Mapping Hacks

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Chapter 2, Mapping Your Neighborhood

#19 Analyze Elevation Profiles for Wireless Community Networks

HACK

Caveats

Clearly, SPLAT! is useful software. It does a small set of things—RF propa-

gation and coverage analysis—and it does them fairly well. Still, there are

minor caveats to using it. The map size isn’t really configurable, there’s not

much way to control which cities get shown and/or which color they get

shown in, and the only supported base map is the digital elevation model

used to calculate lines of sight. In “Plot Wireless Network Viewsheds with

GRASS”

[Hack #74], we’ll look at how to circumvent some of the limitations of

SPLAT! by replicating its basic functionality in GRASS.

HACK

#19

Analyze Elevation Profiles for Wireless

Community Networks Hack #19

A web application and a few digital elevation models can significantly ease

the pain of building wireless community networks in remote areas.

If you’re trying to build wireless community networks out in the hills, like

the NoCat Network has done in Sonoma County, California, the first thing

you discover is that hills eat Wi-Fi signals for lunch. Modern wireless net-

working technologies, like 802.11b, need a line of sight to establish a con-

nection, and any significant amount of intervening terrain, trees, or

buildings between two points will quickly ruin your chances of setting up a

long-distance, point-to-point wireless connection. In