Broadcast Band DXing - The Grey Line

It doesn't take long before you realise that the way the ionosphere works is quite chaotic with conditions rarely the same two days running.

So you can never be quite sure what conditions will be like when you switch on and that single factor is what makes any form of amateur radio listening fun. However, there are some broad guidelines which can help, one of which is Gray Line, or Grey Line if you prefer, DXing.

What is Grey Line DXing?
The Grey Line is simply the line between darkness and light. As the Earth rotates, this line moves across the surface from East to West as parts of the world experience the change from night into day.

The best time to hear a distance signal is when the path between both stations is changing from night into day or, in other words, as the Grey Line is sweeping across the two paths.

Obviously, that would restrict you just to North-South propagation paths. However, if just one location is at the grey line and the other is in darkness then the effect will still work.

How Do You Use It?
You can get a program to run on your computer which will show you the Grey Line against a map of the Earth or you can look at it in real time here:

http://dx.qsl.net/propagation/greyline.html

This map shows, quite correctly, the line as a hard dividing line but it's best to treat it as if it were a softer, much wider line since the effect of Grey Line DXing will work for a few hours both before and after sunrise or sunset.

Try to find a time to listen when either you have the line near to your location or near to the location of the station you want to hear or, if you can manage it, near to both.

Of the two times, sunrise at your location is better than sunset as at this time it is usually electrically quieter for you.

How can I see it in operation?
It's very useful to listen to a station to see the Grey Line actually working and in the next post, next Wednesday, I will suggest an easy way that you can do this.

This will allow you to get some practice at Grey Line DXing which will explain its operation far better than I can explain it in words!