CN107192902B - Cable conduction sensitivity time domain testing method using multiple Gaussian pulses - Google Patents
Cable conduction sensitivity time domain testing method using multiple Gaussian pulses Download PDFInfo
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Abstract
The invention relates to a cable conducted sensitivity time domain testing method using multiple Gaussian pulses, which specifically comprises the following steps: step one, analyzing a multi-Gaussian pulse frequency spectrum; designing a sensitive frequency point positioning process; and step three, realizing a positioning process by using LABVIEW. The invention also discloses a time domain test system of the cable conducted sensitivity applied by the method, which comprises a time domain pulse forming module, an injection probe module, a tested object and a signal monitoring and data processing module. The method has the advantages that: 1. the complex electromagnetic environment of the equipment in actual work can be well simulated; 2. the possible existing forms of the interference signals can be comprehensively reflected; 3. the multi-Gaussian pulse belongs to a broadband time domain signal, the test spectrum is wide, the test efficiency is high, and the sensitive frequency point distribution condition of the tested object can be relatively comprehensively examined; 4. the automatic test is realized through LABVIEW, and the operation is simpler; 5. the test efficiency is greatly improved, and the test time is saved.
Description
Technical Field
the invention relates to a cable conducted sensitivity time domain testing method using multiple Gaussian pulses, and belongs to the field of electromagnetic sensitivity testing. The cable conducted sensitivity time domain test uses multiple Gaussian pulses as broadband time domain test signals, multiple Gaussian pulses are selected to be injected into a tested object, the sensitive frequency points of the tested object are measured by using the diversity of the frequency spectrum of the multiple Gaussian pulses, the test efficiency is greatly improved, and the method has a wide application prospect.
background
the cable conducted sensitivity test plays a key role in the electromagnetic compatibility test. Cable quantity is huge among the large-scale complicated electronic system, the variety is various, the distribution is extensive, consequently various cables can pick up the electromagnetic energy from actual work environment, and when external electromagnetic field shined the cable, the cable will collect electromagnetic energy, with in the noise coupling gets into the cable. Noise coupled into the cable may cause transient currents and voltages to be conductively coupled into the terminal electronics or system to which the cable is connected, causing the circuitry in the terminal electronics or system to become sensitive, which may cause catastrophic damage to the more sensitive electronics and circuitry. A large body of statistical data shows that: at present, the most common cause of the problem of electromagnetic compatibility of large-scale electronic equipment is that an interconnection cable in the equipment is coupled with an electromagnetic interference signal in an actual working environment, so that an all-around cable sensitivity test on the interconnection cable in the equipment is necessary and urgent, and is more important for improving the reliability of the equipment.
At present, items for assessing cable sensitivity in electromagnetic compatibility tests mainly comprise frequency domain scanning type conducted injection sensitivity tests (CS114 and the like), time domain sensitivity tests (electrostatic discharge, surge and the like) of specific form pulse signal coupling injection, and assessment tests for antenna terminal nonlinear effects (CS103/CS104/CS 105). With the increasing functions of electronic devices and the increasing number of electronic devices, the number, types, lengths, bundling manners and layouts of cables are more and more complex. The cable conduction sensitivity test method can not meet the electromagnetic compatibility test requirements of large-scale complex equipment in the aspects of efficiency, no change of the state of a tested object and the like. For example, when performing a frequency domain scanning sensitivity test, if the test is performed strictly according to the test frequency band, the step requirement and the test procedure specified in the equipment subsystem level national military standard, a single test usually takes 1 to 2 hours. The experiment is used for testing a device containing a large number of complicated cables, immeasurable time cost can be consumed, and the development period of equipment is greatly delayed. Meanwhile, in the existing test, the CS114 injection signal is a single frequency point, and the frequency domain scanning mode is adopted to test the tested object, so that whether a frequency band between adjacent test frequency points has a sensitive frequency point is difficult to test, and the frequency point leakage condition may occur.
The concept of time domain electromagnetic interference detection was first proposed by e.l.bronaugh, and based on the analysis of the literature published by the present disclosure, a research prototype in a laboratory can meet the requirements of CISPR on electromagnetic interference receivers in a frequency band below 18 GHz. 9, 2012, a time domain EMI test receiver ESR is provided by Germany R & S company, and can perform conduction and radiation disturbance tests within the range of 10Hz-7GHz, the ESR has a time domain scanning function based on FFT (fast Fourier transform), can perform electromagnetic disturbance measurement at an extremely high speed, and saves precious time for users. In addition, the test method is very suitable for industries such as automobiles, mobile communication, medical treatment, electric power, lighting and the like. In the apamc meeting of 2012, time domain electromagnetic interference receivers were introduced as a special topic for discussion. Russer professor p.russer, munich, germany, university of industry, made a report entitled "EMC Measurements in the Time-Domain" leading a huge revolution in Time Domain electromagnetic interference testing.
