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Previous work has addressed adaptive radar waveforms that may be designed to be spectrally orthogonal to a received, in-band, time-varying, interference environment. This paper introduces a different adaptive waveform technique whereby a standard LFM waveform is modified to minimize its adjacent-band interference to other spectral users. In addition, results are shown for in-band and/or adjacent-band spectral suppression for improving radar performance and minimizing interference to other spectral users while maintaining good ambiguity function performance. Ambiguity functions are plotted for each case showing good approximation to the ideal LFM ambiguity function.

Subband adaptive filters have been used extensively in system modeling configurations to model unknown systems with large impulse responses. This paper will illustrate the advantages of a non-uniform subband adaptive filter over a uniform subband adaptive filter while giving insight to subband bandwidth allocations for system modeling configurations. By implementing small subbands which isolate the transition regions in the unknown system, while using larger subbands for other, more spectrally flat regions, one can minimize convergence time and lower misadjustment.

A practical algorithm is developed for on-board plan ning ofn-impulse fuel-optimal maneuvers for establishment and reconfiguration of spacecraft formations. The method is valid in circular and elliptic orbits and includes first-order secular h effects. The dynamics are expressed in terms of differential mean orbital elements, and relations are provided to allow the formation designer to transform these into intuitive geometric quantities for visualization and analysis. The maneuver target ing problem is formulated as an optimal control problem in both continuous and discrete time. The continuous-time formulation cannot be solved directly in an efficient manner, and the discrete time formulation, which has an analytical solution, does not directly yield the optimal thrust times. Therefore, a practi cal algorithm is designed by iteratively solving the discrete time formulation while using the continuous-time necessary conditions to refine the thrust times until they converge to the optimal values.Simulation results are shown for a variety of reconfiguration maneuvers and reference orbits, including simulations with and without navigation errors for the NASA CubeSat Proximity Operations Demonstration mission.

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Nonuniform filterbanks have recently been proposed for subband adaptive filters (SAFs). However, nonuniform SAFs have not yet been given a thorough performance analysis. This paper gives a comprehensive mean square error (MSE) analysis of system modeling, nonuniform (and, degeneratively, uniform) SAFs after convergence for a specified filterbank. Using the equivalent polyphase representation suggested by Ono et al., minimum MSE (MMSE) estimates for the individual subband errors are presented with respect to a given filterbank for finite length (FIR), infinite length causal (IIR), and infinite noncausal adaptive filters. Using these subband MMSE estimators, an MMSE estimator is derived for the overall fullband error. Finally, the derived MMSE estimators are verified by a numerical simulation. The intent of this paper is not to compare nonuniform and uniform SAF performance but merely to present a unified mathematical methodology to predict their MMSEs.