JP7713331B2 - Noise measurement program, noise measurement method, and noise measurement device - Google Patents

Description

The present invention relates to a noise measurement program, a noise measurement method, and a noise measurement device.

Conventionally, in order to evaluate noise in a circuit board built into an electronic device, a technology related to near-field measurement is known that measures the near-field distribution, which indicates the strength distribution of the electric field/magnetic field generated from the board. In near-field measurement, a measurement probe is scanned near the circuit board under test to obtain the distribution of near-field strength at each of multiple measurement points. In addition, by rotating the probe at each of the multiple measurement points to measure the magnetic field strength at multiple angles, the maximum value of the magnetic flux at each of the multiple measurement points can be obtained, and the current direction in the board under test can be estimated.

However, because the near electromagnetic field distribution changes depending on the measurement conditions, such as the section and frequency extracted from the time waveform of the electric field/magnetic field strength, it was necessary to perform near electromagnetic field measurements for each measurement condition. Furthermore, to estimate the current direction, it was necessary to perform near electromagnetic field measurements for multiple angles for each measurement condition. In this situation, when performing multiple measurements, there was a risk that repeatability and reproducibility would decrease due to, for example, human error or the rotation accuracy of the probe.

JP 2002-340943 A JP 2003-199723 A

The problem that this invention aims to solve is to reduce the number of measurements required when measuring the near electromagnetic field of a circuit board.

In order to solve the above-mentioned problems and achieve the object, a noise measurement program according to one aspect of the present invention causes a computer to acquire time series data and output a plane vector. The time series data indicates an electromagnetic field intensity from a circuit under test measured at each of a plurality of measurement points set in the vicinity of the circuit under test. The circuit under test performs a switching operation in response to a reference signal. The time series data is measured in synchronization with a trigger detected based on a signal waveform of the reference signal input to the circuit under test. The time series data is measured during a measurement time having a time width of at least one wavelength of the reference signal. Outputting the plane vector includes extracting time series data of a designated section, which is designated with a time width shorter than the time width of the measurement time, from the acquired time series data. Outputting the plane vector includes calculating an electromagnetic field intensity and a phase component at a designated frequency designated for each of the plurality of measurement points based on the time series data of the designated section. The plane vector corresponds to the electromagnetic field intensity and the phase component for the plurality of measurement points under the conditions of the designated section and the designated frequency. Calculating the electromagnetic field intensity and phase component at a specified frequency for each of the plurality of measurement points based on the time series data of the specified section includes calculating a power spectrum from the time series data of the specified section by fast Fourier transform, and obtaining the electromagnetic field intensity and the phase component at the specified frequency from the power spectrum calculated for each of the plurality of measurement points.

The present invention makes it possible to reduce the number of measurements required when measuring the near electromagnetic field of a circuit board.

FIG. 1 is a block diagram showing an example of the configuration of a noise measuring device according to an embodiment. FIG. 2 is a schematic diagram showing an example of a DCDC power supply board as a circuit board under test according to the embodiment. FIG. 3 is a flowchart illustrating an example of a measurement process according to the embodiment. FIG. 4 is a diagram showing an example of a reference trigger waveform obtained when a DCDC power supply board is measured by a reference probe in the noise measurement process according to the embodiment. FIG. 5 is a diagram showing an example of a magnetic field strength waveform at specified coordinates obtained when a reference probe is triggered and a measurement probe is used to measure a DCDC power supply board in a noise measurement process according to the embodiment. FIG. 6 is a diagram for explaining acquisition of a voltage waveform of a near magnetic field in the noise measurement process according to the embodiment. FIG. 7 is a diagram for explaining acquisition of a voltage waveform of a near magnetic field in the noise measurement process according to the embodiment. FIG. 8 is a flowchart illustrating an example of a display process according to the embodiment. FIG. 9 is a diagram showing an example of a magnetic field intensity waveform obtained by extracting section A in FIG. FIG. 10 is a diagram showing an example of a magnetic field intensity waveform obtained by extracting section B of FIG. FIG. 11 is a diagram showing an example of a magnetic field spectrum obtained by performing FFT processing on the magnetic field intensity waveform relating to section A in FIG. FIG. 12 is a diagram showing an example of a magnetic field spectrum obtained by performing FFT processing on the magnetic field strength waveform relating to section B of FIG. FIG. 13 is a diagram showing an example of the phase component of the magnetic field obtained by performing FFT processing on the magnetic field intensity waveform relating to section A in FIG. FIG. 14 is a diagram showing an example of the phase component of the magnetic field obtained by performing FFT processing on the magnetic field intensity waveform relating to section B of FIG. FIG. 15 is a diagram showing an example of the results of calculation using a cos function for the phase component of the magnetic field in section A of FIG. FIG. 16 is a diagram showing an example of the results of calculation using a cos function for the phase component of the magnetic field in section B of FIG. FIG. 17 is a diagram showing an example of the coefficient k calculated from the calculation results related to the section A in FIG. FIG. 18 is a diagram showing an example of the coefficient k calculated from the calculation results related to the section B in FIG. FIG. 19 is a diagram for explaining a method of calculating a magnetic flux vector at target coordinates (m, n). FIG. 20 is a diagram for explaining a method of calculating a current vector at target coordinates (m, n). FIG. 21 is a diagram showing an example of a map of current distribution at 100 MHz in section A, which is displayed in the display process according to the embodiment. FIG. 22 is a diagram showing an example of a map of current distribution at 100 MHz in section B, displayed in the display process according to the embodiment. FIG. 23 is a diagram showing an example of a map of the magnetic field strength distribution at 100 MHz in section A, which is displayed in the display process according to the embodiment. FIG. 24 is a diagram showing an example of a map of the magnetic field strength distribution at 100 MHz in section B, which is displayed in the display process according to the embodiment. FIG. 25 is a diagram showing an example of a map in which the magnetic field strength distribution and the current distribution at 100 MHz in section A are combined, which is displayed in the display process according to the embodiment. FIG. 26 is a diagram showing an example of a map in which the magnetic field strength distribution and the current distribution at 100 MHz in section B are combined, which is displayed in the display process according to the embodiment. FIG. 27 is a block diagram showing an example of the hardware configuration of each device in the noise measurement device according to the embodiment.

Each embodiment of the noise measurement program, noise measurement method, and noise measurement device according to the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to these embodiments.

Figure 1 is a block diagram showing an example of the configuration of a noise measurement device 1 according to an embodiment. Figure 2 is a schematic diagram showing an example of a DCDC power supply board as a measured circuit board 2 according to an embodiment.

