When I went on vacation in 2009, I took with me not only recording gear, but lots of radios, too. I enjoy vacationing in places that are far from any sizable human habitation. This is due partially to my tendency to be a hermit. It is also because I really enjoy short wave listening.

And so I did a great deal of that this year. I heard something that really got me curious. On the Long Wave (LW) band, I heard what at first sounded like  a pure carrier. This would have been the exact opposite of rare, except that I suddenly began hearing an extremely small changes in frequency.I realized that what I was hearing had to be data. Of course, I recorded it. When I got back home, I opened the recording in Audacity.  Sure enough, I could see that my ears weren't deceiving me. I wasn't able to discover anthing about this data, but I did stick it in the back of my mind.

Now it has been four months since then. One of the blogs I read every day is Make Magazine online. I saw someone had built a really neat High Quality Sine Wave Generator (which is very cool all by itself). But what caught me like a bear trap was the reason they built this device: to produce Four Frequency Shift Keying (4-FSK) data signals using the MEPT-JT protocol. It was developed by Nobel Prize laureate and astrophysicist Joe Taylor, who was Professor of Physics at Princeton University. This protocol is nearly unbelieveable. People have documented reception of digital signals transmitted at a power of one milliwatt at a distance of over ten thousand miles! Have human beings ever accomplished that? The receiving decoder can decode data that is 25dB below the noise floor1. Not above the noise, below it – so deep inside the noise that humans can often not hear anything at all, yet there is the received data on the screen.

One of the reasons for this  is because the system relies on an extremely narrow passband: about Six hertz. Second, it relies on an "out-of-band" sync signal: A GPS provided clock.

So, I've downloaded the software and my little Acer Aspire One netbook is dutifully decoding signals and logging them to this web page. You can find sample wave files included in the software.

1 – Oh yes, I've been wanting to use that phrase in a post here for a long time.