Electro optical radar transmission chain modeling and simulation

In traditional radar systems, the use of electronic analog devices, such as mixers and oscillators, introduces some noise sources which complicate the realization of a completely digital radar systems. In fact, non linear behaviors of such systems as well as low Spurious Free Dynamic Range (SFDR) and low phase coherence, compromise radar performance in terms of detection and coherent signal processing. Therefore a hybrid approach that merges optical techniques generating highly stable Radio Frequency (RF) carrier with electrical systems for radar signal amplification and transmission, could be the way to overcome the drawbacks related to the electrical radio frequency generation. In this paper we present a theoretical and computer modeling of an electro-optical radar transmission chain. The architecture, which guarantees the high phase coherence of the generated radar signal with direct radio frequency up conversion, is based on the use of a highly stable Mode locked Laser, an optical IQ modulator, and a photodetector. The developed parametric model is necessary to understand the effectiveness and limits of the photonic radar links. To this purpose, results for the simulated radio frequency radar signal are compared with practical measurements in order to validate the proposed simulator.