Showing papers in "IEEE Aerospace and Electronic Systems Magazine in 2007"

Moving towards a more electric aircraft

Abstract: The latest advances in electric and electronic aircraft technologies from the point of view of an "all-electric" aircraft are presented herein. Specifically, we describe the concept of a "more electric aircraft" (MEA), which involves removing the need for on-engine hydraulic power generation and bleed air off-takes, and the increasing use of power electronics in the starter/generation system of the main engine. Removal of the engine hydraulic pumps requires fully-operative electrical power actuators and mastery of the flight control architecture. The paper presents a general overview of the electrical power generation system and electric drives for the MEA, with special regard to the flight controls. Some discussion regarding the interconnection of nodes and safety of buses and protocols in distributed systems is also presented

Textile antennas: effects of antenna bending on input matching and impedance bandwidth

Abstract: How the performance of wearable textile antennas is affected on the antenna bending is described herein. The authors focus on the resonance frequency fluctuation and input-match bandwidth variation due to the antenna bending. The results are given for three different antennas, namely, a conventional patch, EBG, and dual-band U-slot antennas

UAV Payload and Mission Control Hardware/Software Architecture

Abstract: This paper presents an embedded hardware/software architecture specially designed to be applied on mini/micro unmanned aerial vehicles (UAV). A UAV is a low-cost non-piloted airplane designed to operate in D-cube (Dangerous-Dirty-Dull) situations [8]. Many types of UAVs exist today; however with the advent of UAV's civil applications, the class of mini/micro UAVs is emerging as a valid option in a commercial scenario. This type of UAV shares limitations with most computer embedded systems: limited space, limited power resources, increasing computation requirements, complexity of the applications, time to market requirements, etc. UAVs are automatically piloted by an embedded system named "Flight Control System." Many of those systems are commercially available today, however no commercial system exists nowadays that provides support to the actual mission that the UAV should perform. This introduces a hardware/software architecture specially designed to operate as a flexible payload and mission controller in a mini/micro UAV. Given that the missions UAVs can carry on justify their existence; we believe that specific payload and mission controllers for UAVs should be developed. Our architectonic proposal for them orbits around four key elements: a LAN-based distributed and scalable hardware architecture, a service/subscription based software architecture and an abstraction communication layer.

The Significance of Letter Position in Word Recognition

Abstract: Presents the summary of a PhD thesis on letter position in word recognition, which was written in 1976. The thesis was the source of the text used on the cover of the October 2006 issue of the IEEE Aerospace and Electronic Systems Magazine.

A Beginner's Guide to Interferometric SAR Concepts and Signal Processing [AESS Tutorial IV]

Abstract: Interferometric synthetic aperture radar (IFSAR, also abbreviated as InSAR) employs pairs of high resolution SAR images to generate high quality terrain elevation maps using phase interferometry methods. IFSAR provides an all-weather, day/night capability to generate measurements of terrain elevation on a dense grid of sample points with accuracies of ones of meters. Both spaceborne and airborne IFSAR systems are in use. In this paper we present a tutorial introduction to the concepts, techniques, and applications of IFSAR. After a brief introduction to digital elevation models (DEMs) and digital terrain elevation data (DTED), the fundamental IFSAR equation relating interferometric phase measurements to terrain elevation is derived from simple geometric considerations. The central section of the paper describes the major algorithmic steps required to form an IFSAR terrain map. Finally, variations of IFSAR for mapping terrain elevation or reflectivity changes are briefly described. A Web site at users.ece.gatech.edu/~mrichard/AESSJFSAR.htm provides access to color versions of many of the IFSAR images included in this paper.

Small UAV Automation Using MEMS

Abstract: This paper presents a framework for the automation of a small UAV using a low cost sensor suite, MNAV, and an embedded computing platform, Stargate, which together provide a complete avionics package for aerial robotic applications. In order to provide a complete INS solution (i.e., attitude, velocity, position, and biases), an extended Kalman filter algorithm is developed and implemented in real-time. A devised control strategy utilizes multiple PID loops with a hierarchy enabling simple attitude stabilization to full waypoint navigation. The developed ground station unit, a laptop computer, communicates with the avionics package via 802.11b WiFi, displays the aircraft critical information, provides in-flight PID gain tunings, and uploads waypoints through a simple GUI. The system is installed in an off-the-shelf delta-wing R/C aircraft and demonstrates its performance for aerial robotic applications

