Method for evaluating electromagnetic radiation magnitude of circuit board internal module

Abstract

The application relates to a method for evaluating electromagnetic radiation magnitude of a circuit board internal module, which comprises the following steps: classifying the circuit board internal module to obtain modules of different categories; measuring the radiation emission spectrum of one module of each category as the radiation emission spectrum of the category; measuring the environmental noise spectrum of the circuit board; for each category, performing signal-noise separation on the radiation emission spectrum of the category according to the radiation emission spectrum of the category and the environmental noise spectrum of the circuit board to obtain the broadband noise and the narrowband signal of the category; for each category, obtaining the interference level of the broadband noise of the category according to the broadband noise of the category and obtaining the interference level of the narrowband signal of the category according to the narrowband signal of the category; obtaining the total interference level of the broadband noise according to the interference levels of the broadband noises of all categories and obtaining the total interference level of the narrowband signal according to the narrowband signals of all categories.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic compatibility technology, and more specifically to a method for evaluating the electromagnetic radiation level of internal modules of a circuit board. Background Technology

[0002] Large-aperture radio telescopes possess extremely high system sensitivity, and contain numerous electronic devices both within and between systems, as well as on-site. With the development and application of high-frequency electronics and high-speed digital processing technologies, the construction of digital receivers, digital terminals, commercial equipment, electrical equipment, and on-site optical observation equipment has made the electromagnetic environment at the site exceptionally complex.

[0003] In particular, with the development of digital technology, board-level integration is becoming increasingly advanced and the functions are becoming more and more powerful. The development trend is towards wider bandwidth and higher speed. For example, the rapidly developing radio frequency system-on-a-chip (RFSoC) integrates modules such as ADC (analog-to-digital converter), FPGA (field-programmable gate array), and CPU (central processing unit) onto a single chip, which has powerful signal acquisition, conversion, computing and storage capabilities while reducing size and power consumption.

[0004] However, excessive electromagnetic interference from the circuit board can affect radio astronomy observations. Therefore, how to intuitively assess the electromagnetic radiation levels of the modules inside the circuit board is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a method for evaluating the electromagnetic radiation level of internal modules of a circuit board, so as to intuitively evaluate the electromagnetic radiation level of internal modules of the circuit board, and provide important support for further development of electromagnetic protection and interference suppression of internal modules.

[0006] This invention provides a method for evaluating the electromagnetic radiation level of an internal module of a circuit board, comprising:

[0007] The internal modules of the circuit board are classified to obtain different categories of modules;

[0008] When the circuit board is in normal working condition, for each type of module, the radiation emission spectrum of one of the modules in that type is measured as the radiation emission spectrum of that type;

[0009] Measure the ambient noise spectrum of the circuit board when it is in the off state;

[0010] For each type of module, based on the radiated emission spectrum of that type and the ambient noise spectrum of the circuit board, signal-to-noise separation is performed on the radiated emission spectrum of that type to obtain the broadband noise and narrowband signal of that type.

[0011] For each type of module, the interference level of the broadband noise of that type is obtained based on the broadband noise of that type, and the interference level of the narrowband signal of that type is obtained based on the narrowband signal of that type.

[0012] The total interference level of broadband noise is obtained based on the interference levels of all categories of broadband noise, and the total interference level of narrowband signals is obtained based on all categories of narrowband signals.

[0013] Furthermore, for each module category, signal-to-noise separation is performed on the radiated emission spectrum of that category and the ambient noise spectrum of the circuit board to obtain the broadband noise and narrowband signal of that category, specifically including:

[0014] Based on the radiated emission spectrum of this category, calculate the separation threshold between broadband noise and narrowband signal;

[0015] Calculate the environmental noise threshold based on the environmental noise spectrum of the circuit board;

[0016] Based on the radiative emission spectrum, separation threshold, and ambient noise threshold of this category, broadband noise and narrowband signals of this category are obtained.

