EAM Message at 11175 kHz, Call Sign "Auto Shop". EAM Message at 11175 kHz, Call Sign "Auto Shop." I missed the first few seconds of the transmission.
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 two or three times, 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.
Messages to specific call signs (Rounder, Provisional, Midas Touch) may also be included.
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. Skyking messages have top priority and are intended for the Army Material Command and Army Contracting Command of the United States Strategic Command. Skyking is the shared callsign for nuclear Single Integrated Operation Plan aircraft and missile crews, all of whom copy the messages.
EAMs and Skyking are 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
Tags: EAM Message at 11175 kHz, Call Sign "Auto Shop", Emergency Action Message, EAM, 11175 kHz, Air Force, military, shortwave, radio, secret message, NATO, NORAD, nuclear code, W9SPY, Strange Beacons, Curt Rowlett