Electromagnetic Noise Measurement Method and Electromagnetic Noise Measurement Device

Abstract

To provide an electromagnetic noise measuring method and an electromagnetic noise measuring device which can accurately identify a noise source.SOLUTION: This electromagnetic noise measuring method executes a step of executing a far-field measurement in the vicinity of a target device to measure an electromagnetic noise in the vicinity of the target device via a first port of a measurement probe at first timing, and storing the measured data therefrom in a memory. Thereafter, this electromagnetic noise measuring method repeatedly executes while changing measurement places: a step of executing a near-field measurement of measuring an electromagnetic noise in the vicinity of a candidate of a noise source that gives the electromagnetic noise to the target device in the vicinity of the candidate of the noise source via the first port at second timing later than the first timing; and a step of calculating a noise source matching index which is a numeric value indicating the degree of approximation between the far-field measurement and the near-field measurement.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electromagnetic noise measurement method and an electromagnetic noise measurement apparatus.

Background Art

[0002] Electromagnetic noise (Electromagnetic Noise, or EM noise), such as electromagnetic radiation noise and conductive noise emitted from an electronic circuit or the like, is required to be suppressed within a range of a predetermined regulation value. When the electromagnetic noise exceeds the range of the regulation value, such electromagnetic noise may affect the operation of other surrounding circuits. For this reason, a technique for identifying a noise source that generates electromagnetic noise exceeding a predetermined regulation value is required.

[0003] Conventionally, as a measurement method for identifying a noise source, a method of obtaining a frequency spectrum by frequency domain measurement or a method of obtaining a frequency spectrum by performing time domain measurement and short-time Fourier transform (ST-FFT) is known. High-frequency noise sources (for example, noise from a clock signal circuit, a communication circuit, etc.) can be easily identified from the frequency spectrum.

[0004] However, in the conventional method, when measuring electromagnetic noise in the vicinity of the target device (far-field measurement) and measuring electromagnetic noise in the vicinity of a noise source candidate (near-field measurement) and analyzing the frequency spectrum, the measurement probe for performing the near-field measurement may affect the measurement probe for the simultaneously measured far-field measurement. For this reason, there is a problem that it is difficult to accurately identify the noise source.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide an electromagnetic noise measurement method and an electromagnetic noise measurement apparatus that enable accurate identification of a noise source.

Means for Solving the Problems

[0007] To solve the above problems, an electromagnetic noise measurement method according to the present invention executes a step of performing a far-field measurement of measuring electromagnetic noise in the vicinity of a target device via a first port at a first timing and storing the measurement data in a memory. Thereafter, in the vicinity of a candidate for a noise source that gives electromagnetic noise to the target device, a step of performing a near-field measurement via the first port at a second timing after the first timing, and a step of calculating a noise source matching index, which is a numerical value indicating the degree of approximation between the far-field measurement and the near-field measurement, are repeatedly executed while changing the measurement location.

Effects of the Invention

[0008] According to the present invention, it is possible to provide an electromagnetic noise measurement method and an electromagnetic noise measurement apparatus that enable accurate identification of a noise source.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3A

Figure 3B

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Figure 12

Embodiments for Carrying Out the Invention

[0010] Hereinafter, this embodiment will be described with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may sometimes be denoted by the same reference numerals. Note that the accompanying drawings show embodiments and implementation examples in accordance with the principles of the present disclosure, but these are for the purpose of understanding the present disclosure and are by no means used for limiting the interpretation of the present disclosure. The description in this specification is merely a typical example and does not limit the scope of the claims or application examples of the present disclosure in any sense.

[0011] In this embodiment, although the description is made in sufficient detail for those skilled in the art to implement the present disclosure, other implementation forms are also possible, and it is necessary to understand that configuration and structural changes and replacement of various elements can be made without departing from the scope and spirit of the technical idea of the present disclosure. Therefore, the following description should not be construed as being limited thereto.

[0012] As examples of various types of information, it may be described in expressions such as "data" and "graph", but various types of information may be expressed in data structures other than these. For example, various types of information such as "XX table", "XX list", and "XX queue" may be referred to as "XX information". When explaining identification information, expressions such as "identification information", "identifier", "name", "ID", and "number" are used, but these can be mutually replaced. When there are a plurality of components having the same or similar functions, they may be described with the same reference numeral and different subscripts. Also, when it is not necessary to distinguish these plurality of components, the subscripts may be omitted in the description.

