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So this is apparently thought to be a number station (for military cryptography). A bit of searching leads to [1] the guy discovering it [2] a software that

So this is apparently thought to be a number station (for military cryptography). A bit of searching leads to [1] the guy discovering it [2] a software that can demodulate the signal [3] that software's manual, which says (from page 28): > JSM refers to a rather strange signal. The consensus is that it is transmitted by the Japanese navy. When one listens to it in USB mode it normally sounds like a continuous repetitive melody. ... > With some investigation the symbol rate was determined to be 1500.00 baud. The regular ticking sound was found to be an exactly repeating sequence of symbols. Clearly that serves as a channel probe and frame synchronization pattern. [1] http://www.ominous-valve.com/mystery.html http://www.ominous-valve.com/mystery.html [2] https://www.saharlow.com/technology/sigmira/ https://www.saharlow.com/technology/sigmira/ [3] https://www.saharlow.com/technology/sigmira/sigmira_manual.pdf https://www.saharlow.com/technology/sigmira/sigmira_manual.p...

TazeTSchnitzel 5y ago
Does it still count as a number station if it isn't something intelligible to a human with just an ordinary radio?
- uniqueuid 5y ago
  I don't know, this is not my area of expertise. But at least from what I've read about other number stations, not all of them are intelligible (e.g. UVB-76 [1]) [1] https://en.wikipedia.org/wiki/UVB-76 https://en.wikipedia.org/wiki/UVB-76
  - TazeTSchnitzel 5y ago
    I should clarify that by “intelligible” I meant that a human can make out the symbols being said (words or numbers) and write them down for later decryption, not that their meaning is readily obvious to people without special knowledge. It sounds like UVB-76's broadcasts (when it's not just buzzing) would be “intelligible” in the sense I was thinking. The Japanese Slot Machine seems like something only machines could work with.
    - randombits0 5y ago
      I could tell the connection speed of a modem by listening to the handshake. Does that count? Serious/not serious.

TazeTSchnitzel 5y ago

Does it still count as a number station if it isn't something intelligible to a human with just an ordinary radio?

uniqueuid 5y ago
I don't know, this is not my area of expertise. But at least from what I've read about other number stations, not all of them are intelligible (e.g. UVB-76 [1]) [1] https://en.wikipedia.org/wiki/UVB-76 https://en.wikipedia.org/wiki/UVB-76
- TazeTSchnitzel 5y ago
  I should clarify that by “intelligible” I meant that a human can make out the symbols being said (words or numbers) and write them down for later decryption, not that their meaning is readily obvious to people without special knowledge. It sounds like UVB-76's broadcasts (when it's not just buzzing) would be “intelligible” in the sense I was thinking. The Japanese Slot Machine seems like something only machines could work with.
  - randombits0 5y ago
    I could tell the connection speed of a modem by listening to the handshake. Does that count? Serious/not serious.