Descriptions & Equivalents
- bomb/drug-sniffing dog
- canary in a coal mine
- dual beam alarm
- glass-break sensor
- gunfire detectors
- laser beam circuits
- metal detectors
- motion detector (active/passive)
- nanny cams
- perimeter intrusion detection system
- radon detector
- scram ankle bracelet
- smoke detector
- surveillance system
- thermal detector
- x-ray machine