The noise measurement device 1 according to the embodiment is a device that measures the electromagnetic field intensity distribution and current vectors that indicate the direction of currents that occur with switching operations in a circuit under test provided on a circuit board under test 2. The noise measurement device 1 according to the embodiment is also a device that outputs a map that indicates the electromagnetic field intensity distribution and/or current distribution in a specified section that includes any timing, such as the rising or falling time, of the reference waveform of the circuit board under test 2 and at a specified frequency, without performing re-measurement. The noise measurement device 1 is configured to convert electromagnetic field intensity data in a section of any time width into electromagnetic field intensity distribution data on the frequency axis using a fast Fourier transform (FFT), and output a map that indicates the electromagnetic field intensity distribution and/or current distribution corresponding to the arbitrary section and frequency.

The circuit board 2 under test according to the embodiment is equipped with a circuit under test that performs switching operations in accordance with a reference signal such as a clock signal. As shown in FIG. 2, the circuit board 2 under test has an output power terminal 21, an output ground terminal 22, an input power terminal 23, an input ground terminal 24, a coil 25, a diode 26, and a control IC 27. As an example, the circuit board 2 under test is a power supply circuit having a power conversion circuit that converts power using a power semiconductor device, and a drive circuit that supplies a driving voltage to the power semiconductor device. The circuit board 2 under test is, for example, a DCDC power supply board. Hereinafter, the circuit under test provided on the circuit board 2 under test may also be referred to as the circuit board 2 under test.

As shown in FIG. 1, the noise measurement device 1 according to the embodiment includes a measurement control device 11, a drive control device 12, a drive device 13, a measurement probe 14, an amplifier 15, an oscilloscope 16, a reference probe 17, a storage device 18, and a display control device 19.

The measurement control device 11 is a device that controls the measurement of the electromagnetic field intensity distribution in the noise measurement device 1. The measurement control device 11 functions as the noise measurement device 1 according to the embodiment by executing a program (application program) for realizing the measurement process according to the embodiment. As the measurement control device 11, for example, an information processing device such as a smartphone, a personal computer (PC), or a tablet PC can be appropriately used.

As shown in FIG. 1, the measurement control device 11 has the functions of a measurement condition setting unit 111 and a data combining unit 112.

The measurement condition setting unit 111 operates the driving device 13 by the driving control device 12 to move the measurement probe 14 within the measurement scanning range of the noise measurement device 1. Specifically, the measurement condition setting unit 111 transmits a signal S1 to the driving control device 12. Here, the signal S1 includes, for example, coordinate indication information indicating the coordinates of each of the multiple measurement points and information indicating the rotation angle of the measurement probe 14 at each measurement point. The coordinates of each of the multiple measurement points are set, for example, based on the scanning range and the measurement resolution. As an example, the measurement condition setting unit 111 indicates the scanning conditions to the driving control device 12 based on the specified movement conditions such as the measurement resolution and the scanning range.

The measurement condition setting unit 111 also transmits a signal S7 for setting the measurement conditions to the oscilloscope 16. Here, the measurement conditions include a threshold for trigger detection and a time length for detecting the waveform. Specifically, the measurement condition setting unit 111 uses a trigger acquired by the trigger detection unit 161 at the timing of the rising and falling edges of the reference waveform to set a measurement time having a time width of at least one wavelength of the reference waveform.

The data combining unit 112 receives a signal S2 indicating the current coordinate status, i.e., the measurement coordinates which are the current position of the measurement probe 14, from the drive control device 12. The data combining unit 112 also receives a signal S8 indicating waveform data of the electromagnetic field waveform synchronized with the trigger, obtained by the waveform acquisition unit 162 of the oscilloscope 16, from the oscilloscope 16. The data combining unit 112 links the information indicated by these two signals S2 and S8 by combining them, and transmits a signal S9 indicating the electromagnetic field waveform of each coordinate to the database 181 in the storage device 18.

The drive control device 12 controls the operation of the drive device 13 according to the signal S1 transmitted from the measurement condition setting unit 111. Specifically, the drive control device 12 transmits a signal S3 to the drive device 13 for controlling the operation of the drive device 13. The drive device 13 moves the measurement probe 14 on the circuit board 2 to be measured in response to the signal S3 from the drive control device 12, and specifies the position and angle of the measurement probe 14. For example, a four-axis scanner that moves and rotates the measurement probe 14 in the X, Y, and Z axes can be used as the drive device 13. The circuit board 2 to be measured is placed on the stage of the four-axis scanner. Note that the drive device 13 is configured to be able to rotate the direction of the loop provided at the tip of the measurement probe 14 along at least two mutually orthogonal directions, but is not limited to this. The drive device 13 may be configured to be able to change the direction of the loop provided at the tip of the measurement probe 14 to at least two mutually orthogonal directions.

The measurement probe 14 is an electromagnetic field probe that measures the electromagnetic field intensity generated on the circuit board 2 under test. The measurement probe 14 supplies a signal S4 corresponding to the measured electromagnetic field intensity to the amplifier 15. The measurement probe 14 is provided, for example, at the tip of the drive device 13, i.e., on the side of the circuit board 2 under test. When a loop probe for measuring magnetic fields is used as the measurement probe 14, the noise measurement device 1 according to the embodiment can obtain multiple magnetic field intensity distributions and current distributions corresponding to multiple measurement conditions from the measurement data obtained from a single measurement of the magnetic field intensity distribution, without remeasurement. Here, a single measurement of the magnetic field intensity distribution includes measurement of the magnetic field intensity distribution in each of two mutually orthogonal directions, such as the X-axis and Y-axis.

The measurement probe 14 is not limited to a magnetic field probe using a loop probe, and a directional electric field probe can also be used. A general electric field probe does not have directionality, so it is not possible to measure vectors on each of the X and Y axes uniaxially, as in the noise measurement process according to this embodiment. However, by using an optical electric field sensor with uniaxial directionality, it is possible to calculate the electric field intensity and electric flux vector based on a process similar to the noise measurement process according to this embodiment. Therefore, according to the technology according to this embodiment, a map showing the electric field intensity distribution and/or the electric flux vector can also be displayed. In this case, the noise measurement device 1 according to the embodiment can obtain multiple electric field intensity distributions corresponding to multiple measurement conditions from the measurement data obtained by measuring the electric field intensity distribution once, without re-measurement. Here, measuring the electric field intensity distribution once includes measuring the electric field intensity distribution in each of two mutually orthogonal directions, such as the X and Y axes.

The amplifier 15 is a signal amplifier that amplifies a signal S4 corresponding to the electromagnetic field strength from the measurement probe 14. The amplifier 15 supplies a signal S5 indicating the amplified electromagnetic field waveform to channel ch2 of the oscilloscope 16.

As shown in FIG. 1, the oscilloscope 16 functions as a trigger detection unit 161 and a waveform acquisition unit 162.

The oscilloscope 16 has two channels, ch1 and ch2. A signal S6 from the reference probe 17 is input to channel ch1. The input signal S6 is detected as a trigger waveform by the trigger detection unit 161. A signal S5 from the measurement probe 14, amplified by the amplifier 15, is input to channel ch2. The input signal S5 is detected as an electromagnetic field waveform by the waveform acquisition unit 162.

