JPH11316253A - Electromagnet disturbing wave measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for measuring an electromagnetic disturbing wave for precisely measuring the electromagnetic wave noise of a digital circuit being an object to be measured. SOLUTION: A clock signal is inputted from a digital circuit mounted on a print wiring board 1 to a clock measuring probe 2, and a magnetic field signal generated from the print wiring board 1 is detected by a magnetic field sensor 3. In this case, the magnetic field sensor 3 is moved to a designated position on the print wiring board 1 by a detecting position moving part 4, and the clock signal from the clock measuring probe 2 and the magnetic field signal from the magnetic field sensor 3 are quantized by digitizers 5 and 6, and the frequency components of the magnetic field signal are analyzed for every one time of clock cycle within a designated measuring time by a frequency analyzing part 7, based on the quantized clock signal and magnetic field signal. Then the frequency component pattern of the analyzed magnetic field signal is classified and evaluated by a similarity evaluating part 8 according to the similarity, and the frequency component pattern is stored in a storage part 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic interference wave measuring apparatus capable of analyzing a source of electromagnetic noise on a printed circuit board on which electronic components having a large amount of unnecessary radiation are mounted.

[0002]

2. Description of the Related Art Conventionally, in a "double-sided interfering wave measuring apparatus" described in Japanese Patent Application Laid-Open No. 6-58970, a method of arranging a plurality of loop antennas in a grid and measuring a near-field magnetic field, or a method of looping with a linear stage. A method of measuring the near magnetic field by controlling the position of the antenna has been proposed, and has an advantage in examining a time-averaged approximate near-field intensity distribution.

[0003]

However, in the measurement method used in the conventional "double-sided interference wave measuring device", when the magnetic field near the digital circuit is examined, the current waveform of the digital circuit has an aperiodic waveform. Therefore, there is a problem that the intensity distribution of the near magnetic field cannot be examined in more detail.

[0004] The present invention has been made in view of the above,
An object of the present invention is to provide an electromagnetic interference wave measuring device capable of measuring electromagnetic wave noise of a digital circuit to be measured in more detail.

[0005]

According to the first aspect of the present invention,
In order to solve the above problems, a clock signal input unit for inputting a clock signal from a digital circuit mounted on a printed wiring board, and unnecessary radiation generated from electronic components including the digital circuit mounted on the printed wiring board Magnetic field detecting means for detecting a magnetic field signal of the following; a 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; A quantizing means for quantizing the magnetic field signal, and a 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 quantizing means. The frequency analysis means to be analyzed and the frequency component pattern of the magnetic field signal analyzed by the frequency analysis means are classified and evaluated according to the similarity. Similarity evaluation means, storage means for storing frequency component patterns evaluated by the similarity evaluation means, and control for setting a designated position in the detection position moving means and setting a measurement time in the frequency analysis means. And the means.

According to a second aspect of the present invention, in order to solve the above problem, the frequency analysis means prohibits generation of a frequency component pattern that does not include a specified frequency.

According to a third aspect of the present invention, in order to solve the above-mentioned problem, the storage means stores the groups based on the similarity of the 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 a high correlation in association with each other based on the correlation.

[0008]

Embodiments of the present invention will be described below 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.

As shown in FIG. 1, an electromagnetic interference wave measuring apparatus according to the present embodiment is mounted on a printed wiring board 1 as an object to be measured having electronic components including a digital circuit, and on the printed wiring board 1. A clock measurement probe 2 for inputting a clock signal from a digital circuit, a magnetic field sensor 3 for detecting a magnetic field signal of unnecessary radiation generated from electronic components including the digital circuit mounted on the printed wiring board 1, and a magnetic field sensor 3 Digitizers 5 and 6 that perform analog / digital conversion of the clock signal from clock measurement probe 2 and the magnetic field signal from magnetic field sensor 3 to quantize by sensor / position moving unit 4 that moves to a designated position on printed wiring board 1. And a clock signal and a magnetic field signal quantized by the digitizers 5 and 6, and Frequency analysis unit 7 that analyzes the frequency component of the magnetic field signal using the fast Fourier transform FFT for each clock cycle of the clock signal, and classifies and evaluates the frequency component pattern of the magnetic field signal analyzed by the frequency analysis unit 7 according to the similarity. A similarity evaluation unit 8, a designated position in the sensor position moving unit 4, a central control unit 9 for setting a measurement time in the frequency analysis unit 7, and a frequency component pattern classified by the similarity evaluation unit 8. And a data storage unit 10 for storing.