[0017] Furthermore, this category of broadband noise The following relationship must be satisfied:

[0018]

[0019] This category of narrowband signals The following relationship must be satisfied:

[0020]

[0021] Where F is the frequency, n is the number of frequency points, and P S For this category of radiation emission spectrum, The environmental noise threshold of the circuit board. The threshold for separating broadband noise and narrowband signals in this category; , and All of these are power values ​​corresponding to specific frequency points.

[0022] Furthermore, the interference level of this category of broadband noise is obtained based on this category of broadband noise, specifically including:

[0023] The threshold values ​​for broadband noise and ambient noise in this category are divided into a preset number of frequency bands;

[0024] The signal-to-noise ratio of broadband noise of this category is obtained by comparing the power of each frequency band of the broadband noise category with the power of the corresponding frequency band of the environmental noise threshold.

[0025] The average signal-to-noise ratio (SNR) of broadband noise for this category is obtained by averaging the SNR of broadband noise for each frequency band.

[0026] The broadband noise signal-to-noise ratio factor for this category is determined based on the average signal-to-noise ratio of this category.

[0027] For each frequency band of the broadband noise signal-to-noise ratio of this category, extract the three power values ​​with the highest power in that frequency band and take the average to obtain the peak factor of the broadband noise signal-to-noise ratio of that frequency band. The peak factors of the broadband noise signal-to-noise ratio of all frequency bands constitute the peak factor of the broadband noise signal-to-noise ratio of this category.

[0028] The frequency band interference level of this category of broadband noise is determined based on the broadband noise signal-to-noise ratio factor and the peak factor of the broadband noise signal-to-noise ratio for this category.

[0029] Furthermore, the frequency band interference level of this category of broadband noise is determined based on the broadband noise signal-to-noise ratio factor and the peak factor of the broadband noise signal-to-noise ratio for this category, specifically including:

[0030] Determine the preference coefficient for this category of broadband noise;

[0031] The bias coefficient of the broadband noise category is used as the weighting parameter of the broadband noise signal-to-noise ratio factor of the category, and the difference between the bias coefficient of the broadband noise category and the peak factor of the broadband noise signal-to-noise ratio of the category is used as the weighting parameter. The broadband noise signal-to-noise ratio factor and the peak factor of the broadband noise signal-to-noise ratio of the category are weighted and summed to obtain the frequency band interference level of the broadband noise category.

[0032] Furthermore, the broadband noise signal-to-noise ratio factor for this category The following relationship must be satisfied:

[0033]

[0034] in B represents the average signal-to-noise ratio of broadband noise in this category, where B is a preset quantity. Let the coefficient of the j-th term (j=1,2...B) satisfy the following relationship:

[0035] .

[0036] Furthermore, the interference level of this category of narrowband signals is obtained based on the specific characteristics of the narrowband signals, including:

[0037] This category of narrowband signals is divided into a preset number of frequency bands;

[0038] The signal-to-noise ratio of the narrowband signal of this category is obtained based on the power of each frequency band of the narrowband signal and the power of the corresponding frequency band of the environmental noise threshold.

[0039] For each frequency band of the narrowband signal-to-noise ratio of this category, extract the power values ​​of that frequency band that are greater than 0 and average them to obtain the average power value of that frequency band; the average power value of all frequency bands constitutes the average signal-to-noise ratio of the narrowband signal of this category.

[0040] The signal-to-noise ratio factor of the narrowband signal in this category is determined based on the average signal-to-noise ratio of the narrowband signal in this category;

[0041] For each frequency band of the narrowband signal-to-noise ratio of this category, extract the three power values ​​with the highest power in that frequency band, and take the average to obtain the peak factor of the narrowband signal-to-noise ratio of that frequency band. The peak factors of the narrowband signal-to-noise ratio of all frequency bands constitute the peak factor of the narrowband signal-to-noise ratio of this category.

[0042] The frequency band interference level of a narrowband signal is determined based on the signal-to-noise ratio factor and the peak factor of the signal-to-noise ratio of that category of narrowband signals.

