How to find line of sight distances
As a technician class licensee who operates only on 2m (for now), I usually live in the world of line of sight communications. If I want to talk to another station, I have a finite number of choices. First, I can be close enough to that other station that the RF from my handheld gets there no matter what. Second, I can use a repeater, which extends my range. Third, I can try to gain altitude. Fourth is use more power. There are definite limits to what I can do with the resources I have, but I want to know what those limits are so that I know if I’m having any luck when I try to stretch them. 
One measure I use is line of sight distance: how far away can my signal go? And how much of a difference does it make if I’m on this hill, or one floor up,or with this or that antenna? I need to plot distances on a map, but since I live in a city that is surrounded by lakes, the amount of water vs farmland between me and another station is important to me as well. I also need to do some calculating; I know there is always a scale on a map that tells me how many miles on the map equate to one inch. So I could get out a ruler, and count the number of inches, but I also have a computer to do that kind of work for me. Enter Google Maps, which will give you a very nice map of the area you’re working in, complete with satellite views. Google Maps is awesome for getting driving directions, but what it doesn’t do is let you plot distances between two points.
Now enter an application intended for runners called MapMyRun. This site lets you plot a run on a Google Map; you begin from a specific address, wherever else you click on the map, MapMyRun plots a straight line from the last point you clicked. If you’re setting up a run in the city, you click at each intersection or curve along your route. As you plot your run, the site keeps track of the distance you’re covering. Hmmm… you can instantly calculate the distance between two points on a map that’s superimposed on a satellite photo of the area you’re operating in.
I’ve found some interesting uses for this; first, I can specify where I’m operating from (the start of my “run”). Then, I can specify a point representing the station I’m talking to or trying to reach. That will tell me that I’m communicating with a station that’s x.xx miles away, line of sight. No calculations, no rulers, etc., and if I’m looking at the satellite view I can tell what kind of terrain is in the way. Second, I can quickly and easily find the distance from any location to a Skywarn reference point. Finally, I can store these plots on the site as saved runs, so I can compare them in case I turn up the power, move to a higher point, or try a new antenna.
There are probably more ways to use MapMyRun in a ham radio sense; if you come up with any, leave a comment and let me know.