Wind Farm Clutter Mitigation in Air Surveillance Radar

Abstract: Windmills provide a renewable energy resource that could become major components of the power infrastructure in the United States, Europe, and Asia within the next decade. However, collections of windmills, known as wind farms, cause interference in radars that are critical to air defense and air traffic systems. Therefore, to maintain and, perhaps, improve air surveillance, methods that mitigate the inevitable performance degradation seen in radar systems must be proven and implemented to deal with wind farms as they become more prevalent. Herein, the authors discuss recommended techniques for wind farm mitigation, which are based on a UK Royal Air Force-sponsored demonstration on a Watchman radar, conducted at Clatter, South Wales. Specifically, false alarm and false track reductions will be quantified.

Radiation Tolerant SpaceWire Router for Satellite On-Board Networking

Abstract: The European Space Agency (ESA) recently proposed the space wire standard for reliable satellite on-board networking at high speeds. This paper presents the design of configurable space wire router and interface hardware macrocells, the first in state-of-the-art compliant with the latest standard extensions, protocol identification and remote memory access protocol. The space wire router with 8 links achieves 100 Mbits/s data rate with 135 W power consumption and 300 Krad radiation tolerance. These performances meet the requirements of planned ESA space missions

Tetrahedral Robotics for Space Exploration

Abstract: A reconfigurable space filling robotic architecture has a wide range of possible applications. One of the more intriguing possibilities is mobility in very irregular and otherwise impassable terrain. NASA Goddard Space Flight Center is developing the third generation of its addressable reconfigurable technology (ART) tetrahedral robotics architecture. An ART-based variable geometry truss consisting of 12 tetrahedral elements made from 26 smart struts on a wireless network has been developed. The primary goal of this development is the demonstration of a new kind of robotic mobility that can provide access and articulation that complement existing capabilities. An initial set of gaits and other behaviors are being tested, and accommodations for payloads such as sensor and telemetry packages are being studied. Herein, we describe our experience with the ART tetrahedral robotics architecture and the improvements implemented in the third generation of this technology. Applications of these robots to space exploration and the tradeoffs involved with this architecture will be discussed.

MEMs for Aerospace Navigation

Abstract: The MEMS aerospace market has its own specificities in terms of market size, standards, and performance characteristics (very long term stability, reliability, and safety levels). Improvements are needed for future applications. THALES Avionics has a twenty-year experience in quartz and silicon MEMS design and manufacturing and is recognized as a leader by the French MOD in this field. MEMS pressure sensors and accelerometers are manufactured in large volume and used for safety-critical applications. THALES technology policy focused on planar architecture, die vacuum packaging, and deep reactive ion etching (DRIE) allowing good characteristics for sensors in development. A Silicon Vibrating Beam Accelerometer single chip is now under development. Its operating principle is described with two resonators in push-pull configuration. A tuning fork planar rate gyro is also developed with exactly the same technology for industrial efficiency. Performance results will be addressed. The development and industrialization road-map of theses inertial products is described for the following five years. Gyro-compassing grade inertial sensors would be available during the next decade allowing low-cost, high-grade navigators using simultaneously GNSS receivers and inertial MEMS navigators.

UAVSAR: New NASA Airborne SAR System for Research

Abstract: NASA's Jet Propulsion Laboratory is currently building a reconfigurable, polarimetric L-band synthetic aperture radar (SAR), specifically designed to acquire airborne repeat track SAR data for differential interferometric measurements. Differential interferometry can provide key deformation measurements, important for studies of earthquakes, volcanoes, and other dynamically changing phenomena. Using precision real-time GPS and a sensor controlled flight management system, the system will be able to fly pre-defined paths with great precision. The expected performance of the flight control system will constrain the flight path to be within a 10 m diameter tube about the desired flight track. The radar will be designed to be operable on a Unpiloted Arial Vehicle (UAV) but will initially be demonstrated on a NASA Gulfstream III. The radar will be fully polarimetric, with a range bandwidth of 80 MHz (2 m range resolution), and will support a 16 km range swath. The antenna will be electronically steered along track to assure that the antenna beam can be directed independently, regardless of the wind direction and speed. Other features supported by the antenna include elevation monopulse and pulse-to-pulse re-steering capabilities that will enable some novel modes of operation. The system will nominally operate at 45,000 feet (13,800 m). The program began as an Instrument Incubator Project (IIP) funded by NASA Earth Science and Technology Office (ESTO).