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 in accordance with the position designation signal.
To move. 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.

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 a control signal from the central control unit 9 to quantize the data. To the frequency analysis unit 7.

The frequency analysis unit 7 converts the magnetic field signal for a fixed measurement time determined by the central control unit 9 into a fast Fourier transform FF.
The frequency component is analyzed for each cycle of the clock signal using T. As a result, as shown in FIG.
1, b1, c1, a2, b2, c2, c3, a3, c4
Is generated.

Next, the similarity evaluation section 8 evaluates the similarity of each time spectrum pattern, and classifies the data into three groups, ie, a group a, a group b, and a group c, as shown in FIG. The information is stored in the unit 10. Here, according to the VCCI standard for electromagnetic interference waves, an electromagnetic interference wave having a large number of repetitions is strongly evaluated. Therefore, the similarity evaluation unit 8 performs an evaluation from the group C having a high frequency of occurrence. This makes it possible to measure in more detail the electromagnetic wave noise whose time spectrum fluctuates even during one clock cycle on the printed wiring board 1.

(Second Embodiment) The configuration of an electromagnetic interference wave measuring apparatus according to a second embodiment of the present invention is the same as the configuration shown in FIG. 1, and a description of the configuration will be omitted.

Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described. The central control unit 9 moves the magnetic field sensor 3 to a designated position on the printed wiring board 1 by the sensor position moving unit 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.

The frequency analysis unit 7 converts the magnetic field signal for a fixed measurement time determined by the central control unit 9 into a fast Fourier transform FF.
The frequency component is analyzed for each cycle of the clock signal using T.

Here, since the frequency of the electromagnetic 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 the 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 them into groups, and stores them in the data storage unit 10.

As described above, by prohibiting the generation of the time spectrum pattern not including the corresponding frequency by the frequency analysis unit 7, the calculation time required for the similarity evaluation processing of the time spectrum not including the corresponding frequency can be omitted.

(Third Embodiment) FIG. 4 is a diagram showing a configuration of an electromagnetic interference wave measuring device according to a third embodiment of the present invention. As shown in FIG. 4, the characteristic of the electromagnetic interference wave measuring apparatus according to the present embodiment is that the magnetic field sensor 11 is moved to an arbitrary position in a grid form in addition to the magnetic field sensor 3 to perform the measurement.

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 to measure. To do.

On the other hand, the clock measuring 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.

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 the data determined by the central control unit 9 using the clock signal as a reference. Analyze the frequency component of the time 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 a short time. As a result, each time spectrum pattern is generated, the similarity evaluation section 8 evaluates the similarity of the time spectrum pattern with respect to the standard magnetic field data, and the data storage section 10 stores the measured magnetic field data classified into groups and corresponding. .

As described above, one magnetic field sensor is added,
First, the digital circuit to be measured is placed near the clock circuit section of the measurement object, and the time spectrum pattern is classified using the time spectrum pattern from the magnetic field sensor near the clock circuit of the measurement object. Magnetic field data at a measurement position distant from the clock circuit unit can be measured in synchronization with the clock signal.

(Fourth Embodiment) The configuration of an electromagnetic interference wave measuring apparatus according to a fourth embodiment of the present invention is the same as the configuration shown in FIG. 4, and a description of the configuration will be omitted.

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.

