[NLRS] Emergency Alert System

[Chris Elmquist]

On Wednesday (01/05/2005 at 01:44PM -0600), Jim Johnson wrote:
> Win a new Icom IC-756PROIII and help QSL/QTH.net
> Details at: http://mailman.qth.net/index.html
> 
> 
> Anyone know how the NOAA Emergency Alert System works? What kind of
> signal forces the reciever on to broadcast the message?

Sure...

They call it "SAME"  Specific Area Messaging and it is a roughly 500
baud AFSK modulation using off-the-wall tones, that carries short ASCII
messages according to a protocol containing the county FIPS code,
alert type, starting and expiration times, etc.

This pretty much tells the story:

http://www.nws.noaa.gov/nwr/nwrsame.htm

I have designed (but never got around to building) a modem for it-- that
along with a simple microcontroller, will source the messages on a serial
port that you can ingest with your PC.  I suppose I should finish that
project one day :-)

Then there is of course the older system which just uses a 1050 Hz tone
to open the receiver.  This does not allow you to selectively decode
alerts for your area though as the SAME system does.

SAME as I understand it, is a subset of the EAS protocol which is the stuff
you hear TV and broadcast radio sending out test alerts for all of the time.

Chris N0JCF

-- 
Chris Elmquist   mailto:chrise at pobox.com   http://www.pobox.com/~chrise