Journal Cover Aerospace and Electronic Systems, IEEE Transactions on
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   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0018-9251
   Published by IEEE Homepage  [191 journals]
  • IEEE Aerospace and Electronic Systems Society
    • Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • From the Editor-in-Chief
    • Authors: M. Rice;
      Pages: 519 - 519
      Abstract: The new Associate Editors-in-Chief Stefano Coraluppi and Pierfrancesco Lombardo are introduced.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Optical Beam Position Tracking in Free-Space Optical Communication Systems
    • Authors: Muhammad Salman Bashir;Mark R. Bell;
      Pages: 520 - 536
      Abstract: Optical beam position on a detector array is an important parameter for optimal symbol detection in a free-space optical communication system; hence it is essential to accurately estimate and track the beam position (which is unknown and may be varying in time). In this paper, we have attempted to solve the beam position tracking problem by setting it up as a state space variable filtering problem in the context of a dynamical system. We propose the following filtering methods for tracking the beam position: a Kalman filter and a particle filter that both use the maximum likelihood estimate of stationary beam position as a measurement in a linear dynamical model setting, and another particle filter which employs the received photon counts as observations for the nonlinear dynamical model. We compare the performance of these three filters in terms of mean-square error assuming that the beam position evolves in time according to a specified model. It is concluded from simulation results that the Kalman filter gives close to optimal performance for high to moderate photon rates for the Gauss-Markov evolution model. However, both the particle filtering algorithms outperform the Kalman filter for the uniformly distributed evolution noise scenario.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Censoring-Based Cooperative Spectrum Sensing with Improved Energy
           Detectors and Multiple Antennas in Fading Channels
    • Authors: Srinivas Nallagonda;Sanjay Dhar Roy;Sumit Kundu;Gianluigi Ferrari;Riccardo Raheli;
      Pages: 537 - 553
      Abstract: In this paper, the performance of cooperative spectrum sensing (CSS) with threshold-based censoring is investigated in the presence of noisy and faded environments. In particular, scenarios with Rayleigh, Hoyt, and Rician fading, affecting both the sensing (S) and reporting (R) channels, are considered. Each secondary user (SU) is equipped with multiple antennas and relies on an improved energy detector (IED). More precisely, the signals from the primary user (PU), received by multiple antennas of an SU, are fed to the IED, the IED outputs are combined using a selection combiner, and the combined signal is used to make a local decision. At the fusion center (FC), censoring of SUs is done on the basis of the quality, evaluated by the FC, of the faded R-channels. The censored decisions received at the FC are fused, using majority logic or maximal ratio combining, to obtain a final decision on the status of the PU. The performance of CSS, in terms of average miss detection probability and error rate, is evaluated considering the impact of relevant network parameters. Optimized values of the censoring threshold, as well as of the required parameters of the IED, are determined under several network conditions. The performance of the proposed IED is compared with that of a conventional energy detector.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Statically Fused Converted Measurement Kalman Filters for Phased-Array
    • Authors: Gongjian Zhou;Zhengkun Guo;Xi Chen;Rongqing Xu;Thiagalingam Kirubarajan;
      Pages: 554 - 568
      Abstract: In this paper, statically fused converted measurement Kalman filters (SF-CMKF) are developed for target tracking using measurements reported by phased array radars in direction cosine coordinates. First, the conversions of position and Doppler measurements and the estimation of the mean and variance of the converted measurement errors are explicitly derived. Then, the filtering procedure of the SF-CMKF working in Direction Cosine coordinates (SF-CMKFcos) is formulated. The pseudostate vector is constructed and the pseudostate equation for the nearly constant velocity motion model in three-dimensional Cartesian coordinates is deduced. The converted Doppler measurement Kalman filter (CDMKF) and converted position measurement Kalman filter (CPMKF) are developed to extract information from position and Doppler measurements in Direction Cosine coordinates, respectively. To generate the final target state estimates, the pseudostate estimates from the CDMKF and the Cartesian-state estimates from the CPMKF are fused statically under the minimum mean squared error criterion. The nonlinear static fusion procedure is maintained outside the dynamic filtering recursions, which keeps the nonlinear approximation errors from being accumulated recursively. Finally, a comprehensive performance comparison is carried out using numerical simulations, where the proposed SF-CMKF is evaluated against several commonly used filters that incorporate Doppler measurements for tracking in Direction Cosine coordinates. Simulation results indicate that the proposed filter is superior to the existing filters, especially in extreme situations where the position measurement errors are large.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Circulation Retrieval of Simulated Wake Vortices Under Rainy Condition
           With a Side-Looking Scanning Radar
    • Authors: Jianbing Li;Hang Gao;Yongzhen Li;Xuesong Wang;V. Chandrasekar;
      Pages: 569 - 584
      Abstract: The strength of a wake vortex can be well described by vortex circulation. In the area of aviation safety, it serves as a crucial parameter for assessing hazards caused by wake vortices, and its retrieval has attracted much attention in the past decades. Generally, radar is a very promising detection sensor for wake vortices generated under rainy condition where the scattering is mainly caused by the raindrops driven by wake vortices. This makes it possible to retrieve the circulation of wake vortices by sensing and quantifying the motion of these raindrops. This paper proposes the use of a side-looking radar, whose beam scans up and down alternatingly, for detecting wake vortices. In this method, raindrops that make major contribution to the total scattering are identified as characteristic-size raindrops, and their motion equation is established to connect their motion to the dynamics of wake vortices. When the velocity and acceleration of characteristicsize raindrops are well estimated from the Doppler spectra, the motion equation can be well solved by the nonlinear least squares method to yield the target parameter, circulation Γ. At the same time, two other important parameters (vortex spacing b0 and vortex-core height y0).
