Elevation plot between two geographic locations - Page 1
Forum section: electronics / general

author: metrologist
author_rank: Super Contributor
timestamp: September 01, 2023, 11:27:29 pm
content: I remember a long time ago I could see this plot from GPS data of a traveled path using what's likely long deprecated tools (Garmin), but I cannot take that data now and I'm interested in a straight line plot anyway. USBest I can think of is looking at a topographic map and manually plotting data points - a skill (or rather a task) that has died with the dinosaurs?

author: themadhippy
author_rank: Super Contributor
timestamp: September 02, 2023, 01:20:34 am
content: if youve a gpx file of the route gpx studio (https://gpx.studio/) gives you a good idea of the upy downess.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: September 02, 2023, 03:43:15 am
content: You can at least automate your old fashioned approach. Just use the lat/long of points along your path to query one of the available databases. Off of the top of my head the only free one that can be addressed this way is the space shuttle database which only has three meter vertical resolution, but I am sure there are others.

author: Fgrir
author_rank: Regular Contributor
timestamp: September 05, 2023, 04:03:41 pm
content: I use Gaia GPS for hiking all the time and it will let you see an elevation profile for a straight line route.https://www.gaiagps.com/map

author: tom66
author_rank: Super Contributor
timestamp: September 05, 2023, 04:07:05 pm
content: Probably not quite what you want as it applies for map routes, but if the route permits cycling, Google Maps can show the elevation profile. The task you're looking for more directly can be solved with DTED data. DTED files are quite easy to read and are openly documented, and available for most of the world from the USGS, though some levels of detail are classified.

author: nali
author_rank: Frequent Contributor
timestamp: September 05, 2023, 04:31:48 pm
content: Plotaroutewill do elevation plot, just turn off auto plot if you want straight-line rather than path/road following. You can also download the data e.g. as GPX if you need it to go on other devices.

author: floobydust
author_rank: Super Contributor
timestamp: September 05, 2023, 04:45:21 pm
content: Careful about using point-point straight line plots. Software does not tell you of obstacles or the map misses some details.We deployed a private radio network using that approach.Well, guess what there was a big hill between two points that ended up blocking the RF signal.The contractor was so desperate he pointed yagi's into the hill and it sorta worked but let's face it RF doesn't like mud and rock.He ended up putting a repeater at the top of the hill, on an existing cell tower. An expensive mistake.

author: abeyer
author_rank: Frequent Contributor
timestamp: September 06, 2023, 12:27:33 am
content: https://www.heywhatsthat.com/has some tools with a slant towards line-of-sight radio propagation.

author: BrianHG
author_rank: Super Contributor
timestamp: September 06, 2023, 12:33:10 am
content: Something like Strava & Veloviewer?https://veloviewer.com/

author: metrologist
author_rank: Super Contributor
timestamp: September 06, 2023, 12:45:24 am
content: These look like great solutions. Thanks!Quote from: floobydust on September 05, 2023, 04:45:21 pmWell, I was looking at 70cm and 50 miles, with 14 element Yagi. Or 2m and 4 element or double biquad reflector, with lips.

author: Someone
author_rank: Super Contributor
timestamp: September 06, 2023, 02:19:51 am
content: Quote from: abeyer on September 06, 2023, 12:27:33 amThanks! I couldn't remember the name of that (and google searches didn't turn it up). Such a great free tool.

author: floobydust
author_rank: Super Contributor
timestamp: September 06, 2023, 03:40:37 am
content: What the project taught me about relying heavily on contour maps and the software omitting:1. Any hills, buildings etc. between nodes (had to add a repeater at a hill top)2. One node is in a valley (has to clear trees and the valley side) or there is a cliff3. Tree height is not includedWith a high tree line, a taller mast means longer cable, and thecoax losseswere many dB more. Master site it was better to put the radio near the antenna and use a longer data cable lead-in.Above certain heights, the mast gets classified for lightning and airplane issues.The treeline also shades any solar power making the day quite short. We have bears and moose that scratch their backs on the masts and knock them out of alignment. Even a few degrees wobble or rotation in wind (you have to cement in the masts with supports) can scuttle signal strength.The system was installed in late Fall and worked but failed next Spring. It was the new tree leaves growing out with the short antenna masts that did not look over them. The Boreal forest is easily 30-50 ft. tall trees.This was 868MHz and 902-928MHz ISM (32cm) where water (in tree leaves, rain etc.) attenuates RF, about 10-20km runs and 1W +30dBm TX power. I can't recall the antenna but guessing 9dB Yagi.I would ask on RF forums about the range/frequency for your project. 50miles is a long run, I could not see it being done on the cheap.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: September 07, 2023, 01:47:23 am
content: Over 50 miles be sure to include earth curvature in your calculations. Topo maps and most related databases give heights relative to a reference spheroid (basically sea level). It takes a good sized tower is needed to see fifty miles even over "flat" terrain.

author: metrologist
author_rank: Super Contributor
timestamp: September 07, 2023, 03:54:07 am
content: yeah, never mind the hills. It looks like a spherical cap.

author: Someone
author_rank: Super Contributor
timestamp: September 07, 2023, 05:20:07 am
content: Quote from: CatalinaWOW on September 07, 2023, 01:47:23 amCare ofhttps://www.heywhatsthat.com/a view over Sydney:

author: Infraviolet
author_rank: Super Contributor
timestamp: September 08, 2023, 06:30:15 pm
content: That HeyWhatsThat site is really nice, gone straight in my bookmarks for next time I want to retroactively work out where the horizon was when hillwalking. Shame it can't pick up big man-made structures too though, I know what a colossal and time-variable dataset to include that would be though. When one is on a hill looking over a plain then TV masts, power stations, wind farms and church towers often form the most noticable points one hopes to be able to use to identify which areas on the flat terrain one is looking at.

author: metrologist
author_rank: Super Contributor
timestamp: September 09, 2023, 04:15:47 pm
content: Quote from: Someone on September 07, 2023, 05:20:07 amIt looks like the earth's curvature is highly exaggerated.

author: switchabl
author_rank: Frequent Contributor
timestamp: September 09, 2023, 04:53:34 pm
content: May just be the result of the vastly different scales on the X and Y axes? ~80km horizon distance seems about right to me.

author: metrologist
author_rank: Super Contributor
timestamp: September 09, 2023, 06:54:27 pm
content: Actually, that's right. It is just over 100m.