[0013] In the examples, the processing performed by executing a program may be described. Here, a computer executes a program by a processor (e.g., CPU, GPU) and performs the processing defined by the program while using storage resources (e.g., memory) and interface devices (e.g., communication ports). Therefore, the subject of the processing performed by executing the program may be the processor. Similarly, the subject of the processing performed by executing the program may be a controller, device, system, computer, or node having a processor. The subject of the processing performed by executing the program only needs to be an arithmetic unit and may include a dedicated circuit for performing a specific process. Here, the dedicated circuit is, for example, an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), a CPLD (Complex Programmable Logic Device), or the like.

[0014] The program may be installed in a computer from a program source. The program source may be, for example, a program distribution server or a computer-readable storage medium. When the program source is a program distribution server, the program distribution server includes a processor and a storage resource for storing the program to be distributed, and the processor of the program distribution server may distribute the program to be distributed to other computers. Also, in an embodiment, two or more programs may be realized as one program, or one program may be realized as two or more programs.

[0015] [First Embodiment] Referring to FIG. 1, an electromagnetic noise measuring device 1501 according to the first embodiment will be described. This electromagnetic noise measuring device 1501 is a device for identifying a noise source 1510 in a target device 1507 in relation to a target device 1508 (Victim). In FIG. 1, only one noise source 1510 is illustrated. The number, position, etc. of the noise source 1510 are unknown before the start of measurement. The user of the electromagnetic noise measuring device 1501 moves the measurement probe 1506 to various locations (near the candidates for the noise source) and identifies the noise source that emits electromagnetic noise affecting the operation of the target device 1508 according to the obtained detection signal. Here, electromagnetic noise (Electromagnetic Noise, or EM noise) is, for example, electromagnetic radiation noise or conductive noise emitted from an electronic circuit or the like.

[0016] The electromagnetic noise measuring device 1501 is configured to include, as an example, an RF interface 1502, a memory unit 1503, a main processor 1504, a measurement probe 1506, an I / O interface 1505, and a display 1509. The measurement probe 1506 is moved near a device that is a candidate for the noise source 1510 and measures the electromagnetic noise at that position. The RF interface 1502 has a function of converting the detection signal detected by the measurement probe 1506 into a signal for processing by the main processor 1504 and transferring it.

[0017] The main processor 1504 constitutes a far-field measurement processing unit 1504A, a near-field measurement processing unit 1504B, and a noise source matching index calculation unit 1504C, which are realized by a computer program stored in the memory unit 1503. The far-field measurement processing unit 1504A executes the measurement of electromagnetic noise in a region (far field) that is near the target device 1508 and far from the noise source 1510. Also, the near-field measurement processing unit 1504B executes the measurement of electromagnetic noise in a region (near field) that is near the device that is a candidate for the noise source 1510. The measurement by the far-field measurement processing unit 1504A and the measurement by the near-field measurement processing unit 1504B are executed at different timings and are executed according to the detection signal input to the RF interface 1502 via a single port. The measurement by the far-field measurement processing unit 1504A precedes the measurement by the near-field measurement processing unit 1504B in terms of time.

[0018] The noise source matching index calculation unit 1504C performs matching between the measurement data in the far-field measurement processing unit 1504A and the measurement data of the near-field measurement processing unit 1504B, and calculates the noise source matching index NSMI according to the result of the matching. The noise source matching index NSMI numerically indicates the likelihood that the electromagnetic noise affects the operation of the target device 1508. That is, the larger the numerical value of the calculated noise source matching index NSMI, the higher the likelihood that the device located near the measurement probe 1506 when the near-field measurement processing unit 1504B is executed is determined to be the noise source.

[0019] The I / O interface 1505 is an interface for outputting the data processed by the main processor 1504 to the display 1509 and other external devices (not shown), and for receiving data from the external devices and commands from the user. The display 1509 is configured to be able to display the data calculated by the main processor 12. The external device may be, for example, an input device (such as a keyboard, a mouse, etc.) for the user to input commands (instructions), an external storage device, or a management device connected via a network. Also, the display 1509 may be a head-mounted display.

[0020] Referring to FIG. 2, the operation (electromagnetic noise measurement method) of the electromagnetic noise measurement device 1501 according to the first embodiment will be described. The electromagnetic noise measurement device 1501 according to this first embodiment first performs a far-field measurement in the vicinity of the target device 1508, and then performs a near-field measurement in the vicinity of the candidate of the noise source 1510 using the measurement probe 1506 and via the same port. This makes it possible to accurately identify the noise source 1510 that affects the operation of the target device 1508.

