JP5527266B2 - Electromagnetic noise distribution detector - Google Patents

Description

  The present invention relates to an electromagnetic noise distribution detection device that detects a propagation path distribution of electromagnetic noise in an electronic device.

  A circuit in an electronic device may malfunction due to the operation of other circuits in the vicinity or the influence of electromagnetic noise caused by external electromagnetic waves. For this reason, an immunity test is performed to evaluate the influence of electromagnetic noise on the operation of electronic equipment.

  As an example of the immunity test, there is a bulk current injection (BCI) method described in ISO (International Organization for Standardization) 11452-4. In this method, electromagnetic noise is injected into the EUT using a current probe, and performance degradation or malfunction of the EUT is evaluated. However, in this test, it is difficult to specify the location where noise countermeasures are taken because the propagation path of the injected electromagnetic noise inside the housing of the EUT cannot be specified.

  Therefore, the conventional technique discloses a method of measuring the near magnetic field of the EUT by placing the EUT on the scan area of the noise visualization antenna. Each micro antenna element provided in the scan area detects electromagnetic noise generated from the EUT, and displays the intensity of the electromagnetic noise associated with the position of each micro antenna element on the monitor, thereby propagating the electromagnetic noise. A method for obtaining a route distribution is disclosed (for example, see Patent Document 1 below).

JP 2002-318252 A

  However, in the conventional technique described in Patent Document 1, the influence of electromagnetic noise injected as a test signal on the propagation path distribution of electromagnetic noise and the operation of an electronic circuit, external electromagnetic waves, etc. The influence of the generated electromagnetic noise is mixed, and there is a problem that it may be difficult to specify a place to take noise countermeasures in the EUT.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to obtain a propagation path distribution of injected electromagnetic noise in which the influence of electromagnetic noise generated in the test equipment is reduced. .

  An electromagnetic noise distribution detection device according to the present invention is detected by signal injection means for injecting electromagnetic noise into a test equipment, and electromagnetic field strength detection means for detecting electromagnetic field strength from a plurality of measurement locations in the test equipment. The maximum value detecting means for measuring the electromagnetic field intensity by maximum value detection, and the measured value obtained from the measurement by multiple times of maximum value detection for the electromagnetic field intensity obtained from any measurement location in the EUT. Among them, a minimum value holding means for holding a minimum value, a noise distribution detection means for detecting a propagation path distribution of the electromagnetic noise on the EUT based on the minimum value held in the minimum value holding means, It is characterized by providing.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that the propagation path distribution of the injected electromagnetic noise by which the influence of the electromagnetic noise which generate | occur | produces in a test equipment was reduced can be obtained, and the place which takes a noise countermeasure can be specified.

It is a figure which shows the structural example of the electromagnetic noise distribution detection apparatus concerning Embodiment 1 of this invention. It is a figure which shows an example of the time fluctuation | variation in the intensity level of the electromagnetic noise detected by the electromagnetic field strength meter concerning Embodiment 1 of this invention. It is a flowchart which shows the operation example of the electromagnetic noise distribution detection apparatus concerning Embodiment 1 of this invention. It is a figure which shows an example of the propagation path distribution of the electromagnetic noise concerning Embodiment 1 of this invention. It is a figure which shows an example about the relationship of the frequency of the inject | poured electromagnetic noise concerning Embodiment 2 of this invention, and the electromagnetic noise which generate | occur | produces in a EUT. It is a figure which shows an example about the relationship of the frequency of the inject | poured electromagnetic noise concerning Embodiment 2 of this invention, and the electromagnetic noise which generate | occur | produces in a EUT. It is a figure which shows an example of the propagation path distribution of the electromagnetic noise concerning Embodiment 2 of this invention. It is a figure which shows an example about the relationship of the frequency of the inject | poured electromagnetic noise concerning Embodiment 3 of this invention, and the electromagnetic noise which generate | occur | produces in a EUT.