The trigger detection unit 161 detects a trigger based on the signal waveform of a reference signal such as a clock signal from the circuit board 2 under test, i.e., the reference waveform. Specifically, the trigger detection unit 161 acquires a trigger at the timing of the rising and/or falling of the signal S6 according to the reference waveform of the circuit board 2 under test measured by the reference probe 17. The acquired trigger waveform becomes a trigger for synchronizing the waveform detected by the waveform acquisition unit 162. When the circuit board 2 under test is the power supply circuit described above, the trigger detection unit 161 detects a trigger in association with the switching operation of the power semiconductor device based on the voltage waveform of the voltage measured at the output terminal on the power semiconductor side of the drive circuit. Here, the output terminal on the power semiconductor side of the drive circuit is the switching part of the control IC 27.

The waveform acquisition unit 162 acquires the electromagnetic field intensity at each angle from the measurement probe 14 at each of the multiple measurement points within the measurement scanning range, using the measurement time set by the measurement condition setting unit 111, in synchronization with the trigger acquired by the trigger detection unit 161. In other words, the waveform acquisition unit 162 measures time series data indicating the electromagnetic field intensity from the measured circuit board 2 at the measurement time, in synchronization with the trigger detected by the trigger detection unit 161, at each of the multiple measurement points set near the measured circuit board 2. The waveform acquisition unit 162 also sequentially outputs the measurement results, i.e., a signal S8 indicating the time series data of the electromagnetic field waveform synchronized with the trigger, to the measurement control device 11.

The reference probe 17 is a voltage probe that is electrically connected to the circuit board 2 under test and measures a reference signal that controls the switching operation of the circuit board 2 under test. The reference probe 17 supplies a signal S6 corresponding to the measured reference signal to channel ch1 of the oscilloscope 16. When the circuit board 2 under test is the power supply circuit described above, the reference probe 17 is electrically connected to the output end of the drive circuit on the power semiconductor side. In the example shown in FIG. 2, the reference probe 17 is electrically connected to the input end side of the coil 25.

A current probe can also be used as the reference probe 17. Also, if the installation position is fixed and it is possible to obtain a reference waveform, a non-contact electric field probe or magnetic field probe can also be used. In this case, the reference probe 17 does not need to be electrically connected to the circuit board 2 under test.

In the noise measurement device 1 according to the embodiment, as shown in FIG. 1, the combination of the oscilloscope 16 that realizes the trigger detection unit 161 and the reference probe 17 may be expressed as the trigger detection unit 20.

The noise measurement device 1 according to the embodiment can also be described as having the function of a measurement unit 10, as shown in FIG. 1. Here, the measurement unit 10 includes a measurement condition setting unit 111 of the measurement control device 11, a data combining unit 112 of the measurement control device 11, and a waveform acquisition unit 162 of the oscilloscope 16, as shown in FIG. 1. In other words, the measurement unit 10 moves the measurement probe 14 to each of the multiple measurement points by the drive device 13, and measures time series data indicating the electromagnetic field intensity from the measured circuit board 2 at the set measurement time, in synchronization with a trigger, at each of the multiple measurement points. Here, the measurement unit 10 is an example of an acquisition unit.

The combination of the measurement control device 11, drive control device 12, drive device 13, measurement probe 14, amplifier 15, and oscilloscope 16 that realizes the measurement unit 10 may be referred to as the measurement unit.

The storage device 18 stores a database 181. The database 181 stores data (data indicated by signal S9) that is output from the data combining unit 112 and that links the measurement positions and the time series of the electromagnetic field strength at multiple measurement points. As the storage device 18, various storage media such as a hard disk drive (HDD), a solid state drive (SSD), and a flash memory can be used.

The display control device 19 is a device that controls the display of the electromagnetic field intensity distribution in the noise measurement device 1. The display control device 19 functions as the noise measurement device 1 according to the embodiment by executing a program (application program) for realizing the display processing according to the embodiment. As the display control device 19, for example, an information processing device such as a smartphone, a personal computer (PC), or a tablet PC can be appropriately used.

As shown in FIG. 1, the display control device 19 has the functions of a display condition setting unit 191, a calculation unit 192, and a display unit 193.

The display condition setting unit 191 sets the conditions of the designated section and the designated frequency, for example, in response to a user input. Here, the designated section is a section with a time width shorter than the time width of the measurement time. Furthermore, the display condition setting unit 191 can reset at least one of the conditions of the designated section and the designated frequency, for example, after the map of the electromagnetic field intensity distribution is displayed. The display condition setting unit 191 is an example of a condition setting unit.

The calculation unit 192 outputs the electromagnetic field intensity distribution and current distribution for the multiple measurement points under the conditions of the specified section and specified frequency set by the display condition setting unit 191 based on the time series data of the electromagnetic field intensity for each of the multiple angles at each of the multiple measurement points stored in the database 181 of the storage device 18.

Specifically, the calculation unit 192 acquires a signal S10 indicating time series data of the electromagnetic field intensity of each of the multiple measurement points from the storage device 18. Therefore, the calculation unit 192 can also be expressed as an example of an acquisition unit. The calculation unit 192 extracts time series data of a specified section from the time series data of the electromagnetic field intensity of each of the multiple measurement points measured by the measurement unit 10. The calculation unit 192 calculates a power spectrum and a phase component from the time series data of the specified section by fast Fourier transform. The calculation unit 192 acquires an electromagnetic field intensity component and a current vector at a specified specified frequency from the power spectrum and phase component calculated for each of the multiple measurement points. The calculation unit 192 outputs the electromagnetic field intensity and/or the current vector for the multiple measurement points under the conditions of the specified section and the specified frequency to the display unit 193.

In addition, when the conditions of the specified section and the specified frequency are reset by the display condition setting unit 191, the calculation unit 192 re-outputs the electromagnetic field intensity and the current vector for the multiple measurement points under the reset conditions of the specified section and the specified frequency.

The display unit 193 plots the electromagnetic field intensity and/or current vector according to the position of each of the multiple measurement points based on the electromagnetic field intensity and/or current vector for the multiple measurement points under the conditions of the specified section and specified frequency output by the calculation unit 192, and generates image data for displaying a map showing the electromagnetic field intensity distribution and/or current distribution. The display unit 193 displays an image showing the map on a display or the like based on the generated image data. The display unit 193 displays an image showing the arrangement of the components of the circuit board 2 under test by superimposing it on the image showing the map.

The display control device 19 that realizes the calculation unit 192 may be expressed as the calculation unit. Similarly, the combination of the display control device 19 that realizes the display unit 193, the display I/F 106 described below, and the display 107 described below may be expressed as the display unit.