[0021] First, in step S102, a far-field measurement and preprocessing are performed by the far-field measurement processing unit 1504A. The measurement data measured and preprocessed by the far-field measurement processing unit 1504A is temporarily held in the memory unit 1503.

[0022] Next, in step S103, the measurement probe 1506 is arranged in a region that is separated from the target device 1508 but is in the vicinity of the candidate of the noise source 1510, and a near-field measurement is performed by the near-field measurement processing unit 1504B. Step S103 is executed at a timing later than step S102. The measurement data obtained by the near-field measurement processing unit 1504B is temporarily held in the memory unit 1503.

[0023] In the subsequent step S104, based on the measurement data of the far-field measurement executed in step S102 and stored in the memory unit 1503, and the measurement data of the near-field measurement executed in step S103, the noise source matching index calculation unit 1504C calculates the noise source matching index NSMI. The calculated noise source matching index NSMI is stored in the memory unit 1503 together with time data and the like.

[0024] Then, in step S105, the calculated noise source matching index NSMI is transferred to the display 1509 or an external device (not shown) via the I / O interface 1505 and notified to the user of this device. Steps S103 to S105 are repeatedly executed by sequentially changing the position (measurement location) of the measurement probe 1506. The user checks the noise source matching index NSMI displayed on the display 1509 or transferred to the external device for each position of the different measurement probes 1506. Then, when a high numerical value is obtained as the noise source matching index NSMI, the device located in the vicinity of the nearest measurement probe 1506 can be determined as the noise source.

[0025] The method for calculating the noise source matching index NSMI in this first embodiment will be described with reference to the flowcharts of FIGS. 3A and 3B. In many cases, electromagnetic noise has a certain periodicity (cyclo-stationarity) when observed over a sufficiently long time. Therefore, an approximate temporal correlation can be expected between the measurement data of the far-field measurement and the measurement data of the near-field measurement.

[0026] Therefore, the noise source matching index NSMI can be calculated by calculating the maximum value of the absolute value of the cross-correlation between one time-dependent frequency of the measurement data of the far-field measurement and the same time-dependent frequency of the measurement data of the near-field measurement (deferred cross-relation at the same frequency). Specifically, as shown in FIG. 3A, the time change σ s of the spectral density at the frequency index k of the detection signal of the near-field measurement is calculated (step S202). On the other hand, as shown in FIG. 3B, the time change σ v of the spectral density at the frequency index k (the same frequency) of the far-field measurement is calculated (step S302). The detection signal of the far-field measurement is stored in the memory unit 1503 after the measurement in step S102.

[0027] Then, in steps S203 and S303, the average value of σ s [k, n], σ v [k, n] / σ s 、 / σ v is calculated, and signals So[k, n] and Vo[k, n] obtained by subtracting this average value / σ s [k]、 / σ v [k] from σ s [k, n], σ v [k, n] are calculated (the first and second equations of [Equation 1] below). Then, these signals So and Vo are normalized, and the time interval m that maximizes the sum of the products of the normalized signals is searched, and the sum that becomes the maximum value is used as the cross-correlation value Id[k] (the third equation of [Equation 1]).

[0028]

Equation

[0029] As described above, according to the electromagnetic noise measurement apparatus of this first embodiment, far-field measurement and near-field measurement are performed at different times via a single port, and the noise source matching index NSMI between the two is calculated to identify the noise source 1510. For this reason, since the measurement result of the far-field measurement is not affected by the measurement probe during the near-field measurement, it becomes easier to perform the far-field measurement more accurately and accurately identify the noise source.

[0030] [Second Embodiment] Subsequently, an electromagnetic noise measurement apparatus according to a second embodiment will be described with reference to FIGS. 1, 2, 4, and 5. Since the configuration of the electromagnetic noise measurement apparatus is substantially the same as that of the first embodiment, duplicate descriptions will be omitted. Also, the method for determining the noise source is the same as that of the first embodiment (FIG. 2). However, in this second embodiment, the calculation method of the noise source matching index NSMI is different from that of the first embodiment. Specifically, the second embodiment employs a method of analyzing the cross-correlation between the far-field measurement and the near-field measurement in different frequency regions (deferred cross-correlation at different frequencies), which is different from the first embodiment in this regard.