  Embodiments of the present invention will be described below in detail with reference to the drawings. Note that each of the embodiments described below is an embodiment when the present invention is embodied, and the present invention is not limited to the scope.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of an electromagnetic noise distribution detection apparatus according to the present embodiment. The electromagnetic noise distribution detection apparatus according to the present embodiment includes a signal generator 1, an amplifier 2, an injection probe 3, a detection probe 4, an amplifier 5, an electromagnetic field strength meter 6, a movable unit 7, a scanning unit 8, a control unit 9, A display unit 10 is provided. The electromagnetic field strength meter 6 has a maximum value detecting means 6a and a minimum value holding means 6b. The control unit 9 has noise distribution detection means 11. The configuration shown in FIG. 1 is an example, and the mounting form of each part is not limited to this. For example, it is allowed to be modified such that the functions of the respective units are realized by common hardware, or separated into a plurality of hardware. The same applies to Embodiments 2 and 3 described later. The minimum value holding unit 6b is realized by a memory, for example. In the example of FIG. 1, the maximum value detection means 6a and the minimum value holding means 6b are included in the electromagnetic field strength meter 6, but the present invention is not limited to this. That is, the electromagnetic field strength meter 6 only measures the electromagnetic field strength, and the maximum value detecting means 6a and the minimum value holding means 6b can be modified to be disposed outside the electromagnetic field strength meter 6. For example, these may be realized by other functional units such as the control unit 9 and the noise distribution detection unit 11. Alternatively, it may be realized as an independent functional unit by being configured by software corresponding to a processing operation and hardware that executes the software.

  The signal generator 1 generates electromagnetic noise as a test signal. The amplifier 2 amplifies the test signal generated by the signal generator 1. The injection probe 3 is connected to a connection cable (such as a power cable) of the device under test 100 and injects the test signal amplified by the amplifier 2 into the device under test 100. The detection probe 4 detects electromagnetic noise that propagates through the EUT 100. The amplifier 5 amplifies the detection signal output from the detection probe 4. The electromagnetic field strength meter 6 measures the strength level of the detection signal amplified by the amplifier 5. In FIG. 1, a printed circuit board is shown as an example of the EUT 100 in the present embodiment, but an electronic device other than the printed circuit board may be used as the device under test.

  The signal generator 1, the amplifier 2 and the injection probe 3 correspond to an example of signal injection means. The detection probe 4, the amplifier 5, and the electromagnetic field strength meter 6 correspond to an example of electromagnetic field strength detection means. The amplifier 2 may be omitted if the level of electromagnetic noise is high enough to be detected by the detection probe 4. Similarly, the amplifier 5 may be omitted if the level of the detection signal from the detection probe 4 is high enough to measure the electromagnetic field intensity with the electromagnetic field intensity meter 6. In the example of FIG. 1, the injection probe 3 is a type that is clamped to the connection cable of the EUT 100, but is not limited to this method. If electromagnetic noise can be injected as a test signal, other contact-type or non-contact-type methods can be used.

  The movable portion 7 is configured to move the detection probe 4 in the X (horizontal), Y (vertical), Z (height), and θ (rotation) directions. The scanning unit 8 controls the movable unit 7 in order to scan the detection probe 4 in the XYZθ directions.

  The movable unit 7 and the scanning unit 8 correspond to an example of a scanning unit that moves the detection position on the EUT 100. Although the movable part 7 scans the detection probe 4 in the XYZθ directions, the scanning method is not limited to this. For example, instead of scanning the detection probe 4, the EUT 100 may be moved. Alternatively, both the detection probe 4 and the EUT 100 may be moved. Besides the method of changing the relative positional relationship between the detection probe 4 and the EUT 100, a number of detection devices are arranged in advance in the scanning region, and the propagation path distribution of electromagnetic noise from the data measured by each detection device. Is also possible. As described above, various methods for obtaining a propagation path distribution of electromagnetic noise propagating through the EUT 100 can be applied.

  The control unit 9 controls each part of the electromagnetic noise distribution detection device. For example, the generation signal frequency of the signal generator 1 is set, the scanning direction and the scanning amount of the detection probe 4 are set for the scanning unit 8, and the measurement control of the electromagnetic field intensity meter 6 is performed. The noise distribution detecting means 11 performs numerical processing for obtaining a propagation path distribution of electromagnetic noise based on the output data from the electromagnetic field intensity meter 6. The display unit 10 displays the propagation path distribution of the detected electromagnetic noise. When the control unit 9 is an information processing apparatus such as a computer, the noise distribution detection unit 11 can be realized as software that operates on the information processing apparatus. In the example of FIG. 1, the noise distribution detection unit 11 is included in the control unit 9, but is not limited thereto. For example, it may be realized by a functional unit other than the control unit 9. Alternatively, it may be realized as an independent functional unit by being configured by software corresponding to a processing operation and hardware that executes the software.