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Three-Dimensional Tracking of an Aircraft Using Two-Dimensional Radars
    • Authors: Mahendra Mallick;Sanjeev Arulampalam;Yanjun Yan;Jifeng Ru;
      Pages: 585 - 600
      Abstract: Accurate three-dimensional (3-D) position and velocity estimates of an aircraft are important for air traffic control (ATC) systems. An ATC 2-D radar measures the slant range and azimuth of an aircraft. Thus, a single measurement from a 2-D radar is not sufficient to calculate the 3-D position of an aircraft. Previous researchers have used the multiple-model-based height-parametrized (HP) extended Kalman filter with Cartesian state vector (HP-CEKF) with one or two 2-D radars for an aircraft with nearly constant velocity and altitude. However, the filter initialization algorithms contain errors. In this paper, in addition to the HP-CEKF, we present the HP Cartesian unscented Kalman filter (HP-CUKF) and HP Cartesian cubature Kalman filter (HP-CCKF). We also present two new nonlinear filters for the two-radar problem. The first filter uses modified spherical coordinates based HP-UKF (HP-MSCUKF) where the range and azimuth are components of the target state. The second filter uses a cubature Kalman filter with filter initialization by the bias-compensated pseudolinear estimator. We also consider the climbing motion of an aircraft with nearly constant climbing rate, which has not been studied before. All four aforementioned HP filters use the single-point track initiation algorithm. The state estimation accuracy of an aircraft is analyzed as a function of the distance of the aircraft from the radar(s). We compare the performance of the nonlinear filters with the posterior Cramér-Rao lower bound. The normalized computational times of all algorithms in all scenarios are presented. Our results show that accurate 3-D trajectory estimates of an aircraft can be obtained using one or two ATC 2-D radars.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Optimizing Communication and Computation for Multi-UAV Information
           Gathering Applications
    • Authors: Mason Thammawichai;Sujit P. Baliyarasimhuni;Eric C. Kerrigan;João B. Sousa;
      Pages: 601 - 615
      Abstract: Typical mobile agent networks, such as multi-unmanned aerial vehicle (UAV) systems, are constrained by limited resources: energy, computing power, memory and communication bandwidth. In particular, limited energy affects system performance directly, such as system lifetime. Moreover, it has been demonstrated experimentally in the wireless sensor network literature that the total energy consumption is often dominated by the communication cost, i.e., the computational and the sensing energy are small compared to the communication energy consumption. For this reason, the lifetime of the network can be extended significantly by minimizing the communication distance as well as the amount of communication data, at the expense of increasing computational cost. In this paper, we aim at attaining an optimal tradeoff between the communication and the computational energy. Specifically, we propose a mixed-integer optimization formulation for a multihop hierarchical clustering-based self-organizing UAV network incorporating data aggregation, to obtain an energy-efficient information routing scheme. The proposed framework is tested on two applications, namely target tracking and area mapping. Based on simulation results, our method can significantly save energy compared to a baseline strategy, where there is no data aggregation and clustering scheme.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Multihop Broadcast Protocol in Intermittently Connected Vehicular Networks
    • Authors: Chakkaphong Suthaputchakun;Zhili Sun;
      Pages: 616 - 628
      Abstract: There are great challenges in vehicular networks, i.e., continuous connectivity cannot be guaranteed due to interruptions. This paper proposes a novel multihop broadcasting protocol with low signaling overhead in vehicular networks with frequent interruptions named as trinary partitioned black-burst-based broadcast protocol. The protocol operates without any infrastructure. It has low overhead supporting different quality of service levels. Both analysis and comprehensive simulations show that the proposed protocol outperforms the bench mark schemes.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Social Sensing With Minimal Resources: Profiling Agents by Simply Knowing
           How to Count
    • Authors: Stefano Marano;Peter Willett;
      Pages: 629 - 641
      Abstract: The focus of this paper is on profiling an ensemble of agents-where profiling refers to estimating their probability of taking different courses of actions, under different states of nature-by exploiting a recorded time series of actions made in the past, a problem relevant, among others, for modern social network applications. Agents' actions are coupled by the underlying state of nature, but are otherwise independent. This notwithstanding, agents' profiling is possible and effective, provided that some mild assumption on the agents' behaviors is met. The nonparametric profiling is performed by computing the agents' conditional type by aggregating actions that are believed to be taken under the same state of nature. The time-varying state of nature is unknown and must be inferred, and the effect of such uncertainty on the otherwise classical-type estimator is of central interest here. It is shown that a simple counting procedure leads to an asymptotically strong consistent profiling estimator in the limit of large number of agents and large number of per-agent observations. Analytical formulas are provided for finite values of both of these two parameters, and simulations are presented.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Distributed Attitude Control for Multispacecraft via Takagi–Sugeno
           Fuzzy Approach
    • Authors: Zhuo Zhang;Zexu Zhang;Hui Zhang;
      Pages: 642 - 654
      Abstract: This paper investigates the problem of distributed attitude control for spacecraft formation flying systems based on the Takagi- Sugeno (T-S) fuzzy modeling method, where external disturbances and parameter uncertainties are considered. The spacecraft attitude dynamics is constructed as T-S fuzzy model anda modified distributed fuzzy-based H∞ controller is designed. It is proven that the attitude of multispacecraft can synchronously reach zero by using the designed controller. Numerical examples are provided to illustrate the effectiveness of the proposed controller and comparisons with the existing results.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Sparsity-Driven Micro-Doppler Feature Extraction for Dynamic Hand Gesture