Disclosure of Invention
1. The purpose is as follows: the invention aims to provide a cable conducted sensitivity time domain testing method using multiple Gaussian pulses. The electromagnetic environment signal form of the electronic equipment in the working process is complex and various, and the electronic equipment exists in a time domain broadband signal form, so that the time domain broadband signal is selected as the test signal, the real working environment of the tested object can be simulated to the maximum extent under the condition that the state of the tested equipment is not changed, and the electromagnetic sensitivity phenomenon which possibly appears under the real working environment is excited. The invention uses multi-Gaussian pulse as a broadband time domain test signal, utilizes the characteristics of the spectrum width and the spectrum distribution range of the multi-Gaussian pulse changing along with the pulse interval to sequentially inject the test signal into the tested object to excite the sensitive response of the tested object, and accurately measures the sensitive frequency point distribution range of the tested object by comprehensively analyzing the sensitive condition of the tested object and the spectrum of the input test signal. The cable conducted sensitivity time domain test can make up the defects of the traditional measuring method, improve the testing efficiency and greatly shorten the testing time.
2. the technical scheme is as follows: the conducted sensitivity time domain test system uses single Gaussian pulse, double Gaussian pulse and Gaussian even pulse with full-bottom pulse width of 0.5ns as test signals, determines the distribution range of sensitive frequency points of a tested product by selecting multiple Gaussian pulses with different forms and different intervals, and requires the measurement range to be 0-800 MHz. The conducted sensitivity time domain testing system consists of a time domain pulse forming circuit, an injection probe, a tested object, a signal acquisition part and a data analysis part. The pulse forming circuit can generate single Gaussian pulse, double Gaussian pulse and Gaussian even pulse with different intervals according to requirements. The test signal is coupled to the tested object through the injection probe, the tested object generates sensitive response to the injected signal, and the injection probe is required to ensure the injection flatness in the test range and ensure that the test signal can be completely injected. The signal acquisition and data analysis part acquires the sensitive response of the tested object, extracts corresponding characteristic information, judges whether the tested object is sensitive or not, selects the next test pulse according to a sensitive frequency point positioning algorithm, and drives the pulse forming circuit to generate a new test pulse. Through the hardware operation, the system can gradually determine the distribution range of the sensitive frequency points of the tested object according to the positioning algorithm of the sensitive frequency points.
the invention designs a complete sensitive frequency point positioning process which is used for analyzing a sensitive response signal of a tested article, extracting sensitive information, judging whether the tested article is sensitive or not, further selecting and generating a proper test pulse to be injected into the tested article by combining a sensitive frequency point positioning algorithm, and gradually determining the distribution range of sensitive frequency points. The core of the data processing flow is a sensitive frequency point positioning algorithm based on a time domain Gaussian pulse signal.
