Emergency Alert System (EAS)

From Signal Identification Wiki
Jump to: navigation, search
Emergency Alert System (EAS)
EAS NFM.jpg
Frequencies 162.400MHz162,400,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
162,400 kHzKiloHertz (kHz) 10^3 Hz
,162.550MHz162,550,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
162,550 kHzKiloHertz (kHz) 10^3 Hz
162,400 kHzKiloHertz (kHz) 10^3 Hz
162.4 MHzMegaHertz (MHz) 10^6 Hz
162,550 kHzKiloHertz (kHz) 10^3 Hz
162.55 MHzMegaHertz (MHz) 10^6 Hz
Frequency Range 162.4 MHzMegaHertz (MHz) 10^6 Hz162,400,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
162,400 kHzKiloHertz (kHz) 10^3 Hz
- 162.55 MHzMegaHertz (MHz) 10^6 Hz162,550,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
162,550 kHzKiloHertz (kHz) 10^3 Hz
Mode NFMNarrowband Frequency Modulation
Modulation FSKFrequency-Shift Keying
ACFAutoCorrelation Function
Bandwidth 5 kHzKiloHertz (kHz) 10^3 Hz5,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
0.005 MHzMegaHertz (MHz) 10^6 Hz
,30 kHzKiloHertz (kHz) 10^3 Hz30,000 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz).
0.03 MHzMegaHertz (MHz) 10^6 Hz
kHzKiloHertz (kHz) 10^3 Hz
0.005 MHzMegaHertz (MHz) 10^6 Hz
30 kHzKiloHertz (kHz) 10^3 Hz
0.03 MHzMegaHertz (MHz) 10^6 Hz
Location United States
Short Description The Emergency Alert System (EAS) is a national warning system in the United States, implemented since 1997, superceding the Emergency Broadcast System (EBS).
I/Q Raw Recording
Audio Sample
The Emergency Alert System (EAS) is a national warning system in the United States, implemented since 1997, superceding the Emergency Broadcast System (EBS). The official EAS is designed to enable the President of the United States to speak to the public within 10 minutes. In addition to this requirement, EAS is also designed to alert the public of local weather emergencies such as tornadoes and flash floods.

EAS is jointly coordinated by the Federal Emergency Management Agency (FEMA), the Federal Communications Commission (FCC) and the National Weather Service (NOAA/NWS).


Message Format[edit]

Messages in the EAS are composed of four parts: Specific Area Message Encoding (SAME) header, an attention signal (1050 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). for NOAA Weather Radio, 853 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). and 960 HzHertz (Hz), unit of frequency, defined as one cycle per second (1 Hz). together for commercial broadcast stations), an audio announcement, and a SAME end-of-message marker. For NOAA Weather Alerts, SAME uses NWR-SAME Codes to relay specific alerts, such as tornado warnings, and hurricane advisories.

SAME is an AFSKAudio Frequency-Shift Keying (Audio Frequency Shift-Keying) protocol used in North America to send digitally encoded information about alerts, advisories, and warnings. Canada and Mexico both utilize SAME in some fashion for weather and disaster alerts The SAME FSKFrequency-Shift Keying signal itself is 1200Hz wide with a 260Hz shift. Each individual bit lasting 1920 μs (1.92 msmilliseconds (.001 of a second)) each, giving a bit rate of 520.8333 bits per second

Samples[edit]

Samples Displayed in USBUpper Side Band Modulation (Radio, referring to reception and modulation mode)Universal Serial Bus (Computer, referring to USB Ports and cables) format for clarity.

NWR-SAME Full NWR Alert
EAS.jpg
EAS Weather.jpg
The SAME message raw format:

ZCZC-WXR-TOR-017021-017115+0045-1000042-KILX/NWS-

The SAME message codes decoded:

The National Weather Service in Lincoln, Illinois has issued a Tornado Warning valid until 09:27 PM for the following counties in Illinois: Christian, Macon. (KILX/NWS)

Additional Samples[edit]

Frequencies[edit]

NOAA Weather Radio:

  • 162.400
  • 162.425
  • 162.450
  • 162.475
  • 162.500
  • 162.525
  • 162.550

Decoding Software[edit]

Hobby Level Software

Video Examples[edit]

Additional Links[edit]

Additional Images[edit]