Sub-Nyquist/Chaotic Deception Jammer for Spoofing Radars

We can define the airborne system proposed in this book as an airframe that works on the enemy side, so it is in danger of attack from the enemies' missiles systems and detected by radars. Therefore, the need to support this system with immunity from these threats is important for the safety of this system. After proposing the advanced method for high speed target detection in the presence of clutter and jamming, now the authors discuss how to support this system with immunity against ground radar and missile stations. The deception jammer is a type of spoofing radar. As discussed in Chapter 2, the digital radio frequency memory (DRFM) will be used to generate the deceptive jamming, and the sub-Nyquist sampling theory will be used to improve the performance of the jammer. In addition, chaotic algorithm is proposed to give more improvement to the jammer source.

Space-Time Adaptive Processing and Jamming

Space-time adaptive processing (STAP) has been a well-established technique, whose basic concept and theory are first put forward by Brennan and Reed. However, it is difficult to implement in the practical system because of the computational complexity and the sample limitation for estimating the clutter covariance matrix. STAP is a modern signal processing technique that can improve target detectability in the presence of a strong clutter Klemm.

Target Detection

Target detection means to illuminate the target and then calculate its parameters, such a range, speed, azimuth, and altitude. The target range can be obtained using one of several methods: by calculating the time between the detected target echo and the transmitted wave, then calculating the difference in frequency between the received echo and the transmitted wave in the case of linear frequency modulation, and finally calculating the differential phase of the double detection of an echo obtained using two transmissions of different frequencies.

Radar Platform and Modeling

The modeling of the system is the most important step in designing procedures. Without modeling, we cannot test our system performance. The simulation and validation can be realized after system modeling. In this chapter, the authors study how to model all the proposed system components. The airborne system consists of two subsystems. The first one is the airborne radar, and the second one is the airborne self-deception jammer system, so they study how to model the airborne radar system and its main components such as transmitter, receiver, and antenna. The radar transmitted signal will be modeled. All the radar system modeling must achieve high probability of detection and low probability of false alarm. The target also will be modeled, and different targets types will be introduced. These targets have different cases, such as fluctuating and non-fluctuating targets. The environment effects such as clutter (ground clutter, sea clutter, weather clutter) and the different jamming models will be also introduced.

Introduction

Although the airborne radar introduced many advantages over other radars, such as ground radars, in detecting high speed air targets, it suffers from many problems. These problems can be concluded as, first, the range migration problem that happens due to the high relative speed between the airborne radar and the high speed air targets and the Doppler ambiguity estimation problem; second, the limited input dynamic power range of the radar receiver and the power loss due to targets range; third, the effects of jamming and clutter which are more effective than ground radars; and finally, the airborne system is a perfect target for enemy threats such as jamming and spoofing.

Advanced Techniques for Range Detection

Range detection is the main significant goal of radar systems. The radar illuminates the targets to the user and then calculates its parameters. The range is the most important parameter. In Chapter 2, the authors discussed the range detection criteria for the general radar and then emphasized the range detection in airborne radar systems. The range detection in radars suffers from many problems, especially in airborne radar systems where the clutter and jamming are highly affected by the targets' echoes. Also, due to the high relative speed between the air targets and the airborne radar, the range migration problem will happen, and the power loss problem will affect the SNR. So, in order to have a high probability of detection, one must compensate for these problems. This chapter will explain all these problems and how to solve them.