Repeater maps!

Mainly out of curiosity, I decided to map the repeaters in my repeater database coded by CTCSS.  This was a bit of fun, because I had to clean the data (it's amazing how many repeaters are listed with silly CTCSS tone values like "961" or "Yes") and then figure out how to generate a map and put the data onto the map.  The last bit was aided immensely by the Generic Mapping Tools, a nice little set of tools very much in the UNIX spirit.  As K6HX put it to me, "it's quirky, but does a good job once you figure it out".

Click on the thumbnail to go to the full size image on my wiki.

I was kinda hoping that you could see the way some coordination councils use CTCSS tones regionally, but it's not very obvious except for a couple places, like Western Pennsyvlania, Michigan, and Wisconsin.  A different color code might help here; I'll have to explore that later.  I might also do another map, coloring by the majority CTCSS tone in each grid square, but first I'll have to figure out how to plot regions.

By the way, the most popular CTCSS tone is 100.0, with the next four (which trail by quite a lot) being 103.5, 123.0, 107.2, and 88.5.

I'm also really curious about the repeater out in the waters off the coast of North Carolina.