CRC Press, 2016. — 217.
The purpose of this book is to provide a systematic explanation of modern synthetic aperture radar (SAR) principles for the use, study, and development of SAR systems. The framework and scope of this book are suitable for students, radar engineers, and microwave remote-sensing researchers.
SAR is a complex imaging system that has many sensing applications, from geoscience studies to planetary exploration. In the last two decades, many excellent books in treatment of one or more specific topics on SAR have been published. This book is unique not in presenting novel topics but in its inclusion of chapters on signal speckle, radar-signal models, sensor-trajectory models, SAR-image focusing, platform-motion compensation, and microwave-scattering from random media. Numerical simulations are presented to cover these important subjects. A groundbased FMCW system is also included. And, as an example, system simulation is provided for target classification and recognition. Simulation flowcharts and results are graphically presented throughout this book to help the reader, if necessary, to grasp specific subjects. The following paragraphs of this preface will elaborate on the aforementioned subjects.
Many publications have sought to connect the wave-scattering process and the radar-signal process by presenting physical, systemic, and signal SAR models, among others. In this book, numerical simulations of polarimetric wave scattering from randomly irregular surfaces are given to illustrate the speckle phenomenon and to validate the fully developed speckle model for a homogeneous target. However, it is logical to extend numerical simulations to volume and surface–volume scattering for more complex targets. The signal model using a point-spread function is given for chirp and FMCW system. This kind of model greatly simplifies the data process but profoundly neglects the coherence within the resolution cell, where many targets are in presence. It remains challenging to work on a full-blown signal model to account for the target homogeneity and the memory effects. This topic will be reserved for future research. For demonstration, we have selected range-Doppler and chirp-scaling algorithms because of their popularity and their high precision. In path trajectory, transformations of time and space coordinates of aircrafts and satellites are presented, the latter being more complicated because of the effect of earth’s rotation. For SAR systems, time and space coordinates are critical. Doppler frequency and Doppler-frequency rates are two other vital parameters for precise and coherent processing. A simple aircraft trajectory with bias and noise is simulated in this book. This proves useful for accounting for platform motion and image focusing, subjects that are treated in Chapters 5 and 6. Chapter 7 specifically deals with a ground-based SAR. Because of the short range of the operation, FMCW is adopted. Suitable focusing algorithms using range-Doppler and chirp scaling are presented. An experimental system operating at Ka-band was built in a microwave aniconic chamber to demonstrate data collection and image focusing. Chapter 8 includes topics from previous chapters to illustrate the complete chain of a SAR operation. Such system simulations are extremely useful in understanding image properties and in developing user applications.
Preliminary Background
SAR Models
SAR Data and Signal
SAR Path Trajectory
SAR Image Focusing
Motion Compensation
Stationary FMCW SAR
System Simulations and Applications