a better border

Seismology

You plant seismic probes all over the desert border area which are tuned into the bipeds and vans

You create an underground radar network. There would be no false positive as not much bigger than 140 pound roams the desert. Any seismic action would be from people and trucks crossing the desert.

SA900 Seismic Sensor
"The Seismic Probe detects micro vibrations in the 10 HZ range, which
makes it particularly sensitive to footsteps."


This would also alert authorities to tunnels being built under the border as well.