Having sussed my software stability problems with the LLAP serial library I polished off the GPS tracking tag I've been making and took it out for a range/accuracy test in the sort of environment it'll get used in, ie. a large hilly wood.
This weekend was our first Lasertag event of the year and the site is a good example of the sort of thing you see in LARP. I wasn't expecting a massive range but in the end was a bit disappointed with only about 50m.
For this I did a slightly unscientific test using a USB stick radio and wandering off with a laptop until I stopped seeing packets from the tag. The USB stick only has an integral chip antenna so I'd expect a bit more with a wire fitted, but this is nothing like the 150m I'd hoped for.
Still, my plan was for this stuff to work in a mesh as even 150m isn't very far in a large wood, so making some high power transmitters with decent aerials to act as relays was kind of always on the cards.
The good thing is that under the trees the GPS module gets accuracy 100% of spec or occasionally better, so that's down to a 2m area. Which is great, 5m or so would be good enough.
I already have a couple of high power radios and sticking them in boxes to act as relays should be fairly easy. The sticky bit will be the software, so I mustn't underestimate how long that will take. It always takes me 2-3 times longer than I leave time for and I end up pulling some late nights before I need it.