[0031] The execution procedure for calculating the noise source matching index NSMI of the second embodiment will be described with reference to the flowchart of FIG. 4. This calculation method is effective when there is broadband noise generated by low-frequency switching.

[0032] In this second embodiment, as in the first equation of [Equation 2] below, the absolute value |s[n]| of the detection signal s[n] in the time domain of the low-frequency region of the near-field measurement is calculated, and from this absolute value |s[n]|, the average value of the absolute value of the detection signal s[n] / |s| is subtracted to generate a signal so[n] (step S402).

[0033] Regarding the far-field measurement, as shown in FIG. 5 and the second equation of [Equation 2], the time variation σ of the spectral density of one high-frequency component k of the detection signal of the far-field measurement vCalculate the square root of [k, n] (step S502). Then, subtract the average value of the square root from the square root to calculate the signal Vo[k, n] (step S503). Then, as in the third equation, normalize the signals so and Vo, search for the time interval m at which the sum of the products of the normalized signals becomes the maximum value, and set the sum that becomes the maximum value as the cross-correlation value Im[k] (step S403).

[0034]

Number

[0035] [Third Embodiment] Subsequently, an electromagnetic noise measurement device according to the third embodiment will be described with reference to FIGS. 1, 2, 6, and 7. Since the configuration of the electromagnetic noise measurement device is substantially the same as that of the first embodiment, duplicate explanations will be omitted. Also, the method for determining the noise source is the same as that of the first embodiment (FIG. 2). However, in this third embodiment, the calculation method of the noise source matching index NSMI is different from that of the first embodiment. Specifically, in the calculation of the noise source matching index, it is different from the above-described embodiments in that modulation frequency analysis is performed (Modulation Frequency Analysis (MFA) projection at same frequency).

[0036] With reference to FIG. 7, a procedure for processing the measurement results of the far-field measurement in step S102 of FIG. 2 for the third embodiment is described. Modulation frequency analysis is applied to the detection signal in the time domain of the far-field measurement. Next, the modulation frequency data Xv[k, i] at the frequency k of interest is extracted for all modulation frequencies i (step S703), and as shown in [Equation 3], the normalized modulation frequency pattern ^V[k, i] is obtained (step S704).

[0037]

Number

[0038] Referring to FIG. 6, the procedure for calculating the noise source matching index NSMI in the third embodiment will be described. First, in step S602, modulation frequency analysis is applied to the detected signal in the time domain of the near-field measurement to calculate the modulation frequency data X sL [k, i]. Here, the modulation frequency data is information in which the frequency of the electromagnetic noise, the modulation frequency of the electromagnetic noise, and the intensity of the electromagnetic noise are associated with each other.

[0039] Subsequently, in step S603, the maximum modulation degree (modulation amplitude) Sm[i] among all frequencies in the modulation frequency data is calculated as in the first equation of [Equation 4] below. Then, as in the second and third equations of [Equation 4], the average value / Sm is subtracted from the maximum modulation degree Sm[i] and normalization is performed (step S604).

[0040]

Equation

[0041] Then, the normalized modulation frequency data ^V[k] of the far-field measurement obtained in this way is projected onto the normalized modulation frequency data ^S of the near-field measurement (step S605). Specifically, as shown in [Equation 5], the absolute value of the dot product of the two is calculated. According to the result of this projection (dot product), the noise source matching index NSMI is calculated.

[0042]

Equation

[0043] Referring to FIG. 7, another procedure for calculating the noise source matching index NSMI in the third embodiment will be described. Similar to FIG. 6, modulation frequency analysis is applied to the detection signal in the time domain of the near-field measurement and the detection signal in the time domain of the far-field measurement to calculate modulation frequency data (step S702). Next, the modulation frequency data at the frequency of interest is extracted from both pieces of modulation frequency data (step S703). Then, both modulation frequency patterns are normalized (step S704), and the noise source matching index NSMI is calculated by performing projection in the same way.

[0044] FIG. 8 is an example of modulation frequency data 801 related to the detection signal of the far-field measurement, and FIG. 9 is an example of modulation frequency data 901 related to the detection signal of the near-field measurement. In FIG. 8, reference numeral 802 indicates the modulation pattern of the frequency data related to the frequency of interest (step S703). FIG. 10 is a graph showing the frequency at which the maximum modulation amplitude (after normalization) is obtained in the modulation frequency data of FIG. 9.

