Unattended ground sensor systems and networked weapons systems are a major component of modern tactical military strategies. One thrust calls for increasing capability and network capacity combined with ECCM features, while lowering production prices and decreasing size and energy consumption. A second thrust calls for radio implementations that comply with the Software Communications Architecture (SCA). SCA-compliance can provide several benefits; among them are software re-use, common hardware and software platforms to reduce production cost, and upgradeability in the field. At the same time, some users and developers have raised concerns about the cost of SCA-compliance in terms of size, cost and power. This paper describes the implications of SCA-compliance and the implementation of the SCA Operating Environment for sensor data radios. In particular, we show that limited band implementations of some waveforms can be accomplished in an SCA-compliant manner with relatively small incremental increases in production cost, size and power. At the same time, a relatively significant investment is
required to reach a critical mass where the appropriate "SCA-lite" architecture has been demonstrated in multiple applications.
Unattended Ground Sensors (UGS) have proven to be invaluable in various military missions. Specifically, UGS systems add significantly to the capability and security of reconnaissance and surveillance units during military operations by monitoring the battlefield. Recent initiatives for Homeland Defense target the use of DoD technologies for use in the public sector for Offices under the Department of Homeland Defense. UGS systems can be utilized for Homeland Defense for perimeter security, surveillance, tracking, and intrusion detection. This paper depicts the use of present UGS technologies for use in Homeland Defense applications.
The networked communications requirements for programs such as Future Combat Systems and others have spawned numerous developments in the area of low profile, low cost, yet high performance transceivers. A primary objective for these next-generation unattended devices is maximum mission life, hence the radios employ not only low power circuit designs, but also power-efficient routing protocols and fast acquisition waveforms to support duty cycling.
The network architecture of the systems employing these transceivers is similarly optimized. In numerous scenarios, low power (< 1 watt transmitted output) transceivers compose the local network that interconnects relatively closely spaced nodes, typically front line sensors. A typically higher-powered, and higher data rate transceiver within the network provides the longer link (tens of kilometers) to a Command and Control Station.
Operational considerations specific to each system, such as the number of nodes, anticipated traffic volume, latency requirements, forward error correction, encryption, etc., are used to determine the data rate for both the local and long haul links. Additional requirements for low probability of detection, low probability of intercept, and anti-jam protection provide the final input to the process of waveform selection or design.
In many cases, unique transceivers are designed to satisfy the requirements for each of the two links. However, judicious trade-offs between the two can yield a single dual-mode device capable of operating in a low power, low rate mode for sensor interoperability while also offering higher layer communications. This paper outlines the design considerations for networked sensor system transceivers and presents performance data for prototype systems.
Short-range RF propagation models with antenna elements placed at or near the earth's surface often fail to accurately predict path loss. Adequate mathematical models can be developed and validated to ensure deployed communication systems maintain link closure. Specifically, Unattended Ground Sensor (UGS) systems are deployed to be physically undetected, that is, the units are frequently buried with the antenna extended above earth's surface. This paper reviews the physical effects that determine propagation loss and synthesizes a mathematical model to predict this loss. These predictions are compared to real world propagation measurements in both open fields and in dense foliage for ranges up to 500m.