So, you’re interested in shortwave radio?

So, you’ve gotten yourself intrigued in the world of shortwave radio huh? If your answer is yes, wonderful, because I’d love to help guide you through it the best I can. 

Frequently, specifically on my Twitter page you’ll see me talk about “Emergency Action Messages”. If you’re wondering, “What the hell does the Doge mean by this?”, then you’ve come to the right place. The US Air Force frequently uses Emergency Action Messages (EAMs) as a source of encrypted communication, meaning we’re not 100% sure what the messages mean. 

The US Air Force uses a form of encryption called one time pad, where there’s a sheet given out at the start of the day that has the meaning for characters on it. For example, during an EAM you’ll hear a series of characters, ranging in length. The deliverer and the recipient will use their one time pad sheet for the day to deliver the message. The one time pad (OTP) sheet is changed and is different every single day to ensure the best possible encryption day in and day out. So, before you ask, it’s virtually impossible for people like me and you to decode these transmissions.

It’s still not known exactly what these messages mean however. But, here’s what we do know. We know that these messages are delivered by the United States Air Force to send instructions to their operators through encrypted messages. We know that the HFGCS (High Frequency Global Communications System) isn’t exclusive to just the US Air Force, nor is it exclusive to just the United States.  The US Air Force frequently uses this form of communication, and it’s actually quite easy to listen to messages, which we’ll dive into in a little bit. 

The “Emergency Action Message” system also has a little bit of a sinister side to it, considering it can be used to order missile launches, or other forms of force by the United States. However, 99.9% of the time these messages are either tests, drills or just general communications that require encryption. I remember last year on November 6th there was a ton of activity on the HF-GCS in terms of EAMs, 100+ EAMs out the wazoo, and all was calm in the world.

A basic Emergency Action Message has a consistent format. It goes a little something like this, “All Stations, All Stations this is *INSERT CALLSIGN HERE* break. *INSERT SIX CHARACTER PREAMBLE HERE* standby, 
*INSERT SIX CHARACTER PREAMBLE HERE* standby, 
*INSERT SIX CHARACTER PREAMBLE HERE* message follows.. (if there’s more than the normal amount of characters, it’ll be “Message of *blank* characters follows). *MESSAGE IS SAID AND REPEATED ONE MORE TIME* it then concludes with “This is *insert callsign here* out.

Now, let’s dive into something else that’s EAM related. Occasionally, you’ll hear me talk about something called a “SKYKING”. These messages are much more rare compared to typical EAMs, and are genuinely much more important. SKYKING messages are a higher priority message and are also sent in a different format which we’ll talk about in a second. SKYKING messages will interrupt all radio traffic occurring at the time, even an EAM.

SKYKING messages are sent like this. First, it’ll begin with “SKYKING SKYKING do not answer” and is then followed by a code word which can be anything, but for some reason the US Air Force has an infatuation with classic rock bands. It’s then followed by two numbers for the time of hour the SKYKING message is being transmitted, and then ends with a two letter authentication. It’s then repeated.

If you ever hear general communications, you’ll likely hear something that doesn’t make sense, don’t worry about it, it won’t make sense, and that’s the point. Requests to “enter the net” will come up, which we don’t know what that means either. Sometimes, you’ll hear airborne messages, requests for refueling sometimes happen as well. Also, you’ll hear test counts sometimes, which come from the flight or the base that’s doing the test count, and will go up to 5, 10, or rarely sometimes even 15, and then back to 1. Just test counts, nothing to worry about.

Now, the part you’ve been waiting for.. how do you listen to these Emergency Action Messages? Well, you’ll start by doing the following. Go to this website http://websdr.ewi.utwente.nl:8901/ then once you’re on the website, the first thing you’ll want to do is press the squelch button, which is located here.

Then, you’ll want to tune to one of the many US Air Force HF-GCS frequencies. I’ve compiled a short list of the main frequencies, if you hear an Emergency Action Message and it’s coming in faint, try some of these other frequencies, it might come in clearer on one compared to the other.

4724 kHz
6712 kHz (Croughton)
6739 kHz
8992 kHz
11175 kHz
13200 kHz
15016 kHz

All of those frequencies listed above will be entered in the white box that’s to the left of the filter area, below the waterfall. Which, if you’re curious, the waterfall is the black/blue area, which shows the traffic coming over the radio for your specific frequency. 

I’d also recommend adjusting your filter to a max of about 3.75 kHz, anything other than that and it gets tough to hear the messages coming through, don’t go lower than the default filter kHz either.

Finally, I’ll be listing the different HF-GCS sites the US Air Force uses, note how they’re all over the globe, and in different countries, hence where the “Global” in “Global Communications System” comes from. Thanks Numbers-Station.org for this list.

Andersen Air Base, Guam
Andrews AFB, Maryland
Ascension Island
Croughton AB, United Kingdom
Diego Garcia Naval Station, Indian Ocean
Elmendorf AFB, Alaska
Hickam AFB, Hawaii
Keflavik NAS, Iceland
Lajes AB, Azores
McClellan, California
Offutt AFB, Nebraska
Salinas, Puerto Rico
Sigonella Naval Station, Sicily, Italy
Yokota AB, Japan
Air Force Eastern Test Range, Florida
“MPA”, Unknown
Closed Sites:
Thule Air Base, Greenland
Keflavik Global, Keflavik NAS, Iceland

Each of the sites listed above have their own automatic link establishment call sign. The Automatic Link Establishment is the system used to connect to the high frequency station, or a network of stations.

If you’ve found this “tutorial” interesting, or helpful please let me know. Also, please note this is perfectly legal. It’s encrypted for a reason. It only becomes a problem with the US Air Force if you try to decode their messages, or somehow you successfully decode their messages, which I wouldn’t recommend or you’ll be spending some time here.. 

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