[0043] Furthermore, the frequency band interference level of this category of narrowband signals is determined based on the signal-to-noise ratio factor and the peak factor of the signal-to-noise ratio of this category of narrowband signals, specifically including:

[0044] Determine the preference coefficient for this category of narrowband signals;

[0045] The preference coefficient of the narrowband signal of this category is used as the weighting parameter of the signal-to-noise ratio (SNR) factor of the narrowband signal of this category, and a factor minus the preference coefficient of the narrowband signal of this category is used as the weighting parameter of the peak factor of the SNR of the narrowband signal of this category. The SNR factor and the peak factor of the narrowband signal of this category are weighted and summed to obtain the frequency band interference level of the narrowband signal of this category.

[0046] Furthermore, the signal-to-noise ratio factor of this category of narrowband signals The following relationship must be satisfied:

[0047]

[0048] in B represents the average signal-to-noise ratio of broadband noise in this category, where B is a preset quantity. Let the coefficient of the j-th term (j=1,2...B) satisfy the following relationship:

[0049] .

[0050] Furthermore, the total interference level of the broadband noise is equal to the sum of the interference levels of all categories of broadband noise divided by 100; the total interference level of the narrowband signal is equal to the sum of the interference levels of all categories of narrowband signal divided by 100.

[0051] The method for evaluating the electromagnetic radiation level of internal modules of the circuit board of the present invention involves measuring the electromagnetic interference of the circuit board in both working and non-working states to obtain the electromagnetic interference power spectrum and environmental noise power spectrum of various types of modules. Then, the broadband noise and narrowband signal in the electromagnetic interference power spectrum are separated and analyzed separately to obtain the total interference level of the broadband noise and the total interference level of the narrowband signal, so as to evaluate the electromagnetic radiation level of the internal modules of the circuit board. Attached Figure Description

[0052] Figure 1 A flowchart illustrating a method for evaluating the electromagnetic radiation level of an internal module of a circuit board according to an embodiment of the present invention;

[0053] Figure 2 This is a schematic diagram showing the classification and numbering of internal modules of a circuit board according to an embodiment of the present invention;

[0054] Figure 3 This is a schematic diagram of a measurement system for measuring the radiation emission spectrum of an internal module of a circuit board according to an embodiment of the present invention.

[0055] Figure 4 This is a spectrum of the radiation emission spectrum of a certain type of module according to an embodiment of the present invention;

[0056] Figure 5A This is an interference level diagram of the broadband noise division band of an RFSoC board according to an embodiment of the present invention;

[0057] Figure 5B This is an interference level diagram of the broadband noise across the entire frequency band of an RFSoC board according to an embodiment of the present invention;

[0058] Figure 6A This is an interference level diagram of the narrowband signal frequency division of an RFSoC board according to an embodiment of the present invention;

[0059] Figure 6B This is an interference level diagram of the narrowband signal across the entire frequency band of an RFSoC board according to an embodiment of the present invention. Detailed Implementation

[0060] The preferred embodiments of the present invention are given below with reference to the accompanying drawings and described in detail.

[0061] like Figure 1 As shown, this embodiment of the invention provides a method for evaluating the electromagnetic radiation level of an internal module of a circuit board, including the following steps:

[0062] S100: Classify the internal modules of the circuit board to obtain different categories of modules.

[0063] The circuit board contains different functional modules composed of different components (i.e., different types of modules). Different types of modules produce different levels of electromagnetic radiation. Therefore, the modules inside the circuit board can be classified first, and then the electromagnetic radiation levels of different types of modules can be evaluated.

[0064] When classifying, modules in the same category can be represented by the same number, such as... Figure 2 As shown, in an exemplary embodiment, the internal modules of the circuit board can be divided into 9 categories, wherein the module categories represented by each number are as follows: No. 1: Power management module, No. 2: Power voltage regulator module, No. 3: Clock chip, No. 4: Ethernet IC chip, No. 5: Memory module, No. 6: SD card module, No. 7: ADC / DAC (analog-to-digital converter / digital-to-analog converter) module, No. 8: Memory chip, No. 9: ZU28DR chip.

[0065] S200: When the circuit board is in normal working condition, for each type of module, measure the radiation emission spectrum of one of the modules in that type as the radiation emission spectrum of that type.