A method for time domain testing of cable conducted sensitivity using multiple gaussian pulses, characterized by: the method specifically comprises the following steps:
(one) analysis of multi-Gaussian pulse spectra
Using multiple Gaussian pulses as sensitive frequency point time domain test signals, firstly analyzing the spectrum distribution rule of the multiple Gaussian pulses, and observing the relation between the spectrum distribution of the multiple Gaussian pulses and the pulse intervals;
The gaussian monopulse time domain expression is: where a is amplitude, μ and σ 2 are expectation and standard variance of a gaussian function, a gaussian pulse with the same distribution is substantially the same as a signal energy distribution distributed in the gaussian function, and frequency distributions of the gaussian pulse and the signal energy distribution are also similar, so that a spectrum of the gaussian function is used to approximate a spectral distribution of the gaussian pulse, and a gaussian single-pulse spectral expression is: b is the spectrum amplitude, the formula shows that a proper threshold value is selected, and the spectrum distribution of the Gaussian single pulse can be approximately regarded as Gaussian distribution;
By utilizing the analysis result and combining with the time shift characteristic of Fourier transform, the spectrum distribution condition of multi-Gaussian pulse can be obtained; assuming that the distance between double-Gaussian pulses is T, the amplitude spectrum expression is as follows: the spectrum component of the double-Gaussian pulse within-3 dB can be effectively injected into a tested object, the tested object is an effective test frequency band, and the relational expression of the effective test frequency band boundary omega bd and the pulse interval T is as follows: the test signal used by the method is a multi-Gaussian pulse with the full-bottom pulse width of 0.5ns, and the shape parameter sigma of the pulse is approximately equal to 1.4 multiplied by 10 < -11 > at the moment; because sigma is approximately equal to 1.4 multiplied by 10-11, omega is less than or equal to 800MHz, the relationship between the effective test frequency band boundary with double Gaussian pulse and the pulse interval can be simplified to cos omega bdT which is 0; multiple solutions exist on the boundary omega bd of the effective test frequency band of the double-gauss pulse, the distribution of the effective test frequency band of the double-gauss pulse is comprehensively analyzed by a sensitive frequency point positioning algorithm, a proper pulse interval is selected to ensure that the effective test frequency band of the double-gauss pulse is only [0, omega bd0], the region [0, omega bd0] can be scanned by changing the interval of the double-gauss pulse, and the distribution of the sensitive frequency points of a tested product in a low-frequency region is determined;
by adopting the same analysis method, the expression of the Gaussian even pulse amplitude spectrum is as follows: the same as the double-Gaussian pulse calculation method, the relational expression of the boundary value of the effective test frequency band of the Gaussian even pulse and the pulse interval T is obtained as follows: cos ω beT ═ 0; therefore, the effective test frequency band critical points of the double-Gaussian pulse and the Gaussian even pulse with the same pulse interval are the same, the two effective test frequency band critical points can completely cover the frequency spectrum range of 0-800 MHz required to be tested, the test frequency band can be gradually adjusted along with the change of the pulse interval, and finally the accurate sensitive frequency point range is obtained.
(II) design sensitive frequency point positioning process
By the above spectrum analysis of the Gaussian single pulse, the double Gaussian pulse and the Gaussian even pulse, the fact that the spectrum of the single Gaussian pulse can completely cover the range of 0-800 MHz can be found, whether sensitive frequency point distribution exists in the range of a tested object can be detected by using the signal, the spectrum distribution of the double Gaussian pulse and the Gaussian even pulse respectively covers the low-frequency region and the high-frequency region of the range to be detected, the pulse distribution range is gradually changed along with the change of the pulse interval T, the frequency range to be detected can be scanned by comprehensively using the two pulses by utilizing the rule, the frequency band possibly existing in the sensitive frequency point is gradually reduced, and the distribution range of the sensitive frequency point is finally determined by combining with the positioning algorithm of the sensitive frequency point;
The method comprises the steps of firstly selecting an initial detection pulse and driving an electric control module of a pulse forming circuit to generate the pulse when a test is started, injecting the pulse into a tested object through a probe, monitoring the response of the tested object and judging whether the tested object is sensitive at the moment, further selecting a proper pulse to test the tested object according to the current test state and the sensitive test condition of the tested object, and finally determining the sensitive frequency point distribution range of the tested object by analyzing the frequency spectrum difference among the pulses.
(III) positioning process is realized by using LABVIEW
The data processing part in the conducted sensitivity time domain testing method is realized in an LABVIEW program, signals are transmitted to a PC terminal through data acquisition equipment, sensitive response data are called in the LABVIEW program, sensitive information is acquired, a next group of testing pulses are selected according to corresponding sensitive conditions by combining the current testing state and a sensitive frequency point positioning process, and a pulse forming module is instructed to generate corresponding testing pulses to continue to be tested next step.
In the sensitive frequency point positioning process, firstly, a single Gaussian pulse with an effective frequency band completely covering 0-800 MHz is used for testing, if the tested article has a sensitive phenomenon, the tested article is indicated to have a sensitive frequency point in a testing range, otherwise, the test is finished if the tested article does not have the sensitive frequency point; if the sensitive frequency points exist, performing a second test, namely selecting double Gaussian pulses with the pulse spacing of 0.5ns to test the tested object, if a sensitive phenomenon occurs, indicating that the sensitive frequency points are distributed in the range of 0-500 MHz, otherwise, distributing the sensitive frequency points in the range of 500-800 MHz; if the second test shows the sensitivity phenomenon, selecting a double-Gaussian pulse with a pulse spacing of 1.0ns for testing the tested object in the third test, if the sensitivity phenomenon appears, indicating that the sensitivity frequency points are distributed at 0-250 MHz, otherwise, distributing at 250-500 MHz; if the second test does not have the sensitivity phenomenon, selecting a Gaussian even pulse with a pulse spacing of 1.0ns for testing the tested object in the third test, wherein if the sensitivity phenomenon occurs, the sensitivity frequency points are distributed at 500-750 MHz, otherwise, the sensitivity frequency points are distributed at 750-800 MHz; by analogy, the multi-Gaussian pulse with proper spacing and form is selected to gradually reduce the possible range of the sensitive frequency point, and finally, an accurate result is obtained.