Below, an example of the operation of the noise measurement device 1 according to this embodiment will be described with reference to Figures 3 to 27. Here, as an example, a case will be described in which a magnetic field distribution is measured at a specified frequency of 100 MHz at (32, 20) points in a range of 2 mm pitch for a DCDC power supply board as a measured circuit board 2 with a size of 64 mm x 40 mm that switches at 750 kHz.

FIG. 3 is a flowchart showing an example of a measurement process according to the embodiment. FIG. 4 is a diagram showing an example of a reference trigger waveform obtained when a DCDC power supply board as a measured circuit board 2 is measured by a reference probe 17 in a noise measurement device 1 according to the embodiment. FIG. 5 is a diagram showing an example of a magnetic field intensity waveform at a specified coordinate obtained when a trigger is applied by the reference probe 17 and a DCDC power supply board as a measured circuit board 2 is measured by a measurement probe 14 in a noise measurement device 1 according to the embodiment. In the graphs shown in FIGS. 4 and 5, the vertical axis indicates intensity (Level) [V] and the horizontal axis indicates time (Time) [μsec]. FIGS. 6 and 7 are diagrams for explaining the acquisition of a voltage waveform of a near magnetic field in a noise measurement process according to the embodiment.

The flow in FIG. 3 begins with the circuit board 2 under test placed on the stage of a four-axis scanner acting as the driving device 13 and in operation. The reference probe 17 is electrically connected, for example, to the input end of the coil 25, and is capable of measuring the clock waveform of a clock signal as a reference waveform. The initial position (0,0) and end position (32,20) of the measurement scanning range are set. The voltage waveform of the nearby magnetic field is measured for each of two angles in the X and Y directions.

The trigger detection unit 161 acquires a reference waveform (S101) and sets a measurement time of at least one period of the reference waveform under conditions instructed by the measurement condition setting unit 111 (S102). Specifically, the trigger detection unit 161 takes a trigger at the timing of the rising or falling edge of the clock signal on channel ch1 of the oscilloscope 16, and sets the measurement time to a time including at least one period of the clock waveform as the reference waveform as shown in FIG. 4.

The measurement condition setting unit 111 instructs the driving device 13 to move the measurement probe 14 to the initial position (0,0) of the specified coordinates on the circuit board 2 under test (S103). The measurement condition setting unit 111 also sets trigger conditions such as a threshold value for the trigger detection unit 161 of the oscilloscope 16, and sets the measurement time, etc. for the waveform acquisition unit 162. In channel ch2 of the oscilloscope 16, the voltage waveform from the measurement probe 14 is held with the trigger set by the trigger detection unit 161, and a time series of the voltage waveform of the near electromagnetic field at the measurement time as shown in FIG. 5 is acquired (S104). The waveform acquisition unit 162 transmits the acquired time series data of the near electromagnetic field to the data combination unit 112. At this time, the data combination unit 112 acquires the current position coordinates from the driving control device 12. As a result, the time series data can be made into data of a file name (0,0.csv) linked to the coordinates of the measurement location by the data combination unit 112. The data combining unit 112 stores the time series data showing the electromagnetic field waveforms at each coordinate in a specified folder in the database 181 of the storage device 18 (S105).

When the measurement of the entire range is not completed (S106: No), the measurement control device 11 issues a command to the oscilloscope 16 to release the hold on the voltage waveform (S107), and issues a command to the drive control device 12 to move the measurement probe 14 to the next specified coordinate (e.g., 1,0) (S103). At the next coordinate, the voltage waveform is acquired as described above (S104), and the acquired time series data of the near electromagnetic field is saved in a specified folder of the database 181 with a file name of, for example, (1,0.csv) (S105). In the same manner, after measuring up to the end coordinate of the X coordinate, (2,0), (3,0), (4,0) ... (32,0), the Y coordinate is moved, and the X coordinate is returned to the initial position (0,1), (1,1) ... (32,1), and measurements are performed at each measurement point. The voltage waveform is obtained repeatedly in the same manner, from (0, 20) (1, 20) ... (32, 20) up to the end Y coordinate (32, 20), and scanning of the entire set range on the circuit board 2 under test is performed.

After data saving for the end position (32,20.csv) is completed and all waveforms in the set range are acquired (S106: Yes), a message is displayed indicating that the measurement has been completed without any problems, and the process of measuring the magnetic flux φ in Figure 3 is completed.

In the flow of FIG. 3, the processes of S103 to S107 are executed for each of the X and Y directions. For example, as shown in FIG. 6, in measuring the magnetic flux φx in the X direction, the loop of the measurement probe 14 is rotated at an angle of 90° with respect to the front. At this time, a voltage waveform Vx obtained by time-differentiating the magnetic flux φx in the left-right direction with respect to the front, i.e., the X direction, is acquired and stored. Similarly, in measuring the magnetic flux φy in the Y direction, the loop of the measurement probe 14 is rotated at an angle of 0° with respect to the front, as shown in FIG. 7. At this time, a voltage waveform Vy obtained by time-differentiating the magnetic flux φy in the front-back direction with respect to the front, i.e., the Y direction is acquired and stored. Therefore, in the process of S106, in response to the completion of the measurement of the magnetic flux φ in each of the two directions, the X direction and the Y direction, a message is displayed indicating that the measurement has been completed without any problems, and the process of FIG. 3 for measuring the magnetic flux φ is terminated.

The processes in steps S103 to S107 are not limited to the X and Y directions, but may be performed for two mutually orthogonal directions other than the X and Y directions.

In this embodiment, the measurement probe 14 is rotated by the driving device 13, or the measurement probe 14 is replaced to change the mounting angle to the driving device 13, and the electromagnetic field intensity is measured in each of two mutually orthogonal directions in synchronization with a trigger, but this is not limited to the above. The measurement probe 14 may be configured as a probe array in which multiple probes are arranged. In the measurement probe 14, the multiple probes may be arranged one-dimensionally or two-dimensionally. In the measurement probe 14, the loop direction of each of the multiple probes may be one direction or two mutually orthogonal directions. When the loop direction of each of the multiple probes is one direction, the measurement probe 14 may be rotated by the driving device 13, or the measurement probe 14 may be replaced to change the mounting angle to the driving device 13. When the loop direction of each of the multiple probes is two mutually orthogonal directions, the movement by the driving device 13 may be controlled according to the loop direction of each probe. In these cases, the measurement unit 10 switches between the multiple probes at positions corresponding to the multiple measurement points in synchronization with the detected trigger, and measures time-series data indicating the electromagnetic field strength from the circuit board 2 under test at the set measurement time in synchronization with the trigger at each of the multiple measurement points.

Figure 8 is a flowchart illustrating an example of a display process according to an embodiment. The flow in Figure 8 is executed after the measurement of the magnetic flux φ in each of the X and Y directions is completed according to the flow in Figure 3.

