(20 feet or more) antenna systems for effective operation. LADAR, such as Jigsaw, can be more compact; such LADARs, however, are limited by the characteristics of the obscuration: As the foliage increases in density, Jigsaw performance degrades. The use of several smaller, electrically coherent sensors on low-tier, autonomous UASs may be an option to overcome the challenges of obscured target detection at the squad level.

Spectrum surveillance—tactical SIGINT—in support of the squad must provide information with low latency and operate effectively in diverse and spectrally congested environments. Urban and mountainous terrains result in signal multipath and signal obscuration. Spectral congestion is a result of the significant demand for spectral allocation; spectral management techniques include architecting wireless cells with disjoint frequency allocations that repeat after a specified number of cells. Airborne collectors “see” the many emitters on Earth’s surface, averting line-of-sight issues but increasing the co-channel interference problem. Multichannel processing and near-vertical incidence collection geometry are mitigating strategies. This technology area receives a yellow assessment because the squad’s specific needs—ease of deployment, operation in complex environments, autonomous platform operation, and advanced TCPED—are not readily addressed by current technology.

Navigation in GPS-denied environments has been the target recently of RDT&E investment. Specific programs have considered navigation in caves and below ship decks. The key challenge is the transmitter deployment. GPS is easily jammed owing to low signal strength and simple receiver design, and so a separate radio navigation satellite system is unlikely to be useful. A better strategy from the squad’s perspective is to deploy transmit signal sources on several (generally four or more) low tier UASs, such as the ScanEagle or to set up a regional network using larger UAS platforms; squad members then could rely on lightweight navigation receivers based on modifications to commercial designs. Alternative approaches, such as active ranging, require a communications link back to the squad; at the same time less desirable navigation communication links could present blue force tracking information directly to the squad. This technology receives a red assessment since investment would be required to develop and implement an appropriate solution.

Concealed weapons detection technology is currently available. The National Institute of Justice, for example, has invested in handheld mmw technology to image weapons hidden under clothing. Airport security screening includes mmw scanners to image hidden objects. The challenge from the squad’s perspective is to develop and deploy a low-SWAP, mobile capability with a CONOP useful to the squad. Handheld devices are plagued by operator motion, and tripod mounted devices are unfortunately fixed and still require calibration. Packing mmw technology in a useful form for squad operation remains an open issue. For this reason, this technology area is given a yellow assessment.

Life signs monitoring technology does not appear to be currently available. DARPA has made some investments in this area and requested proposals from a number of potential sources. Likely sensor technologies include mmw radar and



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