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Emergency Alert System Participants

This section contains information on the modernization of the Emergency Alert System (EAS), the most resilient form of emergency alert notification.

EAS is used by alerting authorities to send detailed warnings via broadcast, cable, satellite, and wireline radio and television channels. EAS participants (radio and TV providers nationwide) are the stewards of this important public service in close partnership with alerting officials at all levels of government.

Common Alerting Protocol

The IPAWS Open Platforms for Emergency Networks (IPAWS-OPEN) collects Common Alerting Protocol (CAP) alerts issued by authorized public officials and distributes them to EAS participants via an EAS CAP feed. The EAS CAP feed is available on the internet, and EAS participants require an internet connection to poll IPAWS-OPEN. In addition, EAS participants may poll state CAP servers or other CAP-based networks via the internet where appropriate.

FEMA announced the adoption of Common Alerting Protocol Version 1.2 on September 30, 2010. The CAP 1.2 standard is further customized by the Common Alerting Protocol Version 1.2, USA Integrated Public Alert and Warning System Profile Version 1.0, an Organization for the Advancement of Structured Information Standards (OASIS) Technical Committee Specification. The IPAWS Profile ensures that CAP data will be compatible with U.S. channels for alert distribution, including the EAS.

CAP-based networks do not replace, but rather strengthen, the resiliency of over-the-air methods of monitoring EAS tones. Likewise, CAP does not replace the existing EAS protocol, compatible with the National Weather Service’s Weather Radio Specific Area Message Encoding (SAME). EAS participants will use CAP-based equipment to translate CAP messages to the EAS protocol and message format. CAP-based equipment consists of stand-alone converters, firmware upgrades to existing encoders/decoders, or newer encoder/decoder models with CAP fully integrated.

CAP-based equipment converts CAP to EAS/SAME protocol using a set of recommendations developed by the EAS CAP Industry Group (ECIG). See the ECIG Recommendations for a CAP EAS Implementation Guide for specific details.

The following links correspond to the documents below; you must copy and paste the links onto the address bar instead of clicking on them

Common Alerting Protocol Version 1.2 –


Common Alerting Protocol, v1.2 USA Integrated Public Alert and Warning Systems Profile Version 1.0


ECIG Recommendations for CAP EAS Implementation Guide

Benefits of CAP

  • CAP alerts are transmitted in digital format; therefore, there is no degradation of quality of the content that may be experienced with analog methods such as radio.
  • CAP alerts can be directly available to encoder/decoder equipment within seconds of their creation; therefore, delays or disruptions relating to station-to-station, over-the-air relay are reduced.
  • The internet infrastructure has a high level of redundancy and reliability and may survive when other channels of communication do not.
  • In addition to EAS-required data, CAP alerts may carry rich information such as audio, video, geographical-location data, etc., that EAS participants may opt to provide supplemental information to their audiences.

EAS Participant Requirements

The Federal Communications Commission’s (FCC) Second Report and Order required EAS participants to “accept CAP-based alerts” within 180 days of CAP adoption by FEMA. A subsequent FCC waiver extended the deadline an additional 180 days, to September 30, 2011. The Fourth Report and Order further extended the deadline to June 30, 2012.

In January 2012, the FCC announced its Fifth Report and Order to clarify FCC rules relating to CAP implementation. Among the provisions is a new requirement for EAS participants’ EAS equipment to interface with IPAWS to enable the distribution of CAP-formatted alert messages from the IPAWS system. As EAS rules and the CAP standard evolve over time, IPAWS-OPEN is updated to accommodate new requirements.

Encoder/Decoder CAP Conformity

To support EAS participants in their selection of CAP-capable encoder/decoder equipment, the IPAWS Conformity Assessment Program tested voluntarily submitted equipment for conformance to CAP 1.2, the IPAWS CAP Profile, and the Emergency Alert System Common Alerting Protocol Industry Group.

FEMA published the Integrated Public Alert and Warning System (IPAWS) Guide for Independent Testing of Emergency Alert System Equipment to describe testing requirements for any Independent Testing Authority that wishes to provide testing services for the manufacturers of EAS decoder equipment for purposes of meeting FCC equipment certification requirements.

Monitoring IPAWS-OPEN

The IPAWS Program Management Office (PMO) released the information necessary to allow CAP compatible EAS equipment to poll the IPAWS-OPEN system. Once equipment manufacturers update and release their firmware for this new system, EAS participants will be able to enter the following URL,, into encoder/decoder devices. However, please note that CAP-compatible EAS equipment manufacturers must first provide firmware updates before message polling will work. EAS participants should check their equipment manufacturer’s web sites for information on when these software updates will be available.

Testing with IPAWS-OPEN

Beginning December 12, 2011, FEMA began generating, processing and serving one CAP message per week for each of the nine local U.S. time zones.  This CAP message consists of a Required Weekly Test (RWT) message directed to all states and is issued at 11:00 AM local time each Monday. (For purposes of these exercises, states divided into two time zones are assigned to the time zone that includes the largest area within the state.) These log-only RWT messages serve as non-disruptive internal test messages to provide EAS participants with the opportunity to verify configuration and message connections.

Additional References

IPAWS Architecture Diagram

EAS Sound Header

Last Updated: 
11/27/2019 - 10:44