Recent Breakthroughs in RF Photonics for Radar Systems

Abstract: Radar systems require transmission of very high purity signals. Photonics is now mature enough to achieve analog transmission with very low noise, strong immunity, and wide-bandwidth even in harsh environments. We present our recent developments of optimized optical links dedicated to radar and multifunction systems

Intelligent Transportation Systems in Transitional and Developing Countries

Abstract: Intelligent transportation systems (ITS) are state-of-the-art approaches based on information, communication and satellite technologies in mitigating traffic congestion, enhancing safety, and improving quality of environment. ITS are being used in many industrialized and emerging economies for the last two decades to facilitate traffic managers in tackling surface mobility problems. In the case of many developing countries, policy makers and practitioners have neglected this "non-conventional" approach on the pretext inter alia, "technological sophistication," cost and institutional ill-preparedness. This aims to underscore the importance and relevance of ITS for developing countries as a complementary tool in the 21st century. In so doing, the intention is to bestow some fresh thinking into the transport debate that will serve as a catalyst for resolving mobility problems in developing countries still dwelling on conventional options.

General Aviation Aircraft Flight Operations Quality Assurance: Overcoming the Obstacles

Abstract: This describes the initiative to introduce a capable yet affordable Flight Operations Quality Assurance (FOQA) program into the general aviation industry. A brief overview of the FOQA concept is given along with a historical perspective to the evolution of such programs. Initial development of a FOQA program for general aviation by the Center for Sensors and Sensor Systems at Saint Louis University is introduced herein. A brief discussion of the obstacles in developing such a system is presented, as well as strategies for overcoming these obstacles. The system consists mainly of a quick access recorder (QAR) that is conceived to be a stand-alone, non-intrusive system that collects parametric flight data, a preprocessor system to analyze initial data sets and validate their use, and post-processor software used in the analysis of available flight parameters. The program concepts are presented for initial determination of the needs and possibilities, and examples are presented along with flight data collected in the University's fleet of aircraft.

Vacuum Electronics: Status and Trends

Abstract: The vast preponderance of US radar transmitters today use vacuum electronic amplifiers, spanning the spectrum from UHF to EHF. Enhancements to performance, reliability, and cost of ownership are being applied continuously to these systems: routine in-service life extensions mandate continuing vacuum electronics research and development to support system needs for the foreseeable future. In addition, exciting advances in vacuum electronics will provide dramatic improvements in millimeter-wave radar resolution, broadband low-noise power at microwave frequencies, compact high power sources operating at lower voltages, and life-cycle cost improvement. Recent progress in key enabling technologies, e.g., advanced device modeling and micro-fabrication, is expected to continue. This reviews the status and trends of vacuum electronics, with selected applications emphasizing recent advances in device performance in the microwave regime: multiple-beam klystrons (MBKs), microwave power modules (MPMs), and gyro-amplifiers in the millimeter-wave regime.

Image Quality Evaluation in Security Imaging Systems

Abstract: The subjective image quality of image or video information is a crucial item in security imaging systems. During the last five years our lab has tested and verified various approaches to the image compression for security purposes and the evaluation of subjective image quality. In the paper we discuss selected important facts related to the subjective image quality evaluation and we present some anomalous experimental behavior of image compression techniques. An object-defined approach is investigated and advantageous characteristics of chosen methods are deployed to achieve the optimal performance of the surveillance video coder. Among others, we propose to use the artificial neural network (ANN) to predict resulting image quality rating scores. The proposed quality assessment model has been trained and tested using a set of grayscale images distorted by selected image compression algorithms

On-The-Fly Location Referencing Methods for Establishing Traffic Information Services

Abstract: The paper presents different use cases for location referencing. It shows how a full service chain for traffic information services could be established and gave an overview of the widely used method traffic message channel (TMC). After a discussion about the growing requirements of telematics systems, a new approach to location referencing is presented: the on-the-fly methods. The difficulties regarding the development of on-the-fly methods was discussed and present the AGORA-C method which is currently in the standardisation process. An overview of the publicised test results using the AGORA-C method concerning its reliability and applicability was given. In addition, another algorithm for location referencing, MEI-LIN, was presented which focuses on a better identification of a location using topological information of the surrounding road network. An outlook on the current research in Europe shows the main future tasks of establishing location referencing methods

