[clug] WiFi Direction Finder

[tmc at dreamcraft.com.au]

Of course (yet) another approach is to build up a position (gps) vs
relative signal strenght (each packet is tagged with MAC address) "topo
map" and then apply the terrain model on top and use EM proagation
principles to find where the singal is most likely to be comming from...

Tomasz

> On Fri, 6 May 2005 10:39 am, Paul Wayper wrote:
>
>> 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.
>
> The sin function is flat at 1 (maximum)
>  but has a gradient of 1 at 0 (minimum).
>
> So you will get a more accurate angle
>  by turning till the signals arrive simultaneously
>  and sighting down the perpendicular bisector.
> Probably easier to pick in hardware too.
>
> Yes, checking which aerial was ahead at maximum
>  would tell you which way to sight...  ;^)
>
> One solution would digitise both inputs,
>  use software to define windows
>  when the target station is transmitting,
>  and check the alignment within those windows.
>
> When we see you wandering around
>  with a pair of wifi aerials rotating
>  we will know what you are up to.
>
> Echoes...
> How far can you get before you have to de-convolute echoes?
>
> --
> Michael James                         michael.james at csiro.au
> System Administrator                    voice:  02 6246 5040
> CSIRO Bioinformatics Facility             fax:  02 6246 5166
>
> Internet Explorer is fine for downloading Firefox,
>  but after that....
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