The calculation unit 192 specifies a folder in the database 181 in which measurement results linked to the coordinates of each of a plurality of measurement positions are stored (S201). The folder in the database 181 stores measurement data linked to each of a plurality of measurement coordinates. Therefore, by specifying the coordinates, the calculation unit 192 can read out from the database 181 the measurement data of the magnetic fluxes φx and φy in the X and Y directions of the specified coordinates.

The display condition setting unit 191 sets a specified interval and a specified frequency, for example, in response to a user input (S202). Specifically, the display condition setting unit 191 sets the start time and end time of the time to be extracted as the specified interval based on the reference waveform acquired by the reference probe 17. In the example shown in FIG. 4, interval A (0 μsec to 0.1 μsec) and interval B (0.6 μsec to 0.7 μsec) are set as the specified intervals to be extracted. In addition, the display condition setting unit 191 sets the frequency of the magnetic field distribution to be extracted, such as 100 MHz, as the specified frequency.

After setting the designated section and the designated frequency, the calculation unit 192 calls up the measurement data of the magnetic field strength waveform in the X direction and the Y direction, which are respectively linked to the coordinates, in order from the initial position data (0,0.csv) (S203). The calculation unit 192 extracts the voltage waveform of the designated section from each of the called waveform data (S204). FIG. 9 is a diagram showing an example of a magnetic field strength waveform in which section A in FIG. 5 is extracted. FIG. 10 is a diagram showing an example of a magnetic field strength waveform in which section B in FIG. 5 is extracted. In the graphs shown in FIG. 9 and FIG. 10, the vertical axis indicates the strength (Level) [V], and the horizontal axis indicates the time (Time) [μsec]. For example, when section A is the designated section, the calculation unit 192 extracts the waveform data of section A as shown in FIG. 9 from the waveform data shown in FIG. 5. For example, when section B is the designated section, the calculation unit 192 extracts the waveform data of section B as shown in FIG. 10 from the waveform data shown in FIG. 5.

The calculation unit 192 performs an FFT transformation on the voltage waveform of the extracted specified section, and extracts the intensity component and phase component of the specified frequency (S205). Specifically, the calculation unit 192 performs an FFT transformation on the voltage waveform of the extracted specified section, and generates information indicating the power spectrum (magnetic field spectrum) and the phase component of the frequency axis. In other words, the calculation unit 192 converts the voltage waveform of the extracted specified section into information indicating the power spectrum (magnetic field spectrum) and the phase component of the frequency axis. After that, the calculation unit 192 extracts the intensity D corresponding to the specified frequency from the magnetic field spectrum as a numerical value of power [mW] (or [μW]) converted from [dBm]. The calculation unit 192 also extracts the phase θ as a numerical value of [°] from the information indicating the phase component of the frequency axis.

Figure 11 is a diagram showing an example of a magnetic field spectrum obtained by FFT processing of the magnetic field strength waveform for section A in Figure 9. Figure 12 is a diagram showing an example of a magnetic field spectrum obtained by FFT processing of the magnetic field strength waveform for section B in Figure 10. In the graphs shown in Figures 11 and 12, the vertical axis indicates intensity (Level) [dBm] and the horizontal axis indicates frequency (Frequency) [MHz]. For example, when section A is the specified section, the calculation unit 192 generates the magnetic field spectrum shown in Figure 11 from the voltage waveform on the time axis shown in Figure 9. For example, when section B is the specified section, the calculation unit 192 generates the magnetic field spectrum shown in Figure 12 from the voltage waveform on the time axis shown in Figure 10.

Figure 13 is a diagram showing an example of the phase component of the magnetic field obtained by FFT processing the magnetic field intensity waveform for section A in Figure 9. Figure 14 is a diagram showing an example of the phase component of the magnetic field obtained by FFT processing the magnetic field intensity waveform for section B in Figure 10. In the graphs shown in Figures 13 and 14, the vertical axis indicates phase [deg.] and the horizontal axis indicates frequency [MHz]. For example, when section A is the specified section, the calculation unit 192 converts the voltage waveform on the time axis shown in Figure 9 into phase information on the frequency axis shown in Figure 13. For example, when section B is the specified section, the calculation unit 192 converts the voltage waveform on the time axis shown in Figure 10 into phase information on the frequency axis shown in Figure 14.

The calculation unit 192 calculates the magnetic field strength distribution from the strength components of the extracted specified frequencies for each of the X-axis and Y-axis (S206). The calculation of the magnetic field strength distribution will be described later with reference to formula (7).

The calculation unit 192 calculates vectors in each direction from the extracted intensity and phase components for each of the X and Y axes (S207). FIG. 15 is a diagram showing an example of the result of calculation using a cos function for the phase component of the magnetic field related to section A in FIG. 13. FIG. 16 is a diagram showing an example of the result of calculation using a cos function for the phase component of the magnetic field related to section B in FIG. 14. In the graphs shown in FIG. 15 and FIG. 16, the vertical axis indicates the value of cos θ of the phase [-], and the horizontal axis indicates the frequency (Frequency) [MHz]. Specifically, the calculation unit 192 converts the phase θ extracted from the phase information of the frequency axis related to section A shown in FIG. 13 into a value from -1 to +1 using a cos function as shown in FIG. 15. Also, the calculation unit 192 converts the phase θ extracted from the phase information of the frequency axis related to section B shown in FIG. 14 into a value from -1 to +1 using a cos function as shown in FIG. 16.

Here, if the value of the phase θ extracted from the phase information of the frequency axis converted using the cos function is the coefficient k, the direction of the vector arrow on each of the X-axis and Y-axis corresponds to the positive and negative of the coefficient k. In displaying the vector, it is sufficient to be able to distinguish the direction of the vector arrow. For this reason, the calculation unit 192 sets the value of the coefficient k corresponding to each frequency to "+1" or "-1" based on each of the calculation results shown in FIG. 15 and FIG. 16. FIG. 17 is a diagram showing an example of the coefficient k calculated from the calculation result related to the section A in FIG. 15. FIG. 18 is a diagram showing an example of the coefficient k calculated from the calculation result related to the section B in FIG. 16. In the graphs shown in FIG. 17 and FIG. 18, the vertical axis indicates the value of the coefficient k [-], and the horizontal axis indicates the frequency (Frequency) [MHz]. Specifically, as shown in FIG. 17 and FIG. 18, when the value of cos θ is -1 or more and less than 0, the calculation unit 192 sets all the coefficients k to "-1". On the other hand, when cosθ is greater than or equal to 0 and less than or equal to 1, the calculation unit 192 sets all of the coefficients k to "+1" as shown in Figures 17 and 18. Note that when the value of cosθ is 0, the coefficients k may be set to "-1".

