Could be fun for those high tech larps
This project started some time ago, (early 2008?) but is finally here.
As the name implies it can track multiple GPS units.
The tricky bit was the software.
There are some off the shelf products aimed at fleet management.
I tried to get some going but gave up.
The best candidate ran on linux but my kungfu is not strong there.
So after learning VB6, I wrote my own.
It’s pretty no frills at the moment.
-The test site
http://maps.google.co.nz/maps?ll=-36.815914,174.643008&spn=0.002358,0.003954&t=k&z=18
-Review
You can see me driving into the park.
I walk all 3 with me until IO loose the signal and then place the Red unti there.
I then walk around the bush to check signal, no loss.
Down the hill until I loose it near the bottom.
Place the yellow unit.
Down a path, don’t get far until I loose it.
Understandable once you see the picture.
The Red unit drifts quite a bit after placement as you can see by the clump of red around it.
Looks like about ±5m.
I forgot to take a pic of placement, it was in a tree, sideways.
So the gps antenna was not pointing up.
The Yellow not so much but probably more due to the fact it was not there long.
5 mins at most.
The Red was there for 13 mins?
A MediaTek MT3329 based module
http://www.quadroufo.com/product_info.php?products_id=68&osCsid=30f5671f821443f0877ab545feea6c3f
PAN4561 wireless module, loaded with Synapse Meshing firmware.
Each radio can repeat the signal until it gets to the destination.
The test from A to D would be 3 hops.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P14236CT-ND
http://www.synapse-wireless.com/
How small could it be made?
Comes down to how long you want it to run.
It draws about 3.3v 180mA.
The battery pictured will run it for 6 hrs.
It is a 2s lipo pack which would be reconfigured to 1s2p
Cost?
The gps can be had as cheap as nz$40 per unit
$35 radio
$5 battery
$5? suitable case.
$85
On the base station side,
$35 radio
$10 USB > RS232 converter
$5? suitable case.
$50
-To do
Adjustable trail length
Smart updating, eg no extra markers if unit is not moving
Since the Radios are 2 way, we could add a screen and send each unit text messages.