Radio Apocalypse: The Emergency Broadcast System

Some sounds are capable of evoking instant terror. It might be the shriek of a mountain lion, or a sudden clap of thunder. Whatever your trigger sound, it instantly stimulates something deep in the lizard brain that says: get ready, danger is at hand.

For my part, you can’t get much scarier than the instantly recognizable two-tone alert signal (audio link warning) from the Emergency Broadcast System (EBS). For anyone who grew up watching TV in the 60s and 70s in the US, it was something you heard on at least a weekly basis, with that awful tone followed by a grave announcement that “the broadcasters of your area, in voluntary cooperation with the FCC and other authorities, have developed this system to keep you informed in the event of an emergency.” It was a constant reminder that white-hot death could rain from the sky at any moment, and the idea that the last thing you may ever hear was that tone was sickening.

While I no longer have a five-year-old’s response to that sound, it’s still a powerful reminder of a scary time. And the fact that it’s still in use today, at least partially, seems like a good reason to look at the EBS in a little more depth, and find out the story behind the soundtrack of the end of the world.

Replacing the CONELRAD System

The EBS system was developed as a response to shortcomings in the CONELRAD system for civil preparedness announcements. As Al Williams noted in his recent article on CONELRAD, the system was troubled by nuisance alarms and a complicated operating procedure that required every TV and radio transmitter to go dark and have designated AM stations retune their transmitters to one of the two CONELRAD frequencies. Expecting broadcast engineers to perform these tasks under the threat of sudden annihilation was probably something that should have been subjected to a little human-factors testing.

As a response to this, EBS was first fielded in 1963. It was designed to deal with the changing nature of the threat; CONELRAD imposed radio silence to deny bomber pilots of electronic landmarks, while EBS recognized that ballistic missiles needed no such aids. EBS was more inclusive, too, requiring TV stations and FM broadcasters to participate, in a tacit acknowledgment that AM radio was no longer the big kid on the block.

The EBS system did take cues from CONELRAD, though. The basic architecture was the same — to create one nationwide network that the government could use to transmit consistent messages and instructions quickly and efficiently. Linking the national carriers into a single network was initiated by a teletype message with codeword authentication to primary stations like the Big Three networks and news services like UPI and AP. To get the attention of station employees tasked with monitoring teletypes in station newsrooms often full of the clattering devices, this Emergency Action Notification (EAN) was preceded by a line of X characters and a bunch of control-Gs to sound the teletype’s bell.

Once the codeword was authenticated — it was changed daily — the transmitter was turned off then back on again twice in a row, followed by a 15-second transmission of a 1,000 Hz attention tone. Again, this was a holdover from the “carrier drop” signaling of the CONELRAD system, often wryly referred to by broadcaster engineers as the “EBS stress test” for its ability to kill transmitters. The loss of carrier in the specific pattern dictated by the EBS rules would activate decoders in the other stations, allowing the seamless network to be stitched together rapidly.

Recognizing that carrier-drop signaling was no longer optimal, in 1976 the EBS system was changed to support the now-familiar two-tone Attention Signal. A form of in-band signaling, the two pure sine tones of 853 Hz and 960 Hz were chosen so that false decoding of normal audio programming would be unlikely. The Attention Signal also had the advantage of being discordant and unpleasant to hear, therefore standing out from normal programming. The initiation process would then be followed by the official announcement of the end of the world.

EBS Goes Digital

Faced with changing technology, the EBS system was scrapped in 1997 in favor of the Emergency Alert System. The EAS includes not only terrestrial broadcasters but cable providers, satellite services, digital radio, and smartphones. EAS incorporates Specific Area Message Encoding (SAME), a digital header that’s pretty terrifying in its own right, which allows targeting emergency messages to specific geographic areas. This is the system used in weather radios to issues severe storm warnings to specific locations.

While none of these emergency notifications systems has ever been used to announce the apocalypse, the later versions have been activated many times for smaller-scale disaster, both natural and man-made. EBS was activated something like 20,000 times for weather alerts, and EAS warnings down to the level of Amber Alerts regularly appear on smartphones. While there’s no such thing as a minor emergency when it’s happening to you, here’s hoping we continue to use these systems for everyday emergencies rather than their intended purpose.

