[aprssig] Off-Topic

[Wes Johnston, AI4PX]

another way would be to use IR led's to send fake GPS positions
serially.  Make several of these small IR serial beacon devices and
place them around the cooler on the ceiling.  Then use a tiny trak or
open track with a 38khz IR reciever (like the ones used on TV remote
controls) attached instead of a GPS.

When the user walks under one of the "fake" GPS ir senders, his tiny
trak will think it's seen a single valid sentence from a GPS unit.
After he leaves the beam, the tiny track should rememeber this last
position and use it the next time it wants to transmit.

Of course the other way to do it is to have the users wear IR beacons
that beacon continuously as long as they are moving (so they don't run
down battery at night when not in use).... and have IR receivers on
the ceiling that are uniquely numbered such that you know that user #1
was heard by receiver #A or reciever #Z.

The people who make VNC used to make an active badge system that used
IR beacons... then they made an active bat system that used ultrasound
to measure time of arrival and calcualte positions.  Can't find the
pages right now....

Wes

On 5/25/07, Tom Hayward <tom at tomh.us> wrote:
> Stuck on GPS? This is such small scale, I don't think GPS is what you need.
>
> If you just need to be able to find people within the freezer, you
> could use avalanche beacons.
>
> If you want to make GPS work, you could try a GPS with the SiRF III
> chipset. These are ultra-sensitive receivers and I've never lost lock
> in a building. I've never taken one into a giant freezer either
> though.
>
> Tom KD7LXL
>
> On 5/25/07, Dave Kaplan <davek at cloverleaf.com> wrote:
> > I am interested in being able to use GPS to locate people and equipment
> > inside a -22 freezer that is roughly 100 meters square.
> >
> > I was reading about a product to bring a GPS signal inside a building:
> >
> > http://www.mobilegpsonline.com/gpsantrk304.htm
> >
> > At the same time I am looking for high accuracy (less than 1 meter) so I
> > might need to set up a DGPS in addition.
> >
> > Has anyone had any experience with doing something like this? Please
> > contact me off-line at davek at cloverleaf dot com
> >
> > Dave
> > WB0WNX
> >
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> >
>
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