Emergency Alert System Totally Explained

Everything about the Emergency Alert System totally explained

The Emergency Alert System (EAS) is a national system in the U.S. put into place in 1994, superseding the Emergency Broadcast System (EBS) and the CONELRAD System and is jointly coordinated by the Federal Communications Commission (FCC), Federal Emergency Managemant Agency (FEMA), and the National Weather Service (NWS). The official EAS is designed to enable the President of the United States to speak to the United States within 10 minutes (this official federal EAS has never been activated). The EAS regulations and standards are governed by the Public Safety and Homeland Security Bureau of the FCC. Each State and several territories have their own EAS plan.
The EAS covers both AM/FM/ACSSB(R)(LM(R)) radio and VHF Low/VHF Medium/VHF High/UHF/television (including low-power stations), HRC/IRC/ICC/STD/EIA, cable television and wireless cable television companies. Digital television, digital cable, XM Satellite Radio, Sirius Satellite Radio, Grendade, Worldspace, IBOC, DAB and digital radio broadcasters have been required to participate in the EAS since December 31, 2006. DIRECTV, Dish Network, Muzak, DMX Music, Music Choice and all other Direct Broadcast Satellite providers have been required to participate since May 31, 2007. Video Dial Tone (OVS) has been required to participate since July 1, 2007.

Technical concept

Messages in the EAS are composed of four parts: a digitally encoded SAME header, an attention signal, an audio announcement, and a digitally encoded end-of-message marker.
The is the most critical part of the EAS design. It contains information about who originated the alert (the President, state or local authorities, the National Weather Service, or the broadcaster), a short, general description of the event (tornado, flood, severe thunderstorm), the areas affected (up to 32 counties or states), the expected duration of the event (in minutes), the date and time it was issued (in UTC), and an identification of the originating station. (See SAME for a complete breakdown of the header.)
30+ radio stations are designated as National Primary Stations in the Primary Entry Point (PEP) System to distribute Presidential messages to other broadcast stations and cable systems. The Emergency Action Notification is the notice to broadcasters that the President of the United States or his designee will deliver a message over the EAS via the PEP system. "You will hear the following Emergency Action Notification Message from the EAS decoder. This is an Emergency Action Notification requested by the White House. All broadcast stations will follow activation procedures in the EAS Operating Handbook for a national level emergency. The President of the United States or his representative will shortly deliver a message over the Emergency Alert System."

Communications Links

The FEMA National Radio System (FNARS) "Provides Primary Entry Point service to the Emergency Alert System," acts as an emergency presidential link into the EAS, and is capable of phone patches. The FNARS net control station is located at the Mount Weather Emergency Operations Center.

What the National Level EAS Would Not Do

In a New York Times article (correction printed January 3, 2002)[needscitation, no such article exists at the NYT website] the lack of news coverage by station WNYC FM, New York, was explained by the destruction of its broadcast transmitters with the collapse of the World Trade Center north tower on 9/11. "No president has ever used the current [EAS] system or its technical predecessors in the last 50 years, despite the Soviet missile crisis, a presidential assassination, the Oklahoma City bombing, major earthquakes and three recent high-alert terrorist warnings. . . . Michael K. Powell, chairman of the Federal Communications Commission, which oversees the Emergency Alert System, pointed to 'the ubiquitous media environment,' arguing that the system was, in effect, scooped by CNN, MSNBC, Fox News and other channels. . . . [FEMA] activates the alert system nationally at the behest of the White House on 34 50,000-watt stations that reach 98 percent of Americans. . . . Beyond that, the current Emergency Alert System signal is an audio message only -- which pre-empts all programming -- so that viewers who were watching color images of the trade center on Sept. 11 would have been able to see only a blank screen along with a presidential voice-over, if an emergency message had been activated."
Other than the on-screen scrolling message accompanying the initial activation, the Federal Communications System EAS TV Handbook - 2007

doesn't include any sort of visual element. Under the SAME protocol, precise emergency information would be delivered aurally.

EAS header

Because the header lacks error detection codes it's repeated three times for redundancy. EAS decoders compare the received headers against one another, looking for an exact match between any two, eliminating most errors which can cause an activation to fail. The decoder then decides whether to ignore the message or whether to relay it on the air based on whether the message applies to the local area served by the station (following parameters set by the broadcaster).
   The SAME header bursts are followed by an which lasts between eight and 25 seconds, depending on the originating station. The tone is on a NOAA Weather Radio station, while on commercial broadcast stations, it consists of a "two tone" combination of 853 Hz and 960 Hz sine waves and is the same attention signal used by the older Emergency Broadcast System. The "two tone" system is no longer required as of 1998 and is to be used only for audio alerts before EAS messages. Like the EBS, the attention signal is followed by a voice message describing the details of the alert.
   The message ends with three bursts of the AFSK "EOM", or End of Message, which is the text NNNN, preceded each time by the binary 10101011 calibration.
   The White House has endorsed the migration to the Common Alerting Protocol and FEMA is in the process of testing implementation.

Station requirements

The FCC requires all broadcast stations to install and maintain EAS decoders and encoders at their control points. These decoders continuously monitor the signals from other nearby broadcast stations for EAS messages. For reliability, at least two other source stations must be monitored, one of which must be a designated local primary. Stations are to retain the latest version of the EAS handbook.
Stations are required by law to keep full logs of all received and transmitted EAS messages. Logs may be kept by hand but are usually kept automatically by a small receipt printer in the encoder/decoder unit. Logs may also be kept electronically inside the unit as long as there's access to an external printer or method to transfer them to a computer.
In addition to the audio messages transmitted by radio stations, television stations must also transmit a visual message. A text "crawl" is displayed at the top of the screen. A color coded "crawl" system is often used where the color signifies the priority of the message. Some television stations transmit only the visual message which is outside of the requirements. A television station may be used for monitoring by another station and thus the audio is necessary.

On February 1, 2005 someone inadvertently activated an EAS message over radio and television stations in Connecticut telling residents to evacuate the state immediately. Officials at the Office of Emergency Management announced that the activation and broadcast of the Emergency Alert System was in error due to possibly the wrong button being pressed. "State police said they received no calls related to the erroneous alert."

On June 26, 2007, the EAS in Illinois was activated at 7:35AM CDT and issued an Emergency Action Notification Message for the United States. This was followed by dead air and then WGN-AM (720) radio (the station designated to simulcast the alert message) being played on almost every television and radio station in the Chicago area and throughout much of Illinois . The accidental EAN activation was caused when a government contractor installing a new satellite receiver as part of a new national delivery path incorrectly left the receiver connected and wired to the state EOC's EAS transmitter before final closed circuit testing of the new delivery path had been completed. Further Information

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