The calculation unit 192 extracts the coefficient k corresponding to the section and the specified frequency (100 MHz in this embodiment) from FIG. 17 or FIG. 18, and multiplies it by the intensity D of the specified frequency extracted in the process of S205 to calculate kD. As a result, the measurement results become vectors of the directional magnetic fluxes φx and φy. Therefore, the calculation unit 192 can calculate the vector +Dx(m,n) or -Dx(m,n) at the target coordinates (m,n) from the measurement results in the X direction. Similarly, the calculation unit 192 can calculate the vector +Dy(m,n) or -Dy(m,n) at the target coordinates (m,n) from the measurement results in the Y direction.

In this embodiment, the direction of the vector arrow on each of the X-axis and Y-axis is determined according to the value of the phase θ extracted from the phase information on the frequency axis converted using a cos function, i.e., the positive or negative value of the coefficient k, but this is not limited to the above. The direction of the vector arrow on each of the X-axis and Y-axis may be determined according to whether or not a predetermined duty ratio is satisfied for the phase θ extracted from the phase information on the frequency axis, for example.

After that, the calculation unit 192 combines the vectors of each direction calculated in the process of S207 to calculate the magnetic flux vectors φx, φy (S208). FIG. 19 is a diagram for explaining a method of calculating the magnetic flux vectors φx, φy of the target coordinates (m, n). As shown in FIG. 19, the calculation unit 192 calculates the magnetic flux vector φx of the magnetic flux X component at the target coordinates (m, n) using the following formula (1). Similarly, as shown in FIG. 19, the calculation unit 192 calculates the magnetic flux vector φy of the magnetic flux Y component at the target coordinates (m, n) using the following formula (2). In this way, the two magnetic flux vectors magnetic flux vectors φx, φy are vectors whose magnitude corresponds to the intensity D and whose direction corresponds to the phase θ. However, the coefficients kx and ky are respectively "+1" or "-1". In this case, the magnetic flux vector φxy in the X-Y plane of the target coordinates (m, n) is expressed by formula (3). Here, the magnetic flux vector φxy in the XY plane is an example of a plane vector.

The calculation unit 192 also calculates current vectors Ix and Iy from the orthogonal components of the magnetic flux vectors φx and φy calculated in the process of S208 (S209). FIG. 20 is a diagram for explaining a method for calculating the current vectors Ix and Iy at the target coordinates (m, n). By calculating the orthogonal components for each of the magnetic flux vectors φx and φy, it is possible to indicate the flow of current. As shown in FIG. 20, the calculation unit 192 calculates the current vector Ix in the X direction at the target coordinates (m, n) using the following formula (4). Similarly, as shown in FIG. 20, the calculation unit 192 calculates the current vector Iy in the Y direction at the target coordinates (m, n) using the following formula (5). However, the coefficients kx and ky are "+1" or "-1", respectively. In this case, the current vector Ixy in the X-Y plane at the target coordinates (m, n) is expressed by formula (6). Here, the current vector Ixy in the X-Y plane is an example of a plane vector.

Then, the display unit 193 displays or updates a map showing the current distribution and/or magnetic field strength distribution based on the current vector Ixy and/or strength Dxy calculated for the target coordinates (m, n) (S210). The display of the map showing the current distribution and/or magnetic field strength distribution will be described later.

When display of the entire range has not been completed (S211: No), the above-mentioned processing of S203 to S210 is executed for the electromagnetic field measurement data of the next target coordinates. Note that, like during measurement, the above-mentioned processing of S203 to S210 is executed in the order of (0,0), (1,0), (2,0), (3,0), (4,0) ... (32,0) ... (0,1), (1,1) ... (32,1) ... (0,20) (1,20) ... (32,20) up to the data of the end position (32,20.csv). Note that the processing order is not limited to this and can be set arbitrarily.

On the other hand, when display of the entire range is completed (S211: Yes), the processing in FIG. 8 ends.

Here, a map showing the current distribution that may be displayed in S210 of the flow in FIG. 8 will be described. FIG. 21 is a diagram showing an example of a map of the current distribution at 100 MHz in section A, which is displayed in the display process according to the embodiment. FIG. 22 is a diagram showing an example of a map of the current distribution at 100 MHz in section B, which is displayed in the display process according to the embodiment. When the display of the entire range is completed, that is, when the display of the last target coordinate of the (32, 20) point has been performed, a display screen including a map of the current distribution as shown in FIG. 21 and FIG. 22 is displayed. In the map of current distribution, the current vector Ixy calculated for each coordinate position is shown at each coordinate position.

In addition, on the display screen, the layout of each element on the measured circuit board 2 as shown in FIG. 2 may be superimposed on the map, as shown in FIG. 21 and FIG. 22, respectively.

Note that displays including maps such as those in Figures 21 and 22 may be displayed sequentially for each location data, as described above, or may be displayed together after mapping of the entire range is completed.

Here, a map showing the magnetic field strength distribution that can be displayed in S210 of the flow in FIG. 8 will be described. FIG. 23 is a diagram showing an example of a map of the magnetic field strength distribution at 100 MHz in section A, which is displayed in the display process according to the embodiment. FIG. 24 is a diagram showing an example of a map of the magnetic field strength distribution at 100 MHz in section B, which is displayed in the display process according to the embodiment. When displaying a map showing the magnetic field strength distribution, the display unit 193 uses the intensity D corresponding to the specified frequency as a numerical value for the frequency spectrum. The calculation unit 192 calculates the intensity Dxy in the X-Y plane of the target coordinates (m, n) using the following formula (7) based on the intensity Dx(m, n) obtained from the measurement results in the X direction and the intensity Dy(m, n) obtained from the measurement results in the Y direction.

The calculation unit 192 converts the unit of Dxy(m,n) calculated by formula (7) from [mW] or [μW], which is a linear notation value, to [dBm] and outputs it as the intensity of the coordinate (m,n). The display unit 193 then maps the converted intensity of each coordinate (m,n) and displays a display screen including a map showing the magnetic field intensity distribution. In the map showing the magnetic field intensity distribution, the intensity of each coordinate is displayed in a color scheme associated with the intensity. As an example, when the intensity is strong, a warm color scheme such as red is used, when the intensity is medium, a yellow or green color is used, and when the intensity is weak, a cool color scheme such as blue or dark blue is used, so that the user can intuitively grasp the intensity distribution. Note that this color scheme according to the intensity can be set again after all the intensities in the map showing the magnetic field intensity distribution are displayed. Note that, in the display screen, the maximum and minimum values in the map may be displayed as numerical values next to the map showing the magnetic field intensity distribution as a reference when resetting the color scheme.