MEMS Electronically Steerable Antennas for Fire Control Radars

Abstract: Large apertures are of great benefit to applications that are prime powered limited as is found on aerostat and other airborne platforms. Electronically scanned array antennas are often proposed for these applications. However, increasing the aperture area with conventional array technology is met with prohibitive cost, weight, and prime power increases because of the dense spacing of phase shifters and/or active T/R modules. This discusses the recent development of RF MEMS (Microelectromechanical System) switch technology and the use of these switches in a Radanttrade lens configuration for arrays of approximately 10 m2 at X-band. A proof-of-concept 0.4 m2 MEMS Electronically Steerable Antenna (ESA) containing 25,000 MEMS switches has been successfully designed, fabricated, and tested. The 0.4 m2 MEMS ESA was then integrated with an AN/APG-67 radar system to form the MEMS Demonstration Radar System. The MEMS Demonstration Radar System successfully detected both airborne and ground moving targets during a series of extensive radar demonstrations. This is believed to be the first large scale employment of MEMS switches in a scanning antenna and radar system. The low-cost, lightweight, and low power technology demonstrated can enable weight and power constrained platforms with electronic steering.

Adaptive Rectification Filter for Detecting Small IR Targets

Abstract: Clutter suppression is one of the most important subjects in the field of small target detection under infrared (IR) strong clutter background. While removing the clutter background, however, such methods may reverse the relative energy distribution of target and noise in the clutter suppressed image, and disturb the subsequent target segmentation and detection. This paper analyzes the causation of such problems, does research on the relationship between target energy characteristics and detection probability, and presents a novel filter of energy distribution adaptive rectification (EDARF). Based on the EDARF, an improved framework of dim small target detection is proposed to rectify the energy distribution in the clutter-suppressed images by conventional adaptive filters. The proposed EDARF's performance is estimated by experimental comparisons of three linear/nonlinear filters before and after using EDARF. Extensive experimental results show that the proposed EDARF improves efficiently the performance of detecting dim small targets against strong undulant cloud-cluttered backgrounds.

Secure access system using signature verification over tablet PC

Abstract: Low-cost portable devices capable of capturing signature signals are being increasingly used. Additionally, the social and legal acceptance of the written signature for authentication purposes is opening a range of new applications. We describe a highly versatile and scalable prototype for Web-based secure access using signature verification. The proposed architecture can be easily extended to work with different kinds of sensors and large-scale databases. Several remarks are also given on security and privacy of network-based signature verification

Software reuse: A safety-critical primer

Abstract: Numerous standards exist to assist software developers in producing higher quality software products. The International Standards Organization (e.g., ISO 9001) and the Software Engineering Institute capability maturity model provide good foundations upon which to improve software development processes and quality. These standards are not often used to develop safety-critical software although some organizations have successfully used SEI-CMM to develop mission critical software. Organizations who sponsor or develop guidance for development of safety-critical software include the US DoD, the United Kingdom Ministry of Defence, the International Electrotechnical Commission (IEC), the Institute for Electrical and Electronics Engineers (IEEE), the Motor Industry Software Reliability Association (MISRA), and RTCA, Inc., (formerly the Radio Technical Commission for Aeronautics)

Loran Data Modulation: A Primer [AESS Tutorial IV]

Abstract: Loran has provided navigation service since 1958. Though not originally designed with data broadcast capabilities, Loran's versatility has enabled data to be broadcast with great benefits. Research in the last two decades has resulted in a tremendous increase in the data capacity of Loran thereby increasing its utility. Currently, a modernized Loran is being evaluated for its capability to backup GPS and data modulation is an integral part of this Loran design. An overview and analysis of Loran modulation techniques is provided.

Robot System to Search for Signs of Life on Mars

Abstract: This describes a robot system that can be used to look for the tell-tale signs of life on Mars. Currently, NASA has satellites in orbit that can identify broad regions to explore in its search for life. NASA also has instruments that can examine samples of Martian soil to see if they contain any indications of biological activity. This leaves the problem of deciding specifically where to look for suitable samples in the large area around a landing site. This also describes a robot system that can rapidly search thousands of square meters around the landing position to find sources of biogenic gas samples that may harbor important clues in the search for extra-terrestrial life.

