JP3603143B2 - Electromagnetic interference measuring device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electromagnetic interference wave measuring device that can analyze a source of electromagnetic noise on a printed wiring board on which electronic components with a large amount of unnecessary radiation are mounted.
[0002]
[Prior art]
Conventionally, in a "double-sided interfering wave measuring apparatus" described in JP-A-6-58970, a method of arranging a plurality of loop antennas in a grid and measuring the near magnetic field, or controlling the position of the loop antenna by a linear stage. A method of measuring the near magnetic field by performing the method has been proposed, and has an advantage in examining the approximate time-averaged intensity distribution of the near magnetic field.
[0003]
[Problems to be solved by the invention]
However, in the measurement method used for the conventional “double-sided interference wave measuring device”, when examining the magnetic field near the digital circuit, the current waveform of the digital circuit is an aperiodic waveform. There was a problem that it was not possible to examine in more detail.
[0004]
The present invention has been made in view of the above, and an object of the present invention is to provide an electromagnetic interference wave measuring apparatus capable of measuring electromagnetic wave noise of a digital circuit to be measured in more detail.
[0005]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a clock signal input unit for inputting a clock signal from a digital circuit mounted on a printed circuit board, and a digital circuit mounted on the printed circuit board. Magnetic field detecting means for detecting a magnetic field signal of unnecessary radiation generated from an electronic component; detecting position moving means for moving the magnetic field detecting means to a designated position on the printed wiring board; and a clock signal from the clock signal input means. A quantizing means for quantizing a magnetic field signal from the magnetic field detecting means; and a clock cycle within a designated measuring time based on the clock signal and the magnetic field signal quantized by the quantizing means. Frequency analysis means for analyzing the frequency component of the magnetic field signal for each, and frequency component patterns of the magnetic field signal analyzed by the frequency analysis means. Similarity evaluation means for classifying and evaluating according to the degree, storage means for storing frequency component patterns evaluated by the similarity evaluation means, and setting a designated position in the detection position moving means, and performing the frequency analysis. The gist is that the means is provided with a control means for setting a measurement time.
[0006]
According to a second aspect of the present invention, in order to solve the above-described problem, the frequency analysis means prohibits generation of a frequency component pattern that does not include a specified frequency.
[0007]
According to a third aspect of the present invention, in order to solve the above-described problem, the storage unit is configured to generate a group based on a similarity of magnetic field signals detected at at least two or more designated positions on the printed wiring board, The gist of the present invention is to store frequency component patterns having high correlation in association with each other.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First Embodiment)
FIG. 1 is a diagram showing a configuration of an electromagnetic interference wave measuring device according to a first embodiment of the present invention.
[0009]
As shown in FIG. 1, the electromagnetic interference wave measuring apparatus according to the present embodiment includes a printed circuit board 1 as an object to be measured having electronic components including a digital circuit, and a digital circuit mounted on the printed circuit board 1. A clock measuring probe 2 for inputting a clock signal, a magnetic field sensor 3 for detecting a magnetic field signal of unnecessary radiation generated from an electronic component including a digital circuit mounted on the printed wiring board 1, and a magnetic field sensor 3 for the printed wiring board 1, digitizers 5 and 6 for analog / digital converting and quantizing a clock signal from the clock measuring probe 2 and a magnetic field signal from the magnetic field sensor 3 and a digitizer. One clock within a designated measurement time based on the clock signal and the magnetic field signal quantized by 5, 6 A frequency analysis unit 7 that analyzes a frequency component of a magnetic field signal using a fast Fourier transform FFT every period, and a similarity that classifies and evaluates a frequency component pattern of a magnetic field signal analyzed by the frequency analysis unit 7 according to the similarity. A central control unit 9 that sets a designated position in the degree evaluation unit 8, a sensor position moving unit 4, and sets a measurement time in the frequency analysis unit 7, and stores frequency component patterns classified by the similarity evaluation unit 8. And a data storage unit 10.