Here, a map showing the current vector or magnetic flux vector and the magnetic field strength distribution that can be displayed in S210 of the flow in FIG. 8 will be described. Here, the map showing the current vector can be treated as the current distribution itself. Also, the map showing the magnetic flux vector can be treated as a display directly related to the current distribution from the viewpoint that the magnetic flux vector is generated perpendicularly from the current. FIG. 25 is a diagram showing an example of a map that combines the magnetic field strength distribution and the current distribution in 100 MHz in section A, which is displayed in the display process according to the embodiment. FIG. 26 is a diagram showing an example of a map that combines the magnetic field strength distribution and the current distribution in 100 MHz in section B, which is displayed in the display process according to the embodiment. The display unit 193 may display the magnetic field strength distribution and the current distribution on the same map, as shown in FIG. 25 and FIG. 26. Alternatively, the display unit 193 may display the magnetic field strength distribution and the current distribution on different maps, as shown in FIG. 21 to FIG. 24, from the viewpoint of ensuring ease of viewing. The display unit 193 can change the distribution displayed on the map, for example, in response to an input operation by the user.

Here, as shown in Figures 21, 22, 25, and 26, the current distribution based on the voltage waveform extracted in the specified section of section A is different from the current distribution based on the voltage waveform extracted in the specified section of section B. Also, as shown in Figures 23 to 26, the magnetic field strength distribution based on the voltage waveform extracted in the specified section of section A is different from the magnetic field strength distribution based on the voltage waveform extracted in the specified section of section B. These show that section A indicates the section when the switching signal rises, and section B indicates the section when the switching signal falls, and that magnetic field strength distribution and current distribution results were obtained for different specified sections of the same specified frequency. In other words, with the noise measuring device 1 according to the embodiment, multiple results can be displayed according to conditions from a single measurement data.

In this way, the noise measurement process according to this embodiment can output the near electromagnetic field distribution and current distribution generated from the switching circuit board 2 under test under multiple specified sections and specified frequency conditions without re-measurement. In addition, since the near electromagnetic field measurement results can be obtained under multiple conditions, it is possible to distinguish the time when noise occurs during switching operation, such as when it rises or falls, without re-measurement.

Conventionally, in measuring the near electromagnetic field of a circuit board, it has been difficult to perform measurements in synchronization with the rise or fall of the switching frequency of the circuit board. On the other hand, the noise measurement process according to this embodiment measures the electromagnetic field strength in a measurement time with a time width of at least one wavelength of the reference signal in synchronization with a trigger detected based on the signal waveform of a reference signal for switching operation input to the circuit board 2 under test. This makes it possible to reduce the number of measurements in measuring the near electromagnetic field of the circuit board 2 under test to identify the noise source and grasp the conduction state. Reducing the number of measurements contributes to suppressing deterioration in repeatability and reproducibility due to human error, etc.

In addition, in the noise measurement process according to this embodiment, a current vector indicating the current direction can be output without re-measurement, making it easy to grasp the flow of noise. Furthermore, while a vector display of only the magnetic flux intensity can only express a range of 0° to 90°, in the noise measurement process according to this embodiment, by giving a sign component to each of the magnetic flux intensity of the X and Y components, it is possible to display a vector of 360° on the X-Y plane, that is, in all directions. By obtaining a vector display of the in-plane current direction, it is possible to identify the noise source in more detail and grasp the conduction state.

Here, the hardware configuration of each device (measurement control device 11, oscilloscope 16, storage device 18, and display control device 19) of the noise measurement device 1 according to each of the above-mentioned embodiments will be described. FIG. 27 is a block diagram showing an example of the hardware configuration of each device of the noise measurement device 1 according to the embodiment. The measurement control device 11, oscilloscope 16, storage device 18, and display control device 19 are realized, for example, by an information processing device 100 having a hardware configuration as shown in FIG. 27.

The information processing device 100 has a hardware configuration similar to that of a normal computer, for example. That is, the information processing device 100 includes a processor 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a storage device 104, and a network interface (I/F) 105. The processor 101, the ROM 102, the RAM 103, the storage device 104, and the network I/F 105 are communicatively connected via a bus.

The processor 101 controls the overall operation of each device. For example, a CPU (Central Processing Unit) is used as the processor 101, but other processors such as a GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), or FPGA (Field Programmable Gate Array) may also be used.

The processor 101 loads a program stored in the storage device 104 into the RAM 103 and executes it to realize the functions of each unit illustrated in FIG. 1. The ROM 102 stores a start program that loads a program for starting the operating system from the storage device 104 into the RAM 103, and the like.

As the storage device 104, various storage media such as HDD, SSD, and flash memory can be used. The storage device 104 stores an operating system, application programs, data, and parameters such as thresholds used in each process.

The network I/F 105 is an interface circuit for communicating with the outside world. The network I/F 105 includes a communication circuit for wireless communication or a communication circuit for wired communication that is compatible with various communication standards such as BLE (Bluetooth (registered trademark) Low Energy), Wi-Fi (registered trademark), Sub-1 GHz, IEEE 802.15.4, and LTE Cat-1 that are supported by each device.

The measurement control device 11, the oscilloscope 16, and the display control device 19 further include an input/output I/F 108 and an input device 109. The input device 109 is communicatively connected to the processor 101, the ROM 102, the RAM 103, the storage device 104, and the network I/F 105 via the input/output I/F 108. The input/output I/F 108 outputs information acquired by the input device 109 to the bus according to the control of the processor 101. As the input/output I/F 108, a general-purpose I/F such as USB, GP-IB, or Ethernet (registered trademark) or a bus of a unique I/F for machine control can be appropriately used. The input device 109 of the measurement control device 11 is a measurement system including the drive control device 12, the drive device 13, the measurement probe 14, the amplifier 15, the oscilloscope 16, and the reference probe 17 described above. In addition, the input device 109 of the measurement control device 11, the oscilloscope 16, and the display control device 19 includes an operation unit that accepts user operations. As the operation unit, various input devices such as a keyboard, mouse, touch panel, button, lever, and switch can be used as appropriate.

The display control device 19 further includes a display I/F 106 and a display 107. The display I/F 106 is communicatively connected to the processor 101, ROM 102, RAM 103, storage device 104, network I/F 105, and input/output I/F 108 via a bus. The display I/F 106 supplies an image signal to the display 107 under the control of the processor 101. The display 107 is a display device, such as a liquid crystal display or an organic EL display, that displays information (display screens 510, 520) in response to the supplied image signal.

In addition, at least two of the devices of the measurement control device 11, oscilloscope 16, storage device 18, and display control device 19 according to the embodiment may be configured as one device. In other words, the noise measurement device 1 according to the embodiment may be configured as one device, or may be configured as a noise measurement system including multiple devices.

In addition, the measurement control device 11, oscilloscope 16, storage device 18, and display control device 19 according to the embodiment may each be connected to a network such as the Internet, and may be connected to each other via the network.

The program executed by the information processing device 100 according to the embodiment is provided in the form of an installable or executable file recorded on a computer-readable recording medium such as a CD-ROM, flexible disk (FD), CD-R, DVD, or flash memory.