The time domain test system for the cable conducted sensitivity comprises a time domain pulse forming module, an injection probe module, a tested object and a signal monitoring and data processing module, wherein the time domain pulse forming module is a test pulse signal generator and can generate multi-Gaussian pulses with the full-bottom pulse width of 0.5ns according to the pulse form and space requirements of the data processing module, and the module is connected with the injection probe module and transmits the generated test signals to the injection probe module; the injection probe module ensures that the maximum attenuation of the frequency spectrum component of the test signal is 10dB in the test range of 0-800 MHz, is connected with the tested object, and injects the test signal into the tested object completely to accurately excite the sensitive phenomenon of the tested object; when a tested object receives a test signal, sensitive response is generated on certain frequency spectrum components of the signal, and a response signal is transmitted to the signal monitoring and data processing module; the signal monitoring and data processing module monitors the sensitive response of the tested object, extracts and analyzes the sensitive characteristic of the response signal, stores the response information after obtaining the sensitive information of the tested object, judges the next group of test pulses according to the sensitive frequency point positioning algorithm, is connected with the pulse forming module at the same time, transmits the test pulse information to be generated to the time domain pulse forming module, and controls the time domain pulse forming module to generate new test pulses to continue the next group of tests.
3. The advantages are that: the invention provides a cable conducted sensitivity time domain testing method using multiple Gaussian pulses, which has the advantages that:
the method has the advantages that multiple Gaussian pulses are used as test signals, and the condition that a leakage frequency point does not exist, so that the complex electromagnetic environment of the equipment in actual work can be well simulated;
The multi-Gaussian pulse has various forms, and can comprehensively reflect the possible forms of interference signals;
the multi-Gaussian pulse belongs to a broadband time domain signal, the test spectrum is wide, the test efficiency is high, and the sensitive frequency point distribution condition of the tested object can be relatively comprehensively examined;
Fourthly, automatic testing is realized through LABVIEW, and the operation is simpler;
The testing efficiency is greatly improved, and the testing time is saved.
drawings
FIG. 1 is a block diagram of a time domain test system.
FIGS. 2a-1 and 2a-2 show single Gaussian pulse shapes and spectra.
FIGS. 2b-1 and 2b-2 show the waveform and spectrum of a double Gaussian pulse.
FIGS. 2c-1 and 2c-2 show Gaussian even pulse waveforms and frequency spectra.
Fig. 3 is a data processing flow diagram.
Fig. 4 is a flow chart of sensitive frequency point positioning.
fig. 5 front panel of the sensitive frequency point location procedure.
Fig. 6 is a block diagram of a procedure for locating sensitive frequency points.
FIG. 7a is a front panel of a sample.
FIG. 7b is a block diagram of a sample program.
FIG. 8 shows the test results of the test article.
Detailed Description
The present invention will be described in further detail with reference to the drawings.
The invention discloses a cable conducted sensitivity time domain test system, which comprises a time domain pulse forming module, an injection probe module, a tested object and a signal monitoring and data processing module, wherein the time domain pulse forming module is a test pulse signal generator and can generate multi-Gaussian pulses with the full-bottom pulse width of 0.5ns according to the pulse form and space requirements of the data processing module, and the module is connected with the injection probe module and transmits the generated test signals to the injection probe module, as shown in figure 1; the injection probe module ensures that the maximum attenuation of the frequency spectrum component of the test signal is 10dB in the test range of 0-800 MHz, is connected with the tested object, and injects the test signal into the tested object completely to accurately excite the sensitive phenomenon of the tested object; when a tested object receives a test signal, sensitive response is generated on certain frequency spectrum components of the signal, and a response signal is transmitted to the signal monitoring and data processing module; the signal monitoring and data processing module monitors the sensitive response of the tested object, extracts and analyzes the sensitive characteristic of the response signal, stores the response information after obtaining the sensitive information of the tested object, judges the next group of test pulses according to the sensitive frequency point positioning algorithm, is connected with the pulse forming module at the same time, transmits the test pulse information to be generated to the time domain pulse forming module, and controls the time domain pulse forming module to generate new test pulses to continue the next group of tests.
