Takashi Shinozuka

APD Measurement for Evaluating Disturbances Related to the Performance of Digital Communication Systems

The measured values of electromagnetic disturbances should strongly correlate with degradation in the communication quality of digital wireless communication systems. The Amplitude Probability Distribution (APD) of a disturbance represents statistical information as applicable measurement readings that meet the above requirement. In this paper, correlations between APD measurements of disturbances and the bit error rate (BER) as a quality degradation index for victim systems are quantitatively investigated. Disturbance regulation by APD measurements is discussed from the viewpoint of protecting systems from disturbances. This investigation specifically considers the situation in which a repetition pulse disturbance impacts PHS and W-CDMA systems assumed as victims. The results confirm high correlations between the APD and BER not only experimentally but also theoretically under some conditions. A disturbance regulation criterion based on APD measurements is thus proposed for compliance testing of electronic appliances with the potential to act as disturbance noise sources.

Electric-Field Distribution Estimation in a Train Carriage due to Cellular Radios in order to Assess the Implantable Cardiac Pacemaker EMI in Semi-Echoic Environments

The electromagnetic field (EMF) distributions created inside a train carriage by the cellular radios of the passengers are analyzed and the impact their electromagnetic interference (EMI) on the implantable cardiac pacemakers is evaluated based upon the analysis results. Both computer simulations and experiments using 800 MHz and 2 GHz transmitters in an actual train carriage confirm that excessively high EMF, high enough to affect the normal functions of the pacemaker, does not occur inside the carriage provided the safe distance of 22 cm specified for pacemaker users is kept. A simplified histogram estimation method for electric field strength is newly developed to deal with the complicated EMF distributions. It allows the EMI risk to pacemakers by cellular radio transmission to be quantitatively evaluated. Methodologies are described first. Typical results of FDTD analysis and actual measurement data are then shown. Finally, considerations and conclusions are made.

Evaluation of electromagnetic radiation from the DC side of a photovoltaic power generation system

The radiation mechanism from the DC side of a photovoltaic (PV) power generation system is investigated at frequencies between 150 kHz and 30 MHz. To determine the source of the outbreak of the common mode noise, the balancing of the PV measurement model, which is composed of a PV panel and a 2-m-long DC cable, is measured by the mixed-mode S-parameter method. Results showthatthe PV model has good balance. Then, a balanced PV simulation model is proposed. To express the common mode noise, the input signal is supplied to only one of the two wires of the PV simulation model. To confirm the validity of the PV simulation model, the current flowing in the DC cable and the magnetic field from the PV simulation model are compared with those of the PV measurement model. A good agreement between the measured and simulation results is obtained. The PV simulation model is valid for evaluating the radiation noise from the DC side of the PV power generation system. Moreover, the effect of the frame wire of the PV power generation system on the radiation noise is evaluated. The radiation noise from the PV power generation system will strengthen or weaken depending on the layout of the frame wire, especially at low frequency. The radiation noise from the PV power generation system with a plurality of PV panels is also investigated. The peak of the frequen cy spectrum of the radiation noise shifts to lowfrequency when the number of PV panels is increased.

A Method for Converting Amplitude Probability Distribution of Disturbance from One Measurement Frequency to Another

To estimate the impact of electromagnetic disturbances on multi-carrier wireless systems, a method for converting an amplitude probability distribution (APD) of disturbance measured at a frequency to be valid for another frequency is presented. The conversion uses two parameters, the receiver noise power of the APD measuring equipment and a scale factor that can be estimated from a measured disturbance spectrum. The method is based on the assumption that the difference in measurement frequency affects only the relative scale of the probability distribution of band-limited disturbance amplitude, and is applicable to disturbances of practically importance such as 1) continuous or pulse-modulated wideband Gaussian noise, 2) disturbance with a much narrower bandwidth than receiver bandwidth B, and 3) repetitive short pulses with similar waveforms with an interval much longer than 1/B. The validity of the proposed method is examined by measurements of actual disturbances.