Fast Frequency Hopping/Direct Sequence (FFH/DS) hybrid spread spectrum is an effective technique of the communication network for the robot swarms operating in complex electromagnetic environment. It combines the advantages of both Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS), and also uses the diversity-combining in time and frequency domain to effectively reject unwanted jamming. Multi-Tone Interference (MTI) is one of the most deleterious jamming waveforms for frequency hopping systems, and consequently a severe threat for FFH/DS systems. In this article, we explore the effect of MTI on coherent FFH/DS, and we have shown that, if spectral sensing mechanism for MTI frequency and power monitoring is available, the MTI in FFH/DS reception is a set of complex sinusoid components with deterministic amplitudes and random phases, instead of the conventionally assumed Gaussian random variables. In light of this new finding, a novel combining method is proposed. It utilizes the spectral sensing information to adaptively compute the combining weights, following Maximum Signal to Interference plus Noise (MSINR) law. Its combining performance is analyzed and compared with other existing methods, and verified by simulations. It is shown that the proposed adaptive MSINR combining has satisfactory performance under both medium and strong MTI scenarios.

中文翻译：

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存在多音干扰时相干 FFH/DS 扩频接收机的最佳组合

快速跳频/直接序列（FFH/DS）混合扩频技术是一种有效的通信网络技术，适用于在复杂电磁环境中运行的机器人群。它结合了跳频扩频（FHSS）和直接序列扩频（DSSS）的优点，还利用时域和频域的分集组合来有效地抑制不需要的干扰。多音干扰 (MTI) 是跳频系统最有害的干扰波形之一，因此对 FFH/DS 系统构成严重威胁。在本文中，我们探讨了 MTI 对相干 FFH/DS 的影响，并且我们已经证明，如果 MTI 频率和功率监测的频谱感知机制可用，FFH/DS 接收中的 MTI 是一组具有确定性幅度和随机相位的复杂正弦分量，而不是传统假设的高斯随机变量。根据这一新发现，提出了一种新的组合方法。它利用频谱感测信息自适应地计算组合权重，遵循最大信号干扰加噪声 (MSINR) 定律。对其组合性能进行了分析，并与其他现有方法进行了比较，并通过仿真进行了验证。结果表明，所提出的自适应 MSINR 组合在中等和强 MTI 场景下都具有令人满意的性能。它利用频谱感测信息自适应地计算组合权重，遵循最大信号干扰加噪声 (MSINR) 定律。对其组合性能进行了分析，并与其他现有方法进行了比较，并通过仿真进行了验证。结果表明，所提出的自适应 MSINR 组合在中等和强 MTI 场景下都具有令人满意的性能。它利用频谱感测信息自适应地计算组合权重，遵循最大信号干扰加噪声 (MSINR) 定律。对其组合性能进行了分析，并与其他现有方法进行了比较，并通过仿真进行了验证。结果表明，所提出的自适应 MSINR 组合在中等和强 MTI 场景下都具有令人满意的性能。