Unattended Ground Sensor Network

Introduction: NRL's Tactical Electronic Warfare Division (TEWD) scientists are exploring a novel unattended ground sensor network, the Adaptive Reactive Sensor and Effector Network and Insertion Capability (ARSENIC). The system is a heterogeneous mixture of unattended ground sensors and effectors that provide an adaptive distributed system with the ability to detect signals of interest and influence the environment. Key considerations for our unmanned ground sensor and effector network include size, mission duration, delivery method, precise and covert emplacement, probability of detection, sensor ruggedization, network communications, and detection classification. Additional issues include reach-back communications, antennas, and data visualization. Results of this research will be directly applicable to parties interested in countering threat radar, Weapons of Mass Destruction (WMD), and vehicle and/or infantry movements.

Unmanned Delivery: Unattended ground sensor networks have typically been deployed by "putting boots on the ground," or from manned aircraft. NRL has significant experience with unmanned air vehicles (UAVs) and UAV payloads-thus the desire to capitalize on these efforts to use an unmanned asset to provide precise and covert placement. As currently designed, the ARSENIC network is composed of 48 physically identical nodes deployed from a Finder Unmanned Air Vehicle (Fig. 1). Finder was developed by TEWD and is currently deployed from a Predator (MQ-1L) aircraft, shown in Fig. 2 carrying two Finder UAVs. The Finder was chosen because it provides a 400 km combat radius and a precision emplacement delivery system. In the absence of satellite communications, Finder can also operate as an airborne tactical relay. The unattended node (Fig. 3) is configured in an MJU-27B form factor. The MJU-27B is a common chaff or flare round carried by U.S. Naval aircraft, such as the F/A-18 Hornet. (Also shown is a small circuit board that incorporates an integrated CPU and Local Area Network (LAN) radio and battery.) A U.S. quarter is shown for comparison. After being dropped from the Predator, the Finder UAV will fly a pre-programmed route. When the area of interest is reached, the ARSENIC nodes will be deployed from the Finder and the wings will extend, causing the node to spiral down.

FIGURE 1
Finder unmanned air vehicle.

FIGURE 2
Finder aircraft on wing stations of Predator unmanned aircraft.

FIGURE 3
Prototype device using MJU-27B flare form factor.

Electronics: The electronics package includes a Texas Instruments MSP430F149 ultra-low power microcontroller, which provides limited computational ability, and a ChipCon CC1000 UHF transceiver, which provides a low-power communication network capability. Also shown in Fig. 3 is a lithium sulphur dioxide (LiSO2) battery. An electronic warfare payload is incorporated into the node. The EW payload provides a jamming capability designed to work against radars and communication networks. Efforts are underway to increase the mission duration by increasing the battery size while maintaining the same overall size and weight of the node.

Uses: The primary use of the ARSENIC system is to covertly deny the use of enemy radars and or communication equipment in tactically relevant areas. Because of the up-close placement, the power levels required can be extremely low. The ARSENIC system provides an established delivery system, volume, computational ability, and power bus for other sensors. Future efforts will involve creating a true multimodal network. The ARSENIC node is sufficiently large and of a robust design to incorporate infrared, chemical, seismic, or acoustic sensors. This would prove useful for covertly characterizing traffic on a road or on a mountain path. A heterogeneous network of ARSENIC nodes could be seeded along a road to provide multispectral in situ assessment.

Data Visualization: A critical piece of an unmanned sensor and effector system is the command and control infrastructure. TEWD scientists have developed a radio frequency (RF) tactical decision aid called Builder. Builder is a PC-based tool for visualizing RF energy in a geospatial manner. Builder provides the operator an assessment of the internode communications and of the ability of the jammers to effect threat assets based on geometry and radiated power levels. The ARSENIC network uses the Builder Radio Frequency Tactical Decision Aid to assist both in the placement of the nodes and for visualizing the data reports back from the nodes.

[Sponsored by ONR]