[0045] [Fourth Embodiment] Subsequently, the electromagnetic noise measurement device according to the fourth embodiment will be described with reference to FIG. 11. Since the configuration of the electromagnetic noise measurement device is substantially the same as that of the first embodiment, duplicate explanations will be omitted. Also, the method for determining the noise source is the same as that of the first embodiment (FIG. 2). The method for processing the measurement result of the far-field measurement in step S102 is the same as that of the third embodiment (FIG. 7). However, in this fourth embodiment, the calculation method of the noise source matching index NSMI is different from that of the first embodiment. Specifically, it is different from the foregoing embodiments in that modulation frequency analysis is performed in the calculation of the noise source matching index (Modulation Frequency Analysis (MFA) projection at different frequency).

[0046] Referring to FIG. 11, the procedure for calculating the noise source matching index NSMI in the fourth embodiment will be described. In this embodiment, modulation frequency analysis is not applied to the detection signal in the time domain of the near-field measurement. The frequency spectrum Sp[i] of the detection signal σs in the time domain of the near-field measurement is estimated, for example, by estimating the power spectral density using the Fourier transform of the waveform measured by an oscilloscope (not shown), or measured using a spectrum analyzer (step S603'). Then, the average value / Sp is subtracted from the frequency spectrum Sp[i] and normalization is performed (step S604'). FIG. 12 is an example of the waveform of the frequency spectrum after normalization. Then, the modulation frequency data of the far-field measurement is projected onto the frequency spectrum of the near-field measurement (step S605). As a result of the projection, the noise source matching index NSMI is calculated according to the degree of approximation of the two data.

[0047] Note that the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Also, it is possible to add, delete, or replace other configurations for a part of the configuration of each embodiment.

[0048] In addition, each of the above configurations, functions, processing units, processing means, etc. may be realized in hardware by designing a part or all of them, for example, by an integrated circuit. Also, each of the above configurations, functions, etc. may be realized in software by a processor interpreting and executing a program for realizing each function. Information such as programs, tables, files, etc. for realizing each function can be placed in a memory, a recording device such as a hard disk, an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, a DVD.

Description of Reference Numerals

[0049] 1501…Electromagnetic noise measuring device 1502…RF interface 1503…Memory unit 1504…Main processor 1505…I / O interface 1506…Measurement probe 1507…Target device 1508…Object device 1510…Noise source 1509…Display

