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本文论述EMC(电磁兼容性)的基本限制和目前技术发展水平的限制,重点是前者。基本限制是从天然的和人为的电磁噪声得出的,它们影响两个基本的比值,即S/N(信号噪声比)和I/N(外来输入与噪声比)。对于数字和模拟通信系统讨论了允许的S/N值。从而得出两种通信系统的允许S/I比(信号与外来输入比),也得出雷达和声纳的S/I比。对发射机的技术发展水平的限制包括射频噪声辐射、寄生辐射和相互调制。对接收机的限制则包括相邻通道的相互作用,镜象、中频和其它寄生响应包括交叉调制、相互调制和降低灵敏度。也讨论了非有意的辐射和接收。并从原理方面考虑了在不希望有的辐射源和接收器之间的耦合限制,包括辐射、感应和传导。
This article addresses the fundamental limitations of EMC (electromagnetic compatibility) and the limitations of current state of the art, with the emphasis on the former. The basic restrictions are derived from natural and artificial electromagnetic noise. They affect two basic ratios, S / N (signal to noise ratio) and I / N (external input to noise ratio). The allowed S / N values are discussed for digital and analog communication systems. Thus, the allowable S / I ratio (signal to external input ratio) of both communication systems is derived as well as the S / I ratio of radar and sonar. Limits to the transmitter’s level of technological development include radio frequency noise emissions, parasitic radiation and intermodulation. Receiver limitations include adjacent channel interactions, mirroring, intermediate frequency and other parasitic responses including cross-modulation, mutual modulation, and reduced sensitivity. Inadvertent radiation and reception are also discussed. And from the principle of considering the unwanted coupling between the radiation source and the receiver limits, including radiation, sensing and conduction.