graham/w5isp.com
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Clarify data source and invite more log contributions

Browse source 
The 97% blocked-path stat was presented without caveat. Attribute it to
the ARRL 10 GHz and Up contest logs that feed prop.w5isp.com, and add a
call for more submissions so the sample can keep improving.
This commit is contained in:
Graham McIntire 2026-04-22 17:30:25 -05:00
parent 5e0a41b4d1
commit 486cc8ed56
No known key found for this signature in database
GPG key ID: F4ABF488E6029E59
1 changed files with 1 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
content/blog/why-signals-bend.md
View file

@ -126,7 +126,7 @@ A few things I didn't expect going in, now painfully clear from the data.
<div id="scene-data"></div>
**The path is almost always blocked.** 97 percent of logged amateur microwave contact paths are terrain-blocked at an average diffraction loss of 36 dB. Beyond-LOS is not the exceptional case, it is the default case. Clear LOS paths are short and rare. The long contacts that show up in contest logs are all riding atmospheric enhancement of some kind.
**The path is almost always blocked.** The numbers in this section come from the [ARRL 10 GHz and Up Contest](https://www.arrl.org/10-ghz-up) logs I've been able to collect so far. In that dataset, 97 percent of logged amateur microwave contact paths are terrain-blocked at an average diffraction loss of 36 dB. Beyond-LOS is not the exceptional case, it is the default case. Clear LOS paths are short and rare. The long contacts that show up in contest logs are all riding atmospheric enhancement of some kind. The sample is as good as it currently is; if you have logs I don't, [please send them](https://prop.w5isp.com/contribute) so the distributions sharpen instead of drift.
**Binary duct detection is a coin flip.** The median contact distance when HRRR says "there is a duct" is statistically identical to when it says "there is not." What separates a working 10 GHz morning from a silent one is the *strength* of the gradient (how far past −200 N/km it gets), the *thickness* of the layer in meters, and whether that thickness matches the wavelength. Ducting is a shape, not a switch.