A time domain test method for the conducted sensitivity of a cable by using multiple Gaussian pulses comprises the following specific steps:
The method comprises the following steps: fourier transform is performed on the frequency spectrum of the multi-Gaussian pulse to obtain the spectrum distribution characteristics of different multi-Gaussian pulses, and a correlation mathematical model between the form of the time domain Gaussian pulse signal and the frequency domain coverage frequency band is established, as shown in fig. 2a-1, fig. 2a-2, fig. 2b-1, fig. 2b-2, fig. 2c-1 and fig. 2 c-2. The gaussian monopulse time domain expression is:
Where A is the amplitude and μ and σ 2 are the expectation and standard deviation of the Gaussian function. Since the gaussian pulse with the same distribution and the signal energy distribution distributed in the gaussian function are basically the same, and the frequency distributions of the gaussian pulse and the signal energy distribution are also approximate, the spectrum of the gaussian function is used to approximate the spectrum distribution of the gaussian pulse, and the expression of the gaussian single-pulse spectrum is:
By choosing a suitable threshold, the spectral distribution of a gaussian monopulse can be approximately regarded as a gaussian distribution.
The requirement of positioning the sensitive frequency point cannot be met only by using the Gaussian single pulse, and the sensitive frequency point positioning is completed by using multiple Gaussian pulses. By using the analysis result and combining with the time shift characteristic of Fourier transform, the spectrum distribution condition of multi-Gaussian pulse can be obtained. Assuming that the distance between double-Gaussian pulses is T, the amplitude spectrum expression is as follows:
The spectrum component of the double-Gaussian pulse with the amplitude within-3 dB can be effectively injected into a tested product, and the relational expression of the boundary value omega bd of the effective test frequency band and the pulse interval T is as follows: the test signal used by the system is a multi-Gaussian pulse with a full-bottom pulse width of 0.5ns, so the shape parameter sigma of the pulse is approximately equal to 1.4 multiplied by 10 < -11 >. Since σ ≈ 1.4 × 10-11 also has ω ≦ 800MHz, the relationship between the effective test band boundary and pulse spacing for that double Gaussian pulse can be simplified as:
cosωT＝0
The effective test band boundary ω bd of the double-gauss pulse is inversely proportional to the pulse interval T and has a plurality of solutions, and a plurality of effective test bands may exist at 0-800 MHz with the change of the double-gauss pulse interval. When designing a sensitive frequency point positioning algorithm, the effective test frequency band [0, ω bd0] of the double-Gaussian pulse is considered first. Meanwhile, with the change of the pulse spacing, part or all of the effective test frequency bands [ omega bd1 and omega bd2] are increased, and the sensitive frequency point can be accurately positioned by comprehensively analyzing the two frequency band conditions of the double-Gaussian pulse.
By adopting the same analysis method, the expression of the Gaussian even pulse amplitude spectrum is as follows:
the same as the double-Gaussian pulse calculation method, the relational expression of the boundary value omega be of the Gaussian even pulse effective test frequency band and the pulse interval T is obtained as follows:
cosωT＝0
Therefore, the effective test frequency band critical points of the double-Gaussian pulse and the Gaussian even pulse with the same pulse interval are the same, the two effective test frequency band critical points can completely cover the frequency spectrum range of 0-800 MHz required to be tested, the test frequency band can be gradually adjusted along with the change of the pulse interval, and finally the accurate sensitive frequency point range is obtained.
step two: a sensitive frequency point positioning process is designed through the spectrum analysis of the multi-Gaussian pulse. The single-Gaussian pulse frequency spectrum in the multi-Gaussian pulse can completely cover the range of 0-800 MHz, whether the tested object has sensitive frequency point distribution in the range can be detected by using the signal, the effective test frequency band boundaries of the double-Gaussian pulse and the Gaussian even pulse frequency spectrum are the same, and the two pulses can be comprehensively used and the interval of the pulses can be adjusted to complete the detection of the sensitive frequency point range. The data processing flow chart is shown in fig. 3, when the test is started, an initial detection pulse is selected and an electric control module of a pulse forming circuit is driven to generate a pulse, the pulse is injected into a tested article through a probe, the response of the tested article is monitored, whether the tested article is sensitive at the moment is judged, a proper pulse is further selected to test the tested article according to the current test state and the sensitive test condition of the tested article, and finally the sensitive frequency point distribution range of the tested article is determined by analyzing the frequency spectrum difference among the pulses.