    • Authors: Gang Li;Rui Zhang;Matthew Ritchie;Hugh Griffiths;
      Pages: 655 - 665
      Abstract: In this paper, a sparsity-driven method of micro-Doppler analysis is proposed for dynamic hand gesture recognition with radar sensors. First, sparse representations of the echoes reflected from dynamic hand gestures are achieved through the Gaussian-windowed Fourier dictionary. Second, the micro-Doppler features of dynamic hand gestures are extracted using the orthogonal matching pursuit algorithm. Finally, the nearest neighbor classifier is combined with the modified Hausdorff distance to recognize dynamic hand gestures based on the sparse micro-Doppler features. Experiments with real radar data show that the recognition accuracy produced by the proposed method exceeds 96% under moderate noise, and the proposed method outperforms the approaches based on principal component analysis and deep convolutional neural network with small training dataset.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Novel Multichain-Based Loran Positioning Algorithm for Resilient
    • Authors: Pyo-Woong Son;Joon Hyo Rhee;Jiwon Seo;
      Pages: 666 - 679
      Abstract: Intentional high-power global positioning system jamming is a significant threat for ships in the South Korean waters and has occurred multiple times in recent years. The South Korean government intends to utilize the existing long-range navigation (Loran) infrastructure to provide a backup navigation capability to maritime users. However, the observed accuracy of a conventional Loran positioning fix during a field test in Incheon, South Korea, was 592.88 m, far from the 20-m accuracy that the South Korean government tries to provide. The largest error source for Loran is the additional secondary factor (ASF) delay. A conventional time of flight based ASF correction is not applicable in Northeast Asia because several transmitters are not synchronized to universal time coordinated. Thus, we propose a time difference of arrival based ASF correction method that is applicable to the existing Loran signals in Northeast Asia. The demonstrated accuracy with this correction was 32.12 m when using a single Loran chain for positioning. In order to utilize the full capability of the observed signals from the five transmitters of two Loran chains in the region, we further propose a novel multichain-based Loran positioning algorithm. By applying this algorithm together with the ASF correction method, we achieved a 15.32-m accuracy with 100% position availability. This result shows the potential of the existing Loran transmitters in Northeast Asia to provide a reliable and accurate backup maritime navigation service.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • $mathcal{L}_1$ +Adaptive+Output+Feedback+Augmentation+for+Missile+Systems&rft.title=Aerospace+and+Electronic+Systems,+IEEE+Transactions+on&rft.issn=0018-9251&;&rft.aufirst=Hanmin&;Steven+Snyder;Naira+Hovakimyan;"> $mathcal{L}_1$ Adaptive Output Feedback Augmentation for Missile Systems
    • Authors: Hanmin Lee;Steven Snyder;Naira Hovakimyan;
      Pages: 680 - 692
      Abstract: This paper develops an £1 adaptive output feedback controller for a class of underactuated multi-input multi-output (MIMO) systems. The proposed approach is applied as an augmentation of an existing three-loop autopilot. The adaptive scheme is introduced to compensate for the uncertainties and to recover the nominal performance. Stability and performance, both in transient and steady state, are analyzed. Nonlinear simulation results demonstrate the performance of the augmented control system.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Zero-Effort-Miss Shaping Guidance Laws
    • Authors: Chang-Hun Lee;Hyo-Sang Shin;Jin-Ik Lee;Min-Jea Tahk;
      Pages: 693 - 705
      Abstract: This paper suggests a new approach in designing homing guidance laws to enable direct shaping of the pattern of zero-effort-miss (ZEM) as desired. The proposed approach uses the concept of weighted ZEM and its specific desired error dynamics: the former is to provide an additional degree of freedom in shaping actual ZEM and the latter is to guarantee a finite-time convergence. Utilization of these two concepts allows simple determination of the guidance law that can achieve the desired pattern of ZEM. The resultant guidance law is shown a type of proportional navigation guidance law with the specific form of time-varying gain not revealed in previous studies. It provides unique information on how the time-varying gain should be shaped to obtain the desired pattern of ZEM. Accordingly, the resultant guidance laws can cope with various operational objectives in a more direct way compared with the previously existing approaches. This paper also performs theoretical analysis to investigate the properties of designed guidance laws including the closed-loop solutions of ZEM and acceleration command. Also, we determine the feasible set of desired ZEM patterns that can be achieved in the proposed framework. Two illustrative examples are considered to show how to design guidance laws using the proposed approach. Moreover, the characteristics of the guidance laws designed are validated and demonstrated via numerical simulations.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Cooperative Missile Guidance for Active Defense of Air Vehicles
    • Authors: Eloy Garcia;David W. Casbeer;Zachariah E. Fuchs;Meir Pachter;
      Pages: 706 - 721
      Abstract: In air combat, an active countermeasure against an attacking missile homing into a Target aircraft entails the launch of a defending missile. The Target is protected by the Defender, which aims to intercept the Attacker before the latter reaches the Target aircraft. A differential game is presented where the Target-Defender team strives to maximize the terminal separation between the Target and the Attacker at the time instant where the Attacker is intercepted by the Defender, whereas the Attacker strives to minimize the said separation. This paper discusses the case where the Defender is endowed with a positive capture radius. Optimal strategies for the three agents are derived and simulation examples illustrate the effectiveness of the proposed approach.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • A Semi-Open Loop GNSS Carrier Tracking Algorithm for Monitoring Strong
