I've been attempting to survey the growth of Wi-Fi in the Phoenix AZ metro area since 2002. I selected a standard route that happens to include my home and office, as well as a few other spots I have at least an intermittent need to visit on a monthly basis. The route includes the cities of Scottsdale, Tempe, and Phoenix, and a variety of neighborhoods, from toney residential to college to just-plain-Joe neighborhoods, as well as commercial, light industrial, and resort/lodging. A broad mix, by no means perfect, but it fit where I needed to go, and quite often I actually find myself along that route during the month.

I also wrote a couple pieces of software to help me analyze the NetStumbler summary logs generated over that month. There could be dozens of logs, each for a day or less, or a short trip, and rarely more than a day in length. I use Stumbler to create one giant .ns1 file for the entire month (open the first file of the month, then merge the subsequent files for the remainder of the month). Next, export from that a NetStumbler "Summary" file, and use the .sum suffix for that. Next, I created an Excel spreadsheet that had a hunk of Visual Basic behind it to allow me to import that summary file, and to throw out all the APs that were not within a certain distance (in my filter, 100m) from the standards route. That way, I could drive hither and yon, and so long as I'd cross the route, I could collect data. Also, This allowed me to do a drive of the route, but if I needed to go off route for a stop at the grocery store, then return to the route, the extra APs inevitably collected while off-route would get tossed.

Finally, with the scrubbed AP summary file, I run that through a mapping program I wrote in VB that takes a premade map and plots, as a function of received signal strength, each access point that was determined to be on the route. Easy, huh?

Now, I haven't been perfect about completing the route every month, and I've gone through a couple of computers, several WI-Fi client cards, and the conversion from Win ME to Win XP Pro. Also, NetStumbler went from version 0.30 to 0.40, which added a few kinks to the equation. But, it seems to be working properly now, and my current setup appears to get about 80+% of all the hearable APs in the first pass. I consider that fair, but it could be better!

Copyright © 2006 Jon Trent Adams
jon (at) jonadams.com