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I have line of sight issues with repeaters I want/need to use (it's a repeater network my club uses). One of the options that might be available to me is to install a "passive repeater" in a location that has line of sight both to my home and to one or another of the repeaters.

Is there a public tool that can be used to plot line of sight from arbitrary heights above ground between selected points (say, using Google Maps data)?

Mike Waters
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Zeiss Ikon
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3 Answers3

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I've used this one several times.

added:

  1. Go to the graphic under: Surface Elevation Tool.
  2. Scroll (zoom out to speed things up) OR use the search to get to your geographic area. Search somewhat reliably recognizes town,state names and zip codes.
  3. Zoom into and Click on a location to drop a balloon.
  4. Zoom out and scroll to other location - zoom in and click again to drop other balloon

  5. Click balloons to enter heights (in meters)

    Note that for longer distances (where it matters!) the earth's curvature is NOT being taken into account.

mike65535
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    For distances reachable with a hand-held or mobile, Earth curvature is negligible -- a few feet in thirty miles to the mountain-blocked repeater in this question. – Zeiss Ikon Mar 28 '19 at 12:15
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    Well, the good news is, this tells me for sure. The bad news is, the mountain in between is a good thousand feet above my sight line to the receiver that direction, at just over 1/10 the distance. I don't think diffraction (as suggested in comments on my other question) is going to help. – Zeiss Ikon Mar 28 '19 at 22:46
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HeyWhatsThat is a free web app that can show you the view from any location and elevation. From what I've seen (I haven't used it seriously), it's a bit clunky but it does the job.

You can also see a plot of elevation between two points, which is useful if you want to consider Fresnel zones in your propagation analysis.

Kevin Reid AG6YO
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    I've used HeyWhatsThat for years. It was really ahead of its time when it first came out, and it's still pretty cool. There used to be a phone number one could call; the caller would punch in his or her coordinates with the touch-tone pad, and then the computer would read out the names of the prominent mountains and their bearings. Super-cool in the pre-"smart"-phone days! – rclocher3 Mar 28 '19 at 17:39
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Google Earth Pro (now free. $0) has a Viewshed tool.

"A viewshed is the geographical area that is visible from a location. It includes all surrounding points that are in line-of-sight with that location and excludes points that are beyond the horizon or obstructed by terrain and other features (e.g., buildings, trees)." --Wikipedia

https://support.google.com/earth/answer/3064261

https://www.gearthblog.com/blog/archives/2015/02/google-earth-pro-viewshed-tool.html

https://www.youtube.com/watch?v=9SP1O8q2Lng

https://www.youtube.com/watch?v=DcZ8hyHZnu0

https://techcrunch.com/2013/04/22/google-launches-google-earth-pro-7-1-with-new-viewshed-visualization-tool-and-improved-printing-options/

https://www.forbes.com/sites/amitchowdhry/2015/01/30/google-earth-pro-is-now-available-for-free/

Dan Jacobson
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