"Roger Long" wrote in
:

I just realized that the SPOT probably doesn't have a GPS in it but
works like the cell phone GPS. All it does in tracking mode is wake
up ever 10 minutes and transmit a short series of numbers to the
satellite. One is the unit identifier and the other is the raw GPS
data received. This little burst probably takes a millisecond. The
rest of the time, it's just sleeping unless someone pushes one of the
buttons. All the position processing is done on the big computer back
in Texas. Everything except the unit ID, is input into the website by
the user so does not need to be transmitted.


It has a full GPS chipset in it. GPS isn't like the old receivers, now.
Once they have a fix initially, they resync in milliseconds as soon as the
3rd bird completes its statement. It's quite fast.

The GPS won't be far from its last position, so it doesn't have to do a
bunch of searching when it's in tracking mode. That's why the battery is
so long running. Then it goes back to sleep.