Claims

A method for measuring electromagnetic noise by an electromagnetic noise measuring device, the method comprising a processor included in the electromagnetic noise measuring device, at a first timing, performing a far-field measurement of measuring electromagnetic noise in the vicinity of a target device via a first port included in the electromagnetic noise measuring device, and storing the measurement data in a memory included in the electromagnetic noise measuring device, and then, performing a near-field measurement via the first port at a second timing after the first timing in the vicinity of a candidate of a noise source that applies electromagnetic noise to the target device; calculating a noise source matching index which is a numerical value indicating an approximation degree between the far-field measurement and the near-field measurement; executing the above steps while repeatedly changing the measurement location; characterized in that, the step of calculating the noise source matching index includes: calculating, for each time, a change over time of a first spectral density at a frequency index k of interest of a detection signal of the far-field measurement as a first time change; calculating, for each time, a change over time of a second spectral density at a frequency index k of interest of a detection signal of the near-field measurement as a second time change; calculating a signal obtained by subtracting an average value of the first time change from the first time change, and normalizing the signal to calculate a first normalized signal; calculating a signal obtained by subtracting an average value of the second time change from the second time change, and normalizing the signal to calculate a second normalized signal; calculating the product of the first normalized signal and the second normalized signal for each time interval on the time axis of the first time change, searching for a time interval in which the sum of the products over the entire time length of the operation between the first time change and the second time change becomes the maximum value, and calculating the sum of the products at that time as the noise source matching index; including an electromagnetic noise measurement method. A method for measuring electromagnetic noise by an electromagnetic noise measuring device, the method comprising a processor included in the electromagnetic noise measuring device, at a first timing, performing a far-field measurement of measuring electromagnetic noise in the vicinity of a target device via a first port included in the electromagnetic noise measuring device, and storing the measurement data in a memory included in the electromagnetic noise measuring device, and then, In the vicinity of a candidate for a noise source that applies electromagnetic noise to the target device, at a second timing after the first timing, execute near-field measurement via the first port; calculate a noise source matching index, which is a numerical value indicating the degree of approximation between the far-field measurement and the near-field measurement; Repeat the above steps while changing the measurement location; comprising: The step of calculating the noise source matching index includes: calculating the absolute value of the detection signal in the time domain of the first frequency region of the far-field measurement, and calculating a first signal obtained by subtracting the average value of the absolute value of the detection signal from the absolute value; calculating the square root of the change over time of the spectral density of the frequency components in the second frequency region, which is higher in frequency than the first frequency region, of the near-field measurement, and calculating a second signal obtained by subtracting the average value of the square root from the square root; normalizing the first signal and the second signal, and calculating the product of the normalized signals for each time interval on the time axis of the second signal, thereby searching for the time interval at which the sum of the products over the entire time length of the calculation of the first signal and the second signal becomes the maximum value, and calculating the sum of the products at that time as the noise source matching index; including: An electromagnetic noise measurement method. **Claim 3**: A method for measuring electromagnetic noise by an electromagnetic noise measurement device, the method comprising steps in which a processor included in the electromagnetic noise measurement device at a first timing, executes a far-field measurement of measuring electromagnetic noise in the vicinity of a target device via a first port included in the electromagnetic noise measurement device, and stores the measurement data in a memory included in the electromagnetic noise measurement device, and then in the vicinity of a candidate for a noise source that applies electromagnetic noise to the target device, at a second timing after the first timing, executes near-field measurement via the first port; calculates a noise source matching index, which is a numerical value indicating the degree of approximation between the far-field measurement and the near-field measurement; Repeat the above steps while changing the measurement location; comprising: The step of calculating the noise source matching index includes: applying modulation frequency analysis to the detection signal in the time domain of the near-field measurement and the detection signal in the time domain of the far-field measurement to calculate modulation frequency data; Calculate the maximum modulation degree among all frequencies in the modulation frequency data, subtract the average value of the modulation degrees of the modulation frequency data from the maximum modulation degree, and perform normalization to calculate the normalized modulation frequency data for the near-field measurement. Project the normalized modulation frequency data for the far-field measurement onto the normalized modulation frequency pattern for the near-field measurement, and calculate the noise source matching index based on the approximation degree between the two projected data. including Electromagnetic noise measurement method.

4. A method for measuring electromagnetic noise by an electromagnetic noise measuring device, wherein the method comprises a processor included in the electromagnetic noise measuring device At a first timing, perform a far-field measurement of measuring electromagnetic noise near a target device via a first port included in the electromagnetic noise measuring device, and store the measurement data in a memory included in the electromagnetic noise measuring device, and then Near the candidate of the noise source that gives electromagnetic noise to the target device, at a second timing after the first timing, perform a near-field measurement via the first port. Calculating a noise source matching index, which is a numerical value indicating the approximation degree between the far-field measurement and the near-field measurement Execute by changing the repeated measurement location comprising The step of calculating the noise source matching index Measure the frequency spectrum of the detection signal in the time domain of the near-field measurement. Apply modulation frequency analysis to the detection signal in the time domain of the far-field measurement to calculate modulation frequency data. Project the modulation frequency data of the far-field measurement onto the data of the frequency spectrum of the near-field measurement, and calculate the noise source matching index based on the approximation degree between the two projected data. including Electromagnetic noise measurement method.

5. The method according to any one of claims 1 to 4, further comprising the step of presenting the noise source matching index to the user.

6. A measurement probe for measuring electromagnetic noise near a target device and near a noise source, A computer system connected to the measurement probe via a first port comprising The computer system In the vicinity of the target device, at a first timing, perform a far-field measurement to measure the electromagnetic noise in the vicinity of the target device via the first port, and store the measurement data in a memory, and then, In the vicinity of the candidate noise source, at a second timing after the first timing, perform a near-field measurement to measure the electromagnetic noise in the vicinity of the candidate noise source via the first port; Calculate a noise source matching index, which is a numerical value indicating the degree of approximation between the far-field measurement and the near-field measurement; The steps are configured to be repeatedly executed while changing the measurement location, The step of calculating the noise source matching index includes: Calculating, for each time, as a first time change, the change over time of the first spectral density at a frequency index k of interest of the detection signal of the far-field measurement; Calculating, for each time, as a second time change, the change over time of the second spectral density at a frequency index k of interest of the detection signal of the near-field measurement; Calculating a first normalized signal by calculating a signal obtained by subtracting the average value of the first time change from the first time change and normalizing the signal; Calculating a second normalized signal by calculating a signal obtained by subtracting the average value of the second time change from the second time change and normalizing the signal; Calculating the product of the first normalized signal and the second normalized signal for each time interval on the time axis of the first time change, searching for the time interval at which the sum of the products over the entire time length of the operation between the first time change and the second time change becomes the maximum value, and calculating the sum of the products at that time as the noise source matching index; An electromagnetic noise measurement device, comprising:

