Fresnel Zone/Terrain Visualizer

When I started tinkering with DMR on my OpenGD77 modified TYT MD-UV390 Plus I found that I was able to Parrot off of a repeater with a couple hundred feet of hill in between. According to The SCADACore line of sight tool there is no line of sight. The signal should clearly be blocked by hills. However, the signal got through at transmission power less than 1 watt. 

So that prompted me to dig deeper into why this might be. Fresnel zones popped up right away as a possible contributor to my unexplained link. And while it seemed like it wouldn't account for the entirety of the effect it might give me clues. After a quick search yielded nothing, I decided to make a tool and because I had limited time to devote to the project I asked my favorite coding language model for assistance.  

This coding project went surprisingly fast. I am used to arguing back and forth with a language model to get details just how I want them, so this was a nice change of pace.

One of the key things that I set out to accomplish was to show multiple Fresnel Zones clearly because reflections at the boundary of odd numbered zones provide constructive interference and even numbered zones provide destructive interference. The code will be made available soon. I'll just be updating the post, so check back if you are interested in using it offline or forking it. For now feel free to use it here

Big thanks to  KJ7SU [Glenn Lebrassuer], KO4TL [Josh Mendez], and KK7UUN [Ben Crall] for you assistance in this investegation.


We'll save SNR and Eb/No for another investigation.