Monday, August 2, 2010

I learned that the station was 500 miles away from me. Was this sporadic E propagation? ...

Q Last night I heard a strange CW signal on 6 meters. It was hissing and buzzing, but I was still able to copy. To my astonishment, I learned that the station was 500 miles away from me. Was this sporadic E propagation?

A My guess is that you heard auroral propagation. The clue is your description of the signal as having a hissing or buzzing characteristic.

Those of us who reside at the higher latitudes are occasionally treated to the visual spectacle of the aurora borealis, better known as the “northern lights.” (Yes, there are “southern lights” as well, visible occasionally in South America and Africa.) The aurora is caused when the Earth intercepts a stream of charged particles ejected from the Sun, resulting in a “geomagnetic storm.” These fast-moving particles funnel into the polar regions of the Earth thanks to our magnetic field. As the particles interact with the upper atmosphere, the air glows, which we see as an aurora. The shimmering, ghostly curtain of light is not only a treat for the eyes, it can reflect radio signals like a giant mirror (see Figure 2). 

Like sporadic E, you’ll encounter auroral propagation more
often on 6 meters than on 2 meters. Nevertheless, 2-meter aurora is far more common than 2-meter sporadic E. You can also work distant stations using auroral propagation on 222 and 432 MHz. 

As you’ve discovered, auroral DX signals are very distorted.
That’s why CW is the most commonly used mode, although you’ll hear SSB from time to time. Auroral CW signals have the raspy, buzzing quality you heard. (It sounds like the other guy is operating an ancient spark-gap transmitter!) Just listen carefully and you’ll be able to decode the signals. 

You do not need directional antennas and high power to work
aurora on 6 meters. The Doctor has done it with dipoles and 100 W. Many hams have even enjoyed success with 6-meter aurora from mobile stations! 

From QST November 2000