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Terrain Mapping - Marvin VE3VCG - 2021-05-17
Plotting a path between two points for 2 meter line of sight communications is an interesting exercise. The DX commander discovered a feature in Google Earth which allows the easy creation of a terrain elevation profile between 2 points with a couple of mouse clicks. This should be very useful for those, like me with an interest in 2 meter simplex or those working 2 meter side band. This is very short but interesting illustration of how to use this handy feature.
RE: Terrain Mapping - Richard VE3OZW - 2021-05-17
(2021-05-17, 08:05:43)marvin.double Wrote: Plotting a path between two points for 2 meter line of sight communications is an interesting exercise...Hey Marvin, looks good. I have been using this website that Dave Newcombe forwarded last fall. It works very well although sadly it shows that I am pretty much trying to get through a large portion of earth to get out anywhere.
https://www.scadacore.com/tools/rf-path/rf-line-of-sight/
RE: Terrain Mapping - Marvin VE3VCG - 2021-05-17
(2021-05-17, 08:29:18)VE3OZW Richard Wrote:(2021-05-17, 08:05:43)marvin.double Wrote: Plotting a path between two points for 2 meter line of sight communications is an interesting exercise...Hi Richard, and thanks for the link. I saw this site in my research but didn't try using it until you shared the link. Here's the amusing result I got plotting a line roughly between Paisley and Barrie. As improbable as it seems, I can hear Barrie, although not reliably, even on my mobile. I have reasoned that, in spite of the apparent massive Escarpment between here and there, the terrain may contain valleys or gaps which allow RF to sneak through. John VE3KOT and I have had a couple of discussions about this idea. He indicated that at one of his previous locations he made use of something called the edge effect to hit a repeater which could not be reached directly. I'm not of course ruling out ducting and skip as possible explanations for hearing Barrie on 2 meters but I'm considering all possible angles (pun intended). My plot follows below.
Hey Marvin, looks good. I have been using this website that Dave Newcombe forwarded last fall. It works very well although sadly it shows that I am pretty much trying to get through a large portion of earth to get out anywhere.
https://www.scadacore.com/tools/rf-path/rf-line-of-sight/
RE: Terrain Mapping - VE3WI Dave - 2021-05-17
Marvin your plot is hard to read, looks like an encrypted message to a spy :-)
I gave the Google Earth method a try for my QTH to VE3OSR. See attached.
I couldn't find a way to copy the graph so I used the snipping tool & pasted it into a LibreOffice Draw page. Had to add my mast elev. & OSR tower manually. The app in the link I sent to Richard is designed for this purpose, so it lets you input those parameters. I think Tom said OSR ant. was at 300' but I drew a 200' line as well. Easy to see why my net attendance was iffy until the link came up.
EM ground waves do bend around the curvature of the earth a bit so the actual range is a little more than direct line-of-sight.
73
Dave, VE3WI
RE: Terrain Mapping - Marvin VE3VCG - 2021-05-17
(2021-05-17, 14:48:11)VE3WI Dave Wrote: Hi Dave and thanks for your reply.
When I did my plot I had my screen capture utility capture it to my clipboard. I though it would just paste the image into the post as one does with email. However the result obviously, was not the image but the underlying code. My apologies, but I didn't really have time to delete the post and then do it over by saving the clipped image to a proper image file then uploading that.
I will have another go at it when I get time to do it properly.
Marvin your plot is hard to read, looks like an encrypted message to a spy :-)
I gave the Google Earth method a try for my QTH to VE3OSR. See attached.
I couldn't find a way to copy the graph so I used the snipping tool & pasted it into a LibreOffice Draw page. Had to add my mast elev. & OSR tower manually. The app in the link I sent to Richard is designed for this purpose, so it lets you input those parameters. I think Tom said OSR ant. was at 300' but I drew a 200' line as well. Easy to see why my net attendance was iffy until the link came up.
EM ground waves do bend around the curvature of the earth a bit so the actual range is a little more than direct line-of-sight.
73
Dave, VE3WI