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On many of the DX sites, one will find many variables for solar weather to include flux, A, K, sunspots, etc… I’d like to know how to read those and know what to look for. As I understand it, the sun’s activities affect the ionosphere which affects HF propagation in so many ways. I also hear of interplanetary magnetic fields, solar winds, terrestrial conditions, etc… more than I know what to do with.

What I’d like to be able to do is factor for myself what the band conditions are like, or will be like at a future time and know what conditions to take into account, aside from the general practice of knowing what bands are good at what times of the day or night. There’s also the fact that it takes me some effort to get my antenna’s out.

I realize this can be pretty broad and too much to put in a single post, and I’m also sure it will likely take considerable practice and time to learn, so I’m hoping for a summary about the process overall (i.e., how to make the decision that at X time, conditions will be great to GOTA), and I’ll break it down and study each topic individually from there.

Any help much appreciated.

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  • $\begingroup$ The methods for predicting radio performance in general (by time of day, season, or year) are different from predicting radio performance right now or an hour or two from now. Which specifically are you trying to do? $\endgroup$
    – Phil Frost - W8II
    Commented Jan 10, 2020 at 16:15

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Quick and easy propagation forecast tools are at VOACAP Online http://www.voacap.com/prediction.html and http://www.voacap.com/coverage.html for area coverage. Required are the transmitter and receiver positions, transmitter power, mode, antenna types, date and sunspot number. It does not consider the effects of geomagnetic ionospheric disturbances. The website has reference material on the the art and science of ionospheric propagation prediction.

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The Band Activity chart at DX Heat is a good way to evaluate propagation from the standpoint of "who is working whom, right now." Combining the color coded activity depiction with your general knowledge of when bands are more likely to be open can guide you as to what bands are opening and which are closing. The filtering tools allow you to target specific bands, modes, regions and DXCC entities.

WSPRNet displays automated connections between stations around the world. While not quite as convenient to use as DX Heat, station automation doesn't rely on individuals to be active on a band for propagation information to be available.

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If you want to get a more automated prediction, look for propagation prediction software (many available on the 'net) and plug in the data. Of course, it's still useful to know the basics, such as how the ionosphere works (see ARRL handbook), to understand what the programs do.

And very important: Even if you take into account all of the data you have available, you cannot rely on the numbers alone. Several factors are near to random, such as short-lived magnetic solar storms, or comet-trails. Others are global, and might not be directly applicable for your location.

Even all the wisdom from classic books such as Kenneth Davies' Ionospheric Radio (300+ pages!) cannot predict instantaneous behaviour - only what's 'expected'.

So, if you decide what you want to do and want the tech background, consult the chapter on propagation in the ARRL Handbook; for the juicy details, see the above book.

I'd say you are approaching the problem the wrong way. You should probably decide first what you want to do, say eg. making contacts on the 10m band, and then find out which elements influence that goal.

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  • $\begingroup$ Let’s leave aside what I want to work. My goal is to find out what band conditions are like now, or in the very near-term. Just knowing the basics of what to consider and what to expect sounds like where I want to start. I’ll take a look at this book. Even the automated software has a logic process it goes through to come to a conclusion. Maybe looking at some OSS wouldn’t be a bad idea as well. $\endgroup$
    – Ender
    Commented Sep 1, 2014 at 1:08
  • $\begingroup$ I hate to repeat myself, but as an introduction, and its knowledge forms the basis of most of the prediction program around, the ARRL chapter on propagation is hard to beat. $\endgroup$
    – jcoppens
    Commented Sep 2, 2014 at 5:38
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The DXLab Suite includes PropView, a convenient front-end to VOACAP, which makes current and near-term propagation predictions. PropView works in conjunction with the other components of the DXLab Suite, so it works best when you use DXLab for all of your logging and operating functions.

You can download N6BV's Propagation Prediction Files with the purchase of the 2019 ARRL Antenna Book. The files predict the strength of communication (in S-units) over virtually any path as a function of frequency and sun spot number. Instructions are given to "discount" the S-units to account for stations' output power and antenna gain.

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Here is a useful site for both long-term (monthly) and near-term propagation conditions. http://propagation.hfradio.org/

For VHF and UHF skip conditions (just in case you are interested) try here: http://www.dxinfocentre.com/tropo.html

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