In the sensitive frequency point positioning algorithm, the sensitive frequency points of the tested device can be positioned by (1) selecting multi-Gaussian pulses of different types and (2) adjusting the pulse spacing to scan the test frequency band. In the actual test process, a proper multi-Gaussian pulse is selected and generated according to the coverage requirement of the test frequency band to test the tested object. Therefore, a comparison table of the correspondence between the boundary values of the valid test bands of the multiple gaussian pulses and the pulse spacings can be generated as shown in table 1, and the adjustment step size of the pulse spacings is selected to be 0.5 ns. And the positioning process of the sensitive frequency point can be designed by analyzing the comparison table.
TABLE 1
according to the data processing flow of the conducted sensitivity time domain test system and the analysis of the multi-Gaussian pulse effective test frequency band, a complete sensitive frequency point positioning flow can be designed, and a sensitive frequency point positioning flow chart is shown in fig. 4. In the test process, firstly, a single Gaussian pulse with an effective frequency band completely covering 0-800 MHz is used for testing, if the tested object has a sensitivity phenomenon, the tested object is indicated to have a sensitive frequency point in the test range, otherwise, the test is finished if the tested object does not have the sensitive frequency point. If the sensitive frequency points exist, performing a second test, namely selecting double Gaussian pulses with the pulse spacing of 0.5ns to test the tested object, if a sensitive phenomenon occurs, indicating that the sensitive frequency points are distributed in the range of 0-500 MHz, otherwise, distributing the sensitive frequency points in the range of 500-800 MHz. If the second test shows the sensitivity phenomenon, selecting a double-Gaussian pulse with a pulse spacing of 1.0ns for testing the tested object in the third test, if the sensitivity phenomenon appears, indicating that the sensitivity frequency points are distributed at 0-250 MHz, otherwise, distributing at 250-500 MHz. If the second test does not have the sensitivity phenomenon, selecting a Gaussian even pulse with the pulse spacing of 1.0ns for testing the tested object in the third test, wherein if the sensitivity phenomenon occurs, the sensitivity frequency points are distributed at 500-750 MHz, otherwise, the sensitivity frequency points are distributed at 750-800 MHz. By analogy, the multi-Gaussian pulse with proper spacing and form is selected to gradually reduce the possible range of the sensitive frequency point, and finally, an accurate result is obtained. All possible conditions of the distribution of the sensitive frequency points, corresponding test procedures and sensitive conditions are listed in table 2, wherein the distribution frequency band represents the distribution range of the sensitive frequency points, and the test signal sequence represents the injection sequence of the multi-gaussian pulse and the corresponding sensitive condition of the tested sample when the sensitive frequency points are distributed in the range (the number in brackets represents that the interval unit of the pulse is ns, Y represents that the tested sample is sensitive at the moment, and N represents that the tested sample is not sensitive at the moment). The positioning algorithm can be seen that 121 sub-frequency bands with unequal distribution in the range of 0-800 MHz to be measured are measured by the positioning algorithm, the width of each sub-frequency band is the measurement precision when the sensitive frequency points are distributed in the range, and when the measurement is finished, the sensitive frequency point positioning algorithm determines which sub-frequency band the sensitive frequency points are distributed in.
TABLE 2
Step three: and writing the sensitive frequency point positioning process into an LABVIEW program to realize automatic data processing and pulse selection. Firstly, transmitting the collected response of the tested object to a PC (personal computer) terminal, calling data by using LABVIEW (laboratory instrumentation engineering) and extracting sensitive features, judging whether the tested object is sensitive or not, and finally storing a test signal and sensitive response information. By combining the current test pulse with the sensitivity information of the test object, the LABVIEW program selects the next group of test pulses using the above-mentioned sensitivity frequency point location algorithm. The front panel and the program block diagram of the sensitive frequency point positioning program are shown in fig. 5 and fig. 6, the program is divided into three parts, namely a sampling parameter control part, a data processing part and an instruction state display area, and the functions of collecting sensitive responses of a tested object, storing sampling data, judging the current test state, selecting the next test pulse, displaying the distribution range of the sensitive frequency points in real time and the like can be realized. The LABVIEW program provides an interface for interaction between a tester and a test system, can adjust system parameters according to the requirement of the tester, and realizes automatic test at a PC (personal computer) end, thereby greatly shortening the test time and saving test resources.