[0010]
Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described.
First, the central control unit 9 outputs a position designation signal to the sensor position movement unit 4 in order to move the magnetic field sensor 3 to a designated position on the printed wiring board 1. Next, the sensor position moving unit 4 moves the magnetic field sensor 3 to a designated position on the printed wiring board 1 according to the position designation signal.
On the other hand, the clock measurement probe 2 is connected to the clock portion of the printed wiring board 1 so that a clock signal can be sent to the digitizer 5.
[0011]
The digitizers 5 and 6 convert the clock signal input by the clock measurement probe and the magnetic field signal input by the magnetic field sensor 3 from analog to digital in accordance with the control signal from the central control unit 9 and quantize the data. Send to Part 7.
[0012]
The frequency analysis unit 7 analyzes a frequency component of the magnetic field signal for a fixed measurement time determined by the central control unit 9 using the fast Fourier transform FFT for each cycle of the clock signal.
As a result, as shown in FIG. 2, a time spectrum pattern of a1, b1, c1, a2, b2, c2, c3, a3, and c4 is generated for each time series.
[0013]
Next, the similarity evaluation unit 8 evaluates the similarity of each time spectrum pattern, classifies it into three groups of a group, a group b, and a group c as shown in FIG. Remember.
Here, in the VCCI standard for electromagnetic interference waves, since the electromagnetic interference waves having many repetitions are strongly evaluated, the similarity evaluation unit 8 performs the evaluation from the group C having a high frequency of occurrence.
This makes it possible to measure in more detail the electromagnetic noise whose time spectrum fluctuates even during one clock cycle in the printed wiring board 1.
[0014]
(Second embodiment)
The configuration of the electromagnetic interference wave measuring device according to the second embodiment of the present invention is the same as the configuration shown in FIG. 1, and the description of the configuration will be omitted.
[0015]
Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described.
The central control section 9 moves the magnetic field sensor 3 to a designated position on the printed wiring board 1 by the sensor position moving section 4.
On the other hand, the clock measurement probe 2 is connected to a clock portion of the printed wiring board 1 so that a clock signal can be sent to the digitizers 5 and 6.
The digitizers 5 and 6 convert the clock signal and the magnetic field signal into analog / digital signals by a control signal from the central control unit 9, quantize the signals, and send the data to the frequency analysis unit 7.
[0015]
The frequency analysis unit 7 analyzes a frequency component of the magnetic field signal for a fixed measurement time determined by the central control unit 9 using the fast Fourier transform FFT for each cycle of the clock signal.
[0016]
Here, since the frequency of the electromagnetic wave noise exceeding the regulation value is generally known in advance, the central control unit 9 sets this frequency in the frequency analysis unit 7.
Next, the frequency analysis unit 7 prohibits generation of such a time spectrum pattern that does not include the corresponding frequency.
Then, the similarity evaluation unit 8 evaluates the similarity of the time spectrum patterns, classifies the groups into groups, and stores the groups in the data storage unit 10.
[0017]
Thus, by prohibiting the frequency analysis unit 7 from generating a time spectrum pattern that does not include the corresponding frequency, it is possible to save the calculation time required for the similarity evaluation processing of the time spectrum that does not include the corresponding frequency.
[0018]
(Third embodiment)
FIG. 4 is a diagram showing the configuration of the electromagnetic interference wave measuring device according to the third embodiment of the present invention.
As shown in FIG. 4, the characteristic of the electromagnetic interference wave measuring apparatus in the present embodiment is that the magnetic field sensor 11 is moved to an arbitrary position in a grid shape to perform the measurement separately from the magnetic field sensor 3.
[0019]
Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described.
The central control unit 9 moves the magnetic field sensors 3 and 11 to designated positions on the printed wiring board 1 by the sensor position moving unit 4, respectively.
