North Korean numbers station detected; possible submarine instructions?

The website features an Op Ed piece regarding a recently detected numbers station supposedly originating from North Korea. The station, reported by a ham radio operator, is in single-side band and adjacent to the Voice of Korea.

Below is an excerpt from this Op Ed piece; note my comments following:


Within hours of South Korean news sources breaking a story that several Sang-Ho class submarines had disappeared from their North Korean bases, a ham radio operator named Tim, picked up a “numbers station” broadcasting on the same frequency as “The Voice of Korea” propaganda station. [check out our recent post]  What makes this even more interesting is that at the tail end of the numbers transmission there was a long duration digital transmission as well.

So what makes this number station significant is the proximity in timing to the disappearance of the San-Ho class submarines, as well as the digital transmission.

[…]What is more significant is the digital signal at the end of the transmission.  Digital transmissions such as this one may indicate the presence of a burst transmission which contains a compressed and encrypted message bound for some covert force, somewhere.  Typically a burst transmission is used to minimize the download time at the end point to prevent discovery.  The unusual part of this potential burst transmission is being attached to a numbers station as well as the length and the power of the broadcast.  Normal burst transmissions are in the one second to two second range.  This transmission was in the 10 to 15 second range which is almost unheard of, unless the end point is a submarine.

[…]The ham operator who picked up this particular transmission was located in the Midwest of the United States, and he reported the transmission was received 4 by 5 indicating a significant power was used to send the transmission.  That level of power coupled with the length and possible submarine end point opens up a new and alarming tangent to this escalating conflict. It is important to point out that the numbers are being read in Spanish but that is typically done to confuse the original source of the transmission.  In this case the transmission was detected on a upper side band of the AM range used by the Voice of Korea so while the numbers are Spanish the transmission does appear to originate in North Korea.  That fact coupled with the missing submarines seems to provide evidence of the nature of the transmission despite being in Spanish.  Its also important to note that the numbers being in Spanish could also be used to employ a different set of codes in the operatives code books.

Short digital bursts, as they describe, are not necessarily that uncommon since the Cuban numbers station,HM01, has been doing this for years.  (Indeed, perhaps North Korea got a little help from Havana?) You can hear audio from HM01 here and here and learn how to decode RDFT (HM01’s digital mode) here.

Read the full opinion article on

Thanks to Dan for the tip!

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18 thoughts on “North Korean numbers station detected; possible submarine instructions?

    1. Thomas Post author

      Chris, thank you! This is fascinating. I’ve tried to locate his memoir, “No One Reported Me” but can’t seem to locate it. I’m sure it’s a brilliant read.

      1. Chris

        It probably has not been translated, there are dozens of interesting books about North Korea in Korean and Japanese (for example, memoirs of the people who were abducted by North Korea and later released) which never make it into an English translation.

        I wish there was something we could do to let publishers know there is interest. Interest in North Korea in the US has vastly increased from several years ago. People now realize its one of the world’s most important problems – we really have to resolve the problems there in a positive manner.

        If you are really interested in North Korea I highly recommend watching the videos of the recent UN hearings in Seoul and Tokyo.

        1. Thomas Post author

          I’m both fascinated by North Korean culture/history and (being a big believer in free press) deeply sorry for those living under such a repressive regime. The human rights abuses in North Korea are numerous, to say the least.

          I will check out the UN hearings. Thanks so much and keep us informed if anything else appears. I’ll plan to post this NY Times piece soon.


      2. Chris

        Really, watch those Seoul and Tokyo hearings. There is a good chance that this guy testified there. Many of the defectors who have the most interesting stories testified. You can see them giving testimony. Its much more compelling than reading it in a book. On guy, Shin Dong Hyuk who was imprisoned since birth in Camp 14, he was the only person known to have escaped to South Korea successfully, he had his finger chopped off when he was a teenager for dropping a sewing machine. He showed the panel his finger. He said he felt lucky because people would often be killed for making a small mistake like that.

        Seeing those people speak really makes you grateful for the stable lives we enjoy in the West, no matter how bad things are, they can always get worse, as this shows.

