Do they work instantly or do they have to find satellites? My satnav can sometimes take ages to "wake up"
Nick
In theory, there are at least 4 GPS satellites observable from any location at one time (4 is the minimum you need to get a fix). But as the receiver is looking for the radiant energy equivalent of a candle at 100m, it's easy for the signal to be dissipated especially by thick cloud. That's why it can take a few minutes to latch on to sufficient satellite signals to get a usable location.
