American ranchers along the Mexican border have been using ground radar to detect illegal migrants passing through their land. When illegals are detected, and confirmed by other sensors (day/night cameras and ground sensors), a call is made to the Border Patrol, which comes and makes the arrests.
The ranchers are using a British Blighter B202 Radar. This 35 pound device has no moving parts and can run, unattended, for 12 hours on one battery. The radar can detect people walking up to four kilometers away (and large vehicles up to eight kilometers). You can connect the radar to the internet and monitor it from anywhere. The radar software plots the speed and path of anything it detects. The radar does a 78 degree horizontal scan (electronically, not mechanically), and a 20 degree vertical scan. The software can be set to transmit five or one second updates. Up to 700 separate contacts can be tracked at once.
The Blighter B202 is used by police departments and commando units for surveillance. For commandos, the best feature of the Blighter B202 is its light weight (the lightest ground radar available.) The California ranchers are using the radars to discourage the people smugglers from using their property, and eliminate the frequent property damage and risks of other crimes.