Nature2014-06-24 4:04 PM

全光子雷达系统问世 A fully photonics-based coherent radar system

论文摘要 

下一代雷达系统将需要高度自动化,采用软件定义的信号生成和检测来在监测和无线通信应用中灵活操作。然而,必要的 “模-数”转换对传统微波电子元件造成严重技术局限。这使得非常适合数字化操作的光子雷达成为一个有吸引力的选项。此前,基于光子的无线电信号生成和检测一般都是被分开研究的。在这项研究中,Paolo Ghelfi等人将各个元件结合起来生成了一个能够发挥功能的全光子雷达系统。该系统的有效性和精确性在一项涉及对过往飞机进行检测的现场试验中得到了演示。

Abstract 

The next generation of radar (radio detection and ranging) systems needs to be based on software-defined radio to adapt to variable environments, with higher carrier frequencies for smaller antennas and broadened bandwidth for increased resolution. Today’s digital microwave components (synthesizers and analogue-to-digital converters) suffer from limited bandwidth with high noise at increasing frequencies, so that fully digital radar systems can work up to only a few gigahertz, and noisy analogue up- and downconversions are necessary for higher frequencies. In contrast, photonics provide high precision and ultrawide bandwidth, allowing both the flexible generation of extremely stable radio-frequency signals with arbitrary waveforms up to millimetre waves, and the detection of such signals and their precise direct digitization without downconversion. Until now, the photonics-based generation and detection of radio-frequency signals have been studied separately and have not been tested in a radar system. Here we present the development and the field trial results of a fully photonics-based coherent radar demonstrator carried out within the project PHODIR27. The proposed architecture exploits a single pulsed laser for generating tunable radar signals and receiving their echoes, avoiding radio-frequency up- and downconversion and guaranteeing both the software-defined approach and high resolution. Its performance exceeds state-of-the-art electronics at carrier frequencies above two gigahertz, and the detection of non-cooperating aeroplanes confirms the effectiveness and expected precision of the system.

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