Wireless Sensor Node for Autonomous Monitoring and Alerts in Remote Environments

NASA’s Jet Propulsion Laboratory, Pasadena, California

The current radio infrastructure for firefighters provides voice communications, but does not support data transfer capability for continuous monitoring of people in the field. Current radios require user interaction to perform manual voice check-in for firefighter status. A new infrastructure is required to enable continuous, autonomous monitoring of firefighters at work via a remote command and control center. The system also needs the capability to send two-way alerts in real time as early warning of impending danger to firefighters and as indication of an emergency in the field due to a downed firefighter(s).

The Personal Alert and Tracking System (PATS) prototype node components, including the microcontroller, radios, and sensors, are integrated into a single circuit board.

The Personal Alert and Tracking System (PATS) consists of a networked collection of custom-designed, low-power wireless nodes that provides tracking of the position of the nodes. A PATS node is capable of transmitting sensor information and receiving visual/audible alerts and warnings over an extended rugged area. The nodes are equipped with onboard GPS, temperature, and accelerometer sensors with the ability to interface additional sensors as needed to each node. Mobile nodes form arbitrary network topologies and use a multi-hop packet routing protocol to relay sensor data to the command center. The multi-hop capability enables robust communication in a variety of environments by routing around natural and manmade terrain features. PATS nodes can communicate over several kilometers with burst rates of tens of kilobits per second. Embedded software on each node captures and processes sensor data, and displays alert information to the person carrying the node.

PATS integrates several different technologies to implement a system that is capable of relaying information between widely distributed entities such as between frontline wild land firefighters and remote command centers. PATS nodes may be mobile, and the mesh networking technology is able to route data autonomously via a self-organizing network. The PATS node hardware design integrates all processing, sensing, communication, and display components into one device. In particular, there are two radio transceiver chips that enable operation at two different frequency ranges: 902-to-928-MHz ISM band and 400-MHz licensed band. These two radios enable the same hardware device to operate as either a mobile sensor node or a relay base station. The PATS node includes a RF power amplifier that enables a line-of-sight communication range of 2 km between two nodes in the 902-to-928-MHZ frequency range. The hardware design is extensible, and headers are available for interfacing with external sensors and radios.

The PATS node can be used as a personal monitoring device for astronaut health without requiring a tether, and can be customized with additional sensors due to the flexible architecture of the node. These nodes can also be used to overlay a sensor network onto an array of mobile platforms roving over another planetary body (e.g., Mars) for coordination of the platform movement.

This work was done by Steve P. Monacos of Caltech and Anand V. Panangadan of Children’s Hospital Los Angeles for NASA’s Jet Propulsion Laboratory. For more information, contact This email address is being protected from spambots. You need JavaScript enabled to view it..

In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to: