Whether in military or civilian use, frequency-modulated continuous-wave (FMCW) radars play a very important role, but common FMCW radars need to collect both radar echo signals and hardware synchronization signals during echo signal processing. Therefore, this article proposes a new synchronization algorithm, i.e., the four-threshold frequency band variance (FFBV) synchronization algorithm. Then, we combine theoretical derivation and experimental verification to analyze the performance of the FFBV synchronization algorithm. With assistance of the FFBV synchronization algorithm, the soft synchronization FMCW radar can achieve the same functions without hardware synchronization signals. First, we analyze the principle behind the FMCW radar based on intermittent ramp signals. Second, we analyze the design of the FFBV synchronization algorithm. In addition, we verify the performance of the algorithm when the received signal is corrupted by the additive white Gaussian noise (AWGN). Then, we analyze the performance from two aspects, including the performance of the algorithm under different signal-to-noise ratio (SNR) conditions, as well as the performance comparison with other common synchronization algorithms. Finally, experimental results show that the FFBV synchronization algorithm has achieved good performance in solving the signal synchronization issue of the FMCW radar under the condition of low SNR. Especially, the SNR required by the FFBV synchronization algorithm is 2 and 6.5 dB lower than that required by the three-threshold synchronization algorithm and variance synchronization algorithm, respectively, under the same condition that the accuracy is 90%.

中文翻译：

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软同步FMCW雷达的FFBV算法设计

无论在军事还是民用领域，调频连续波（FMCW）雷达都起着非常重要的作用，但是普通的FMCW雷达需要在回波信号处理过程中同时收集雷达回波信号和硬件同步信号。因此，本文提出了一种新的同步算法，即四阈值频带方差（FFBV）同步算法。然后，我们结合理论推导和实验验证来分析FFBV同步算法的性能。借助FFBV同步算法，软同步FMCW雷达无需硬件同步信号即可实现相同的功能。首先，我们基于间歇性斜坡信号分析FMCW雷达的原理。其次，我们分析了FFBV同步算法的设计。此外，当接收信号被加性高斯白噪声（AWGN）破坏时，我们验证了算法的性能。然后，我们从两个方面分析了性能，包括在不同信噪比（SNR）条件下算法的性能，以及与其他常见同步算法的性能比较。最后，实验结果表明，在低信噪比的情况下，FFBV同步算法在解决FMCW雷达的信号同步问题上取得了良好的性能。特别是，在精度为90％的相同条件下，FFBV同步算法所需的SNR分别比三阈值同步算法和方差同步算法所需的SNR低2和6.5 dB。当接收信号被加性高斯白噪声（AWGN）破坏时，我们验证了算法的性能。然后，我们从两个方面分析了性能，包括在不同信噪比（SNR）条件下算法的性能，以及与其他常见同步算法的性能比较。最后，实验结果表明，在低信噪比的情况下，FFBV同步算法在解决FMCW雷达的信号同步问题上取得了良好的性能。特别是，在精度为90％的相同条件下，FFBV同步算法所需的SNR分别比三阈值同步算法和方差同步算法所需的SNR低2和6.5 dB。当接收信号被加性高斯白噪声（AWGN）破坏时，我们验证了算法的性能。然后，我们从两个方面分析了性能，包括在不同信噪比（SNR）条件下算法的性能，以及与其他常见同步算法的性能比较。最后，实验结果表明，在低信噪比的情况下，FFBV同步算法在解决FMCW雷达的信号同步问题上取得了良好的性能。特别是，在精度为90％的相同条件下，FFBV同步算法所需的SNR分别比三阈值同步算法和方差同步算法所需的SNR低2和6.5 dB。