Here, assuming that the data of the magnetic field sensor 3 is standard magnetic field data and the data of the magnetic field sensor 11 is measured magnetic field data, the frequency analysis unit 7 is determined by the central control unit 9 using the clock signal as a reference. Analyze the wave number component of a fixed-time 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.

As described above, one magnetic field sensor is added and 1
One is placed near the clock circuit of the measurement object, and when classifying the time spectrum pattern, the data from the pattern from the magnetic field sensor near the clock circuit of the fixed object and the pattern from the other magnetic field sensor By storing the pattern having the higher similarity to the pattern stored in the storage unit 10, it is possible to measure the electromagnetic wave noise in synchronization with the clock signal using two magnetic field sensors.

(Fifth Embodiment) The configuration of an electromagnetic interference wave measuring apparatus according to a fifth embodiment of the present invention is the same as the configuration shown in FIG. 1, and a description of the configuration will be omitted.

Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described. The central control unit 9 moves the magnetic field sensor 3 to a designated position on the printed wiring board 1 by the sensor position moving unit 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.

The frequency analysis unit 7 converts the magnetic field signal for a fixed measurement time determined by the central control unit 9 into a fast Fourier transform FF.
The frequency component is analyzed for each cycle of the clock signal using T. 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 in which the similarity exceeds a certain value into groups, and stores them 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.

As described above, when the similarity evaluation is performed, when the measured electromagnetic wave noise is not synchronized with the clock signal, it is not stored in the data storage unit 10 when the measured value does not exceed a certain value. Useless calculations required for the evaluation process can be omitted.

(Sixth Embodiment) The configuration of an electromagnetic interference wave measuring apparatus according to a 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.

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 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.

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 the data determined by the central control unit 9 using the clock signal as a reference. Analyze the frequency component of the time 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 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.

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. In addition, a1, a2, a3,
Is a pattern having a high degree of similarity. Also, in FIG. 6 (2),
7 shows a time spectrum pattern of the standard magnetic field data when moved 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.

As described above, based on the generation order of the groups based on the similarity of the magnetic field data measured at a certain specified position and the generation order of the groups based on the similarity of the magnetic field data measured at another specified position, a time having a high correlation is determined. By storing the spectrum patterns in the data storage unit 10 in association with each other, the time spectra of the same group can be associated with each other in accordance with the order of occurrence.

(Seventh Embodiment) The configuration of an electromagnetic interference wave measuring apparatus according to a seventh embodiment of the present invention is the same as the configuration shown in FIG. 1, and a description of the configuration will be omitted.

Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described. The central control unit 9 moves the magnetic field sensor 3 to a designated position on the printed wiring board 1 by the sensor position moving unit 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.

The frequency analysis unit 7 converts the magnetic field signal for a fixed measurement time determined by the central control unit 9 into a fast Fourier transform FF.
The frequency component is analyzed for each cycle of the clock signal using T. Here, as shown in FIG. 7A, the time spectrum pattern output from the frequency analysis unit 7 is a
1, 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.

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 of the grouped time spectrum patterns is obtained. By performing the evaluation with the pattern, a more accurate similarity evaluation can be performed.

(Eighth Embodiment) The configuration of an electromagnetic interference wave measuring apparatus according to an eighth embodiment of the present invention is the same as the configuration shown in FIG. 1, and a description of the configuration will be omitted.

Next, the operation of the thus configured electromagnetic interference wave measuring device will be described. The central control unit 9 moves the magnetic field sensor 3 to a designated position on the printed wiring board 1 by the sensor position moving unit 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 them, and send data to the frequency analysis unit 7.

The frequency analysis section 7 converts the magnetic field signal for a fixed measurement time determined by the central control section 9 into a fast Fourier transform FF.
The frequency component is analyzed for each cycle of the clock signal using T. Here, the similarity evaluation unit 8 evaluates the similarity of the generated time spectrum pattern, but in practice, the calculation is considerably complicated. Therefore, regarding the generated time spectrum patterns, those exceeding a certain reference value are set to 1 and those not exceeding the reference value are set to 0, as shown in FIG.
The 01 pattern shown in (2) is generated. 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.

