Advanced Computational Techniques for Counterproliferation Problems

Many NMD and TMD radar algorithms are designed with inherent assumptions about the amplitude statistics of the radar returns from objects under observation. These algorithms include mission critical bulk filtering and classification algorithms. In awartime environment, the observed amplitude fluctuations will be due not only to fluctuations in the target radar cross section (RCS), which the radar hopes to measure, but will also be caused by angular scattering of the propagating EM wave. For thenatural ionosphere at UHF through L-band and for nuclear-burst produced environments at S-band through X-band, fluctuations in signal amplitude can degrade the performance of amplitude sensitive radar algorithms. The proposed work will enable NMD and TMDradar to measure the S4 scintillation index. Knowledge of the channel amplitude statistics allows some radar algorithms to be adapted to mitigate the effects of the ionospheric multipath. Additionally, measurement of the S4 scintillation index onpropagation paths to satellites on trajectories that pass near the trajectories of the objects of interest can provide information about the extent of the disturbed region that is of use in radar energy management.Both the NMD UEWR IPT and the NMB XBR IPThave a need (as expressed at various Technical Interchange Meetings) for channel measurements to quantify the degree of signal degradation caused by multipath propagation through the disturbed ionosphere. With knowledge of the severity of the degradation,mitigation algorithms can be turned on (and off) at the appropriate time to help optimize the expenditure of radar resources. Radar algorithms can also be designed to adapt based on knowledge of channel multipath fluctuation statistics.Such information is vital to the allocation of radar resources during TMD and NMD engagements, is vital to the development of algorithms to provide successful object classification during wartime and is thus vital to the future defense of the UnitedStates.This work will help to build a successful National Missile Defense system that will operate under conditions when the propagation environment is disturbed by nuclear events or by naturally produced ionospheric irregularities in the equatorial or polarregions.The development of mitigation techniques is a key technology area in the deployment of a viable National Missile Defense system. There are two major corporations that are building the NMD and TMD radars, namely Raytheon (UEWR, XBR and THAAD), andLockheed-Martin (Aegis, (SPY 1)) radar. The techniques addressed under the proposed work have the potential to be incorporated by these companies into the design of these DOD assets.The recognition of the severity of multipath propagation conditions is a long-term issue for RF sensors, particularly in the frequency range above 30 GHz. At such frequencies the multipath propagation channel is often the limiting factor that controlssensor performance. The results from this project on measurement of the severity of propagation channels will potentially be useful in the development of systems in the millimeter wave regime. Such systems include earth environment sensing, airportground traffic control, and automatic automobile control. All these systems are affected by atmospheric multipath caused by ambient low-altitude atmosphere turbulence.