Mapping wireless accesspoints

Posted by Rudi on onsdag dec 25, 2013 Under Fritid

This summer I did a small prof-of-concept test, where the goal was to estimate the position of a wireless accesspoints by collecting datasets containing signalstrength and position. The first approach was to search the free software marked available on my phone. unfortunately none of the applications I tried did as I wanted. The solution was to write a simple android app to continuously make a site surway on the wireless network and store it in a datafile along with the position from the GPS. Afterwards a small python script was written, facilitating matplotlib, numpy and some GPS utils from the robot software platform Frobomind to analyse the data and produce a map.

For the test, two accesspoints were used: One transmitting with default power and standard antennas. The second one was set to transmit at 250mW using two high gain antennas. The output map from the test can be seen below.

ssid:_smiley2

Accesspoint 1 (~50mW, Standard antenna)

ssid:_dd-wrt

Accesspoint 2 (250mw, high gain antenna)

The white area in the map shows where the phone where not able to detect the accesspoint, and the blue line is the path i walked to collect the data.  Note that the scale of the  color intensity is not comparable between the two maps.

Below is a picture where a satellite image has been placed roughly below the produced map (standard accesspoint).

2_smiley_maps

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