At this time, as shown in FIG. 5, one magnetic field sensor 3 is placed in the vicinity of the clock circuit or the central processing unit of the printed wiring board 1, and the other magnetic field sensor 11 is moved to an arbitrary position in a grid for measurement. To do
[0020]
On the other hand, the clock measurement probe 2 is connected to a clock portion of the printed wiring board 1 so that a clock signal can be sent to the digitizer 5.
The digitizers 5 and 6 convert the clock signal and the magnetic field signal into analog / digital signals by a control signal from the central control unit 9, quantize the signals, and send the data to the frequency analysis unit 7.
[0021]
Here, assuming that the data of the magnetic field sensor 3 is the standard magnetic field data and the data of the magnetic field sensor 11 is the measured magnetic field data, the frequency analysis unit 7 uses the clock signal as a reference and determines the magnetic field of a fixed time determined by the central control unit 9. Analyze the frequency components of the signal.
In the frequency analysis, the frequency component is analyzed for the standard magnetic field and the measured magnetic field data for each period of the clock signal using the fast Fourier transform FFT for a short time.
As a result, each time spectrum pattern is generated, the similarity evaluation unit 8 evaluates the similarity of the time spectrum pattern with respect to the standard magnetic field data, and the measured magnetic field data classified into groups is stored in the data storage unit 10. .
[0022]
In this way, one magnetic field sensor is added, and one is placed near the clock circuit section of the object to be measured, and the time spectrum pattern from the magnetic field sensor near the clock circuit of the object to be measured is used when classifying the time spectrum pattern. By using the classification, the magnetic field data at a measurement position remote from the clock circuit unit of the digital circuit to be measured can be measured in synchronization with the clock signal.
[0023]
(Fourth embodiment)
The configuration of the EMI measuring apparatus according to the fourth embodiment of the present invention is the same as the configuration shown in FIG. 4, and the description of the configuration is omitted.
[0024]
Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described.
The central control unit 9 moves the magnetic field sensors 3 and 11 to a designated position on the printed wiring board 1 by the sensor position moving unit 4.
At this time, as shown in FIG. 5, the magnetic field sensor 3 is placed near the clock circuit or the central processing unit of the printed wiring board 1, and the sensor 11 is measured at an arbitrary position in a lattice.
The clock measurement probe 2 is connected to a clock portion of the printed wiring board 1 so that a clock signal can be sent to the digitizer 5.
The digitizers 5 and 6 convert the clock signal and the magnetic field signal into analog / digital signals by a control signal from the central control unit 9, quantize the signals, and send the data to the frequency analysis unit 7.
[0025]
Here, assuming that the data of the magnetic field sensor 3 is the standard magnetic field data and the data of the magnetic field sensor 11 is the measured magnetic field data, the frequency analysis unit 7 determines, based on the clock signal, the Analyze the wave number component of the magnetic field signal.
In the frequency analysis, the frequency component is analyzed for the standard magnetic field and the measured magnetic field data for each period of the clock signal using the fast Fourier transform FFT for the time.
As a result, each time spectrum pattern is generated, and the similarity evaluation unit 8 evaluates the similarity of the time spectrum pattern with respect to the standard magnetic field data and the measured magnetic field data. The data is classified into groups and stored in the data storage unit 10.
[0026]
Thus, one magnetic field sensor is added, one is placed near the clock circuit of the measurement target, and when classifying the time spectrum pattern, the pattern from the magnetic field sensor near the clock circuit of the fixed target is By storing the pattern having the higher similarity to the pattern stored in the data storage unit 10 among the patterns from the other magnetic field sensor, the clock signal can be further converted to a clock signal using the two magnetic field sensors. The electromagnetic wave noise of the synchronized one can be measured.
[0027]
(Fifth embodiment)
The configuration of the electromagnetic interference wave measuring apparatus according to the fifth embodiment of the present invention is the same as the configuration shown in FIG. 1, and the description of the configuration will be omitted.
[0028]
Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described.
The central control section 9 moves the magnetic field sensor 3 to a designated position on the printed wiring board 1 by the sensor position moving section 4.
