[plug] Wanted: dirt cheap wireless LAN

[Harry McNally]

On Fri, 3 Jan 2003 14:04:29 +0800 (WST) Mike Holland
<myk at plug.linux.org.au> wrote:

> On Fri, 3 Jan 2003, Harry McNally wrote:
> 
> > On Fri, 3 Jan 2003 08:59:35 +0800 "Daniel Pearson" <plug at flashware.net>
> > wrote:
> > 
> > > You can purchase an irda adapter that plugs in through serial or USB
> > > port for around $100.
> > 
> > Altronics have a kit for $27.95 STOCK-CODE: KC5323 
> 
> > http://www1.jaycar.com.au/produ...
> 
> Altronics??

Err. Sorry. Brain fade. Yep .. that'd be Jaycar that I meant :-}

> > I was looking at this last night in the cattle dog but it won't have
> > the range unless you attach IR laser pointers which haven't really
> > taken
> 
> Harry, would you be able to substitute a red laser diode and matching 
> photo-transitor in that kit?

On closer examination, no you can't. The irda device has a 5 volt supply
and tx and rx signals. I remember now from a previous look at these that
the LED driver and photo receiver amp and signal conditioning are all
inside the irda tranceiver thingami.  

Leon would do well to look at this site and accompanying links ..

http://www.epanorama.net/links/irda.html

because, given that there is a Linux implemention and that irda has
error recovery as part of the protocol it might offer a more robust
link. I think the Leon driver concept is ok but some sort of AC
coupling or other "ambient rejection" in the receiver signal path
might still be useful.

Wait! Found it. Go to Vishay and download data for TOIM3000 and
TOIM3232. These devices offer the interface in a chip to drive LEDs
laser or whatever. Or check the Altronics kit to see if they are
using this. If so, Mr Altronics (not Jaycar) is your friend.  

Also, this link ..

http://www.alphalink.com.au/~derekw/upntcvr.htm

.. also makes the interesting point ..

"
The need for stable mounting is by far the most significant disadvantage.
Building structures often move with time, temperature and wind. Building
foundations also generally move. Anticipate at least monthly realignment
for all but short (<100 metre) links between very stable buildings.
"  

I know. You mentioned lenses. Good plan.

> Alternatively, what about two accoustic modems and a length of garden 
> hose? Beats the avian suggestion :)

Someone else in the office here suggested colourful little semaphore
flags which I thought "yeah .. couple of stepper motors, ccd camera at
each end, image capture cards, some image analysis software on a
reasonably powerful Linux box.

But then again, fog could be a problem. 
Or the semaphore flags might shred (proportional to data rate).
Or you'll get some annoying little kids sticking there faces in the
camera doing that five fingers then two fingers thing. Bless em.

Other than that it'd be quite feasible :)
 
Harry

-- 
linux.conf.au 2003		The Australian Linux Technical Conference
http://linux.conf.au/		22-25 January 2003 in Perth, Western Australia

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