[0066] like Figure 3 As shown, in some embodiments, the measurement system for measuring the radiated emission spectrum of modules inside a circuit board includes an anechoic chamber 1000, a signal analyzer 2000, and a near-field probe 3000. The signal analyzer 2000 and the near-field probe 3000 are both located within the anechoic chamber 1000. The circuit board 4000 and the power supply 5000 are also located within the anechoic chamber 1000. One end of the circuit board 4000 is connected to the power supply 5000, and the other end is grounded. The signal analyzer 2000 is connected to the near-field probe 3000 via an RF cable 6000. When the circuit board is operating normally, the near-field probe 3000 can be brought close to or contacted with one of the modules of the test category on the circuit board 4000. The radiated emission of this module will be transmitted to the signal analyzer 2000 via the RF cable 6000, and the signal analyzer 2000 will output the radiated emission spectrum of that module, i.e., the radiated emission spectrum of the test category. For example, when measuring the power supply module (i.e.... Figure 2 When measuring the radiated emission spectrum of a module (category 2) in the power supply module, the near-field probe 3000 can be brought close to or in contact with one of the power supply modules, and then the signal analyzer 2000 will output the radiated emission spectrum of the power supply module, which is the radiated emission spectrum of that category; similarly, the radiated emission spectra of other categories can also be measured using a similar method.

[0067] Different types of radiation emission spectra can be represented by P SThe array W[s] represents the emission spectrum of a module in category 2 (i.e., a power supply module), where s represents the category number. For example, P2 represents the emission spectrum of a module in category 9 (i.e., a ZU28DR chip). The emission spectra of all categories form an array W[s], where:

[0068] W[s]=[P1, P2,…,P S (1)

[0069] P S =P(F[n], V S [n])(2)

[0070] In the formula, F is the frequency, and V is the frequency. S The power value corresponding to the frequency point, where n is the number of frequency points measured.

[0071] S300: Measure the ambient noise spectrum of the circuit board when it is in the off state.

[0072] The ambient noise spectrum of the circuit board can be measured by a measurement system. Specifically, when the circuit board 4000 is in the off state, the near-field probe 3000 is placed at the center of the circuit board 4000, and the ambient noise spectrum of the circuit board 4000 can be obtained by the signal analyzer 2000. The ambient noise spectrum PL can be expressed as:

[0073] P L =P L (F[n], V L [n])(3)

[0074] In the formula, F is the frequency, and V is the frequency. L Here, n represents the power value corresponding to a frequency point, and n is the number of frequency points measured.

[0075] S400: For each type of module, based on the radiated emission spectrum of that type and the ambient noise spectrum of the circuit board, signal-to-noise separation is performed on the radiated emission spectrum of that type to obtain the broadband noise and narrowband signal of that type.

[0076] like Figure 4 As shown, a certain category of radiated emission spectrum includes broadband noise and narrowband signal. The characteristic of broadband noise is that the overall noise power is higher than that of the ambient noise. In order to assess the magnitude of electromagnetic radiation, it is necessary to first perform signal-to-noise separation on the radiated emission spectrum to obtain broadband noise and narrowband signal, and then assess the interference level of broadband noise and narrowband signal respectively.

[0077] In some embodiments, step S400 specifically includes:

[0078] S410: Calculate the separation threshold between broadband noise and narrowband signal based on the radiated emission spectrum of this category; where the separation threshold PbS It can be represented as:

[0079] P bS =P bS (F[n], V bS [n])(4)

[0080] S420: Calculate the ambient noise threshold based on the ambient noise spectrum of the circuit board; where the ambient noise threshold P L1 It can be represented as:

[0081] P L1 =P L1 (F[n], V L1 [n])(5)

[0082] S430: Based on the radiated emission spectrum, separation threshold, and ambient noise threshold of this category, obtain the broadband noise and narrowband signal of this category.

[0083] Among them, broadband noise P W The following relationship must be satisfied:

[0084] (6)

[0085] Narrowband signal P N The following relationship must be satisfied:

[0086] (7)

[0087] In some embodiments, the broadband spectrum signal-to-noise separation method based on neighbor-value statistics in patent application No. 201811510587.5 can be used to separate the radiated emission spectrum, and the specific steps are not described here.