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.

(Ninth Embodiment) The configuration of an electromagnetic interference wave measuring apparatus according to an eighth embodiment of the present invention is the same as the configuration shown in FIG. 1, and a description of the configuration will be omitted.

Next, the operation of the thus configured electromagnetic interference wave measuring apparatus will be described. The central control unit 9 moves the magnetic field sensor 3 to a designated position on the printed wiring board 1 by the sensor position moving unit 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.

The frequency analysis unit 7 converts the magnetic field signal for a fixed measurement time determined by the central control unit 9 into a fast Fourier transform FF.
The frequency component is analyzed for each cycle of the clock signal using T. Here, the similarity evaluation unit 8 evaluates the similarity of the generated time spectrum patterns, classifies the groups into groups, and stores them in the data storage unit 10.

As shown in FIG. 9, (1), (2),
The time spectrum pattern of (3) is the data storage unit 1
It is assumed that it is stored in 0. The common part of each pattern is “common part 1 to 3”, and the difference is “difference part 1 to 3”.
It has become. Then, the difference is emphasized as shown in FIG. 9D and stored in the data storage unit 10 again.

As described above, with respect to the grouped time spectrum patterns stored in the data storage unit 10, the value of the pattern of the difference part between the respective patterns is increased and stored in the data storage unit 10 again. Even with such a time spectrum pattern, the similarity can be evaluated more accurately.

[0049]

As described above, according to the first aspect of the present invention, it is possible to measure in more detail the electromagnetic noise whose spectrum varies even with one clock cycle of the digital circuit to be measured. Can be.

According to the second aspect of the present invention, it is possible to save time for calculating a time spectrum not including the corresponding frequency.

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 illustrating 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 showing 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 showing a time spectrum pattern of standard magnetic field data when the magnetic field sensor 11 is moved to a certain position, and FIG. 6 is a diagram showing a time spectrum pattern of standard magnetic field data when the magnetic field sensor is moved to another position (2). ).

FIG. 7 is a diagram (2) illustrating a time spectrum pattern (1) output from a frequency analysis unit 7 and a state of being classified into three groups by a similarity evaluation unit 8;

FIG. 8 is a diagram showing a state in which a 01 pattern is generated by a similarity evaluation section 8;

FIG. 9 is a diagram (1) showing “common parts 1 to 3” and “difference parts 1 to 3” stored in a data storage unit 10;
(2), (3) and (4) showing a state in which the difference is emphasized.

[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)

[Claims] 1. A clock signal input means for inputting a clock signal from a digital circuit mounted on a printed wiring board, and a magnetic field of unnecessary radiation generated from an electronic component including the digital circuit mounted on the printed wiring board. Magnetic field detecting means for detecting a signal; 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 magnetic field signal from the magnetic field detecting means. And a frequency component of the magnetic field signal is analyzed for each clock cycle within a designated measurement time based on the clock signal and the magnetic field signal quantized by the quantizing means. A frequency analyzing means, and a class for classifying and evaluating a frequency component pattern of the magnetic field signal analyzed by the frequency analyzing means according to the similarity. A degree evaluation means, storage means for storing a frequency component pattern was evaluated by the similarity evaluating means sets a designated position in said detecting position moving means,
An electromagnetic interference wave measuring apparatus, comprising: a control means for setting a measurement time in the frequency analysis means. 2. The electromagnetic interference wave measuring apparatus according to claim 1, wherein said frequency analysis unit prohibits generation of a frequency component pattern not including a designated frequency. 3. The storage means associates frequency component patterns with a high correlation with each other based on the order of generation of groups based on the similarity of magnetic field signals detected at at least two or more designated positions on the printed wiring board, and stores them. The electromagnetic interference wave measuring device according to claim 1, wherein: