Search

In order for a closed-loop radar system to adapt properly to changing operational conditions, the performance standards and requirements of the radar system must be known. Often, these performance standards are contained in statements made in language, which describe the different goals of the radar system. In this article, we explore the use of language-based cost functions (LBCFs) to encode performance standards made in imprecise language into an objective function, which a fully adaptive radar (FAR) can use to optimize its performance in real time. To enable the LBCFs, we also propose a statement decomposer, which takes in statements as inputs and yields the information required by LBCFs as outputs. A simulation study of a FAR tracking a running human is conducted with four different cost function methodologies: quadratic, weighted global criterion, fuzzy optimization, and LBCFs. Results show that when statements are properly formulated and presented, the statement decomposer is able to successfully extract the relevant information. Results also show that when paired with a previously developed optimization routine, the LBCF system is capable of autonomously creating cost functions that outperform the other cost functions in the simulated FAR target tracking scenario. [ABSTRACT FROM AUTHOR]

Advanced receiver autonomous integrity monitoring (ARAIM) is under development to support both lateral and vertical guidance. A key component of ARAIM is the integrity support message (ISM), which contains validated input parameters including the probabilities of satellite and constellation failure. A service commitment for the former is provided in the global positioning system (GPS) performance standards, whereas further commitments from GLONASS, Galileo, and Beidou are expected to follow. However, air navigation service providers may demand some flexibility in setting the ISM. This article presents a procedure for setting ISM parameters employing a means to determine the a priori probabilities using the Bayesian inference of a Poisson process model given in the literature. This method and a novel way to accumulate the service history are used to analyze the effects of satellite block and age. Results show that while the type and age of satellite are clearly drivers in the likelihood of a fault; such effects may be accounted for without significant impact on the broadcast values. This article also addresses the probability of unscheduled satellite outages using the new method. Finally, this article gives a high-level scheme of how the validity of the ISM parameters may be assured. [ABSTRACT FROM AUTHOR]

The automatic dependent surveillance—broadcast (ADS-B) system adopts an open communication mode, and the lack of designed-in security measures in the ADS-B system makes it vulnerable to various types of attacks (jamming, spoofing, etc.). In view of the low-bandwidth and less-data-bit features of the ADS-B, this paper studies the integrity and authenticity of information by signing messages and proposes an ADS-B message authentication method based on certificateless short signature. This method uses short signature and does not require certificate management and has efficient performance. Compared with the existing approach, the computation costs of the proposed method in the signature phase are reduced by 1/2, and the signature length is reduced by 3/4. Additionally, we used the extended NS2 simulation platform to simulate 1090ES data link in different scenarios of the network; the simulation results show that our solution is suitable for minimum operational performance standard of ADS-B. [ABSTRACT FROM AUTHOR]

Feature-aided tracking can often yield improved tracking performance over the standard multiple target tracking (MTT) algorithms. However, in many applications, the feature signal of the targets consists of sparse Fourier-domain signals. It changes quickly and nonlinearly in the time domain, and the feature measurements are corrupted by missed detections and misassociations. In this paper, we develop a feature-aided multiple hypothesis tracker for joint MTT and feature extraction in dense target environments. We use the atomic norm constraint to formulate the sparsity of feature signal and use the $\ell _1$ -norm to formulate the sparsity of the corruption induced by misassociations. Based on the sparse representation, the feature signal are estimated by solving a semidefinite program. With the estimated feature signal, refiltering is performed to estimate the kinematic states of the targets, where the association makes use of both kinematic and feature information. Simulation results are presented to illustrate the performance of the proposed algorithm. [ABSTRACT FROM AUTHOR]

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 multipath and DLOS signal have different angles of arrival (AOA), the average correlator outputs are identical for all channels if no multipath is present. The ANOVA test is applied to detect the presence of multipath. Receiver operating characteristic (ROC) curves under various signal conditions are presented to assess the performance of the ANOVA method. Theoretical analysis and simulation results show that good detection performance can be achieved under most operating conditions using less than 10 CA code periods of data. The detection performance improves as the multipath delay time decreases. [ABSTRACT FROM PUBLISHER]