Glossary
2D/3D GPS reception
The GPS receiver uses signals from satellites to calculate its current
position (the user's position), but to acquire a 3D position at least four
signals are necessary, including altitude. The GPS device may not be
able to acquire signals from four satellites as they are constantly moving
and obstacles may block satellite signals. Although the accuracy
decreases when only three signals can be acquired, and altitude data
cannot be sent, the receiver can calculate a latitude and longitude GP 0