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This study describes the application development of multiple-input multiple-output radios to provide persistent mobile ad hoc network (MANET) for the Department of Homeland Security. By using Man Portable Unit (MPU5) fifth generation radios (manufactured by Persistent Systems) with the Android Team Awareness Kit (ATAK), an Android smartphone geospatial infrastructure and military situational awareness application, the Remote Sensing Laboratory has developed a MANET connectivity to monitor deployed nuclear/radiological search operation assets. Network-capable radiation monitoring systems such as backpacks, vehicle-mounted sensors, and high-resolution high-purity germanium (HPGe) detectors have been integrated to facilitate surveillance operations, routine maintenance and status of health checks, radiation alerts and alarm monitoring, and adjudication. This network connectivity application is particularly useful for maritime search operations. Shipboard search is conducted with backpack detectors and long dwell detector systems. Search techniques that involve the use of spectral anomaly detection algorithms applied to data from low-resolution gamma detectors, as well as the use of spatial interpolation tools, provide higher sensitivity to masked sources that may elude basic gross-count-rate-based algorithms. Small-vessel search techniques involve mounting large-volume mobile detectors on small boats and operating them in the same way as land-based mobile detection systems (i.e., searching for radiological/nuclear signatures emanating from nearby vessels or from targets on the water or shore). Data communication is difficult in a maritime environment because satellite communications may not be steady and multi-hop wireless networks with stations having backhaul infrastructure along coastlines may not be available. The MANET structure described in this study resolves data loss and network latency issues associated with maritime search operations.
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