The program executed by the information processing device 100 according to the embodiment may be configured to be stored on a computer connected to a network such as the Internet and provided by downloading it via the network. The program executed by the information processing device 100 according to the embodiment may be configured to be provided or distributed via a network such as the Internet. The program executed by the information processing device 100 according to the embodiment may be configured to be provided by being pre-installed in ROM 102 or the like.

The program for causing the information processing device 100 to function as the measurement control device 11 has a modular configuration including a measurement condition setting unit 111 and a data combining unit 112. The program for causing the information processing device 100 to function as the oscilloscope 16 has a modular configuration including a trigger detection unit 161 and a waveform acquisition unit 162. The program for causing the information processing device 100 to function as the display control device 19 has a modular configuration including a display condition setting unit 191, a calculation unit 192, and a display unit 193. These programs are examples of noise measurement programs according to the embodiment.

In the information processing device 100, the processor 101 reads and executes a program from a storage medium such as a storage device 104 as the actual hardware, and each module is loaded onto the main storage device (RAM 103). As a result, the processor 101 of the measurement control device 11 functions as a measurement condition setting unit 111 and a data combining unit 112. The processor 101 of the oscilloscope 16 functions as a trigger detection unit 161 and a waveform acquisition unit 162. The processor 101 of the display control device 19 functions as a display condition setting unit 191, a calculation unit 192, and a display unit 193. Note that some or all of the functional configuration of the information processing device 100 may be realized by hardware.

According to at least one of the embodiments described above, it is possible to reduce the number of measurements required in measuring the near electromagnetic field of a circuit board.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

REFERENCE SIGNS LIST 1 Noise measuring device 10 Measuring unit 100 Information processing device 101 Processor 102 ROM
103 RAM
104 Storage device 105 Network I/F
108 Input/Output Interface
109 Input device 106 Display I/F
107 Display 11 Measurement control device 111 Measurement condition setting unit 112 Data combination unit 12 Drive control device 13 Drive device 14 Measurement probe 15 Amplifier 16 Oscilloscope 161 Trigger detection unit 162 Waveform acquisition unit 17 Reference probe 18 Storage device 181 Database 19 Display control device 191 Display condition setting unit (condition setting unit)
192 Arithmetic unit 193 Display unit 2 Circuit board to be measured

Claims (9)

At each of a plurality of measurement points set in the vicinity of a circuit under test, time series data is acquired which indicates an electromagnetic field intensity from the circuit under test, the electromagnetic field intensity being measured for a measurement time having a time width of at least one wavelength of the reference signal, in synchronization with a trigger detected based on a signal waveform of the reference signal input to the circuit under test which performs a switching operation in accordance with the reference signal;
extracting, from the acquired time series data, time series data of a designated section that is designated by a time width shorter than the time width of the measurement time, calculating electromagnetic field intensity and phase components at a designated frequency designated for each of the plurality of measurement points based on the time series data of the designated section, and outputting plane vectors corresponding to the electromagnetic field intensity and the phase components for the plurality of measurement points under the conditions of the designated section and the designated frequency ;
Calculating the electromagnetic field intensity and the phase component at the designated frequency for each of the plurality of measurement points based on the time series data of the designated section includes calculating a power spectrum from the time series data of the designated section by fast Fourier transform, and acquiring the electromagnetic field intensity and the phase component at the designated frequency from the power spectrum calculated for each of the plurality of measurement points.
Noise measurement program. The noise measurement program according to claim 1, further comprising: calculating the electromagnetic field strength and the phase component at the specified frequency for each of two mutually orthogonal directions; and calculating the plane vector based on two magnetic flux vectors whose magnitude corresponds to the electromagnetic field strength and whose direction corresponds to the phase component. The noise measurement program according to claim 2, further comprising calculating a current vector based on the orthogonal components of the two magnetic flux vectors. The noise measurement program according to claim 2 or 3, wherein the directions of the two magnetic flux vectors are determined according to a value obtained by applying a cos function to the phase components or a duty ratio of the phase components. 5. The noise measurement program according to claim 1, further comprising: when at least one of the conditions of the specified section and the specified frequency is reset, outputting the plane vector for the plurality of measurement points under the reset condition based on the time series data of each of the plurality of measurement points . 6. The noise measurement program according to claim 1, further comprising: measuring, in each of the plurality of measurement points, time series data indicating an electromagnetic field intensity from the circuit under test during a measurement time having a time width of at least one wavelength of the reference signal, in two directions perpendicular to each other, in synchronization with the detected trigger. 6. The noise measuring program according to claim 1, further comprising: measuring time series data relating to each of the plurality of measurement points by switching each of a plurality of probes at positions corresponding to each of the plurality of measurement points in synchronization with the detected trigger. At each of a plurality of measurement points set in the vicinity of a circuit under test, time series data is acquired which indicates an electromagnetic field intensity from the circuit under test, the electromagnetic field intensity being measured for a measurement time having a time width of at least one wavelength of the reference signal, in synchronization with a trigger detected based on a signal waveform of the reference signal input to the circuit under test which performs a switching operation in accordance with the reference signal;
extracting, from the acquired time series data, time series data of a designated section designated by a time width shorter than the time width of the measurement time, calculating electromagnetic field intensity and phase components at a designated frequency designated for each of the plurality of measurement points based on the time series data of the designated section, and outputting plane vectors corresponding to the electromagnetic field intensity and the phase components for the plurality of measurement points under the conditions of the designated section and the designated frequency ,
Calculating the electromagnetic field intensity and the phase component at the designated frequency for each of the plurality of measurement points based on the time series data of the designated section includes calculating a power spectrum from the time series data of the designated section by fast Fourier transform, and acquiring the electromagnetic field intensity and the phase component at the designated frequency from the power spectrum calculated for each of the plurality of measurement points.
Noise measurement method. an acquisition unit that acquires, at each of a plurality of measurement points set in the vicinity of a circuit under test, time series data indicating an electromagnetic field intensity from the circuit under test, measured over a measurement time having a time width of at least one wavelength of the reference signal, in synchronization with a trigger detected based on a signal waveform of the reference signal input to the circuit under test, the circuit performing a switching operation in accordance with the reference signal;
a calculation unit that extracts time series data of a designated section that is designated by a time width shorter than the time width of the measurement time from the acquired time series data, calculates electromagnetic field intensity and phase components at a designated frequency designated for each of the plurality of measurement points based on the time series data of the designated section, and outputs a plane vector corresponding to the electromagnetic field intensity and the phase components for the plurality of measurement points under the conditions of the designated section and the designated frequency ,
Calculating the electromagnetic field intensity and the phase component at the designated frequency for each of the plurality of measurement points based on the time series data of the designated section includes calculating a power spectrum from the time series data of the designated section by fast Fourier transform, and acquiring the electromagnetic field intensity and the phase component at the designated frequency from the power spectrum calculated for each of the plurality of measurement points.
Noise measuring device.