IEEE Transactions on Aerospace and Electronic Systems

In this paper, an integrated cubic phase function (ICPF) is introduced for the estimation and detection of linear frequency-modulated (LFM) signals. The ICPF extends the standard cubic phase function (CPF) to handle cases involving low signal-to-noise ratio (SNR) and multi-component LFM signals. The asymptotic mean squared error (MSE) of an ICPF-based estimator as well as the output SNR of an ICPF... View full abstract»

Newton algorithms are commonly used in the final "refinement" stage of parameter estimation for sinusoids and higher order phase polynomial signals. Such parameter estimation scenarios arise commonly in radar applications where the radial target velocity (which is possibly time-varying) must be estimated. The author and coworkers have previously proposed an elegant and efficient alte... View full abstract»

The problem addressed in this work is to simultaneously separate multiple maneuvering sources and track their kinematics (position, velocity, and acceleration) in the working space. It is developed upon the incorporation of the nonstationary independent component analysis (ICA) and the nonlinear state estimator problems in a noisy environment. The sampling importance resampling (SIR) particle filt... View full abstract»

In this paper, we present a new synthetic aperture radar (SAR) processor relying on subspace detectors. The scattering pattern of the constituent element of the man-made target (MMT) to detect is used to improve the detection capabilities. In the particular case of foliage penetration (FOPEN), we propose to reduce the probability of false alarms by considering the scattering pattern of almost vert... View full abstract»

We address the problem of radar target detection under clutter heterogeneity. Traditional approaches, designated as the two-data set (TDS) algorithms, require a training data set in order to estimate the interference covariance matrix and implement the adaptive filter. This training data is usually drawn from range gates adjacent to the cell under test (CUT) that are deemed to be statistically hom... View full abstract»

Starting from the reborn international interest in lunar exploration and the widely documented need for hyper-accurate measurements of Earth crustal dynamics, at a high revisit frequency and on a global scale, the idea of a Moon-based interferometric synthetic aperture radar (SAR) is presented. After introducing models to describe synthetic antenna formation and discussing key issues of a Moon-bas... View full abstract»

We propose a novel beamforming algorithm for a three-element system that suppresses an interference signal while still being able to measure a target's interferometer phases. Unlike most direction-of-arrival (DOA) estimation algorithms, our algorithm does not use a grid search. Instead the estimates result from a closed-form solution, a great advantage in time-sensitive applications. The derivatio... View full abstract»

While a Global Positioning System (GPS) is the most widely used sensor modality for aircraft navigation, researchers have been motivated to investigate other navigational sensor modalities because of the desire to operate in GPS denied environments. Due to advances in computer vision and control theory, monocular camera systems have received growing interest as an alternative/collaborative sensor ... View full abstract»

This paper describes the first feasibility study using dynamic time warping (DTW) to classify the micro-Doppler signature (μ-DS ) for radar automatic target recognition (ATR). Real radar data has been used in the testing, and the performance of the DTW classifier has been benchmarked against the conventional k-nearest neighbour (k-NN) algorithm. The basic theory behind the &#x... View full abstract»

Guiding the rotational motion of a spacecraft subject to constraints on its permissible orientation often leads to nonconvex optimal control problems. In this paper, we consider convex parameterizations of sets associated with the constrained rigid body orientations. We then elaborate on ramifications of such a parameterization in the development of steering laws for autonomous spacecraft reorient... View full abstract»

Techniques available to sustain dual-frequency ionosphere performance when a dual-frequency airborne Global Positioning System (GPS)/wide area augmentation system (WAAS) user loses all but one GPS frequency while descending into radio frequency interference (RFI) are investigated. We are particularly interested in the case where the user transitions from L1–L5 to having L5-only since the unce... View full abstract»

We propose a new technique for target detection in RADAR range-Doppler maps in the presence of nonhomogeneous backgrounds with gamma-distributed fluctuations. This technique is based on a cell-averaging (CA) constant false alarm rate (CFAR) detection test for which the ratio threshold and the set of values involved in the detection test are adaptively optimized in order to improve the false alarm ... View full abstract»

We present several techniques for maximizing the contact time between low Earth orbiting satellites (LEOs) and a ground station (GS). The GS comprises an adaptive array of electronically steered space-fed lenses (SFLs). Each SFL is manufactured as a low-cost printed circuit with the result that it exhibits scanning loss. By differently orienting the boresights of the SFLs in the adaptive array, th... View full abstract»

The problem of sequential Bayesian estimation in linear non-Gaussian problems is addressed. In the Gaussian sum filter (GSF), the non-Gaussian system noise, the measurement noise, and the posterior state densities are modeled by the Gaussian mixture model (GMM). The GSF is optimal under the minimum-mean-square error (MMSE) criterion, however it is impractical due to the exponential model order gro... View full abstract»

We present a statistical detection test for GPS multipath based on a one-way ANOVA method. Given an antenna array with a multi-channel software GPS receiver in tracking mode, the signal from each channel is correlated with a reference signal in batches of one CA code period. The relative phase delay for the direct line-of-sight (DLOS) GPS signal from each antenna is then removed. Assuming the mult... View full abstract»

The embedding of a covert communication signal amongst the ambient scattering from an incident radar pulse has previously been achieved by modulating a Doppler-like phase shift sequence over numerous pulses (i.e., on an inter-pulse basis). In contrast, this paper considers radar-embedded communications on an intrapulse basis whereby an incident radar waveform is converted into one of K comm... View full abstract»

Airborne ultrawideband (UWB) synthetic aperture radar (SAR) can perform wide-area detection of unexploded ordnance (UXO) to locate former bombing ranges efficiently. Two main issues in UWB SAR UXO detection, feature extraction, and discriminator design are considered. A space-wavenumber distribution and moment invariants-based method is proposed to extract the multi-aspect feature of UXO with both... View full abstract»

Two ground-based coherent imaging systems designed on the basis of noise radar technology (NRT) using continuous waveform with a linear synthetic aperture and pulse coherent noise waveform with a circular synthetic aperture are presented. A short description of noise waveform synthetic aperture radar (SAR) theory and data processing algorithms are given. Experimental results obtained show that the... View full abstract»

The bandwidth of an interference source affects the performance of an adaptive array. The nature and degree of this effect, however, depends on the application considered. To analyze the bandwidth's effects correctly, therefore, a metric that reflects an adaptive array's performance for that application must be chosen. This paper employs a quantity known as the percentage of available sky (PAS) to... View full abstract»

Among the receiver autonomous integrity monitoring (RAIM) algorithms treating multiple failures, multiple hypothesis solution separation algorithms (MHSS)—a type of solution separation algorithm—offer several advantages: First, the link between threat model, upper bound on the position error—the protection level and probability of hazardously misleading information is an easy and st... View full abstract»

In this article a method to calculate near fuel optimal trajectories for imaging missions using multi-spacecraft interferometric imaging systems (MSIIS) is described. The trajectories are calculated using an algorithm that calculates near-minimum fuel solutions subject to near-Earth orbit dynamics, taking into account that the relative distance between target and formation is varying during the ti... View full abstract»