CW Sar Signal Model and System Implementation (original) (raw)

Introduction to Synthetic Aperture Radar (SAR

The synthetic aperture radar principle has been discovered in the early 50 th. Since then, a rapid development took place all over the world and a couple of air-and space-borne systems are operational today. Progress made in technology and digital signal processing lead to very flexible systems useful for military and civilian applications. Radar has proved to be valuable before, because of its day-and-night capability and the possibility to penetrate clouds and rain. Optical instruments however had great advantages in the interpretation of depicted objects. The great wavelength of radar signals limits the achievable resolution in cross range direction of real aperture radar systems. Thus, imaging cannot be realized using static radar systems 1. The idea of SAR was to transmit pulses and store the scene echoes along a synthetic aperture (i.e. the path of the SAR sensor) and to combine the echoes afterwards by the application of an appropriate focussing algorithm. The combination is carried out coherently. As we will see, it is quit easy to understand the basic idea of SAR. We will show also the hardware concept or a SAR system and give an idea for a processing algorithm. 1.0 GENERAL FACTS ABOUT SAR Today, synthetic aperture radar (SAR) plays an important role in military ground surveillance and earth observation. Since the late eighties a couple of SAR-systems have been developed for both space and airborne operation. The underlying radar principle offers advantages compared to competing sensors in infrared or visible spectral area. This chapter describes the field of applications where SAR can be used to gain valuable information. Physical conditions like propagation of electromagnetic waves and scene reflectivity affect the choice of several radar design parameters.

Synthetic Aperture Radar Systems for Small Aircrafts: Data Processing Approaches

Recent Advances in Aircraft Technology, 2012

Time-domain SAR processing with clutter-lock and geometric correction by resampling, 2. Time-domain SAR processing with built-in geometric correction and multi-look radiometric correction, 3. Range-Doppler algorithm with the 1-st and 2-nd order motion compensation. The proposed solutions have been successfully implemented in Ku-and X-band SAR systems developed and produced at the Institute of Radio Astronomy of the National Academy of Sciences of Ukraine. The efficiency of the proposed algorithms is illustrated by SAR images obtained with these SAR systems. The chapter is organized as follows. In Section 2, basic principles of SAR data processing is described. In Section 3, the problem of motion errors of airborne SAR systems is considered, and the appearance of geometric distortions and radiometric errors in SAR images is discussed. The three data processing approaches are considered in details in Sections 4, 5, and 6. Section 7 describes the RIAN-SAR-Ku and RIAN-SAR-X systems used in our experiments. The conclusion is given in Section 8.

Special Issue “Synthetic Aperture Radar (SAR) Techniques and Applications”

Sensors

This editorial of the special issue titled “Synthetic Aperture Radar (SAR) Techniques and Applications”, reviews the nineteen papers selected for publication. The proposed studies investigate different aspects of SAR processing including signal modelling, simulation, image analysis, as well as some examples of applications. The papers are grouped according to homogeneous subjects, then objectives and methods are summarised, and the more relevant results are commented.

SYNTHETIC APERTURE RADAR SIMULATION AND MEASUREMENT

This paper outlines basic theoretical principle of Synthetic Aperture Radar (SAR). Pulse and azimuth compression techniques for obtaining finer images are also presented and explained in theory supplemented with some simple matlab simulations. SAR image obtained by simple measurement set is also presented together with some RCS measurements and calculations.

The Principles of Synthetic Aperture Radar

Processing of Synthetic Aperture Radar Images, 2008

Synthetic Aperture Radar (SAR) is an active microwave imaging method. It operates independently of Sun illumination and cloud coverage. Current spaceborne systems use wavelengths of 3 to 25 cm and achieve resolutions of 10 to 50 m. The paper attempts to explain the basic SAR imaging principles using a minimum of mathematics. Emphasis is put on the particular properties of SAR images that should be understood before interpreting these data.

Synthetic Aperture Radar Imaging Simulated in MATLAB

This thesis further develops a method from ongoing thesis projects with the goal of generating images using synthetic aperture radar (SAR) simulations coded in MATLAB. The project is supervised by Dr. John Saghri and sponsored by Raytheon Space and Airborne Systems. SAR is a type of imaging radar in which the relative movement of the antenna with respect to the target is utilized. Through the simultaneous processing of the radar reflections over the movement of the antenna via the range Doppler algorithm (RDA), the superior resolution of a theoretical wider antenna, termed synthetic aperture, is obtained. The long term goal of this ongoing project is to develop a simulation in which realistic SAR images can be generated and used for SAR Automatic Target Recognition (ATR). Current and past Master's theses on ATR were restricted to a small data set of Man-portable Surveillance and Target Acquisition Radar (MSTAR) images as most SAR images for military ATR are not released for public use. Also, with an in-house SAR image generation scheme the parameters of noise, target orientation, the elevation angle or look angle to the antenna from the target and other parameters can be directly controlled and modified to best serve ATR purposes or other applications such as three-dimensional SAR holography.