Keep Awake.. Thanks Eli
“EAM: Though generally referring to a category of urgent messages from commanders to deployed forces, EAM is often used as a short-hand expression for a specially coded nuclear attack directive.”
“….Proper coding and formatting of EAMs is of crucial importance, since nuclear forces are prepared to execute any messages they receive that meet rigid specifications. In addition to specific instructions contained in an EAM, proper coding provides the means by which a commander expresses his authority to release nuclear weapons and an officer controlling those weapons verifies that authority.”
From a shortwave utility hobbyist’s standpoint what are they? Park your HF receiver (set to upper side band mode) on 15016.0 kHz, 13200.0 kHz, 11175.0 kHz (the most productive for day to day monitoring of the U.S. military on HF), 8992.0 kHz (ideal for monitoring during North American nights), 6739.0 kHz , 6712.0 kHz or 4724.0 kHz.
Eventually you’ll hear ground stations of the USAF’s HF-GCS (led by ANDREWS or OFFUTT or MCCLELLAN, identified in the clear since 1992) broadcast one or more Emergency Action Message, or EAM. You will hear a six-character alpha-numeric string (known as the “preamble”) read phonetically, repeated three times.
This will be followed by the same 6-character string either by itself (as the entire message), or concatenated with additional alpha-numeric characters to produce alpha-numeric strings that total 28 characters (the most common length; 30-characters prior to 01 Oct 2000; 26-characters prior to 01 Oct 1998), or 22 characters (20 character prior to 01 Oct 2000), or strings with character-counts that can extend into the hundreds of characters
(with the available character set universe consisting of all 26-characters of the English alphabet plus the numerals two, three, four, five, six and seven; with extremely rare exceptions there are no zeros, ones, eights or nines heard in these strings).