           Equatorial Scintillation
    • Authors: Dongyang Xu;Yu Morton;
      Pages: 722 - 738
      Abstract: Strong equatorial ionospheric scintillation of radio signals is often associated with simultaneous deep amplitude fading and rapid random carrier phase fluctuations. It poses a challenge for satellite navigation receiver carrier phase tracking loop operation. This paper presents a semi-open loop algorithm that utilizes the known position of a stationary receiver and satellite orbit information to estimate carrier phase variations during deep signal fading. Strong GPS scintillation data collected on Ascension Island in March 2013 are processed to reveal fast phase changes of half and full cycles over tens of milliseconds on all three GPS frequencies. Simulated signals are used to validate the algorithm and confirm that the fast phase changes are true scintillation effects rather than receiver processing artifacts. The algorithm performance is demonstrated through comparison with several closed-loop implementations. Potential errors associated with receiver clock bias and other environmental factors are also analyzed. A statistical summary of the concurrent fast phase changes and deep fades based on the processing results of the Ascension Island data is presented.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • GNSS Signal Authentication Via Power and Distortion Monitoring
    • Authors: Kyle D. Wesson;Jason N. Gross;Todd E. Humphreys;Brian L. Evans;
      Pages: 739 - 754
      Abstract: We propose a simple low-cost technique that enables civil global positioning system receivers and other civil global navigation satellite system (GNSS) receivers to reliably detect carry-off spooling and jamming. The technique, which we call the power-distortion detector, classilies received signals as interference-free, multipath-afflicted, spoofed, or jammed according to observations of received power and correlation function distortion. It does not depend on external hardware or a network connection and can be readily implemented on many receivers via a lirmware update. Crucially, the detector can with high probability distinguish low-power spooling from ordinary multipath. In testing against more than 25 high-quality empirical datasets yielding more than 900,000 separate detection tests, the detector correctly alarms on all malicious spooling or jamming attacks while maintaining a 0.6% single-channel false alarm rate.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Optimal Design of the Adaptive Normalized Matched Filter Detector Using
           Regularized Tyler Estimators
    • Authors: Abla Kammoun;Romain Couillet;Frédéric Pascal;Mohamed-Slim Alouini;
      Pages: 755 - 769
      Abstract: This paper addresses improvements on the design of the adaptive normalized matched filter (ANMF) for radar detection. It is well acknowledged that the estimation of the noise-clutter covariance matrix is a fundamental step in adaptive radar detection. In this paper, we consider regularized estimation methods that force by construction the eigenvalues of the covariance estimates to be greater than a positive regularization parameter ρ. This makes them more suitable for high-dimensional problems with a limited number of secondary data samples than traditional sample covariance estimates. The motivation behind this paper is to understand the effect and properly set the value of ρ that improves estimate conditioning while maintaining a low-estimation bias. More specifically, we consider the design of the ANMF detector for two kinds of regularized estimators, namely the regularized sample covariance matrix, the regularized Tyler estimator (RTE). The rationale behind this choice is that the RTE is efficient in mitigating the degradation caused by the presence of impulsive noises while inducing little loss when the noise is Gaussian. Based on asymptotic results brought by recent tools from random matrix theory, we propose a design for the regularization parameter that maximizes the asymptotic detection probability under constant asymptotic false alarm rates. Provided simulations support the efficiency of the proposed method, illustrating its gain over conventional settings of the regularization parameter.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Altitude Estimation Using Multipath With a Two-Dimensional Radar Over
           Spherical Earth
    • Authors: Rong Yang;Yaakov Bar-Shalom;Gee Wah Ng;
      Pages: 770 - 782
      Abstract: This paper presents a target altitude estimation approach based on multipath detections with range and range rate information from a two-dimensional (2-D) airborne radar. Using multipath detections has to deal with the following challenges: first, low probability of detection (PD) of the indirect path signal reflected by the sea surface; second, lack of an analytical expression for the relationship between the target motion parameter/state and the indirect path measurements over spherical earth; and third, unknown range measurement error standard deviation (s.d.) for the indirect path signal. Two estimators are developed: an adaptive multiple model iterated least squares (AMMILS) estimator for motion parameter estimation (noiseless target motion) and anAMM unscented Kalman filter (AMM-UKF) for dynamic state estimation (noisy target motion). Altitude estimate accuracy is studied based on simulation data. It shows that the AMM-ILS yields statistically efficient estimates (i.e., optimal and with a quantifiable accuracy), but this is not always true for the AMM-UKF. For a long distant target (e.g., 300 km) with very low indirect path PD (0.1 and 0.2), the AMM-UKF is inconsistent and inefficient statistically, due to biased estimation. The altitude Cramer Rao lower bounds from a 3-D radar with range and elevation measurements are also computed for comparison. The results show that the 2-D radar can provide better altitude estimates than the 3-D radar in most of the cases, except when the 3-D radar has accurate elevation measurement (with error s.d. σe = 0.5°) and the 2-D radar has very low indirect path PD (PD = 0.1).