[0088] S500: For each type of module, obtain the interference level of the broadband noise of that type based on the broadband noise of that type, and obtain the interference level of the narrowband signal of that type based on the narrowband signal of that type.

[0089] In some embodiments, obtaining the interference level of a broadband noise category based on that category specifically includes:

[0090] S510: The broadband noise and ambient noise thresholds of this category are divided into a preset number (hereinafter referred to as B) frequency bands according to the following formulas (8) and (9); wherein each frequency band includes multiple frequency points;

[0091] (8)

[0092] (9)

[0093] Frequency bands can be divided according to the frequencies or bandwidths of interest. Based on engineering experience, the value of B is 6-12.

[0094] S520: Based on the power of each frequency band of the broadband noise of this category and the power of the corresponding frequency band of the environmental noise threshold, obtain the signal-to-noise ratio of the broadband noise of this category;

[0095] Signal-to-noise ratio (SNR) is defined as the ratio of signal power amplitude to noise power amplitude, and its magnitude directly reflects the intensity of interference. Because the amplitude exists in logarithmic form, the SNR of this type of broadband noise... It can be represented as:

[0096] (10)

[0097] S530: Average the broadband noise signal-to-noise ratio for each frequency band of this category to obtain the average broadband noise signal-to-noise ratio for this category; where, the average broadband noise signal-to-noise ratio for this category... It can be represented as:

[0098] (11)

[0099] S540: Determine the broadband noise signal-to-noise ratio factor for this category based on the average signal-to-noise ratio of this category; wherein, the broadband noise signal-to-noise ratio factor for this category... It can be represented as:

[0100] (12)

[0101] in, (j=1,2...B) are undetermined coefficients, the magnitude of which is determined by the average signal-to-noise ratio. Decide:

[0102] (13)

[0103] S550: For each frequency band of the broadband noise signal-to-noise ratio of this category, extract the three power values ​​with the highest power in that frequency band, and take the average to obtain the peak factor of the broadband noise signal-to-noise ratio of that frequency band. The peak factors of the broadband noise signal-to-noise ratio of all frequency bands constitute the peak factor of the broadband noise signal-to-noise ratio of this category.

[0104] Step S550 can be calculated using equations (14)-(16):

[0105] (14)

[0106] (15)

[0107] (16)

[0108] In the formula, The function represents sorting the matrix row by row in ascending order, that is, arranging the power values ​​of each frequency band in ascending order to obtain the sorted matrix. ; Indicates extracting the matrix by row. The first three items of each row form a new matrix. For the matrix The peak factor of the broadband noise signal-to-noise ratio for that category can be obtained by averaging each row. .

[0109] S560: Determine the interference level of this category of broadband noise based on the signal-to-noise ratio factor and the peak factor of the signal-to-noise ratio of this category of broadband noise; wherein, the interference level of this category of broadband noise can be expressed as:

[0110] (17)

[0111] In the formula, The preference coefficient for this category of broadband noise can be obtained based on engineering experience, for example... .

[0112] The interference levels of all categories of broadband noise constitute the total array of broadband noise interference levels. :

[0113] (18)

[0114] In some embodiments, obtaining the interference level of a narrowband signal of a certain category based on that category of narrowband signals specifically includes:

[0115] S510a: Divide the narrowband signal of this category into B frequency bands according to the following formula (19); wherein each frequency band includes multiple frequency points;

[0116] (19)

[0117] S520a: Based on the power of each frequency band of the narrowband signal of this category and the power of the corresponding frequency band of the environmental noise threshold, the signal-to-noise ratio (SNR) of the narrowband signal of this category is obtained; wherein, the SNR of the narrowband signal of this category... It can be represented as:

[0118] (20)

[0119] S530a: For each frequency band of the narrowband signal-to-noise ratio of this category, extract the power values ​​greater than 0 in that frequency band and average them to obtain the average power value of that frequency band; the average power value of all frequency bands constitutes the average signal-to-noise ratio of the narrowband signal of this category; wherein, the average signal-to-noise ratio of the narrowband signal of this category... It can be represented as:

