Grey line map. HUH?

Some of you may or may not know about grey line or using a grey line map. Here is a quick primer as to why I use one. Using a a grey line map is a fantastic visual aid that might help you in catching some rare HF DX.

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I usually have SDRuno running 8 hours a day 6-7 days a week and the reason is, it’s my job. But as soon as Florida sun is starting to set. I’m enjoying HF listening from transmissions originating mostly out of Western Europe (long path).

A greyline map basically separates daylight from darkness. Propagation along the grey line is usually very good.  Why? The D layer (which absorbs HF signals) disappears very fast on the sunset side of the grey line and on the sunrise side The D layer has not yet built up to absorb HF transmissions that I’m after.

You can really optimize your chances of long distance listening to various areas of the world by monitoring when your region is going into grey line.

Here is a great website that I really recommend that you bookmark .

If you use Google Chrome as your browser, you must allow the websites Flash content to run. Just click the Adobe Flash link I highlighted above.

If you run a single monitor setup…It might be time for a 2nd or 3rd monitor. Let us know in the comments section what catches you have made by monitoring HF signals in the grey line.

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