[clug] WiFi Direction Finder

Grant Baldwin kermee at softhome.net
Fri May 6 10:20:50 GMT 2005

Nice Thought, but you'll have trouble with the fading environment for
anything using multiple antenna at 2.4 GHz in a nice urban environment. 

A simple highly directional antenna looking for the maximum signal strength
will be easier to acquire, wont require specialised hardware/software and
should get you within 5m before you hit trouble.

-----Original Message-----
From: linux-bounces+kermee=softhome.net at lists.samba.org
[mailto:linux-bounces+kermee=softhome.net at lists.samba.org] On Behalf Of
Michael James
Sent: Friday, 6 May 2005 11:34 AM
To: linux at lists.samba.org
Subject: Re: [clug] WiFi Direction Finder

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.

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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