  Next, a method for reducing the influence of electromagnetic noise generated in the EUT 100 in the electromagnetic field strength meter 6 will be described. In the present embodiment, it is assumed that the intensity level of electromagnetic noise generated in the EUT 100 varies with time. On the other hand, the intensity level of electromagnetic noise injected as a test signal from the injection probe 3 does not vary with time, or is sufficiently smaller than the temporal variation of electromagnetic noise generated in the EUT 100. Will be described.

  FIG. 2 is a diagram showing an example of temporal variation in the intensity level of electromagnetic noise detected by the electromagnetic field strength meter according to the present embodiment. The vertical axis of FIG. 2 indicates the intensity level of electromagnetic noise, and the horizontal axis indicates time and frequency, respectively. As shown in the figure, a frequency component f1 whose intensity level does not vary with time and a frequency component f2 whose intensity level varies with time are shown. In FIG. 2, for the sake of explanation, the frequency f1 and the frequency f2 are shown at different positions on the frequency axis, but the frequency f1 and the frequency f2 may be the same frequency.

  The maximum value detection means 6a of the electromagnetic field strength meter 6 performs measurement by maximum value detection a plurality of times on a detection signal from an arbitrary measurement location in the EUT 100. In FIG. 2, as an example, measurement by five maximum value detections from t1 to t5 is shown. The minimum value holding means 6b of the electromagnetic field strength meter 6 holds the minimum value among the measurement values obtained from the measurement by the plurality of times of maximum value detection. As a result, the measurement result held in the minimum value holding means 6b has a substantially constant value for the frequency component f1 at which the intensity level of the electromagnetic field strength does not change with time, but for the frequency component f2 with time change, The intensity level at t4. In this case, the noise distribution detecting means 11 adopts the intensity level at t4 for the measurement location. In this way, the electromagnetic field strength is obtained in the same manner for other measurement locations. As a result, the propagation path distribution of the injected electromagnetic noise in which the influence of the electromagnetic noise generated in the EUT 100 is reduced from the minimum value of the minimum value holding means 6b obtained for each of a plurality of locations of the EUT. Can be obtained.

  FIG. 2 shows an example in which the measured value of the frequency component f2 is lowered to the measurement limit level or less when the measured value is time t4. In this case, electromagnetic noise components generated in the EUT 100 are completely removed. If other measurement points can be removed in the same manner, a propagation path distribution in which only the influence of electromagnetic noise injected as a test signal is evaluated can be obtained. In addition, even if the time-varying frequency component does not fall below the measurement limit level, the influence of the electromagnetic noise generated in the EUT 100 in the propagation path distribution of the obtained electromagnetic noise is reduced. Can do. In this way, it is possible to obtain a propagation path distribution of injected electromagnetic noise in which the influence of electromagnetic noise generated in the EUT 100 is reduced. As for the method for deriving the minimum level of the measurement value, there is a deviation in the measurement by the maximum value detection, so that the minimum value among the measurement values obtained from the measurement by the maximum value detection multiple times is held. The number of times of measurement can be determined as appropriate according to the temporal variation of electromagnetic noise generated in the EUT 100.

  Next, the operation of the electromagnetic noise distribution detection apparatus according to this embodiment will be described. FIG. 3 is a flowchart showing an operation example of the electromagnetic noise distribution detection apparatus according to the present exemplary embodiment. The signal generator 1 generates electromagnetic noise as a test signal based on an instruction from the noise distribution detection means 11 (step S31). Electromagnetic noise is injected into the EUT 100 through the injection probe 3 (step S32). The injected electromagnetic noise propagates through the EUT 100 and is distributed over one surface of the EUT 100. Next, in order to detect propagation of electromagnetic noise, the detection probe 4 scans one surface of the EUT 100, and the electromagnetic field intensity in which the injected electromagnetic noise and the electromagnetic noise generated in the EUT 100 are mixed. Is detected (step S33). The maximum value detection means 6a of the electromagnetic field intensity meter 6 performs the measurement by the maximum value detection a plurality of times on the detection signal (step S34). The minimum value holding means 6b of the electromagnetic field intensity meter 6 holds the minimum value among the measurement values obtained from the measurement by the plurality of times of maximum value detection (step S35). The noise distribution detection means 11 detects the propagation path distribution of the injected electromagnetic noise based on the minimum value held in the minimum value holding means 6b (step S36). The detected propagation path distribution of electromagnetic noise is displayed on the display unit 10 (step S37).

