Comment Re:Analysis of tones? (Score 1) 222
It's changed a few times, but it has essentially just been broadcasting the same thing for decades, excepting the spoken word transmissions.
Subtle encoding are completely useless for number stations, so it's unlikely it does that anyway. The point of number stations is that they broadcast to huge areas using shortwave, in easily recordable formats. This way, agents in foreign territory can use basic shortwave radios that can be found anywhere, and decode the messages using the one-time pads they are issued with. This method of encryption is impossible to break, and can be done with essentially no equipment.