While jammers simply block GNSS signals making positioning impossible, GPS spoofers are intended to take control of the positioning output to deceive the end user. This is done by transmitting counterfeit GPS signals into the GPS antenna.  Spoofers can alter the tracks recorded by vehicle monitors and break geofences which are commonly applied to restrict operational areas. Spoofers also pose a risk to critical infrastructure, including power centrals, telecommunication networks and transportation systems, as they rely on GPS for precise timing.