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Conservative Term Constrained Kalman Filter for Autonomous Orbit
    • Authors: Zhai Guang;Li Yuyang;Bi Xingzi;
      Pages: 783 - 793
      Abstract: This paper presents a novel constrained Kalman filter framework for autonomous orbit determination. By using Lagrangian multiplier techniques, the conserved terms of orbit motion are incorporated into the estimation routines to reconstruct the Kalman filter, and then the orthogonal and multipartial-norm-constrained Kalman filters are developed for the satellite in circular orbit and eccentric ones, respectively. Finally, scenarios of both circular and eccentric orbits with unknown measurement bias are simulated by using the proposed constrained Kalman filter; the simulation results show that the estimation accuracy is significantly improved after introducing the conservative terms as constraint.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Tracking Initially Unresolved Thrusting Objects Using an Optical Sensor
    • Authors: Qin Lu;Yaakov Bar-Shalom;Peter Willett;Ronen Ben-Dov;Benny Milgrom;Karl Granström;
      Pages: 794 - 807
      Abstract: This paper considers the problem of estimating the three-dimensional states of a salvo of thrusting/ballistic endo-atmospheric objects using two-dimensional (2-D) Cartesian measurements from the focal plane array (FPA) of a single fixed optical sensor. Since the initial separations in the FP are smaller than the resolution of the sensor, there are merged FP measurements, compounding the usual false-alarm and missed-detection uncertainty. We present a two-step methodology. First, we assume a Wiener process acceleration model for the motion of the images of the objects in the optical sensor's FPA. We model the merged measurements with increased variance, and thence employ a multi-Bernoulli (MB) filter using the 2-D measurements in the FPA. Second, using the set of associated measurements for each confirmed MB track, we formulate a parameter estimation problem, whose maximum likelihood solution can be obtained via numerical search and can be used for impact point prediction. Simulation results illustrate the performance of the proposed method.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Height Measurement of Low-Angle Target Using MIMO Radar Under Multipath
    • Authors: Yuan Liu;Bo Jiu;Xiang-Gen Xia;Hongwei Liu;Lei Zhang;
      Pages: 808 - 818
      Abstract: For a very high frequency radar, multiple reflection paths, i.e., multipaths, of target echoes may cause severe errors in elevation estimation of low-angle targets, especially in the case of complex terrain where exact information of reflection paths is unknown. To deal with this problem, a practical multipath signal model for multiple-input multiple-out (MIMO) radar in complex terrain is first presented, where both transmitted multipaths and received multipaths are considered. A novel altitude estimation technique based on rank-1 constraint and sparse representation is then proposed. Simulation results show that the target localization accuracy can be efficiently improved by using our proposed technique under both simple and complex multipath scenarios.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • A Novel Uplink Scheduling Algorithm for the Galileo System
    • Authors: Marco Porretta;Bernhard Kleine Schlarmann;Alexandre Ballereau;Massimo Crisci;
      Pages: 819 - 833
      Abstract: This paper describes a novel uplink scheduling (ULSC) algorithm for the Galileo system. The algorithm is designed to meet the stringent dissemination requirements that are currently foreseen for the provision of the Galileo Commercial Service (CS). In particular, these include “link availability” (LA) requirements that call for a minimum percentage of time (“availability”) when a minimum number of satellites (“space vehicles,” SVs), connected with an uplink station antenna, shall be in view with a generic user at a minimum elevation angle. LA requirements for CS were not fully considered in the design phase of the ULSC algorithm, which is currently implemented at the Mission and Uplink Control Facility (MUCF) of the Galileo Ground Segment. Similarly, this type of requirements is not considered in the ULSC algorithms available in the scientific literature. In particular, current solutions take into account only specifications about 1) the maximum “gap” duration between two subsequent contacts and 2) the minimum contact duration (MCD). In the new ULSC algorithm, LA specifications are effectively dealt with by a proper selection of the subset of the SVs to be allocated. In particular, the proposed selection scheme takes into account the specifications about both maximum gap duration and MCD while maximizing the “spatial diversity” of the solution. Such a diversity is defined as the union of the coverage areas of the allocated satellites. The performance of the new ULSC algorithm is evaluated based on the final deployment stage (full operational capability) of the Galileo system. The performance is also compared with that of the ULSC algorithm currently implemented at the Galileo MUCF (“reference” algorithm). Numerical results show that, compare- to the reference algorithm, the average disconnection duration is reduced by more than 50%. In addition, the availability of the links needed for the provision of CS is significantly improved (up to 7%). As a result, preliminary LA requirements for CS are met using the new ULSC algorithm, while the reference algorithm has limitations to meet the new stringent LA requirements.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Optimal Rendezvous Trajectory for Unmanned Aerial-Ground Vehicles