On the other hand, the clock measurement probe 2 is connected to a clock portion of the printed wiring board 1 so that a clock signal can be sent to the digitizer 5.
The digitizers 5 and 6 convert the clock signal and the magnetic field signal into analog / digital signals by a control signal from the central control unit 9, quantize the signals, and send the data to the frequency analysis unit 7.
[0029]
The frequency analysis unit 7 analyzes a frequency component of the magnetic field signal for a fixed measurement time determined by the central control unit 9 using the fast Fourier transform FFT for each cycle of the clock signal.
As a result, a time spectrum pattern is generated by the frequency analysis unit 7. Then, the similarity evaluation unit 8 evaluates the similarity of the time spectrum patterns, classifies the time spectrum patterns having similarity exceeding a certain value into groups, and stores the groups in the data storage unit 10.
On the other hand, when performing the similarity evaluation, if the similarity does not exceed a certain value, the data storage unit 10 does not store the similarity.
[0030]
As described above, when the similarity evaluation is performed, when the measured electromagnetic wave noise does not synchronize with the clock signal, it is not stored in the data storage unit 10 when the measured value does not exceed a certain value. Necessary useless calculations can be omitted.
[0031]
(Sixth embodiment)
The configuration of the electromagnetic interference wave measuring apparatus according to the sixth embodiment of the present invention is the same as the configuration shown in FIG. 4, and a description of the configuration will be omitted.
[0032]
Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described.
The central control unit 9 moves the magnetic field sensors 3 and 11 to a designated position on the printed wiring board 1 by the sensor position moving unit 4.
At this time, as shown in FIG. 5, the magnetic field sensor 3 is placed near the clock circuit or the central processing unit of the printed wiring board 1, while the magnetic field sensor 11 is measured at an arbitrary position in a lattice.
The clock measurement probe 2 is connected to a clock portion of the printed wiring board 1 so that a clock signal can be sent to the digitizer 5.
The digitizers 5 and 6 convert the clock signal and the magnetic field signal into analog / digital signals by a control signal from the central control unit 9, quantize the signals, and send the data to the frequency analysis unit 7.
[0033]
Here, assuming that the data of the magnetic field sensor 3 is the standard magnetic field data and the data of the magnetic field sensor 11 is the measured magnetic field data, the frequency analysis unit 7 uses the clock signal as a reference and determines the magnetic field of a fixed time determined by the central control unit 9. Analyze the frequency components of the signal.
In the frequency analysis, the frequency component is analyzed for the standard magnetic field and the measured magnetic field data for each period of the clock signal using the fast Fourier transform FFT for a short time.
As a result, each time spectrum pattern is generated, and the similarity of the time spectrum pattern with respect to the standard magnetic field data is evaluated.
[0034]
Here, FIG. 6A shows a time spectrum pattern of the standard magnetic field data when the magnetic field sensor 11 is moved to a specified position. Note that a1, a2, a3 are patterns having high similarity.
FIG. 6B shows a time spectrum pattern of the standard magnetic field data when moving to another designated position.
Here, the data storage unit 10 stores the time spectrum pattern of the measured magnetic field data in the same generation order of the patterns having the high similarity in association with each other.
[0035]
In this way, based on the order of group generation based on the similarity of the magnetic field data measured at one specified position and the order of group generation based on the similarity of the magnetic field data measured at another specified position, a time spectrum pattern having a high correlation is determined. By storing them in the data storage unit 10 in association with each other, the time spectra of the same group can be associated in accordance with the order of occurrence.
[0036]
(Seventh embodiment)
The configuration of the EMI measuring apparatus according to the seventh embodiment of the present invention is the same as the configuration shown in FIG. 1, and the description of the configuration is omitted.
[0037]
Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described.
The central control section 9 moves the magnetic field sensor 3 to a designated position on the printed wiring board 1 by the sensor position moving section 4.
