The '''Wide Area Tracking System''' [[Wide area tracking system|WATS]] is an prototype [[wireless sensor network]] for detecting a ground-based nuclear device [http://www.llnl.gov/str/Imbro.html] such as a nuclear "briefcase bomb". WATS is presently being developed at the [[Lawrence Livermore National Laboratory]] ([[LLNL]]).
==Theory==
WATS would be made up of wireless gamma and neutron sensors connected through a communications network. Data picked up by the sensors undergoes [[Sensor fusion|"data fusion"]], which converts the information into easily interpreted forms; this data fusion is the most important aspect of the system [http://www.fas.org/spp/starwars/congress/1997_h/has274010_1.htm#79].
The data fusion process occurs ''within'' the sensor network rather than at a centralized computer and is performed by a specially developed algorithm based on [[Bayesian statistics]][http://www.llnl.gov/str/JulAug01/Hills.html]. WATS would not use a centralized computer for analysis because researchers found that factors such as latency and available bandwidth tended to create significant bottlenecks. Data processed in the field by the network itself (by transfering small amounts of data between neighboring sensors) is faster and makes the network more scalable [http://www.llnl.gov/str/JulAug01/Hills.html].
An important factor in WATS development is ''ease of deployment'', since more sensors both improves the detection rate and reduces false alarms [http://www.llnl.gov/str/JulAug01/Hills.html]. WATS sensors could be deployed in permanent positions or mounted in vehicles for mobile protection of specific locations.
One barrier to the implementation of WATS is the size, weight, energy requirements and cost of currently available wireless sensors [http://www.llnl.gov/str/JulAug01/Hills.html]. The development of improved sensors is a major component of current research at the Nonproliferation, Arms Control, and International Security (NAI) Directorate at [[LLNL]].
==History==
WATS was profiled to the [[United States House of Representatives|U.S. House of Representative's]] Military Research and Development Subcommittee on [[October 1]], [[1997]] during a hearing on nuclear terrorism and countermeasures [http://www.fas.org/spp/starwars/congress/1997_h/has274010_1.htm#79]. On [[August 4]], [[1998]] in a subsequent meeting of that subcommittee, Chairman [Curt Weldon]] stated that research funding for WATS had been cut by the Clinton administration to a subsistence level and that the program had been poorly re-organized [http://commdocs.house.gov/committees/security/has216010.000/has216010_1.HTM#12].