7. A measurement probe for measuring electromagnetic noise in the vicinity of a target device and in the vicinity of a noise source, A computer system connected via the measurement probe and a first port, The computer system includes: In the vicinity of the target device, at a first timing, perform a far-field measurement to measure the electromagnetic noise in the vicinity of the target device via the first port, and store the measurement data in a memory, and then, ​ ​ In the vicinity of the candidate noise source, at a second timing after the first timing, execute a near-field measurement for measuring electromagnetic noise in the vicinity of the candidate noise source via the first port; calculate a noise source matching index, which is a numerical value indicating the degree of approximation between the far-field measurement and the near-field measurement; The above steps are configured to be executed by changing the measurement location repeatedly; The step of calculating the noise source matching index includes: calculate the absolute value of the detection signal in the time domain of the first frequency region of the far-field measurement, and calculate a first signal obtained by subtracting the average value of the absolute value of the detection signal from this absolute value; calculate the square root of the change over time of the spectral density of the frequency components in the second frequency region, which is higher in frequency than the first frequency region, of the near-field measurement, and calculate a second signal obtained by subtracting the average value of the square root from the square root; normalize the first signal and the second signal, and calculate the product of the normalized signals for each time interval on the time axis of the second signal, so as to search for the time interval at which the sum of the products over the entire time length of calculating the first signal and the second signal becomes the maximum value, and calculate the sum of the products at this time as the noise source matching index; including an electromagnetic noise measurement device.

8. a measurement probe for measuring electromagnetic noise in the vicinity of the target device and in the vicinity of the noise source; a computer system connected to the measurement probe via a first port; The computer system includes: in the vicinity of the target device, at a first timing, execute a far-field measurement for measuring electromagnetic noise in the vicinity of the target device via the first port, and store the measurement data in a memory, and then in the vicinity of the candidate noise source, at a second timing after the first timing, execute a near-field measurement for measuring electromagnetic noise in the vicinity of the candidate noise source via the first port; calculate a noise source matching index, which is a numerical value indicating the degree of approximation between the far-field measurement and the near-field measurement; The above steps are configured to be executed by changing the measurement location repeatedly; The step of calculating the noise source matching index includes: ​ For the detection signal in the time domain of the near-field measurement and the detection signal in the time domain of the far-field measurement, apply modulation frequency analysis to calculate modulation frequency data. Calculate the maximum modulation degree that is the maximum among all frequencies in the modulation frequency data, subtract the average value of the modulation degrees of the modulation frequency data from the maximum modulation degree, and perform normalization to calculate the normalized modulation frequency data for the near-field measurement. Calculate the noise source matching index by projecting the normalized modulation frequency data of the far-field measurement onto the normalized modulation frequency pattern of the near-field measurement. including an electromagnetic noise measurement device.

9. A measurement probe for measuring electromagnetic noise in the vicinity of the target device and in the vicinity of the noise source, a computer system connected to the measurement probe via a first port comprising The computer system In the vicinity of the target device, at a first timing, perform a far-field measurement of measuring electromagnetic noise in the vicinity of the target device via the first port, and store the measurement data in a memory. After that, In the vicinity of the candidate noise source, at a second timing after the first timing, perform a near-field measurement of measuring electromagnetic noise in the vicinity of the candidate noise source via the first port; calculate a noise source matching index, which is a numerical value indicating the degree of approximation between the far-field measurement and the near-field measurement; configured to perform repeatedly with different measurement locations, The step of calculating the noise source matching index measures the frequency spectrum of the detection signal in the time domain of the near-field measurement, applies modulation frequency analysis to the detection signal in the time domain of the far-field measurement to calculate modulation frequency data, calculates the noise source matching index by projecting the modulation frequency data of the far-field measurement onto the data of the frequency spectrum of the near-field measurement. including an electromagnetic noise measurement device.

10. The electromagnetic noise measurement device according to any one of claims 6 to 9, further comprising a display unit for displaying the noise source matching index to the user.

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