Next-Generation Thin-Film Photovoltaics

Abstract: Future spacecraft and high-altitude airship (HAA) solar array technologies will require high array specific power (W/kg), which can be met using thin-film photovoltaics (PV) on lightweight and flexible substrates [1]. Thin-film array technology, with thin-film specific array support structure, begin to exceed the specific power of crystalline multi-junction arrays with thin-film device efficiencies as low as 8.5% [2]. Thin-film PV devices have other advantages in that they are more easily integrated into HAAs, and are projected to be much less costly than their crystalline PV counterparts. Furthermore, it is likely that only thin-film array technology will be able to meet device specific power requirements exceeding 1 kW/kg (photovoltaic and integrated substrate/blanket mass only).

CWLFM Radar for Ship Detection and Identification

Abstract: Continuous wave lineal frequency modulated (CWLFM) radar presents some interesting advantages for coast surveillance and control as well as low probability of interception (LPI). This paper presents real results obtained with a radar prototype and processed with ISAR techniques. Also, results of an automatic ship identification system applied to simulated ISAR images are exposed. Moreover, radar behavior with unfavorable meteorological conditions is discussed

Sea Clutter: Scattering, the K Distribution and Radar Performance (Ward, K.D., et al.; 2006) [Book Review]

Abstract: Radar sea clutter has been studied since the earliest days of radar; the ability to represent the backscatter from the sea surface in statistical terms, and hence to predict radar performance, is central to the problem of detection of small targets on the sea surface. Various models have been developed and used over the years, but a significant advance was the introduction in 1981 by Keith Ward (one of the authors of this book) of the compound form of the K-distribution clutter model.* This has the advantage that it not only models the \"tail\" of the clutter distribution more accurately than other approaches, but can also take into account the spatial and temporal correlation properties of the clutter that are important with radars of higher and higher resolution. The K-distribution has therefore been widely used, and indeed extended to model other types of radar clutter as well. The publication of a book that treats the K-distribution model and its application in detail, and written by three acknowledged experts, has been eagerly anticipated, and the result certainly does not disappoint! The book is organized in ten chapters and three appendices. Following an introduction, the phenomenological characteristics of radar sea clutter are explained, then three chapters which treat the modelling of electromagnetic scattering, statistical models of sea clutter, and the simulation of clutter and other random processes. The remaining chapters show how the models are used in practice in the design, testing and customer acceptance of real systems, and treat the problem of detection of small targets in sea clutter, imaging ocean surface features, radar detection performance calculations. CFAR detection, and the specification and measurement of radar performance. The style is detailed, clear and authoritative, with a great deal of mathematical detail indeed, the introduction suggests that the reader will need sufficient mathematical maturity to look an unfamiliar equation in the eye without flinching,\" But the three appendices provide a comprehensive review of the mathematics needed to understand the text, in a characteristically entertaining style. Overall, this book can confidently be predicted to become a \"classic,\" demanding a place on the bookshelf of any practising radar engineer or student. It will also be of interest to applied mathematicians, since the stochastic models are more generally applicable to a wider range of problems.

Bistatic Radar Based on DAB Ifluminators: The Evolution of a Practical System

Abstract: Digital Audio Broadcasting (DAB) has massive potential for the development of passive bistatic radar. A project to build DAB based radar is described, together with its advantages and disadvantages. Several serious obstacles need to be overcome in order to make the system a reality. Most importantly, these include the removal of direct signal interference and the extraction of the illuminating signal in a form suitable for detections. Progress toward the solution of these problems will be described. In addition, some real aircraft detections are included to prove the viability of a practical system.

Satellite-Aided Search and Rescue (SAR) System

Abstract: To carry out search and rescue of people in distress on the distressed aircrafts/vessels on land, at sea, or in a remote mountainous region, there are a number of different search and rescue systems and methods that are being used by the different national search and rescue organizations worldwide. Herein, the main terrestrial search and rescue (SAR) systems that are in use are discussed in brief and a satellite-aided search and rescue (SAR) system - COSPAS - SARSAT is discussed in detail highlighting its benefits over other SAR systems.