Example 1
the feasibility of this design concept is verified using triangular wave as the simulation test signal, and a VI is established as the test object using the LABVIEW in the experiment, and the front panel and the program block diagram of the test object are shown in fig. 7a and b. When the test signal frequency spectrum contains 4MHz, the tested object outputs sine wave with amplitude of 2, otherwise, the sine wave with amplitude of 1 is output, namely the sensitive frequency point of the tested object is 4 MHz.
TABLE 3
The data acquisition card is used for acquiring a triangular wave signal of one period and injecting the triangular wave signal into a tested object, the frequency of the signal and the corresponding cut-off frequency of the monocycle signal are shown in table 3, and the selected change step length is 0.1 MHz. Then, as shown in fig. 8, the signals with frequencies of 2MHz, 1MHz, 1.5MHz, 1.3MHz and 1.1MHz are injected in sequence, and the final test result is obtained when the sensitive frequency point is within the range of 3.8-4.1 MHz, which is consistent with the expected result.
Claims (3)
1. A method for time domain testing of cable conducted sensitivity using multiple gaussian pulses, characterized by: the method specifically comprises the following steps:
(one) analysis of multi-Gaussian pulse spectra
using multiple Gaussian pulses as sensitive frequency point time domain test signals, firstly analyzing the spectrum distribution rule of the multiple Gaussian pulses, and observing the relation between the spectrum distribution of the multiple Gaussian pulses and the pulse intervals;
The gaussian monopulse time domain expression is: t ∈ (μ - σ, μ + σ), where a is amplitude, μ and σ are expected and standard deviations of gaussian functions, gaussian pulses with the same distribution are basically the same as signal energy distribution with gaussian function distribution, and frequency distributions of the gaussian pulses and the gaussian function are also approximate, so that the frequency spectrum of the gaussian function is used to approximate the frequency spectrum distribution of the gaussian pulse, and the gaussian single-pulse spectrum expression is: b is the spectrum amplitude, the formula shows that a proper threshold value is selected, and the spectrum distribution of the Gaussian single pulse can be approximately regarded as Gaussian distribution;
By utilizing the analysis result and combining with the time shift characteristic of Fourier transform, the spectrum distribution condition of multi-Gaussian pulse can be obtained; assuming that the spacing of the double-gauss pulse is Td, the amplitude spectrum expression is: the spectrum component of the double-gauss pulse within-3 dB can be effectively injected into a tested object, the tested object is an effective test frequency band, and the relational expression of the effective test frequency band boundary omega bd of the double-gauss pulse and the distance Td of the double-gauss pulse is as follows: the test signal used by the method is a multi-Gaussian pulse with the full-bottom pulse width of 0.5ns, and sigma is approximately equal to 1.4 multiplied by 10 < -11 > at the moment; since σ ≈ 1.4 × 10-11 simultaneously has ω ≦ 800MHz, the relationship between the effective test band boundary ω bd with the double gaussian pulse and the spacing Td of the double gaussian pulse can be simplified to cos ω bdTd ═ 0; multiple solutions exist on the boundary omega bd of the effective test frequency band of the double-gauss pulse, the distribution of the effective test frequency band of the double-gauss pulse is comprehensively analyzed by a sensitive frequency point positioning algorithm, a proper pulse interval is selected to ensure that the effective test frequency band of the double-gauss pulse is only [0, omega bd0], the region [0, omega bd0] can be scanned by changing the interval of the double-gauss pulse, and the distribution of the sensitive frequency points of a tested product in a low-frequency region is determined;
By adopting the same analysis method, the expression of the Gaussian even pulse amplitude spectrum is as follows: the same as the double-Gaussian pulse calculation method, the relational expression of the boundary value omega be of the effective test frequency band of the Gaussian pulse and the distance Te of the Gaussian pulse is obtained as follows: cos ω beTe ═ 0; therefore, the effective test frequency band critical points of the double-Gaussian pulse and the Gaussian even pulse with the same pulse interval are the same, the two effective test frequency band critical points can completely cover the frequency spectrum range of 0-800 MHz required to be tested, the test frequency band can be gradually adjusted along with the change of the pulse interval, and the accurate sensitive frequency point range is finally obtained;
(II) design sensitive frequency point positioning process
By the above spectrum analysis of the Gaussian single pulse, the double Gaussian pulse and the Gaussian even pulse, the fact that the frequency spectrum of the Gaussian single pulse can completely cover the range of 0-800 MHz can be found, whether sensitive frequency point distribution exists in the range of a tested object can be detected by using the Gaussian single pulse, the spectrum distribution of the double Gaussian pulse and the Gaussian even pulse respectively covers the low-frequency region and the high-frequency region of the range to be detected, the pulse distribution range is gradually changed along with the change of the distance Td between the double Gaussian pulse and the distance Te between the Gaussian even pulse, the scanning of the spectrum range to be detected can be realized by comprehensively using the two pulses by using the rule, the frequency bands possibly existing in the sensitive frequency points are gradually reduced, and the distribution range of the sensitive frequency points is finally determined by combining with the positioning algorithm of the sensitive frequency points;
