VSN240 Wireless Flush-Mount SensorA Flush-mount sensor with a state-of-the-art Magnetometer


Sensys: VSN240 Wireless Flush-Mount Sensor

Sensys Networks Wireless Flush-Mount Sensors combine a state-of-the-art magnetometer and a low-power radio in a small, hardened plastic case suitable for installation directly in the pavement.

    • 3-axis magnetometer for vehicle detection
    • Superior accuracy
    • Exceptional reliability
    • Flush-mount in-pavement installation with no wires or lead-in cabling
    • Fast & Simple installation and deployment reduces road closures and worker exposure
    • Extremely long battery life – average of 10 years
    • Reliable 2-way radio communications with access point
    • Can be readily deployed where other systems cannot be used
    • Re-usable and remotely upgradeable
    • Capable of over 300 million detections
    • Impervious to weather
    • Patented, ultra-low “NanoPower” communications protocol
    • Superior accuracy, dependability and extensibility
    • Universal platform for all traffic detection applications


    The Sensys Networks VDS240 Wireless Vehicle Detection System uses wireless magneto-resistive sensors to detect the presence and movement of vehicles. The sensors – installed on the surface or in small holes cored in the roadway – transmit detection data in real-time via low-power radio technology to a nearby Sensys Networks access point. Vehicle detections are further relayed to a traffic signal controller, remote traffic management center or other system.

    In typical traffic management applications, a sensor is placed in the middle of a traffic lane to detect the presence and passage of vehicles. Vehicle speeds and length are measured by two sensors installed in the same lane with the exact distance between them configured in software. The recommended distance between sensors depends on the range of expected speeds to be measured: for typical freeway applications, a separation of 20 to 24 feet (6.1 to 7.3 meters) is recommended; for typical arterial applications, a separation of 10 to 12 feet (3.1 to 3.7 meters) is preferred.

    The state-of-the-art magneto-resistive sensing devices in each wireless sensor measure the x-, y- and z-axis components of the Earth’s magnetic field at a 128 Hz sampling rate. As vehicles come within range, changes in the x, y or z axes of the measured magnetic field become apparent. When no vehicles are present, sensors continually measure the background magnetic field to estimate a reference. Each sensor automatically self-calibrates to the local environment and to any long-term variations of the local magnetic field, by allowing this reference value to change over time.