[0120] (twenty one)

[0121] S540a: Determine the signal-to-noise ratio (SNR) factor for the narrowband signal of this category based on the average SNR of the narrowband signal of this category; wherein, the signal-to-noise ratio factor for the narrowband signal of this category... It can be represented as:

[0122] (twenty two)

[0123] In the formula, (j=1,2...B) by Sure:

[0124] (twenty three)

[0125] S550a: For each frequency band of the narrowband signal-to-noise ratio of this category, extract the three power values ​​with the highest power in that frequency band, and take the average to obtain the peak factor of the narrowband signal-to-noise ratio of that frequency band. The peak factors of the narrowband signal-to-noise ratio of all frequency bands constitute the peak factor of the narrowband signal-to-noise ratio of this category.

[0126] Step S550a can be represented by equations (24)-(26):

[0127] (twenty four)

[0128] (25)

[0129] (26)

[0130] In the formula, This is the peak factor of the signal-to-noise ratio for this category of narrowband signals.

[0131] S560a: Determine the interference level of the narrowband signal of this category based on the signal-to-noise ratio factor and the peak factor of the signal-to-noise ratio of the narrowband signal of this category; wherein, the interference level of the narrowband signal of this category... It can be represented as:

[0132] (27)

[0133] In the formula, This is the preference coefficient for narrowband signals, with a value between 0 and 1.

[0134] The interference levels of all categories of narrowband signals constitute the total array of narrowband signal interference levels. :

[0135] (28)

[0136] S600: Obtain the total interference level of broadband noise based on the interference levels of all categories of broadband noise, and obtain the total interference level of narrowband signals based on all categories of narrowband signals.

[0137] Total interference level of broadband noise The following relationship must be satisfied:

[0138] (29)

[0139] Total interference level of narrowband signals The following relationship must be satisfied:

[0140] (30)

[0141] In the formula, the sum() function represents summing all elements in the array.

[0142] The electromagnetic radiation level of the internal modules of the circuit board can be determined based on the total interference level of broadband noise and the total interference level of narrowband signals. Then, electromagnetic protection and interference suppression of the internal modules can be carried out accordingly.

[0143] The method for evaluating the electromagnetic radiation level of internal modules of a circuit board according to an embodiment of the present invention measures the electromagnetic interference of the circuit board in both working and non-working states to obtain the electromagnetic interference power spectrum and environmental noise power spectrum of each type of module. Then, the broadband noise and narrowband signal in the electromagnetic interference power spectrum are separated and analyzed separately to obtain the total interference level of the broadband noise and the total interference level of the narrowband signal, so as to evaluate the electromagnetic radiation level of the internal modules of the circuit board.

[0144] RFSoC (Radio Frequency Single Chip) is a highly integrated radio frequency system-on-a-chip with powerful signal acquisition, conversion, processing, and storage capabilities. However, its high integration and massive data throughput often come with significant electromagnetic interference (EMI). Therefore, for the proper functioning of the RFSoC and its connected devices, EMI evaluation is necessary. This paper uses an RFSoC board as an example to evaluate its electromagnetic radiation levels using the method described in this invention. The specific steps are as follows:

[0145] Step S1: Collect the spectrum of each module on the RFSoC board. With the ambient noise spectrum ;

[0146] Step S2: Calculate the signal-to-noise discrimination curve of the spectrum. Separate broadband noise and narrowband signals ;

[0147] Step S3: Calculate the signal-to-noise discrimination curve for background noise. ;

[0148] Step S4: Calculate the broadband noise interference level ;

[0149] First, calculate the signal-to-noise ratio (SNR) and peak value (CRP) of the broadband noise segment by segment, and then select the number of segments. This means that each frequency band contains 970 frequency points. Considering the contribution of factors to electromagnetic interference, a linear combination preference coefficient is selected. The final broadband noise interference level of the RFSoC board was obtained. As shown in Table 1:

[0150] Table 1: Broadband Noise Interference Levels of RFSoC Boards in Various Frequency Bands

[0151]

[0152] Figure 5A and Figure 5B The figures show the interference levels of the broadband noise in the frequency band and the full frequency band of the RFSoC board, respectively. It can be seen that the broadband interference of the RFSoC board is mainly distributed in the low frequency region.