    • Authors: Alessandro Rucco;P. B. Sujit;A. Pedro Aguiar;João Borges de Sousa;F. Lobo Pereira;
      Pages: 834 - 847
      Abstract: Fixed-wing unmanned aerial vehicles (UAVs) can be an essential tool for low-cost aerial surveillance and mapping applications in remote regions. There is, however, a key limitation, which is the fact that low-cost UAVs have limited fuel capacity and, hence, require periodic refueling to accomplish a mission. Moreover, the usual mechanism of commanding the UAV to return to a stationary base station for refueling can result in the fuel wastage and inefficient mission operation time. Alternatively, one strategy could be the use of an unmanned ground vehicle (UGV) as a mobile refueling unit, where the UAV will rendezvous with the UGV for refueling. In order to accurately perform this task in the presence of wind disturbances, we need to determine an optimal trajectory in three-dimensional taking UAV and UGV dynamics and kinematics into account. In this paper, we propose an optimal control formulation to generate a tunable UAV trajectory for rendezvous on a moving UGV that also addresses the possibility of the presence of wind disturbances. By a suitable choice of the value of an aggressiveness index that we introduce in our problem setting, we are able to control the UAV rendezvous behavior. Several numerical results are presented to illustrate the reliability and effectiveness of our approach.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • On the Estimation of LFM Signal Parameters: Analytical Formulation
    • Authors: Ahmet Serbes;
      Pages: 848 - 860
      Abstract: We propose analytical formulations, approximations, upper and lower bounds for the angle sweep of maximum magnitude of fractional Fourier transform of mono- and multicomponent linear frequency modulated (LFM) signals. We employ a successive coarse-to-fine grid-search algorithm to estimate the chirp rates of multicomponent nonseparable LFM signals. Extensive numerical simulations show the validity of analytical formulations and performance of the proposed estimator. Obtained analytical results may also find themselves other application areas, where nonstationary signals are of interest.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Modeling Three-Dimensional Passive STAP With Heterogeneous Clutter and
           Pulse Diversity Waveform Effects
    • Authors: James R. Lievsay;Nathan A. Goodman;
      Pages: 861 - 872
      Abstract: As passive radar becomes more popular, modeling its behavior and physics becomes more critical. Particular to space-time adaptive processing (STAP) for ground moving target indication, the way in which clutter is modeled will directly impact performance expectations and results. Furthermore, modeling Doppler modulation from uncooperative waveforms can also impact performance assessments. This paper introduces a three-dimensional model that incorporates a novel method for modeling clutter and waveform impacts in passive STAP.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Characterization of Received Signal Strength Perturbations Using Allan
    • Authors: Chunbo Luo;Pablo Casaseca-de-la-Higuera;Sally McClean;Gerard Parr;Peng Ren;
      Pages: 873 - 889
      Abstract: The received signal strength (RSS) of wireless signals conveys important information that has been widely used in wireless communications, localization, and tracking. Traditional RSS-based research and applications model the RSS signal using a deterministic component plus a white noise term. This paper investigates the assumption of white noise to have a further understanding of the RSS signal and proposes a methodology based on the Allan variance (AVAR) to characterize it. Using AVAR, we model the RSS unknown perturbations as correlated random terms. These terms can account for both colored noise or other effects such as shadowing or small-scale fading. Our results confirm that AVAR can be used to obtain a flexible model of the RSS perturbations, as expressed by colored noise components . The study is complemented by introducing two straightforward applications of the proposed methodology: the modeling and simulation of RSS noise using Wiener processes, and RSS localization using the extended Kalman filter.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Statistical Modeling of Wireless Communications Interference and Its
           Effects on Adaptive-Threshold Radar Detection
    • Authors: David P. Zilz;Mark R. Bell;
      Pages: 890 - 911
      Abstract: Recent changes in U.S. policy call for spectrum sharing between radar and wireless communications. In order to inform choices of protection criteria for a radar sharing spectrum with communications systems, this paper models communications interference and its effects on a cell-averaging adaptive-threshold radar detector. First, we propose a statistical model for communications interference based on existing models and original simulations, and we find support for both Gaussian and non-Gaussian models, depending on the application. Then, we assess the impact of communications interference on radar detection. Our results suggest that when interference is not well modeled as white Gaussian noise, mean interference-to-noise ratio (INR) is not sufficient to characterize interference effects on radar, and additional interference characteristics such as kurtosis/impulsiveness and coherence time can significantly impact radar performance. We also find degradation in radar performance in relatively low-INR Gaussian interference (e.g., about -6 to -2 dB mean INR at the output of the matched filter).
