Wireless Sensor Node for Autonomous Monitoring and Alerts in Remote Environments

A method, apparatus, system, and computer program products provides personal alert and tracking capabilities using one or more nodes. Each node includes radio transceiver chips operating at different frequency ranges, a power amplifier, sensors, a display, and embedded software. The chips enable the node to operate as either a mobile sensor node or a relay base station node while providing a long distance relay link between nodes. The power amplifier enables a line-of-sight communication between the one or more nodes. The sensors provide a GPS signal, temperature, and accelerometer information (used to trigger an alert condition). The embedded software captures and processes the sensor information, provides a multi-hop packet routing protocol to relay the sensor information to and receive alert information from a command center, and to display the alert information on the display

Fast high-resolution terahertz radar imaging at 25 meters

We report improvements in the scanning speed and standoff range of an ultra-wide bandwidth terahertz (THz) imaging radar for person-borne concealed object detection. Fast beam scanning of the single-transceiver radar is accomplished by rapidly deflecting a flat, light-weight subreflector in a confocal Gregorian optical geometry. With RF back-end improvements also implemented, the radar imaging rate has increased by a factor of about 30 compared to that achieved previously in a 4 m standoff prototype instrument. In addition, a new 100 cm diameter ellipsoidal aluminum reflector yields beam spot diameters of approximately 1 cm over a 50×50 cm field of view at a range of 25 m, although some aberrations are observed that probably arise from misaligned optics. Through-clothes images of concealed pipes at 25 m range, acquired in 5 seconds, are presented, and the impact of reduced signal-to-noise from an even faster frame rate is analyzed. These results inform the requirements for eventually achieving sub-second or video-rate THz radar imaging

Detecting Anomalous Human Interactions Using Laser Range-finders

We present a laser range-finder-based system for tracking people in an outdoor environment and detecting interactions between them. The system does not use identities of people for tracking. Observed tracks are automatically segmented into individual activities using an entropy-based measure (Jensen-Shannon divergence [12]). Two people situated close to each other throughout the duration of an activity represents an interaction. The observed activities are combined using a hierarchical clustering algorithm to generate a representative set. The frequency of occurrence of these activities is modeled by a Poisson distribution. During the monitoring phase, this model is used to compute the probability of observing the detected activities and interactions; an anomaly is flagged if this probability falls below a threshold. Experimental results from an outdoor courtyard environment are described where the system indicates anomalies when there is a sudden increase in the number of people in the environment or in the number of interactions. This detection occurs without giving the system any a priori concepts of space occupancy