[0153] Step S5: Calculate the total broadband noise interference level of the RFSoC board. ; =12.7;

[0154] Step S6: Calculate the narrowband signal interference level

[0155] Calculate the signal-to-noise ratio factor and peak factor for segmented spectral data of narrowband signals, and determine the number of segments. linear combination preference coefficient of factors Narrowband signal interference level. As shown in Table 2:

[0156] Table 2: Narrowband Signal Interference Levels of RFSoC Boards at Various Frequency Bands

[0157]

[0158] Figure 6A and Figure 6B The figures show the interference levels of narrowband signals in different frequency bands and across the entire frequency band of the RFSoC board. As can be seen from the figures, narrowband signals are prevalent in all frequency bands of the device, and the differences in the interference levels of narrowband signals between different devices are relatively small.

[0159] Step S7: Calculate the total narrowband signal interference level at the RFSoC board level. ; =11.4.

[0160] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A method for evaluating the electromagnetic radiation level of an internal module of a circuit board, characterized in that, include: The internal modules of the circuit board are classified to obtain different categories of modules; When the circuit board is in normal working condition, for each type of module, the radiation emission spectrum of one of the modules in that type is measured as the radiation emission spectrum of that type; Measure the ambient noise spectrum of the circuit board when it is in the off state; For each type of module, based on the radiated emission spectrum of that type and the ambient noise spectrum of the circuit board, signal-to-noise separation is performed on the radiated emission spectrum of that type to obtain the broadband noise and narrowband signal of that type. For each type of module, the interference level of the broadband noise of that type is obtained based on the broadband noise of that type, and the interference level of the narrowband signal of that type is obtained based on the narrowband signal of that type. The total interference level of broadband noise is obtained based on the interference levels of all categories of broadband noise, and the total interference level of narrowband signal is obtained based on all categories of narrowband signal. The interference level of this type of broadband noise is obtained based on this category of broadband noise, specifically including: The threshold values ​​for broadband noise and ambient noise in this category are divided into a preset number of frequency bands; The signal-to-noise ratio of broadband noise of this category is obtained by comparing the power of each frequency band of the broadband noise category with the power of the corresponding frequency band of the environmental noise threshold. The average signal-to-noise ratio (SNR) of broadband noise for this category is obtained by averaging the SNR of broadband noise for each frequency band. The broadband noise signal-to-noise ratio factor for this category is determined based on the average signal-to-noise ratio of this category. For each frequency band of the broadband noise signal-to-noise ratio of this category, extract the three power values ​​with the highest power in that frequency band and take the average to obtain the peak factor of the broadband noise signal-to-noise ratio of that frequency band. The peak factors of the broadband noise signal-to-noise ratio of all frequency bands constitute the peak factor of the broadband noise signal-to-noise ratio of this category. The frequency band interference level of this category of broadband noise is determined based on the broadband noise signal-to-noise ratio factor and the peak factor of the broadband noise signal-to-noise ratio for this category.

2. The method for evaluating the electromagnetic radiation level of an internal module of a circuit board according to claim 1, characterized in that, For each module category, signal-to-noise separation is performed on the radiated emission spectrum of that category and the ambient noise spectrum of the circuit board to obtain the broadband noise and narrowband signal of that category, specifically including: Based on the radiated emission spectrum of this category, calculate the separation threshold between broadband noise and narrowband signal; Calculate the environmental noise threshold based on the environmental noise spectrum of the circuit board; Based on the radiative emission spectrum, separation threshold, and ambient noise threshold of this category, broadband noise and narrowband signals of this category are obtained.

3. The method for evaluating the electromagnetic radiation level of an internal module of a circuit board according to claim 2, characterized in that, This category of broadband noise The following relationship must be satisfied: , This category of narrowband signals The following relationship must be satisfied: , Where F is the frequency, n is the number of frequency points, and P S For this category of radiation emission spectrum, The environmental noise threshold of the circuit board. The threshold for separating broadband noise and narrowband signals in this category; , and All of these are power values ​​corresponding to specific frequency points.