On the other hand, the clock measurement probe 2 is connected to a clock portion of the printed wiring board 1 so that a clock signal can be sent to the digitizer 5.
The digitizers 5 and 6 convert the clock signal and the magnetic field signal into analog / digital signals by a control signal from the central control unit 9, quantize the signals, and send the data to the frequency analysis unit 7.
[0038]
The frequency analysis unit 7 analyzes a frequency component of the magnetic field signal for a fixed measurement time determined by the central control unit 9 using the fast Fourier transform FFT for each cycle of the clock signal.
Here, as shown in FIG. 7A, the time spectrum patterns output from the frequency analysis unit 7 are a1, b1, c1, a2, b2. . . It has become.
When the similarity evaluation unit 8 evaluates the time spectrum pattern, as shown in FIG. 7B, a1 and a2 are assigned to the group a, b1 and b2 are assigned to the group b, and c1 and c2 are assigned to the group c. , C3 are classified.
Therefore, when newly evaluating the similarity of the pattern a3, the similarity is evaluated using an average pattern obtained by averaging a1 and a2 belonging to the group a and stored in the data storage unit 10.
[0039]
As described above, when evaluating the similarity between the time spectrum pattern grouped in the data storage unit 10 based on the similarity and the time spectrum pattern of the new measurement data, the average pattern and the evaluation of the grouped time spectrum pattern are evaluated. , More accurate similarity evaluation can be performed.
[0040]
(Eighth embodiment)
The configuration of the EMI measuring apparatus according to the eighth embodiment of the present invention is the same as the configuration shown in FIG. 1, and the description of the configuration is omitted.
[0041]
Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described.
The central control section 9 moves the magnetic field sensor 3 to a designated position on the printed wiring board 1 by the sensor position moving section 4.
The clock measurement probe 2 is connected to a clock portion of the printed wiring board 1 so that a clock signal can be sent to the digitizer 5.
The digitizers 5 and 6 convert the clock signal and the magnetic field signal into analog / digital signals by a control signal from the central control unit 9, quantize the signals, and send the data to the frequency analysis unit 7.
[0042]
The frequency analysis unit 7 analyzes a frequency component of the magnetic field signal for a fixed measurement time determined by the central control unit 9 using the fast Fourier transform FFT for each cycle of the clock signal.
Here, the similarity evaluation unit 8 evaluates the similarity of the generated time spectrum pattern. However, the calculation is actually quite complicated. Therefore, with respect to the generated time spectrum pattern, a pattern exceeding a certain reference value is set to 1 and a pattern not exceeding the reference value is set to 0 to generate a 01 pattern shown in FIGS. 8 (1) and 8 (2). For this pattern, for example, a similarity can be easily obtained by taking the sum of logical products. Then, the patterns are classified into groups and stored in the data storage unit 10.
[0043]
As described above, by converting the time spectrum pattern into the 01 pattern and calculating the sum of the logical product, the processing of the similarity evaluation can be simplified.
[0044]
(Ninth embodiment)
The configuration of the EMI measuring apparatus according to the eighth embodiment of the present invention is the same as the configuration shown in FIG. 1, and the description of the configuration is omitted.
[0045]
Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described.
The central control section 9 moves the magnetic field sensor 3 to a designated position on the printed wiring board 1 by the sensor position moving section 4.
On the other hand, the clock measurement probe 2 is connected to a clock portion of the printed wiring board 1 so that a clock signal can be sent to the digitizer 5. The digitizers 5 and 6 convert the clock signal and the magnetic field signal into analog / digital signals by a control signal from the central control unit 9, quantize the signals, and send the data to the frequency analysis unit 7.
[0046]
The frequency analysis unit 7 analyzes a frequency component of the magnetic field signal for a fixed measurement time determined by the central control unit 9 using the fast Fourier transform FFT for each cycle of the clock signal. Here, the generated time spectrum patterns are evaluated for similarity by the similarity evaluation unit 8, classified into groups, and stored in the data storage unit 10.
