47 CFR § 11.31 - EAS protocol.
(a) The EAS uses a four part message for an emergency activation of the EAS. The four parts are: Preamble and EAS Header Codes; audio Attention Signal; message; and, Preamble and EAS End Of Message (EOM) Codes.
(1) The Preamble and EAS Codes must use Audio Frequency Shift Keying at a rate of 520.83 bits per second to transmit the codes. Mark frequency is 2083.3 Hz and space frequency is 1562.5 Hz. Mark and space time must be 1.92 milliseconds. Characters are ASCII seven bit characters as defined in ANSI X3.4-1977 ending with an eighth null bit (either 0 or 1) to constitute a full eight-bit byte.
(2) The Attention Signal must be made up of the fundamental frequencies of 853 and 960 Hz. The two tones must be transmitted simultaneously. The Attention Signal must be transmitted after the EAS header codes.
(3) The message may be audio, video or text.
(b) The ASCII dash and plus symbols are required and may not be used for any other purpose. Unused characters must be ASCII space characters. FM or TV call signs must use a slash ASCII character number 47 (/) in lieu of a dash.
(c) The EAS protocol, including any codes, must not be amended, extended or abridged without FCC authorization. The EAS protocol and message format are specified in the following representation.
Examples are provided in FCC Public Notices.
(d) The only originator codes are:
|National Weather Service||WXR|
|Primary Entry Point System||PEP|
(e) The following Event (EEE) codes are presently authorized:
|Nature of activation||Event codes|
|National Codes (Required):|
|Emergency Action Notification (National only)||EAN.|
|National Information Center||NIC|
|National Periodic Test||NPT.|
|Required Monthly Test||RMT.|
|Required Weekly Test||RWT.|
|State and Local Codes (Optional):|
|Child Abduction Emergency||CAE.|
|Civil Danger Warning||CDW.|
|Civil Emergency Message||CEM.|
|Coastal Flood Warning||CFW.|
|Coastal Flood Watch||CFA.|
|Dust Storm Warning||DSW.|
|Extreme Wind Warning||EWW.|
|Flash Flood Warning||FFW.|
|Flash Flood Watch||FFA.|
|Flash Flood Statement||FFS.|
|Hazardous Materials Warning||HMW.|
|High Wind Warning||HWW.|
|High Wind Watch||HWA.|
|Law Enforcement Warning||LEW.|
|Local Area Emergency||LAE.|
|Network Message Notification||NMN.|
|911 Telephone Outage Emergency||TOE.|
|Nuclear Power Plant Warning||NUW.|
|Radiological Hazard Warning||RHW.|
|Severe Thunderstorm Warning||SVR.|
|Severe Thunderstorm Watch||SVA.|
|Severe Weather Statement||SVS.|
|Shelter in Place Warning||SPW|
|Special Marine Warning||SMW.|
|Special Weather Statement||SPS.|
|Storm Surge Watch||SSA.|
|Storm Surge Warning||SSW.|
|Tropical Storm Warning||TRW.|
|Tropical Storm Watch||TRA.|
|Winter Storm Warning||WSW.|
|Winter Storm Watch||WSA.|
|Offshore (Marine Areas) 1|
|Eastern North Pacific Ocean, and along U.S. West Coast from Canadian border to Mexican border||57|
|North Pacific Ocean near Alaska, and along Alaska coastline, including the Bering Sea and the Gulf of Alaska||58|
|Central Pacific Ocean, including Hawaiian waters||59|
|South Central Pacific Ocean, including American Samoa waters||61|
|Western Pacific Ocean, including Mariana Island waters||65|
|Western North Atlantic Ocean, and along U.S. East Coast, from Canadian border south to Currituck Beach Light, N.C||73|
|Western North Atlantic Ocean, and along U.S. East Coast, south of Currituck Beach Light, NC, following the coastline to Ocean Reef, FL, including the Caribbean||75|
|Gulf of Mexico, and along the U.S. Gulf Coast from the Mexican border to Ocean Reef, FL||77|
|Lake St. Clair||94|
|St. Lawrence River above St. Regis||98|
1 The numbers assigned to the offshore marine areas listed in this table are not described under the ANSI standard, but rather are numeric codes that were assigned by the National Weather Service.