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Pilot Control Modeling With Stochastic Periodical Discrete Movement
    • Authors: Ryota Mori;
      Pages: 912 - 922
      Abstract: This paper proposes a novel pilot control model which reflects the following three characteristics of the pilot control behavior: stochastic, periodical, and discrete movement. The focus is on the final descent phase when the pilot controls the aircraft manually based on the flight director commands. The proposed model is developed based on an existing model as well as highly experienced pilot's comments. A flight simulator experiment is conducted and three pilots' landing data are obtained. The parameters of the pilot model are tuned via a genetic algorithm. The simulation result reveals that the proposed model captures well the characteristics of the data obtained in the simulator experiment and shows a good accordance with actual command tracking capability. The obtained parameters also identify the difference of control strategies between the pilots.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Attitude Correction Using Corner Landmarks in 3-D SLAM
    • Authors: Zhen Zhu;Maarten Uijt de Haag;
      Pages: 923 - 931
      Abstract: This paper discusses the use of three-dimensional (3-D) corner features extracted from a 2-D laser scanner as landmarks in a simultaneous localization and mapping solution. The corner landmarks can be identified and tracked using their angles, and the observations of the corners are directly used to correct attitude errors. The proposed method can be used to navigate a small unmanned aerial vehicle in urban and indoor environments.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Clutter Suppression and High-Resolution Imaging of Noncooperative Ground
           Targets for Bistatic Airborne Radar
    • Authors: Samuele Gelli;Alessio Bacci;Marco Martorella;Fabrizio Berizzi;
      Pages: 932 - 949
      Abstract: In a recent paper, the problem of inverse synthetic aperture radar (ISAR) imaging moving ground targets was discussed and an effective solution based on a novel joint space-time adaptive processing (STAP)-ISAR formulation was proposed. In the case of bistatic geometry, ISAR imaging can be simply and effectively enabled via the bistatically equivalent monostatic theory, which allows for monostatic ISAR processing to be used to form bistatic ISAR images. However, the clutter nonstationary introduced by the bistatic geometry strongly degraded STAP performances if a monostatic STAP processing is used. In this paper, a new joint STAP-ISAR processing is introduced that works in the bistatic case. Theoretical figures and numerical simulations are used to prove the effectiveness of the proposed approach.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Compressive Sensing of Sparse Signals in the Hermite Transform Basis
    • Authors: Miloš Brajović;Irena Orović;Miloš Daković;Srdjan Stanković;
      Pages: 950 - 967
      Abstract: An analysis of the influence of missing samples in signals exhibiting sparsity in the Hermite transform domain is presented. Based on the statistical properties derived for the Hermite coefficients of randomly undersampled signal, the probability of success in detection of signal components support is determined and a threshold for the detection of signal components is provided. It is a crucial step in a simple noniterative and iterative matching pursuit (MP)-based algorithm for compressive sensing signal reconstruction.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Distributed RZF Precoding for Multiple-Beam MSC Downlink
    • Authors: Yang Yang;Wenjin Wang;Xiqi Gao;
      Pages: 968 - 977
      Abstract: Regularized zero-forcing (RZF) precoding can be used in multiple-beam mobile satellite communication (MSC) system downlink to combat interbeam-interference for high energy efficiency. We adopt the interference cancelation idea in approximate message passing (AMP) algorithm and propose an interference cancelation message passing (IC-MP) algorithm. To combine the virtues of both IC-MP and AMP, a hybrid message passing (H-MP) algorithm is also proposed. Simulation results show that H-MP has the best performance compared with IC-MP and AMP, and may even outperform the centralized RZF precoding.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Coherent Airborne MIMO Detection of Multiscatter Targets
    • Authors: R. S. Raghavan;
      Pages: 978 - 991
      Abstract: The construction of a virtual array response is integral to the process of target detection for coherent airborne multiple input multiple output (MIMO) radars. Multiple scatterers on a target with complex scattering characteristics have an impact on the virtual array response. In this paper, an analytical expression for the virtual array response of a target is derived in terms of the response vectors of uniform linear arrays involving scatterer characteristics at multiple delays, the auto-ambiguity function and cross-ambiguity function of transmitted signals. Clutter at the same Doppler as the target is modeled similarly as signal returns from an ensemble of scatterers distributed in range. Analysis shows that the ideal Vandermonde vector of the virtual array response to a point scatterer must be modified to account for multiple scatterers and can provide a basis to develop detection/classification algorithms for coherent MIMO radar. A likelihood ratio test formulation of the detection problem is shown to result in the adaptive coherence estimator (ACE) test. The detection performance of the ACE test is derived in terms of parameters such as the signal-to-noise ratio, dimensionality of the MIMO clutter subspace, and the mismatch angle between the virtual array vector for an assumed target scatter model and the signal component of the actual virtual array vector. Illustrative results are presented using a fast-time orthogonal waveforms proposed in the literature as an example. Pulses in the example signal set comprise a sequence of frequency hopping subpulses and the frequency hopping sequences of these waveforms are derived from a subset of the Reed–Solomon code and the waveforms have several interesting properties including insensitivity to frequency errors.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Optimal Collaborative Mapping of Terrestrial Transmitters: Receiver
