An all-digital image synthesizer for countering high-resolution imaging radars

Abstract

The subject of this thesis is a digital image synthesizer (DIS), which is especially useful as a counter-targeting signal repeater, i.e., for synthesizing the characteristic echo signature of a pre-selected target. The DIS has a digital radio frequency memory (DRFM) and associated circuitry, including digital tapped delay lines and a modulator in each delay line to impose both amplitude and frequency modulation in each line. A unique property of the digital image synthesizer is its ability to synthesize false targets using wideband chirp signals of any duration. The system-on-a-chip uses a scalable CMOS technology that increases the bandwidth and sensitivity of such a repeater over prior analog-based systems. The application-specific integrated-circuit reduces the noise of the repeated signal, reduces the size and cost of such a system and permits real-time alteration of operating parameters, permitting rapid and adaptive shifting among different types of targets to be synthesized