外场辐射发射测量中瞬变环境信号的抑制

Transient ambient signals suppressing for in-situ radiated emissions measurement

为了抑制电子设备辐射发射外场测量时环境中的瞬变信号,提出了一种时域频域相结合的测量方法.首先通过时域方法捕捉瞬变环境信号,并使用重叠窗技术避免瞬变环境信号频谱的丢失.然后对瞬变环境信号进行周期延拓,将其变为周期信号,为自适应算法提供足够的采样点数,保证算法的收敛性.最后采用自适应噪声抵消技术实现对瞬变环境信号的抑制.仿真和试验结果表明,无论受试设备辐射信号是连续周期信号还是瞬变信号,所提方法均能够实现对瞬变环境信号40 dB以上的抑制,有效提取受试设备的辐射发射信号,恢复出的辐射信号与其真实值的误差在3 dB以内.在准确测量受试设备辐射发射的同时,所提方法还能够对辐射信号进行时频分析,为设备电磁兼容问题的诊断与整改提供必要的依据.

To suppress the transient ambient signals in in-situ radiated emission measurement of the electronic equipment, a measurement method combining time domain and frequency domain was proposed. First, the transient ambient signals were captured in the time domain, and the overlapping window technique was adopted to avoid the spectrum loss. Then, the transient ambient signals were cyclically extended to be periodic signals, providing sufficient sampling points for the adaptive filtering algorithm to ensure its convergence. Finally, an adaptive noise cancellation technology was used to suppress the transient ambient signals. Simulation and experimental results show that the proposed method can achieve more than 40 dB suppression of the transient ambient signals and obtain the radiated emissions of the equipment under test, they are radiated signals of the equipment under test regardless of continuous periodic signals or transient signals. The error between the recovered radiated signals and their true value is less than 3 dB. While accurately measuring the radiated emissions of the equipment under test, the proposed method can also perform time-frequency analysis on radiated signals, providing a basis for the diagnosis and the rectification of the electromagnetic compatibility problem of the equipment.