  FIG. 4 is a diagram illustrating an example of a propagation path distribution of electromagnetic noise according to the present embodiment. As shown in the figure, the electromagnetic field intensity distribution is visualized, and the propagation path distribution of electromagnetic noise injected from the injection probe 3 can be obtained.

  As described above, the electromagnetic noise distribution detection apparatus according to the present embodiment injects electromagnetic noise into the EUT 100, and performs a plurality of maximum value detections on the detection signal detected from the EUT 100. Measurement was performed, and the minimum value of the measured values was held. Thereby, in the propagation path distribution of electromagnetic noise, the influence of the electromagnetic noise generated in the EUT 100 is reduced, and the propagation path distribution of electromagnetic noise injected as a test signal can be obtained. In addition, it is possible to specify a place to take noise countermeasures based on the obtained propagation path distribution.

Embodiment 2. FIG.
In the method of the first embodiment, when there is no temporal variation in the intensity level of electromagnetic noise generated in the EUT 100, or the temporal variation is small, the intensity level is sufficiently reduced. It becomes difficult. Alternatively, even if the intensity level of electromagnetic noise generated in the EUT 100 is temporally varied and the intensity level can be reduced by the configuration of the first embodiment, the intensity level is still large. In addition, the influence on the intensity level of the injected electromagnetic noise may not be sufficiently eliminated. In the electromagnetic noise distribution detecting apparatus according to the present embodiment, the frequency of the electromagnetic noise to be injected is shifted from the frequency of the electromagnetic noise generated in the EUT 100 by a predetermined value. Since the configuration of each part of the electromagnetic noise distribution detecting apparatus according to the present embodiment is the same as that of the first embodiment, the description of the overlapping parts is omitted.

  The signal generator 1 has a frequency shifted by Δf that is wider than the resolution bandwidth (hereinafter referred to as RBW: Resolution Bandwidth) of the frequency of the electromagnetic field intensity meter 6 from the frequency (f0) of electromagnetic noise generated in the EUT 100. Electromagnetic noise of fn (fn = f0 + Δf or fn = f0−Δf) is output as a test signal. The detection probe 4 detects the signal of the frequency component fn of the test signal while changing the positional relationship with the EUT 100. The electromagnetic field strength meter 6 measures the intensity level of the frequency (fn) of the detection signal by the maximum value detection means 6a by multiple times of maximum value detection, and the minimum value among the measurement values is stored in the minimum value holding means 6b. Hold on.

  FIG. 5 is a diagram illustrating an example of a frequency relationship between injected electromagnetic noise and electromagnetic noise generated in the test equipment according to the present embodiment. As shown in the figure, the frequency of the injected electromagnetic noise is shifted from the frequency f0 of the electromagnetic noise generated in the EUT 100 by Δf. If Δf is small to about RBW of the electromagnetic field strength meter 6, it can be approximated as fn≈f0. For this reason, the electromagnetic field strength distribution of the frequency component f0 of the electromagnetic noise generated in the EUT 100 can be approximately obtained from the electromagnetic field strength distribution of the frequency component fn detected by the detection probe 4.

  In order for the electromagnetic noise injected with the frequency shifted by Δf to exhibit the same tendency as the electromagnetic noise generated in the EUT 100, the order of the electromagnetic noise generated in the EUT 100 and the injected electromagnetic noise is the same. It is desirable that the phase difference does not deviate from λ / 4. For this reason, when setting the frequency of the test signal, Δf is selected in a frequency range that satisfies the above conditions. At this time, the RBW of the electromagnetic field strength meter 6 is such that the frequency of the electromagnetic noise generated in the EUT 100 and the frequency of the injected electromagnetic noise can be measured separately. It is necessary to set narrower than the interval between two frequencies.

