- Sun Dec 21, 2008 5:06 pm
In my mind, the better solution may be using the Xbee systems. These systems in and of themeselves will not give you location information. However, if you have an area your sheep will be in, put FIXED xbee systems in the corners of the area, and then you could track where the sheep are by looking at the signal strength between the sheep and the 4 corners. I saw a company doing something similar to this at the Boston Embedded Systems Conference a few years ago.
The key thing about xbee systems is that they have really good range when used as "Line of sight" especially depending on which devices you use (some of them go as far as 60 km (or miles, I forget which...) line of sight and could go farther but cant due to the curvature of the earth. I"m guessing you dont need really really accurate location for the sheep, just a "rough" idea so if you want to find them you can see where they are. I suspect with the xbee location you can get +/- 20 feet location sensitivity (which may be enough?). If the area is very hilly, you can get smart about putting the fixed xbee systems at the top of the hill (and therefore get good line of sight range).
You can have the fixed XBee systems "ping" each sheep every minute or so, and then have the location information fed back to your computer and have that information put up on google maps.
Using Xbee systems, this wouldnt be too expensive per sheep (~$35-$75 depending on which xbee system you would need.) The software on this wouldn't be trivial, but has many parts (google maps, location determination, etc...). If you have an Engineering college near you, this sounds like an excellent Senior Project for some electrical engineers or computer systems engineers (and a good way to get some free work done!).