Practical Papers, Articles and Application Notes Kye Yak See, Technical Editor
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t’s amazing how fast time flies and another year has quietly passed us by. It is certainly a good time to reflect on what we have achieved in 2012 and make new wishes for 2013! For me, one of my wishes is to solicit more quality papers for this column to benefit all our readers. Unmanned aerial vehicles (UAVs) have been widely used in many surveillance applications. Just like any other electronic systems, EMC consideration for an UAV is necessary to ensure its satisfactory performance for a specific mission. The first paper in this issue, “EMI Suppression of UAV Power in Aeromagnetic Survey,” submitted by Cao Zhiwen, Chen Dongsheng, Yu Fei, Wang Haijuan and Zeng Zhihui from Beijing University of Technology, describes how the unwanted magnetic field emitted by a switching power supply circuit on an UAV can interfere with high-precision aeromagnetic surveys. Through the analysis of possible EMI sources on an UAV and the operating characteristics of optical pumping magnetometers, this paper illustrates that with careful EMC design, the measurement precision of the optical pumping magnetometers will not be degraded. The second paper “Soft Fault Detection in Cables using the Cluster Time-frequency Domain Reflectometry,” authored by Maud Franchet and Nicolas Ravot from CEA-LIST; and Odile Picon from University of Paris-Est Marne-la-Valle, presents a method to detect soft faults of cables based on the cluster time-frequency domain reflec-
tometry technique. Taking advantage of the resultant near-end crosstalk signals from the wires, the proposed method has the ability to identify any faulty wire in a cable bundle. To detect the faults efficiently, a normalized time-frequency cross correlation function has been implemented. Early fault detection before serious damage happens to the cable is very useful for automotive and aerospace systems, where the economic consequences cannot be ignored. The last paper, “Test Methods for RF-Based Electronic Safety Equipment: Part 2 –Development of Laboratory-Based Tests,” is the second part of a two-part series contributed by Kate A. Remley and William F. Young from the National Institute of Standards and Technology. The methodology for categorizing path loss according to various RF-propagation environments is described. These categories enable the development of laboratory-based test methods that are appropriate for types of wireless technology that will be deployed in various environments. Two test methods, designed to evaluate device performance in the presence of RF-propagation-channel attenuation less than 100 dB and in the presence of in-band RF interference, are discussed in detail. As more wireless electronic-safety equipment become available, these test methods described here will be useful for testing such systems. For those who are interested in submitting a paper for this column, feel free to contact me through email:
[email protected]. Enjoy reading these papers!
EMI Suppression of UAV Power in Aeromagnetic Survey Cao Zhiwen, Chen Dongsheng, Yu Fei, Wang Haijuan, Zeng Zhihui, College of Electronic Information and Control Engineering, Beijing University of Technology;
[email protected],
[email protected],
[email protected],
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[email protected] Abstract - Recently, unmanned aerial vehicles (UAVs) have become one of the latest application technologies in the aeromagnetic field. Furthermore, high-precision aeromagnetic gradient surveys need higher precision magnetometers, and higher dynamic measurement precision of UAVs. The problem of magnetic interference of UAVs must be solved to implement high-precision aeromagnetic surveys, as the switch mode power supply (SMPS) is one of the most important interference sources of UAVs. Through the analysis of electromagnetic interference (EMI) sources of UAVs and the working characteristics of optical pumping magnetometers, this paper intends to design and optimize the switching power supply circuit, reduce the generation of EMI, and improve the measurement precision of optical pumping magnetometers. Keywords - aeromagnetic survey; UAV; measurement precision; EMI
I. Introduction Aeromagnetic surveys are a common type of geomagnetic survey carried out using a sensitive magnetometer, aboard or towed behind an aircraft, for the detection of underground ore and geological changes in the magnetic field. To expand the application scope of aeromagnetic surveys and improve the application effect, further direction should be focused on improving the precision of aeromagnetic surveys[1]. A magnetometer is a measuring instrument used to measure the strength or direction of magnetic fields, with its magnetic method based on small variations in magnetic fields. High-precision aeromagnetic gradient surveying is a new technology which has been improved internationally over the past three decades. However, it
©2013 IEEE Electromagnetic Compatibility Magazine – Volume 2 – Quarter 1
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