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
View from point D > C. Not the best case scenario for 2.4ghz rf.
View from point C > B
View from point B > A
A from the clear
At the base station
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
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.
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
The gps can be had as cheap as nz$40 per unit
$35 radio modem module
$5? suitable case.
On the base station side,
$10 USB > RS232 converter
$5? suitable case.
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.
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Comment by Ouranos, on 8-Feb-2010 21:07
Comment by d3Xt3r, on 11-Feb-2010 16:40
- Did you use any external GPS antenna, or have considered using one? It would be interesting to see how much difference it would have made.
- How do you plan solve do the 'smart updating' bit. Personally I've thought of using an accelerometer..
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