DESCRIPTION:
EAM through heavy static, recorded 7 May 2014 at 1600 UTC. I kept trying to dial in a clearer signal, but atmospheric conditions were very poor.

What you are hearing is known as an Emergency Action Message (EAM). These transmissions are part of the High Frequency Global Communications System (HF-GCS) run by the United States military as a way to communicate with aircraft in flight, and certain Navy vessels, including submarines.

According to Wikipedia, an EAM is "a preformatted message that directs nuclear-capable forces to execute specific Major Attack Options or Limited Attack Options in a nuclear war." More information about EAMs can be found here: http://en.wikipedia.org/wiki/Emergency_Action_Message

The format for an EAM is a six character preamble, repeated once, followed by "STAND BY, MESSAGE FOLLOWS." Next, a long string of numbers or letters is repeated using the military phonetic alphabet and spoken at the rate of one character per second.

Skyking messages are shorter and always include the preamble, "SKYKING SKYKING DO NOT ANSWER. MESSAGE FOLLOWS" which is then followed by a short string of characters, ending with an authentication code.

EAM and Skyking discussed here: http://www.monitoringtimes.com/html/eam.html

These transmissions are sometimes referred to among amateur radio listeners as "Air Force Numbers Stations." EAMs are phonetically encoded, encrypted messages that utilize the "one time pad," a method of encryption thought to be virtually unbreakable.

More information about the High Frequency Global Communications System can be found here: http://en.wikipedia.org/wiki/High_Frequency_Global_Communications_System

And here: http://www.ominous-valve.com/hfgcs.txt

And here: http://www.ab9il.net/aviation/naoc-tacamo.html