Aerospace and Electronic Systems Magazine September 2017 - 2

In This Issue - Technically
DESIGN FOR GRACEFUL DEGRADATION AND RECOVERY FROM GNSS INTERRUPTIONS
A filter design which allows the flight control system of a small UAV to gracefully degrade from a loss of GNSS and gracefully recover
upon subsequent restoration of GNSS services is presented. The approach makes use of sensors already found on most current small UAV
flight control systems. A decentralized filtering approach is used in which vehicle state estimates derived from a bank of parallel filters are
fused using blending filters. The blending filters assign weights to the estimates derived from each parallel filter while ensuring the final state
estimate is unbiased and has a minimum variance. Operation of the filter is validated using real flight test data collected from a small UAV.

STUDY ON A NEW POWER BY WIRE THRUST VECTOR CONTROL SYSTEM WITH HIGH RELIABILITY
The power by wire (PBW) thrust vector control (TVC) system is a new kind of actuation system developed over the last 20 years. However, the control performance of the pump control PBW system is weak, and the efficiency of the valve control PBW system is low. In
this article, the concept of an ideal PBW system is defined, and a novel PBW TVC system that is close to the ideal PBW system with the
best balance among control performance, efficiency, and reliability is proposed. The simulation results show that the new PBW system
has all of these things. In addition. On the basis of the new PBW system, a quad redundant PBW system with high reliability is designed
to meet the requirement of next generation launch vehicles.

RCS MEASUREMENTS AND ISAR IMAGES OF SMALL UAVS
In this article, radar cross section (RCS) measurements of a small toy drone and a professional quadcopter have been carried out. Both
unmanned aerial vehicles (UAV) are among the smallest ones in their categories. A significant finding of this work is that Swerling
Case I distribution agrees very well with the RCS statistical distribution of the quadcopters we tested. Furthermore, the acquired data
have been processed for obtaining 2D and 3D Inverse Synthetic Aperture Radar (ISAR) images that are clear and well-defined, and
are suitable for identifing the features of the UAVs that give the strongest radar response.

EVALUATING PERFORMANCE OF MEMS BAROMETRIC SENSORS IN DIFFERENTIAL ALTIMETRY SYSTEMS
This article presents a prototype testbed, addressed to evaluate the performance of MEMS barometric pressure sensors in differential
altimetry systems. The proposed testbed is ideal for arranging low-cost experimental observations of the system performance, over the
exceptionally expensive apparatus required for conducting accurate experiments. Practices presented in this article can also be applied
to consumer barometers (e.g., sensors found in smart phones) which are regularly used in research for positioning systems.

EXPERT SYSTEM CFAR: ALGORITHM DEVELOPMENT, EXPERIMENTAL DEMONSTRATION, AND TRANSITION TO AIRBORNE
RADAR SYSTEMS
This article details research and development of an Expert System Constant False Alarm Rate (CFAR) processor, transition to US Air
Force weapon systems, acceptance by the broader radar community, and professional recognition culminating in the 2016 IEEE AESS
Pioneer Award. The Expert System CFAR arose out of a need to detect and track low-flying and slow-moving air-breathing targets in
the presence of strong electromagnetic interference and clutter, and functions by a novel form of data fusion for improved radar target
detection and analysis, e.g. resource management. In 1984, an airborne wide area surveillance radar designed for operation in the postAWACS era was envisioned. Almost a decade later, the application to surface target detection and track processing emerged naturally
from this innovation. Other technology investigations resulting from this research include waveform diversity and knowledge-based
space-time adaptive processing. This technology has been fielded by the user community.

FOCUS-BEFORE-DETECTION RADAR SIGNAL PROCESSING: PART I-CHALLENGES AND METHODS
The working environment of modern radar is becoming more and more challenging. High-speed, highly maneuvering and weak targets
are becoming increasingly important in air, space, sea and ground. Also, strong clutter and jamming are seriously affecting radar target
detection. In this article, it is shown that radar signal processing has much potential and may effectively improve radar target detection
and parameter estimation without changing system parameters in a complicated environment. It can well cope with accurate environment
sensing from echoes. Specifically, focus-before-detection (FBD) is introduced in this article to assist target detection based on the sharp
peaks in a parameter space and to overcome the effects of across range cells (ARC), across Doppler cells (ADC) and even across beam
widths (ABW) in a long coherent integration time. Indeed, the proposed FBD-based methods can improve target detection and parameter
estimation for an uncooperatively moving target via long time coherent integration.

IEEE A&E SYSTEMS MAGAZINE

SEPTEMBER 2017

Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine September 2017