42 thoughts on “Radio Apocalypse: The Emergency Broadcast System

        1. Mid-50s kid here, I remember the first time in the 80s that I heard the EBS come on the radio and say “This is not a test.” Near heart attack time, didn’t remember the US and Russians arguing any more than average so why were we about to blow up the world, but it wasn’t Tuesday at Noon or whenever the usual tests were. Then they said it was a flood warning (and ok, it was raining, and it makes sense to use a system like this if you’ve got one, but still, Expletive Deleted, tell us that you’re going to start doing this sort of thing first!) And as usual, the reason I was listening to the radio was because I was driving a car, which is not what you need to be doing when that thing goes off.

        2. So the thing about duck and cover is that the nuclear fireball at the center, and the lethal overpressure area outside that were a relatively small area of the effect of a nuclear weapon. Then, as any large explosion, there would be two shockwaves, a weaker supersonic one and a more powerful subsonic one. Being limited to the speed of sound it was actually sort of reasonable if you had the flash and supersonic shockwave to have time to cover yourself with a desk to protect yourself when the subsonic blast blew in the windows.

  1. If I remember correctly, the EBS tone would sound, there would be an announcement like “This is a test of the emergency broadcast network”, and then there’d be another tone that would last much longer. I always assumed there had to have been something happening at the station during this second tone. Maybe test announcements being made that were drowned out by the tone? Does anyone know?

    1. each station was triggered from a station it was assigned to listen to, each iteration was subsequently degraded and many times the audio would be a hodgepodge of static, erroneous tones and the like

    1. Oh crap, that was TERRIFYING. I was wondering if it was real almost all the way until it got dark.

      The “accidental broadcast” card at the end was a nice freeze-frame bonus.

  2. Bert the turtle only has to retract his head, tail, and feet. He’s ready! Meanwhile my auto tuned radio goes off lock looking for another station because of the LOS. OK, I’ll listen to records. How about Brittan’s war requiem.

  3. The AP/UPI teletype code was ten ^G (bells) sent followed by a full line of ‘X’, then the message. Both were an unmistakable sound.

    The importance of news on the Teletype was indicated by the number of bells that preceded the message.

    I was at a New Year’s party at the college radio station in ’82 or so when we heard the bells go off on the teletype followed by the full line. You’ve never seen a party stop so fast. There was a brief rush to the tty, which had no more data (which was very scary) then everyone basically went to battle stations. Air talent got ready to cut programming and waited for EBS tones, Engineering staff went to control, and station manager went to get The Envelope with the codes in it.

    However, very shortly, another alert came along saying it was an error, all clear, return to your regularly scheduled lives. I seem to recall most of us went home, adrenal glands emptied out, and stone cold sober.

  4. “Some sounds are capable of evoking instant terror. It might be the shriek of a mountain lion, or a sudden clap of thunder. Whatever your trigger sound, it instantly stimulates something deep in the lizard brain that says: get ready, danger is at hand.”

    Sound a bomb drop makes before it hits.

    1. For my father, who grew up in London during the War, there was the air-raid siren and the spluttering of a V-1 pulse jet – followed by the horrible silence as the engine cut out and the warhead plunged to the ground. He told a story of being away from home and hearing a V-1 in the distance, then the ghastly wait for the explosion, and thinking to himself that if he was killed his mother would never know what happened to him. Fortunately for him he wasn’t – but that, I suppose, just means it killed someone else.

  5. It’s always fun initiating a scheduled EAS test at local FM college station I volunteer at. It’s interesting that for actual EAS alerts we still rely on one of two AM carriers for rebroadcast.

    “I wonder how many devices am I making noise with?” is the thought that comes to mind.

  6. Plane flying into buildings, death destruction and mayhem. Time to sound the EBS system ?

    Not if you live in NYC or DC. What a joke. Don’t panic the masses.

    I have seen more REDLINE text lines on my cable system announcements and never heard a EBS
    alert around NYC. I will say it again. What a joke!

