The website Intellihub.com 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.
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.
Thanks to Dan for the tip!