  In FIG. 5, the frequency shifted to the side higher by Δf than the frequency to be measured f0 is set to fn, but the frequency shifted to the side lower by Δf may be used. Furthermore, as shown in FIG. 6, the electromagnetic noise of the two frequencies of the frequency fn1 = f0−Δf shifted to the lower side by Δf and the frequency fn2 = f0 + Δf shifted to the higher side by Δf with respect to f0. It is also possible to inject as a test signal. The electromagnetic field intensity of the frequency f0 at an arbitrary position on the EUT 100 can be obtained as an average value of detection signals obtained in the frequency components fn1 and fn2. As shown in FIG. 7, the propagation path distribution of electromagnetic noise (FIG. 7A) by the frequency component fn1 of the injected electromagnetic noise and the propagation path distribution of electromagnetic noise by the frequency component fn2 of the electromagnetic noise (FIG. 7). By averaging (b)), it is possible to obtain an approximate electromagnetic noise propagation path distribution (FIG. 7C) of the frequency f0 to be measured. Numerical processing for averaging the minimum value of the minimum value holding means 6b obtained for the frequency components f1 and f2 is executed by the noise distribution detecting means 11. In FIG. 5 and FIG. 6, one electromagnetic noise having a frequency shifted by Δf relative to f0 and one electromagnetic frequency having a frequency shifted by Δf are injected. A plurality of electromagnetic noises may be injected on both sides, and the propagation path distribution of f0 may be obtained therefrom.

  When a test signal having a frequency shifted by 1 / n wavelength (λ / n) is injected with respect to the frequency f0 of electromagnetic noise generated in the EUT 100, the frequency is fn = nf0 / (n + 1). And nf0 / (n-1). A test signal having a frequency of fn1 = nf0 / (n + 1) and fn2 = nf0 / (n−1) is applied by the injection probe 3, and based on the electromagnetic field intensity distribution calculated from the detection signal corresponding to each frequency component, Interpolate the electromagnetic field intensity distribution at the frequency f0 to be measured. Here, if the frequency components fn1 and fn2 are set so as to be as close to the measured frequency f0 as possible, the error from the electromagnetic field intensity distribution of the electromagnetic noise generated in the EUT 100 can be reduced. That is, by setting Δf in the frequency components fn1 and fn2, it is possible to limit an error range between the approximate electromagnetic field intensity distribution and the electromagnetic noise field intensity distribution of the electromagnetic noise generated in the EUT 100. For example, when the wavelength is shifted by a quarter wavelength (λ / 4), 4f0 / 5 and 4f0 / 3 are obtained, so that the error range can be approximated within a range of −20% to about 133.3%. When the wavelength is shifted by 1/20 wavelength (λ / 20), 20f0 / 21 and 20f0 / 19 are obtained, and the error is (about −4.8% to about 105%).

  As described above, the amount of deviation from the frequency f0 of the electromagnetic noise generated in the EUT 100 in the frequency components fn1 and fn2 is defined by the same value Δf, but it must be an equal frequency interval as viewed from f0. There is no. Δf in the expressions of the frequency components fn1 and fn2 can be appropriately selected according to electromagnetic noise generated in the EUT 100.

  As described above, in addition to the configuration of the first embodiment, the signal generator 1 is shifted from the frequency of the electromagnetic noise generated in the EUT 100 by a predetermined value in the electromagnetic noise distribution detection apparatus according to the present embodiment. It is configured to generate electromagnetic noise with different frequencies. As a result, in addition to the same effects as those of the first embodiment, the electromagnetic noise generated in the EUT 100 includes a frequency component that has no temporal variation in intensity level or a small temporal variation. Even in this case, the influence of electromagnetic noise generated in the EUT 100 can be reduced in the propagation path distribution of electromagnetic noise, and the propagation path distribution of electromagnetic noise injected as a test signal can be obtained. In addition, it is possible to specify a place to take noise countermeasures based on the obtained propagation path distribution.

Embodiment 3 FIG.
The electromagnetic noise distribution detection apparatus according to the present embodiment is configured to inject electromagnetic noise in a predetermined frequency band including the frequency of electromagnetic noise generated in the EUT 100. Since the configuration of each part of the electromagnetic noise distribution detecting apparatus according to the present embodiment is the same as that of the first embodiment, the description of the overlapping parts is omitted.

