I’ve always been kind of fascinated by gray-line propagation. The gray line is a band around the Earth where night is turning into day and day is turning into night. Theories differ as to why, but radio propagation along the gray line is often very efficient. NA5N has one explanation of the phenomenon.
This morning, while walking to our ham radio club breakfast get-together, I got to thinking about how I might be better able to take advantage of gray-line propagation.Because this phenomenon is so short-lived, it’s easy to miss the gray line. How cool, I thought, would it be if I could come up with a program that would inform me when my QTH was beginning its transit through the grayline.
I thought up several ways to get my computer to do this. Then, it occurred to me that I should be able to write a Web application that hams could sign up for that would either send them an e-mail or send them a Tweet when their QTH was about to enter the gray line. And, coincidentally, I might be able to sell some advertising to pay for this and maybe make a few bucks off it.
I’m tentatively calling this application the Gray Line Notifier. I talked up this idea a bit at our breakfast this morning, and the guys noted that there are already may gray line maps on the Web, but none of them can be programmed to send you notices. We chatted a bit more about this, and came up with a couple of features for this app, including:
- Will send either an e-mail or a Tweet, when a ham’s QTH is about to enter the gray line.
- Include information about other countries/grid squares that are also along the gray line.
- Perhaps interface with a DX spotter to see if there is good gray line propagation at the time.
- Beam headings to take advantage of gray line propagation.
This year, we’ve decided to build a low-cost version of the Arduino microcontroller called the Bare Bones Boarduino, from 
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