           Placement and Performance Characterization
    • Authors: Joshua J. Morales;Zaher M. Kassas;
      Pages: 992 - 1007
      Abstract: Mapping multiple unknown terrestrial signals of opportunity (SOP) transmitters via multiple collaborating receivers is considered. The receivers are assumed to have knowledge about their own states, make pseudorange observations on multiple unknown SOPs, and fuse these pseudoranges through a central estimator. Two problems are considered. The first problem assumes multiple receivers with random initial states to pre-exist in the environment. The question of where to optimally place an additional receiver so to maximize the quality of the estimate of the SOPs' states is addressed. A novel, computationally efficient optimization criterion that is based on area-maximization is proposed. It is shown that the proposed optimization criterion yields a convex program, the solution of which is comparable to two classical criteria: minimization of the geometric dilution of precision (GDOP) and maximization of the determinant of the inverse of the GDOP matrix. The second problem addresses the optimal mapping performance as a function of time and number of receivers in the environment. It is demonstrated that such optimal performance assessment could be generated off-line without knowledge of the receivers' trajectories or the receivers' estimates of the SOP. Experimental results are presented demonstrating collaborative mapping of an unknown terrestrial SOP emanating from a cellular tower for various receiver trajectories versus the optimal mapping performance.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • A Thrust Model Aided Fault Diagnosis Method for the Altitude Estimation of
           a Quadrotor
    • Authors: Pin Lyu;Jizhou Lai;Jianye Liu;Hugh H. T. Liu;Qingrui Zhang;
      Pages: 1008 - 1019
      Abstract: In this paper, a new fault diagnosis method is presented for the sensors in the vertical direction of a quadrotor. Different from the existing methods that treat the inertial sensors and the measurement sensors separately, the presented method is capable of dealing with both the z-axis accelerometer and the barometer. The knowledge of the thrust model is used to generate an analytical redundancy based fault diagnosis approach for altitude estimation. The filter design, fault detection, isolation, and recovery problems are addressed. An improved chi-test method is used for fault detection. Real-flight data is used to validate the proposed approaches, showing that the faults of the z-axis accelerometer and the barometer can both be detected and the thrust model of a quadrotor can be used to replace the faulty z-axis accelerometer.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Robust Attitude Tracking Control for Spacecraft with Quantized Torques
    • Authors: Baolin Wu;Xibin Cao;
      Pages: 1020 - 1028
      Abstract: The problem of spacecraft attitude tracking with limited communication to actuators is addressed in this paper. A hysteresis quantizer is employed to quantize the signal of control torque. The hysteresis quantizer requires low communication rate and avoids control chattering. An indirect (nonregressor-based) robust adaptive control scheme is proposed to deal with the effects of quantization error and external disturbances. The proposed control scheme together with the quantizer ensures global boundedness of all the signals in the closed-loop system and enables the attitude tracking error to converge toward a residual.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Minimum Residual Vibrations for Flexible Satellites With Frequency
    • Authors: Zhili Hou;Yunhai Geng;Simeng Huang;
      Pages: 1029 - 1038
      Abstract: The resonant frequencies will be excited if satellites perform a rapidly maneuver, which will increase the vibration settling time. In order to reduce the maneuver time and the residual vibration after maneuver, a set of shaped angular acceleration profiles are presented, and their analytical solutions are derived by minimizing the time integral of the squared magnitude of the difference between angular acceleration and its mean value subject to that the magnitude of the residual vibrations at several frequencies surrounding the natural frequency are zero. Then, suitable frequency points, where the residual vibrations are constrained to be zero, are chosen to minimize the acceleration time subject to both the residual vibration magnitude limit and the angular acceleration magnitude limit. Finally, three sets of simulations are presented to demonstrate that the shaped angular acceleration profiles can reduce the residual vibration under the frequency uncertainty.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Technical Areas and Editors: AESS IEEE Aerospace & Electronic Systems
    • Pages: 1039 - 1044
      Abstract: Presents a listing of AESS society technical editors and their areas of expertise.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
  • Information for Authors
    • Pages: 1045 - 1046
      Abstract: These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal.
      PubDate: April 2018
      Issue No: Vol. 54, No. 2 (2018)
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
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