Wireless Hacks

Establishing Line of Sight

Use these methods to quickly tell if a long distance wireless shot is possible.

Wireless networks operate at microwave frequencies and, as such, work much better when the client’s antenna can see the AP’s antenna, with nothing but air between. Over short distances (within a few hundred feet), wireless networks can tolerate a few objects in the way. But as you try to push your signal further, having clean Line Of Sight (LOS) is absolutely critical.

How can you tell if a given point has LOS to another point several miles away? The short answer is that without actually having a look, you can’t. If the far end is more than a couple of miles away, it becomes difficult to tell, even with a high-powered telescope. But using these techniques, you can make an educated guess as to what is at least within the realm of possibility.

Using a GPS to Log Prospective LAT/LONG/ALT

When visiting a potential node site, it’s a good idea to bring along an accurate GPS. It can log not only the (more or less) precise latitude and longitude, but also the altitude of the site. After collecting points, you can pull them into your topographical software and plot them. For example, the Topo! package from National Geographic (http://maps.nationalgeographic.com/topo/) allows you to easily mark up a topographical map and analyze arbitrary points and routes. Draw routes between any two points to figure out how the land lies between them. This gives you an easy visual reference for ...