4. The method for evaluating the electromagnetic radiation level of an internal module of a circuit board according to claim 1, characterized in that, The frequency band interference level of this category of broadband noise is determined based on the signal-to-noise ratio factor and the peak factor of the signal-to-noise ratio of this category, specifically including: Determine the preference coefficient for this category of broadband noise; The bias coefficient of the broadband noise category is used as the weighting parameter of the broadband noise signal-to-noise ratio factor of the category, and the difference between the bias coefficient of the broadband noise category and the peak factor of the broadband noise signal-to-noise ratio of the category is used as the weighting parameter. The broadband noise signal-to-noise ratio factor and the peak factor of the broadband noise signal-to-noise ratio of the category are weighted and summed to obtain the frequency band interference level of the broadband noise category.

5. The method for evaluating the electromagnetic radiation level of an internal module of a circuit board according to claim 1, characterized in that, Broadband noise signal-to-noise ratio factor of this category The following relationship must be satisfied: , in B represents the average signal-to-noise ratio of broadband noise in this category, where B is a preset quantity. Let the coefficient of the j-th term (j=1,2...B) satisfy the following relationship: 。 6. The method for evaluating the electromagnetic radiation level of an internal module of a circuit board according to claim 1, characterized in that, The interference level of this category of narrowband signals is obtained based on the specific characteristics of the narrowband signals, including: This category of narrowband signals is divided into a preset number of frequency bands; The signal-to-noise ratio of the narrowband signal of this category is obtained based on the power of each frequency band of the narrowband signal and the power of the corresponding frequency band of the environmental noise threshold. For each frequency band of the narrowband signal-to-noise ratio of this category, extract the power values ​​of that frequency band that are greater than 0 and average them to obtain the average power value of that frequency band; the average power value of all frequency bands constitutes the average signal-to-noise ratio of the narrowband signal of this category. The signal-to-noise ratio factor of the narrowband signal in this category is determined based on the average signal-to-noise ratio of the narrowband signal in this category; For each frequency band of the narrowband signal-to-noise ratio of this category, extract the three power values ​​with the highest power in that frequency band, and take the average to obtain the peak factor of the narrowband signal-to-noise ratio of that frequency band. The peak factors of the narrowband signal-to-noise ratio of all frequency bands constitute the peak factor of the narrowband signal-to-noise ratio of this category. The frequency band interference level of a narrowband signal is determined based on the signal-to-noise ratio factor and the peak factor of the signal-to-noise ratio of that category of narrowband signals.

7. The method for evaluating the electromagnetic radiation level of an internal module of a circuit board according to claim 6, characterized in that, The frequency band interference level of this category of narrowband signals is determined based on the signal-to-noise ratio (SNR) factor and the peak factor of the SNR of this category of narrowband signals, specifically including: Determine the preference coefficient for this category of narrowband signals; The preference coefficient of the narrowband signal of this category is used as the weighting parameter of the signal-to-noise ratio (SNR) factor of the narrowband signal of this category, and a factor minus the preference coefficient of the narrowband signal of this category is used as the weighting parameter of the peak factor of the SNR of the narrowband signal of this category. The SNR factor and the peak factor of the narrowband signal of this category are weighted and summed to obtain the frequency band interference level of the narrowband signal of this category.

8. The method for evaluating the electromagnetic radiation level of an internal module of a circuit board according to claim 6, characterized in that, This category of narrowband signal-to-noise ratio factor The following relationship must be satisfied: , in B represents the average signal-to-noise ratio of broadband noise in this category, where B is a preset quantity. Let the coefficient of the j-th term (j=1,2...B) satisfy the following relationship: 。 9. The method for evaluating the electromagnetic radiation level of an internal module of a circuit board according to claim 1, characterized in that, The total interference level of the broadband noise is equal to the sum of the interference levels of all categories of broadband noise divided by 100; the total interference level of the narrowband signal is equal to the sum of the interference levels of all categories of narrowband signal divided by 100.

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