  FIG. 8 is a diagram illustrating an example of a frequency relationship between the electromagnetic noise according to the present embodiment and the electromagnetic noise generated in the EUT. The signal generator 1 generates broadband electromagnetic noise including the frequency of electromagnetic noise generated in the EUT 100. The detection probe 4 detects the electromagnetic field intensity on the EUT 100 for each frequency component of the injected electromagnetic noise while changing the positional relationship with the EUT 100. The electromagnetic field strength meter 6 measures the intensity level of the detection signal by a plurality of times of maximum value detection, and holds the minimum value of the measured values in the minimum value holding means 6b.

  In the first and second embodiments, the frequency of electromagnetic noise to be injected is determined in advance before the electromagnetic noise is injected. In the present embodiment, broadband electromagnetic noise is injected without specifying the frequency of electromagnetic noise in advance, and a detection signal is obtained for each frequency. With respect to the obtained detection signal, the propagation path distribution of the electromagnetic noise propagating in the EUT 100 can be detected for the desired electromagnetic noise frequency by the method described in the first or second embodiment. In addition, the frequency bandwidth of the electromagnetic noise to inject | pour can be suitably determined according to the frequency bandwidth made into test object.

  As described above, in the electromagnetic noise distribution detecting apparatus according to the present embodiment, in the configuration of the first or second embodiment, the signal generator is a frequency band including the frequency of the electromagnetic noise generated in the EUT 100. The electromagnetic noise is generated. As a result, in addition to the effects of the first or second embodiment, the test time can be shortened because only one noise injection operation is required for a plurality of electromagnetic noise frequencies.

  In the above description, the configurations of the second and third embodiments are implemented together with the configuration of the first embodiment. However, the configurations of the second and third embodiments are not used without using the configuration of the first embodiment. It is also possible to implement. That is, without using the configuration in which the frequency component that varies with time in the first embodiment is measured a plurality of times by maximum value detection and the configuration in which the frequency value is reduced by holding the minimum value among the measured values, the provision of the second embodiment. A configuration may be implemented in which electromagnetic noise having a frequency shifted by Δf from the frequency f0 of electromagnetic noise generated in the test equipment 100 is injected to approximate the propagation path distribution of the electromagnetic noise having the frequency f0. Similarly, a configuration in which electromagnetic noise in a frequency band including the frequency f0 of electromagnetic noise generated in the EUT 100 may be implemented without using the above configuration of the first embodiment.

DESCRIPTION OF SYMBOLS 100 EUT 1 Signal generator 2 Amplifier 3 Injection probe 4 Detection probe 5 Amplifier 6 Electromagnetic field strength meter 6a Maximum value detection means 6b Minimum value holding means 7 Movable part 8 Scan part 9 Control part 10 Display part 11 Noise distribution detection means

Claims (4)

Signal injection means for injecting electromagnetic noise into the EUT;
Electromagnetic field strength detection means for detecting electromagnetic field strength from a plurality of measurement locations in the EUT,
Maximum value detecting means for measuring the detected electromagnetic field intensity by maximum value detection;
For the electromagnetic field intensity obtained from any measurement location in the EUT, minimum value holding means for holding the minimum value among the measurement values obtained from measurement by multiple times of maximum value detection,
An electromagnetic noise distribution detection apparatus comprising: noise distribution detection means for detecting a propagation path distribution of the electromagnetic noise on the EUT based on the minimum value held in the minimum value holding means. The signal injection means injects electromagnetic noise having a frequency shifted by a predetermined value with respect to the frequency of electromagnetic noise generated in the EUT,
The noise distribution detecting means is a propagation path of electromagnetic noise at a frequency of electromagnetic noise generated in the EUT based on a minimum value held in the minimum value holding means corresponding to the injected electromagnetic noise frequency. The electromagnetic noise distribution detection apparatus according to claim 1, wherein the distribution is approximated. The signal injection means includes electromagnetic noise having a frequency shifted to a higher side by a predetermined value and electromagnetic noise having a frequency shifted to a lower side by a predetermined value than the frequency of the electromagnetic noise generated in the EUT. Inject,
The noise distribution detecting means is a propagation path of electromagnetic noise at a frequency of electromagnetic noise generated in the EUT based on a minimum value held in the minimum value holding means corresponding to the injected electromagnetic noise frequency. The electromagnetic noise distribution detection apparatus according to claim 1, wherein the distribution is approximated.   The electromagnetic noise distribution detection device according to claim 1, wherein the signal injection unit injects electromagnetic noise in a predetermined frequency band including a frequency of electromagnetic noise generated in the EUT.

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