Ming the Merciless
There is no mercy
- Location
- Inside my skull
Can't say I know a huge amount about it: the GPS satellites broadcast on two frequencies. One is an unencrypted signal intended for civilian use and the other is encrypted and used by the military. The unencrypted one can be "jammed" by broadcasting a rogue signal (from the ground) on the same frequency. Because it is unencrypted the GPS can't tell the difference from a real GPS signal. The rogue signal can be as simple as providing a lot of noise to swamp the GPS signals, or to make the handheld GPS think it is somewhere else, or invalid data that could even crash a unit.
There are reported instances of it being used around military bases, over wider areas during NATO exercises, near airports, near speed cameras and other instances. Note it is only the civilian signal being jammed not the military.
I have had my etrex 20 crash in specific locations on seperate occassions seperated by more than one day. It has crashed no matter which direction I approach from. The locations suggest it might have been a jamming signal. It wasn't mapping as I had no mapping or routing deployed on the unit at the time.
As it is a very rare thing indeed for the Garmin Etrex series to crash I don't worry about it.