    1. In a similar vein, I grew up in north central Oklahoma, right in the heart of Tornado Alley. The National Weather Service headquarters, National Severe Storms Lab, and NOAA Storm Prediction Center (among others) were about an hour’s drive south in Norman. There have been a few times that I have been asleep or going to bed, with a storm moving away and thunder fading into the distance… and then an entire city full of Federal Signal 3T22s winds up, perhaps coupled with the EAS alert if the TV was on (EAS was usually late or nonexistent compared to the sirens). THAT sound gets INSTANT action! Tornadoes are unpredictable, and in some cases can form and become extremely violent (house –> bare foundation) in under a minute. The most skin-crawlingly creepy sound, though, was when the alert was over and the sirens were all winding down in slight asynchronicity. Videos don’t do it justice, though you can sort of get the general idea.

  7. I grew up with megaphones performing the tests and you could hear the speed of sound difference of the different megaphones going off in the perimeter. I grew up nestled in between two nuclear plants. I haven’t heard in years. I think the idiots use for subliminal silent sounds and V2K now days as I’ve been told at one plant they act like idiots and will launch gas bottles out into the lake for fun by sledge hammering to top valves off. Crazy that old Palisades plant in Covert Mi.

  8. I lived in a small town were nuclear fuel was manufactured. If there was a spill the air raid siren would sound. I’ll never forget the first time I heard that wail. At first I didn’t know what was happening, then it hit me – the nuclear plant. It sent shivers up my spine back then and it still does today.

    1. Yeah come on, English just couldn’t have evolved naturally and have so many opportunities for confusion, complete opposites here, also phrases like “with a synchronous connection”, and “with asynchronous connection”… awful… if it couldn’t have evolved that badly there’s only one other explanation….

      … it was designed….. by a committee!!!

    2. “IN VOLUNTARY cooperation with the FCC”. Where such cooperation is expect as a license condition, is it voluntary? I exchange for the chance to use a limited public resource in hopes of earning a profit, serving the public good is expected. I asmit I may be living in the past, because I don’t know how the deregulation team Ronald Reagan and Bubba Clinton watered down commercial broadcasting licensing.

  9. For well over half a century we’ve been subjected to this complete waste of time.
    Endless fake drills, then useless in a time of emergency.

    9/11 Attacks. How many of you heard the sirens and as instructed tuned to an emergency station?

  10. I wonder actually if the megaphones and systems implements were a valid concern at one time and now have been hijacked and haced by enemies of the state to be used more for PSYOPS and PSYWARS operations using not only the megaphones in secret silent sound ways… the power lines themselves as power lines communications devices and tracking devices since I bet there are Time Domain Reflection or some other way(s) to measure the different lines and branches in a circuit so to tune the circuits as an antenna specifically to perform not only heterodyne… pulse train operations for sound, body, mind and other MCL 750.200h&i, 750.224a and 750.543p 18 USC 2331&2332a 21 usc 848 assaults.

    I’m thinking I get hit hard here being in between Cook and Palisade Nuclear Plants and at my parents old place since there is a transformer in the front yard as well as a water line hydrant and cable/phone box also.

    I mean… they really targeted this place with whatever moved into the neighborhood afterwards. Polish, German and Dutch Mafias I’m thinking based on communications with the neighbors I wasn’t supposed to associate with growing up since they were known narcotics traffickers, junkies, hitmen and violent nice acting lacing incest pedophiles crime gangs.

    Creepy, and absurd the systems being taken over by juvenile sub human continuing criminal enterprises that mass murder off smart caring and kind or even mean people that try to play by the code/book and earn an education… only to be groomed stealthy with poisons, brain washing, cult programming, ritualistic crimes and religious terrorism to be their victim… framed, pinned and mugged as their scapegoat and watching my family being forensically cleaned murdered by the health care systems that closed back when my Grandparents generation was still alive with what must have been the last of the valid heterosexuals that didn’t sodomize, larceny and arm rob for their lifestyle…. stacking the attorney, law enforcement and courts so no one bothers then so much. Now with exploding health care systems racketeering for not reason other than the retail and even invasive nuisance inbreds must be causing that are left with the resources here in Berrien County and Midwest/east.

  11. LOL; I must invest in aluminum foil manufacturing. You alone can insure those stocks remain steady in value. In the event you mingle with those not immune to your madness, the value of the stocks is certain to rise.

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