[clug] WiFi Direction Finder
paul.wayper at anu.edu.au
Fri May 6 00:39:37 GMT 2005
The Register has an article today on a new device from Cisco which can
track the location of a WiFi device - even an 802.11 RFID tag - down to
about five metres (which is about 16 nanoseconds). It only works with
certain base stations and costs USD$15,000 or so.
Strangely, I was thinking of this problem (it bothers me that someone
can set up a rogue access point and get away with it) the other day.
The basic kit would consist of two WiFi aerials a known distance apart,
connected to a machine that could timestamp them to nanosecond
accuracy. A separate machine or process could then analyse the timing
between the occurrences of each packet on the two aerials out-of-band.
Sweep the stick around, and when the timing difference was exactly the
same as the distance between the aerials (or, more generally, approached
a maximum), your stick points to the access point. Further improvements
would be to include further aerials for triangulation, and change it to
a bunch of access points of known location - longer baselines equal
Anyone interested in working on such a project? Please contact me on
this email address or at home on paulway at mabula.net.
-- Paul Wayper at ANU - +61 2 6125 0643
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