[论文解读] Leakage Mitigation and Internal Delay Compensation in FMCW Radar for Small Drone Detection

Junhyeong Park, Seungwoon Park+1 more|arXiv (Cornell University)|Jul 17, 2018

Radar Systems and Signal Processing参考文献 14被引用 4

一句话总结

本文提出了一种用于FMCW雷达的新颖下变频技术，可减轻收发机泄漏并补偿内部信号延迟。通过结合频率规划与数字信号处理，该方法在近场区域将噪声底 floor 降低7.0 dB，并恢复了最大可探测距离，显著提升了动态范围与小无人机探测的检测性能。

ABSTRACT

One of the notorious problems of frequency modulated continuous-wave (FMCW) radar is leakage between the transmitter and the receiver. The phase noise of the leakage is expressed as a skirt around the leakage signal on power spectrum. It causes the deterioration of the dynamic range, especially, in the near-distance region. Therefore, although FMCW radar has an advantage over pulse radar in terms of near-distance target detection due to its way of operation, the advantage of FMCW radar can be lost because of the leakage. Another problem of FMCW radar is internal delay in the radar system. It leads to the decrease of the maximum detectable range. In this paper, a novel down-conversion technique which resolves these problems is proposed. Detailed theory and procedures to implement the proposed technique are explained. Then, performances of it are verified with the experiment results. The proposed technique can be implemented through frequency planning and digital signal processing without additional parts. The results show that the proposed technique lowers the noise floor about 7.0 dB in the near-distance region and 2.1 dB even in the far-distance region. Also, the results demonstrate the proposed technique recover the reduced maximum detectable range by compensating the internal delay.

研究动机与目标

• 解决FMCW雷达中收发机泄漏的关键问题，该问题会降低动态范围，尤其是在近场区域。
• 解决内部信号延迟限制FMCW雷达系统最大可探测距离的问题。
• 开发一种无需额外硬件组件即可提升雷达性能的解决方案。
• 通过真实环境下的实验验证，确认所提技术的有效性。
• 通过提升近场复杂场景下的灵敏度与动态范围，实现对小型、低RCS无人机的可靠探测。

提出的方法

• 提出一种新颖的下变频技术，可在基带域将泄漏信号与期望的回波信号分离。
• 该方法采用精确的频率规划，将泄漏信号的频谱移离感兴趣的基带信号。
• 应用数字信号处理算法，估计并抵消泄漏信号中呈现为旁瓣的相位噪声分量。
• 通过基于校准的数字校正技术，对雷达链路中的内部延迟进行建模并加以补偿。
• 该方法利用现有信号处理模块，无需增加额外硬件组件。
• 该技术在标准FMCW信号处理链路中实现，确保与现有雷达系统的兼容性。

实验结果

研究问题

• RQ1 如何有效减轻FMCW雷达中的收发机泄漏，以提升近场区域的动态范围？
• RQ2 内部信号延迟在多大程度上会降低FMCW雷达系统的最大可探测距离？
• RQ3 是否可仅通过频率规划与数字信号处理实现泄漏与内部延迟的补偿，而无需额外硬件？
• RQ4 应用所提出的补偿技术后，噪声底 floor 与探测距离的改善程度如何？
• RQ5 该方法在真实环境中对小型、低RCS无人机探测的性能表现如何？

主要发现

• 所提技术在近场区域将噪声底 floor 降低约7.0 dB，显著提升了对近距离目标的灵敏度。
• 即使在远场区域，噪声底 floor 也降低了2.1 dB，整体动态范围得到增强。
• 雷达系统中的内部延迟成功得到补偿，恢复了此前因延迟而降低的最大可探测距离。
• 该方法仅通过频率规划与数字信号处理即实现上述改进，无需额外硬件组件。
• 实验结果证实了该技术在实际FMCW雷达系统中用于小无人机探测的有效性。
• 该工作的升级版本已发表于IEEE Transactions on Microwave Theory and Techniques，验证了其技术贡献与性能表现。