Posted: 10/7/2008 6:30:54 PM EDT
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I know what a sunspot is. WTF do the following mean, and what do they have to do with propagation?
solarcycle24.com/ dx.qsl.net/propagation/ Among others. |
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Wikipedia.... The A-index provides a daily average level for geomagnetic activity, based on the K-index. Because of the non-linear relationship of the K-scale to magnetometer fluctuations, it is not meaningful to take averages of a set of K indices. Instead, each K is converted into a linear scale called the "equivalent three hourly range" a-index (note the lower case). The daily A index is the average of eight "a" indices. Both A and K-index reports are available on WWV or WWW. Go here and dig deeper... http://en.wikipedia.org/wiki/A-index |
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The higher the solar flux number, the the higher the MUF (max. usable freq.) The A and K indexes are in relation to solar storms (read: NOISE) Back in '90-91 the solar flux numbers were in the 180-200 range and we were working Europe in the morning and Asia in the evenings on 10m with just enough power to tickle the wattmeter (1-2 watts) into a 5el. beam. I can't wait till the 'ol sun starts percolating again! ( I missed out on most of the last cycle in the early 2000's.) 10m is my favorite band and now that I'm in AZ I can drive up into the mountains for some serious elevation! 
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Thank you. I read the Wikipedia definitions of those things, and while I could see the words, what I really wanted to know was the "WTF do they have to do with propagation?"part, which none of the websites I looked at explained. |
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When the SFI is high, it allows higher RF frequencies to "bend" through the ionosphere due to the "charging" of this region of the atmosphere. The higher the SFI number, the higher the freqs can be used. The solar fulx charges the ionosphere when sunspots are visible. (none lately) When solar flux is low or none, the lower freqs propagate well, when it is high, lower freqs are absorbed and a higher freq is "bent" reflected. eg: Listen to the AM broadcast band during the day...local stations only are heard..listen to AM band at midnight, stations nationwide can be heard. Also applicable on the ham bands. Basicly, the higher the SFI, the higher the freqs can be used for DX comms, while lower freqs are absorbed. ETA--the higher the SFI, the more it charges the ionosphere. Sunspots increase the SFI. link added propagation link |
