The ATSC 3.0 Standards for AEA
ATSC 3.0 AEA is in fact drawn from features across the ATSC 3.0 suite of standards. Key components supporting ATSC 3.0 AEA are found within A/321 System Discovery and Signaling; A/324 Scheduler/Studio to Transmitter Link; A/331 Signaling, Delivery, Synchronization and Error Protection; A/336 Content Recovery in Redistribution Scenarios; A/338 Companion Devices; A/342 Audio; and A/344 Application Runtime Environment.  Two of the key standards for ATSC 3.0 AEA are:

  • A/321 (System Discovery and Signaling),which describes the ATSC 3.0 bootstrap, which is the initial discovery and entry point in the ATSC 3.0 waveform.  The bootstrap is the most robust part of the transmission signal, containing 3 symbols each with 8 bits.  In the bootstrap is a “wakeup” field which—if enabled—would rouse the ATSC 3.0 television receiver from standby or sleep mode if an urgent emergency message is accompanied by a “wakeup” request.  
  • A/331 (Signaling, Delivery, Synchronization and Error Protection), which defines the service signaling and IP delivery of a wide range of services and content, including electronic service guides, app-based services, linear audio-video services, and AEA.  A specialized emergency messaging approach was needed for ATSC 3.0, tailored for this broadcast environment but also flexible enough to tackle a broad range of messaging requirements, including international, multilingual and multimedia capabilities.

The ATSC 3.0 AEA message format that is included in the ATSC A/331 standard is an XML-based format for ATSC 3.0 urgent message transmission. These XML-based messages are contained within an Advanced Emergency Alert Table (AEAT), which is one instance of low-level service info defined in A/331. The AEAT can contain one or more AEA messages. 

The AEA capability in ATSC 3.0 will support a broad range of urgent information to the public — far beyond the scope and abilities of today’s EAS—for emergency information to the public, as well as restricted messages to closed groups (which could conceivably include first responders).  The AEA capability native to ATSC 3.0 supports a wide range of multimedia content, including cached or live media, multiple languages, and features useful for app developers on mobile, portable and fixed ATSC 3.0 receivers.  

For TV broadcasters, the next-generation ATSC 3.0 standard will allow station-driven emergency information to be integrated into a broad range of services, offering viewers the potential for tailored emergency information over a portfolio of products (TV, web, mobile, etc.).

Contrasting EAS & ATSC 3.0 AEA
Our presumption is that conventional EAS (via FSK based audio relay) and CAP will remain a key element in the national alert and warning strategy.  As such, ATSC 3.0 will support both EAS and ATSC 3.0 AEA capabilities. In the U.S., we presume that FCC regulations requiring stations to carry the Emergency Action Notification (EAN), National Periodic Test (NPT) and Required Monthly Test (RMT) alerts will require that TV stations continue to present an on-screen banner crawl for visual display of EAS messages, and that the EAS audio would likely remain part of the main audio track as defined in A/342.

However, ATSC 3.0 AEA may provide a means to encourage TV stations to provide more emergency alerts in a way that will be more attractive and usable for both the station and its audience.  Some EAS messages, for example, that TV stations typically would not air could be provided as a less intrusive AEA message.  A severe thunderstorm warning, for example, is something that is not typically aired by TV stations as EAS, but could be presented as an AEA message—and the user can decide whether or not they want to access the information.

EAS and AEA may evolve into a complementary relationship, where the conventional EAS alert could be accompanied by an AEA from the station, with more instructions, maps, graphics and information that the conventional EAS just cannot support.

ATSC 3.0 Support for CAP/EAS Relay
ATSC 3.0 transforms TV broadcasting to serve essentially as a wireless broadband data pipe.  Broadcast TV stations may desire to voluntarily provide a data service to forward IPAWS CAP messages as a means of supplementing conventional Internet-based dissemination of CAP alerts.

Today’s ATSC 1.0 signal transmission can broadcast both digital television signals and other non-television digital data.   As seen in a variety of projects fielded in the U.S. – including the FEMA IPAWS DEAS pilot (2004-2010) and the Ohio OEAS CAP datacast relay service (2017-present), this digital data can include CAP XML alerts, and multimedia files.  These ATSC 1.0 initiatives highlighted the role of a secure, robust, redundant transport path for CAP alerts that can be voluntarily provided by interested TV broadcasters.

ATSC 3.0 expands upon this capability for interested broadcast stations, by potentially allowing them to create prioritized data services sent via ROUTE (Real-time Object delivery over Unidirectional Transport).  A potential data service may be to relay CAP alerts and multimedia resources from TV station-to-TV station (essentially creating digital mesh), and TV station to other EAS Participant (extending the digital data broadcast network).

The Next Practical Steps
An ecosystem has already emerged to bring ATSC 3.0 AEA capabilities to reality. The ATSC Implementation Team provides a venue for industry discussions of issues related to implementation of AEA, including operational and technical requirements for the successful inclusion and implementation of emergency alerting as part of the rollout of ATSC 3.0.

Some broadcast manufacturers have moved forward in implementing and integrating ATSC 3.0 capabilities in their product sets for broadcast television stations.  Over-the-air testing of ATSC 3.0 transmission with emergency alerting has been conducted since 2016. This next-generation emergency information capability is a voluntary initiative of broadcasters and equipment manufacturers that is separate from (although potentially complementary) to EAS. As complementary functions, we expect that EAS will continue to provide its essential functions for national and local public alert and warning, while ATSC 3.0 next-generation alerting and capabilities will provide a value-added function from television broadcasters. 

Importantly, for the television broadcast community, the migration to ATSC 3.0 emergency alerting capabilities can leverage many of the assets that most TV broadcasters already have in place in their facilities. Because this portion of the television broadcast industry already has certain specific EAS equipment in place that can be upgraded for ATSC 3.0 support, the migration path for these stations may become even easier.


There are a number of emergency alerting and emerging technologies available to ensure timely delivery of critical information to the relevant individuals or a targeted geographical area. While these techniques provide diversity, it is important for them to work complementary and harmoniously with each other. At the same time, we are gaining a better understanding of how to improve public safety. The CSRIC VI Working Group 2 has made recommendations to streamline and modernize existing systems and to better address public safety.