The method comprises the steps of firstly selecting an initial detection pulse and driving a time domain pulse forming module to generate a pulse when a test is started, injecting the pulse into a tested object through an injection probe module, monitoring the response of the tested object and judging whether the tested object is sensitive at the moment, further selecting a proper pulse to test the tested object according to the current test state and the sensitive test condition of the tested object, and finally determining the sensitive frequency point distribution range of the tested object by analyzing the frequency spectrum difference among the pulses;
(III) positioning process is realized by using LABVIEW
The data processing part of the cable conducted sensitivity time domain testing method using the multiple Gaussian pulses is realized in an LABVIEW program, signals are transmitted to a PC end through data acquisition equipment, sensitive response data are called in the LABVIEW program, sensitive information is acquired, a next group of testing pulses are selected according to corresponding sensitive conditions and the current testing state and the sensitive frequency point positioning process, and a time domain pulse forming module is instructed to generate corresponding testing pulses to continue to test in the next step.
2. the method of claim 1 for time domain testing of conducted sensitivity of a cable using multiple Gaussian pulses, comprising: in the sensitive frequency point positioning process, firstly, a Gaussian single pulse with an effective frequency band completely covering 0-800 MHz is used for testing, if the tested article has a sensitive phenomenon, the tested article is indicated to have a sensitive frequency point in a testing range, otherwise, the test is finished if the tested article does not have the sensitive frequency point; if the sensitive frequency points exist, performing a second test, namely selecting double Gaussian pulses with the pulse spacing of 0.5ns to test the tested object, if a sensitive phenomenon occurs, indicating that the sensitive frequency points are distributed in the range of 0-500 MHz, otherwise, distributing the sensitive frequency points in the range of 500-800 MHz; if the second test shows the sensitivity phenomenon, selecting a double-Gaussian pulse with a pulse spacing of 1.0ns for testing the tested object in the third test, if the sensitivity phenomenon appears, indicating that the sensitivity frequency points are distributed at 0-250 MHz, otherwise, distributing at 250-500 MHz; if the second test does not have the sensitivity phenomenon, selecting a Gaussian even pulse with a pulse spacing of 1.0ns for testing the tested object in the third test, wherein if the sensitivity phenomenon occurs, the sensitivity frequency points are distributed at 500-750 MHz, otherwise, the sensitivity frequency points are distributed at 750-800 MHz; by analogy, the multi-Gaussian pulse with proper spacing and form is selected to gradually reduce the possible range of the sensitive frequency point, and finally, an accurate result is obtained.
3. a cable conducted sensitivity time domain test system applied by the method of claim 1 or 2, which comprises a time domain pulse forming module, an injection probe module, a tested object and a signal monitoring and data processing module, wherein the time domain pulse forming module is a test pulse signal generator and can generate multi-Gaussian pulses with the full-bottom pulse width of 0.5ns according to the pulse form and the spacing requirement of the signal monitoring and data processing module, the time domain pulse forming module is connected with the injection probe module and transmits the generated test signals to the injection probe module; the injection probe module ensures that the maximum attenuation of the frequency spectrum component of the test signal is 10dB in the test range of 0-800 MHz, is connected with the tested object, and injects the test signal into the tested object completely to accurately excite the sensitive phenomenon of the tested object; when a tested object receives a test signal, sensitive response is generated on certain frequency spectrum components of the test signal, and the response signal is transmitted to the signal monitoring and data processing module; the signal monitoring and data processing module monitors the sensitive response of the tested object, extracts and analyzes the sensitive characteristic of the response signal, stores the response information after obtaining the sensitive information of the tested object, judges the next group of test pulses according to the sensitive frequency point positioning algorithm, is connected with the time domain pulse forming module, transmits the test pulse information to be generated to the time domain pulse forming module, and controls the time domain pulse forming module to generate new test pulses to continue the next group of tests.
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| CN114509629A (en) * | 2022-01-12 | 2022-05-17 | 北京航空航天大学 | Precision-adaptive cable conducted sensitivity time domain testing device and method |
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