        People were so hungry they ate rats and mice and bugs to survive. Those (mostly older) people who could not bring themselves to do that, died.

  1. Keith Perron

    Number stations from the DPRK use to be very active. But for the most part they just ended. If you visit the city of Dandong in China, which borders the DPRK. You can pick up some off transmissions that make no sense. As for myself I have not heard any North Korean number stations since around 2003 or 2004.

    1. Chris

      I used to have a (really smart) coworker who grew up in Dandong. He was one of the persons who first got me interested in North Korea.

      At that time he was working at times repairing electronics and also was a film buff, and he and his friends would sometimes watch North Korean television for its entertainment value, because it had a strange, almost hysterical quality. He would probably know about these transmissions. All sorts of rumors circulate in places like Dandong about North Korea. There is a fairly large amount of traffic across the border there, the trade with China is what is keeping many North Koreans alive, since their own economy is an international basket case.

      People in Dandong also would fairly frequently find on the river shore the decomposing, bloated bodies of people who had tried to cross but had fallen through the ice in winter, drowned or been shot by the guards. I saw a photo the other day of an old rusted North Korean patrol boat cruising along the shore, its crew gawking at the bustling, forbidden city of Dandong just a few meters away. The contrast between busy prosperous Dandong and decrepit, brooding Sinuju across the Yalu river could not be starker.

  2. ZoeChris

    Hrm wonder why a DPRK “numbers station” transmitting in Spanish? Gee- maybe because it was Cuban. Also so called ham no call sign? Interestingly enough I posted a comment concerning it was Cuban as they do speak Korean there not Spanish, and my comment was removed. I posted yet another comment wondering who this “ham” is who did not provide call sign, frequency, time or anything and my comments were now listed as “under moderation”- then it was not posted at all. I know question that site entirely now as any site that posts such obvious nonsense shall not be brought up on my browser page again for future reference.

    1. ZoeChris

      sorry bud-confusion and i cant edit my comment! IntelliHub was the one that removed my comments then moderated them after I complained about their fake story in their comments board. I apologize as my comment here wasnt clear and sounded like I was saying YOU removed my comments- not they who did. Just goes to show you how sleazy they are, weird huh. Makes ya wonder!

      1. Thomas Post author

        No worries! You’re right. There are a lot of assumptions in that article with very little facts to support them.

        I believe it’s even possible the ham who heard the numbers station could have been hearing the Cuban station HM01. VOK certainly wouldn’t be limited to broadcasting only on their own frequencies.


        1. tempest

          I am a total newbie here and have some concerns about the source Intellihub. Intellihub has a “writer” named JG Vibes whose material is reminicent of those late night (read Earrrly morning) chemically enhanced conversations some of us had in our teen years in the severties.
          One hopes this writer is not living in his parents basement (figuratively) like Intellihubs JG Vibes.

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  4. W4ASZ

    I looked at the original article from Intellihub. It makes several entirely unwarranted assumptions and reaches an unsupported conclusion. I am surprised to see it quoted here.

    1. Thomas Post author

      Ironically, I actually posted this article because I wanted to point out that it was an Op Ed and not a news item. I agree with you–it has some strong assumptions and is of questionable integrity. They never mention a frequency, a mode, number of broadcasts, etc. It could have been an image from HM01 for that matter (other than it being in SSB).

      Certainly NOT a news item, only an opinion/speculation piece. Thanks for calling me on that–should have made clear what I was thinking.

      And, Geoff, I believe you’re right. Theoretically, I believe some of the older diesel subs have been known to surface for some HF communications. But in reality, there can be no real link between a numbers station and a sub. Doesn’t add up to me either–it would force them to surface at a given time.

      Thanks, guys, for your input!


      1. W4ASZ

        I hope you understood my criticism as falling upon the source site.

        You do a great job here, and a thousand blessings upon you !

  5. Geoff

    My knowledge of radio wave propagation is lacking, so I could be wrong here. I thought that typical radio communication with submerged submarines (in the absence of an antenna array very close to the surface) was done via ULF, rather than HF.

    Further information and corrections welcome.


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