[0047]
As shown in FIG. 9, it is assumed that the time spectrum patterns (1), (2), and (3) are stored in the data storage unit 10. The common portion of each pattern is “common portion 1 to 3”, and the difference is “difference portion 1 to 3”. Then, the difference is emphasized as shown in (4) of FIG. 9 and stored in the data storage unit 10 again.
[0048]
In this way, for the grouped time spectrum patterns stored in the data storage unit 10, by increasing the value of the pattern of the difference part of each pattern and storing it again in the data storage unit 10, Even with a time spectrum pattern, the similarity can be evaluated more accurately.
[0049]
【The invention's effect】
As described above, according to the first aspect of the present invention, it is possible to measure in more detail the electromagnetic wave noise whose spectrum varies even with one clock cycle of the digital circuit to be measured.
[0050]
According to the second aspect of the present invention, it is possible to save time for calculating a time spectrum that does not include the corresponding frequency.
[0051]
According to the third aspect of the present invention, the time spectra of the same group can be associated with each other in accordance with the order of occurrence.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an electromagnetic interference wave measuring device according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a generated time spectrum pattern arranged for each time series.
FIG. 3 is a diagram showing time spectrum patterns classified into groups.
FIG. 4 is a diagram illustrating a configuration of an electromagnetic interference wave measuring device according to a third embodiment of the present invention.
FIG. 5 is a diagram showing a state in which one magnetic field sensor 3 is placed in the vicinity of a clock circuit or a central processing unit of a printed wiring board 1 and the other magnetic field sensor 11 is moved to an arbitrary position in a grid to perform measurement. It is.
FIG. 6 is a diagram (1) showing a time spectrum pattern of standard magnetic field data when the magnetic field sensor 11 is moved to a certain position, and a diagram (2) showing a time spectrum pattern of standard magnetic field data when it is moved to another position. ).
FIG. 7 is a diagram (2) showing a time spectrum pattern (1) output from the frequency analysis unit 7 and a state of being classified into three groups by the similarity evaluation unit 8;
FIG. 8 is a diagram showing a state where a 01 pattern is generated by a similarity evaluation section 8;
FIG. 9 is a diagram showing “common portions 1 to 3” and “difference portions 1 to 3” stored in a data storage unit 10, and FIGS. FIG.
[Explanation of symbols]
Reference Signs List 1 digital circuit 2 clock measurement probe 3 magnetic field sensor 4 sensor position moving unit 5 digitizer 6 digitizer 7 frequency analysis unit 8 similarity evaluation unit 9 central control unit 10 data storage unit 11 magnetic field sensor

Claims (3)

Clock signal input means for inputting a clock signal from a digital circuit mounted on a printed wiring board,
Magnetic field detecting means for detecting a magnetic field signal of unnecessary radiation generated from an electronic component including a digital circuit mounted on the printed wiring board,
Detecting position moving means for moving the magnetic field detecting means to a designated position on the printed wiring board;
A clock signal from the clock signal input means, and a quantization means for quantizing a magnetic field signal from the magnetic field detection means,
Frequency analysis means for analyzing the frequency component of the magnetic field signal for each clock cycle within a designated measurement time based on the clock signal and the magnetic field signal quantized by the quantization means;
Similarity evaluation means for classifying and evaluating the frequency component pattern of the magnetic field signal analyzed by the frequency analysis means according to the similarity;
Storage means for storing the frequency component pattern evaluated by the similarity evaluation means;
An electromagnetic interference wave measuring device, comprising: a control unit that sets a designated position in the detection position moving unit and sets a measurement time in the frequency analysis unit. The frequency analysis means,
2. The electromagnetic interference wave measuring apparatus according to claim 1, wherein generation of a frequency component pattern not including a designated frequency is prohibited. The storage means,
2. A high-correlation frequency component pattern is stored in association with a group generation order based on the similarity of magnetic field signals detected at at least two or more designated positions on the printed wiring board. EMI measurement equipment.

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