[clug] WiFi Direction Finder

[Kim Holburn]

On 2005 May 6, , at 11:33 AM, Michael James wrote:

> 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?

With a good directional antenna you can probably not worry about them?

>
> -- 
> 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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-- 
Kim Holburn
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