> i've read all sorts of crap about direction finding of
> Wifi targets from people who dont know what they are talking about including
 
Beeing a specialized "non specialist", I feel I can answer this kind of 
question.
 
RF direction finding (aka goniometry or RDF for Radio Direction Finding) is a 
sport invented circa 1930 (well, I mean the "serious" way to do it) by a french 
ingeneer called Robert Deloraine, inventor of the "instant goniometer" 
(location of german subs in mediteranean see befor WW2). Deloraine ended his 
carreer sadly as general manager of ITT. 
 
Instant direction finding is able, with very simple trigonometry knowledge and 
a simple couple of switched antenna network, to locate the exact position of a 
transmitter in less than 1/10 of a second, and with a investment under 50 $. 
And without any plane or balloon.or other exotic practices. Switched antenna 
network used for direction finding are based on the same principle that some 
moderne WiFi access point with "optimized radiation patern"
 
It's even easier on 2.4 GHz. The higher the frequency is, the quicker and more 
precise is the location (as you can consider that over 100 MHz, all 
transmission are using a quasi -optical path... or sort of).
The only problem could be the number of Wifi signals in a suburban area, and 
the discrimination of the source amongst hundreds or thousands. But "software 
defined radio" systems are able to solve this question. When your are analyzing 
a radio signal in the "time domain" (opposed to a "frequency" domain), you will 
be able to differenciate the signature of a peculiar transmission. Developping 
this concept would be totally off topic, but I can swear than your can 
fingerprint a transmitter not only with his "direction" and " signal level" 
datas, but also with small particularities of his spectrum and time/spectrum 
signature (three letter agencies are using such an approach to discriminate 
VoIP conversations to spot the voice of a precise person)
 
Would you please excuse my poor english ad the fact that I'm definitely not a 
"security certified" guy.... just a tourist listning to Dailydave for fun and 
profit 
 
PS : by the way... you're right when you are saying that most of people 
speaking about wireless stuff is crap. RDF is like Wep (or WPA) cracking : few 
people are doing it.... far less than people who said they are able to do it.
 
Marc Olanié/f6itu
Journalist
www.cnis-mag.com 
<https://mail.suptel.net/exchweb/bin/redir.asp?URL=http://www.cnis-mag.com> 
A good working kernel is not supposed to crash unless it says "please"
(traduction : Da Power, Fantudjûû ! RuleZ Tartiflette !)
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