Post B5CWJplGJMhLs7Z2Zc by moira@mastodon.murkworks.net
 (DIR) More posts by moira@mastodon.murkworks.net
 (DIR) Post #B5CWJowvKWQrM00q6y by moira@mastodon.murkworks.net
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       okay so let's think this outI have a UHF antenna at a not well known height pinging a location gmaps says is 1084 meters away (line of sight).We'll call the altitude of that location 0m to simplify maths. Openmaps has it on the low side of a 20m line. That matters to get actual altitude at the end; at most, it's another 2-3m down probably?At 850m (straight-line) from my 0m location, a signal clears a +70m hill on its way to either end.So start at 0m and create a right triangle with the signal path, and 70/850 should be the tan() of the angle from the 0m point. Therefore 70/850 = X/1084, and doing the maths gets you X = 90m.90+20=110m, ish.But my best direct estimate from the same topo maps is 93-95m.#gmrs #AmateurRadio
       
 (DIR) Post #B5CWJpGQA21oKT8PVA by moira@mastodon.murkworks.net
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       Being at +93ishm _does_ clear the +70m hill (90m actual) but not at an angle that should let me see the 0m points - but I do.So.Bouncy signals? Bad maths? Weird RF-over-angle behaviours? (Same kind of thing gets you picket fencing)I dunno.hmI don't think I'm fucking up my maths but am I?Or is this "don't mix google maps and open maps it only leads to pain"?#gmrs #AmateurRadio
       
 (DIR) Post #B5CWJpYr3Um1Fdl8Ea by flyingsaceur@ioc.exchange
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       @moira ACHIEVEMENT UNLOCKED: knife-edge diffractionhttps://www.raymaps.com/index.php/knife-edge-diffraction-model/
       
 (DIR) Post #B5CWJplGJMhLs7Z2Zc by moira@mastodon.murkworks.net
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       @flyingsaceur That's (part of) the thing that causes picket fencing, innit? Or am I conflating things that I shouldn't be conflating?anyway that diagramme is helpful thanks, it's a bigger angle add than i expected!