Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
1999-04-16
2002-10-22
Bui, Bryan (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C702S065000, C324S635000, C324S636000
Reexamination Certificate
active
06470282
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and a device for probing a source of electromagnetic waves generated from electronic equipment or the like, and particularly relates to a method and a device adapted for probing a source of electromagnetic waves in a short time.
In the unnecessary electromagnetic radiation control technique, electromagnetic interference occurs frequently as information/communication equipment and so on come into wide use recently, and technique for detecting a source of electromagnetic waves causing the interference is required. As for the system for probing a source of electromagnetic waves, there are papers, for example, by Junichi Kikuchi, “A Suggestion for a Method of Estimating the Position of a Source of Electromagnetic Waves by Aperture Combination” , IEICE (the Institute of Electronics, Information and Communication Engineers of Japan), Transactions B-IJ, October 1985; Junichi Kikuchi, “Positional Estimation of a Source of Electromagnetic Waves with Maximum Entropy Method” , IEICE Transactions B-II, September 1986; Masayo Hayashi, “Electromagnetic Field Measurement and Numerical Analysis in EMC”, NEC Technical Report, September 1993; etc.
FIG. 5
shows such a conventional method for probing a source of electromagnetic waves.
First, in the conventional probing method, frequency to electric field intensity characteristics E(f) at a distance of 3 m or 10 m which was a target of legal controls was measured (Step
501
), and frequency components which did not satisfy a regulation value were extracted from the results of the measurement (Step
502
). Electromagnetic field distribution near a subject to be measured was measured with respect to the extracted frequency components (Step
503
), and places (positions) to be coped with in the subject to be measured were specified from the results of the measurement (Step
504
).
It was therefore necessary to measure both the distant field and the near field before the places to be coped with were specified. In addition, when there were many frequency components which did not satisfy the regulation value, it was necessary to measure electromagnetic field distribution near the subject to be measured corresponding to the number of the frequency components which did not satisfy the regulation value. Accordingly, there was a problem that the whole probing period of time was prolonged.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a quite novel electromagnetic wave source probing device and a method thereof, in which the probing time can be shortened. That is, it is an object of the present invention to provide an electromagnetic wave source probing device and a method thereof, in which it is not necessary to perform conventional measurement of electromagnetic field strength distribution near a subject to be measured with respect to respective frequency components.
In order to attain the foregoing object, according to the present invention, prospect is performed by using a near magnetic field measured value H(t) in time domain, differently from a conventional prospect by using a distant electric field measured value E(f) in frequency domain.
More specifically, according to an aspect of the present invention, provided is an electromagnetic wave source probing method comprising the steps of: measuring magnetic field to time characteristics generated from a subject to be measured in a plurality of positions; calculating electric field to frequency characteristics generated from the subject to be measured by use of the plurality of measured magnetic field to time characteristics; extracting frequency components exceeding a predetermined electric field value in the calculated electric field to frequency characteristics; and outputting positions where currents having the extracted frequency components exist in the subject to be measured.
According to another aspect of the present invention, provided is an electromagnetic wave source probing device comprising: a plurality of measuring means for measuring magnetic field to time characteristics generated from a subject to be measured; a first calculating means for calculating electric field to frequency characteristics generated from the subject to be measured based on the magnetic field to time characteristics measured by the plurality of measuring means; a second calculating means for calculating frequency components exceeding a predetermined electric field value in the calculated electric field to frequency characteristics; and an output means for outputting positions where currents having the calculated frequency components exist in the subject to be measured.
In such a manner, it is not necessary to measure both the distant field and the near field, unlike a conventional case, before places to be coped with are specified, but it will go well if only the near field is measured. It is therefore possible to shorten the prospect time. Particularly, even if there are many frequency components which do not satisfy the regulation value, it is not necessary to measure electromagnetic field distribution near the subject to be measured corresponding to the number of the frequency components unlike the conventional case, and the places to be coped with can be specified simply by a calculation process simply. It is therefore possible to shorten the probing time on a large scale.
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Kensuke Sekihara et al, “Reconstructing Current Distributions from Biomagnetic Measurements under Biomagnetic Measurements under Large External Noise Disturbances”, IEEE Transactions on Medical Imagining, vol. 13, No. 1, Mar. 1994, pp. 144-151.
NEC, vol. 46, No. 9, 1993, “Electromagnetic Field Measurement and Numerical Analysis for EMC Problems”, S. Hayashi. (pp. 50-54).
“A Proposal for Searching for Electromagnetic Wave Sources by Using a Synthetic Aperture Technique”, J. Kikuchi et al, pp. 1194-1200. (No date).
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Bui Bryan
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
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