Measuring Height of Reflection at HF
Posted: Wed Aug 28, 2024 12:32 pm
There's a fine article in the August RadCom (p42-44) by G3ZIL about the height of HF reflection and how to measure it -without an ionosonde. (I just don't happen to have one handy. 
)
So what? The height of reflection has a huge effect on the length of hop, and thus if many hops, how many.
So how's it done? Reception paths of standards such as WWV are measured, from many locations and as the ionosphere layer changes height, so does the length of the propagation path, resulting in a measurable doppler shift. In practice, the HamSCI https://hamsci.org/ collaboration with professionals use many SDRs and available reporting systems such as WSPR etc,
Check out the article for the pictures of exactly what's happening over a 24hr period, and also during the recent annular eclipse. Very cool!
Does it add something useful to the real-time prop tools on, say, ClubLog https://clublog.org/ ? I think so. It shows in graphic form the height variation that we find useful to predict, whereas the fine ClubLog tools are a great guide to right now?
)So what? The height of reflection has a huge effect on the length of hop, and thus if many hops, how many.
So how's it done? Reception paths of standards such as WWV are measured, from many locations and as the ionosphere layer changes height, so does the length of the propagation path, resulting in a measurable doppler shift. In practice, the HamSCI https://hamsci.org/ collaboration with professionals use many SDRs and available reporting systems such as WSPR etc,
Check out the article for the pictures of exactly what's happening over a 24hr period, and also during the recent annular eclipse. Very cool!
Does it add something useful to the real-time prop tools on, say, ClubLog https://clublog.org/ ? I think so. It shows in graphic form the height variation that we find useful to predict, whereas the fine ClubLog tools are a great guide to right now?