[clug] WiFi Direction Finder

Michael James Michael.James at csiro.au
Fri May 6 01:33:33 GMT 2005

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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