GS-21 Underground Sensor

The GS-21 Underground Sensor is the newest addition to Vortex Systems' unattended ground sensor line, designed for buried perimeter protection where pedestrian detection over a longer stretch of ground is required. Where the GS-20 relies on a single internal geophone, the GS-21 supports external seismic line strings — buried transducer strings that extend seismic coverage along a path, boundary or perimeter section for enhanced pedestrian detection. An internal magnetic sensor detects vehicle presence and direction of travel on driveways and access roads, and inputs are provided for external PIR sensors (pedestrian/vehicle presence plus travel direction) and contact-closure devices. Alarm traffic is carried by a built-in 5-Watt VHF radio with line-of-sight range up to 35 miles and strong foliage penetration. The sensor is fully compatible with legacy Vortex and Monitron systems, so it drops into existing deployments alongside GS-20 units, repeaters and base stations. A tamper switch guards the unit against interference, a mechanical relay output can trigger external devices such as cameras, lights and sirens, and programmable self-test messages with a real-time clock support scheduled access windows. Battery life exceeds one year for long-term unattended deployment. Alarms can be monitored through Vortex receivers and the Alert View mapping application, which provides pre-loaded offline maps (no internet required), real-time visual and auditory alerts, email/SMS notification and per-sensor low-battery alerts.