This paper observes electrostatic discharge (ESD) events in terms of electromagnetic interference (EMI) assessments. To characterize the high frequency oscillations present in ESD waveforms, we use two kinds of discharge electrodes: copper and stainless steel spheres. Based on data gathered under charging voltages of 0.25, 0.5, and 1.0 kV, we examine the energy levels of ESD waveforms. As a result, we find that the high-frequency energy, which is related to the high frequency oscillations in the ESD waveform, was affected by the material of discharge electrodes and the fast movement of discharge electrodes.

To clarify the characteristics of high-speed electrostatic discharge (ESD) events, we use two kinds of discharge electrodes: sphere- and cylinder-shape ones. We measure the energy level of ESD waveforms with charging voltages of 0.25, 0.5, and 1.0 kV. We find that the cylindrical electrode yields higher high-speed ESD energies, especially when the charging voltage is high; this indicates that the discharge gap shape is an important factor in ESD events.

The power line communication (PLC) system should be investigated with respect to the influence on electromagnetic environments. Longitudinal conversion loss (LCL) and input impedance are important parameters for evaluating the influence because they are closely related to the radiated, conducted, and inducted emission. An indoor AC mains system consisting of electrical equipment and an AC mains line was modeled by four-port networks, and the LCL and the input impedance were calculated. The parameters of the four-port networks were determined from theory and measurement. The analytical model was examined using a simple network and the results show that the calculated values agreed with the measured ones. The LCL and the input impedance were investigated at the AC mains port in some existing buildings, and the measured results almost agreed with the calculated results derived from the indoor AC mains system model.

We investigated the effect of a high-speed power line communication (PLC) signal induced into a very high-speed digital subscriber line (VDSL) system by conductive coupling based on a network model. Four electronic devices with AC mains and telecommunication ports were modeled using a 4-port network, and the parameters of the network were obtained from measuring impedance and transmission loss. We evaluated the decoupling factor from the mains port to the telecommunication port of a VDSL modem using these parameters for the four electric and electronic devices. The results indicate that the mean value of the decoupling factor for the differential and common mode signals were more than 88 and 62 dB, respectively, in the frequency range of a PLC system. Taking the following parameters into consideration; decoupling factor Ld, the average transmission signal powers of VDSL and PLC, desired and undesired (DU) ratio, and transmission loss of a typical 300-m-long indoor telecommunication line, the VDSL system cannot be disturbed by the PLC signal induced into the VDSL modem from the AC mains port in normal installation.

This paper describes a method of measuring the unsymmetric voltage of conducted noise using a floating measurement system. Here, floating means that there is no physical connection to the reference ground. The method works by correcting the measured voltage to the desired unsymmetric voltage using the capacitance between the measurement instrument and the reference ground plane acting as the return path of the conducted electromagnetic noise. The existing capacitance measurement instrument needs a probe in contact with the ground, so it is difficult to use for on-site measurement of stray capacitance to ground at troubleshooting sites where the ground plane is not exposed or no ground connection point is available. The authors have developed a method of measuring stray capacitance to ground that does not require physical connection of the probe to the ground plane. The developed method can be used to estimate the capacitance between the measurement instrument and ground plane even if the distance and relative permittivity of the space are unknown. And a method is proposed for correcting the voltage measured with the floating measurement system to obtain the unsymmetric voltage of the noise by using the measured capacitance to ground. In the experiment, the unsymmetric voltage of a sinusoidal wave transmitting on a co-axial cable was measured with a floating oscilloscope in a shield room and the measured voltage was corrected to within 2dB of expected voltage by using the capacitance measured with the developed method. In addition, the voltage of a rectangular wave measured with the floating oscilloscope, which displays sag caused by the stray capacitance to ground, was corrected to a rectangular wave without sag. This means that the phase of the unsymmetric voltage can also be corrected by the measured stray capacitance. From these results, the effectiveness of the proposed methods is shown.

Based on the test method proposed by Sub-Committee G of the International Special Committee on Radio Interference, most telephone receivers in Japan have insufficient immunity to acoustic noise caused by radio-frequency fields. This is because the modulation depth of the RF signal used is too high to accurately simulate the audio-frequency components of TV video signals. Reducing the modulation depth from 80% to 5% produces a more realistic simulation.