Sunday 26 May 2019

Grey line to K4COD

Beautiful examples of propagation enhancements are always worthy of a write-up, no matter how many times I cover them.

Last evening, K4COD's 2W signal from Concord, GA, showed just how much the grey line period can enhance the chances of a DX contact.  In this case, the signal enhancement at peak grey line is +27dB (a factor of 500 times) over the pre-grey line period!

To put that into practical context, if you are using the highest, 200 milliwatt setting on a WSPRlite, the propagation enhancement magically gives you 100 Watts effective output!

Note, though, that the definition of the grey line period is certainly not always between two stations mutually lying within the grey line region, which is how the phenomenon is usually explained.

Here's the situation at 23:04UT, the start of the peak strength, about 90 minutes before K4COD enters the greyline.  You can see that the first part of the peak propagation started around 21:45UT, which is when my station was about half way into my local greyline.

23:04UT
Towards the end of the peak propagation (about 01:10UT), the greyline was situated like this.  The drop in propagation from this point on is a product both of my station lying towards the deepest part of the greyline (within which I remain all night during midsummer), and K4COD passing into his, deeper parts of the greyline.

01:10UT

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