Low-frequency noise measuring system and low-frequency noise measuring method

Abstract

The invention relates to the technical field of noise measurement, and provides a low-frequency noise measurement system and a low-frequency noise measurement method. The low-frequency noise measurement system comprises a first signal acquisition channel, a second signal acquisition channel and a processor. The first signal acquisition channel is used for acquiring a signal of tested equipment and outputting a first channel signal; the second signal acquisition channel is used for acquiring a signal of the tested equipment and outputting a second channel signal; the processor is used for executing the following steps: performing cross-correlation calculation on the first channel signal and the second channel signal to obtain a first low-frequency noise signal; performing wavelet conversion on the first low-frequency noise signal to obtain a converted first low-frequency noise signal; and performing separation processing on the converted first low-frequency noise signal according to the entropy value corresponding to the converted first low-frequency noise signal to obtain a second low-frequency noise signal of the tested equipment. By adopting the system, the influence of the noise of the noise acquisition equipment can be suppressed, and the measurement precision of the low-frequency noise is remarkably improved.

Description

Technical Field

[0001] The present application relates to the technical field of noise measurement, and in particular to a low-frequency noise measurement system and a low-frequency noise measurement method, device, computer-readable storage medium and computer program product. Background Art

[0002] Measuring and analyzing the low-frequency noise generated by electronic devices can not only provide valuable information for improving the performance of electronic and optoelectronic systems, but also be used for evaluating the quality and reliability of electronic equipment.

[0003] Currently, a low-frequency noise measurement system can be built based on transformers and amplifiers to measure low-frequency noise of electronic devices. However, the noise of the noise acquisition device itself in the existing low-frequency noise measurement system, such as the nonlinear characteristics of the amplifier and the quantization noise in the digital-to-analog conversion, will affect the measurement accuracy. Summary of the invention

[0004] Based on this, it is necessary to provide a low-frequency noise measurement system and a low-frequency noise measurement method, device, computer equipment, computer-readable storage medium and computer program product to address the above technical problems.

[0005] In a first aspect, the present application provides a low-frequency noise measurement system, the system comprising: a first signal acquisition channel, a second signal acquisition channel and a processor;

[0006] The first signal acquisition channel is used to acquire the signal of the device under test and output a first channel signal;

[0007] The second signal acquisition channel is used to acquire the signal of the device under test and output a second channel signal;

[0008] The processor is used to perform the following steps:

[0009] Performing cross-correlation calculation on the first channel signal and the second channel signal to obtain a first low-frequency noise signal;

[0010] Performing wavelet transformation on the first low-frequency noise signal to obtain a transformed first low-frequency noise signal;

[0011] According to the entropy value corresponding to the converted first low-frequency noise signal, the converted first low-frequency noise signal is separated and processed to obtain a second low-frequency noise signal of the device under test.

[0012] In one embodiment, the first signal acquisition channel includes a first transformer and a first amplifier, the second signal acquisition channel includes a second transformer and a second amplifier, and the first transformer is the same as the second transformer, and the first amplifier is the same as the second amplifier.

[0013] In one embodiment, the primary winding resistance of the first transformer is less than 10Ω, and the magnetizing inductance of the first transformer is greater than 1H.

[0014] In one embodiment, when the processor performs cross-correlation calculation on the first channel signal and the second channel signal to obtain the first low-frequency noise signal, the method specifically includes:

[0015] Obtaining a plurality of signal pairs according to the first channel signal and the second channel signal;

[0016] According to the plurality of signal pairs, a plurality of cross-spectrums corresponding to the plurality of signal pairs are obtained;

[0017] The plurality of cross-spectra are averaged to obtain a first low-frequency noise signal.

[0018] In one embodiment, when the processor obtains, according to the multiple signal pairs, multiple cross-spectrums corresponding to each of the multiple signal pairs, the processor specifically includes:

[0019] Performing discrete Fourier transform on the multiple signal pairs to obtain multiple signal transformation pairs;

[0020] According to the plurality of signal transformation pairs, a plurality of cross-spectrums corresponding to the plurality of signal pairs are obtained.

[0021] In one embodiment, when the processor performs separation processing on the converted first low-frequency noise signal according to the entropy value corresponding to the converted first low-frequency noise signal to obtain the second low-frequency noise signal of the device under test, the method specifically includes:

[0022] Obtaining a white noise signal according to the minimum entropy value corresponding to the converted first low-frequency noise signal;

[0023] The white noise signal is separated from the converted first low-frequency noise signal to obtain a second low-frequency noise signal of the device under test.

[0024] In a second aspect, the present application further provides a method for measuring low-frequency noise, the method being applied to a low-frequency noise measurement system, the low-frequency noise measurement system comprising a first signal acquisition channel, a second signal acquisition channel and a processor;

[0025] The method is executed by a processor and comprises the following steps:

[0026] Acquire a first channel signal output by the first signal acquisition channel for signal acquisition of the device under test;

[0027] Acquire a second channel signal output by the second signal acquisition channel for signal acquisition of the device under test;

[0028] Performing cross-correlation calculation on the first channel signal and the second channel signal to obtain a first low-frequency noise signal;

[0029] Performing wavelet transformation on the first low-frequency noise signal to obtain a transformed first low-frequency noise signal;

[0030] According to the entropy value corresponding to the converted first low-frequency noise signal, the converted first low-frequency noise signal is separated and processed to obtain a second low-frequency noise signal of the device under test.

[0031] In a third aspect, the present application further provides a low-frequency noise measurement device, the device is applied to a low-frequency noise measurement system, the low-frequency noise measurement system includes a first signal acquisition channel, a second signal acquisition channel and a processor; the device includes:

[0032] A channel signal acquisition module is used to acquire a first channel signal output by the first signal acquisition channel for signal acquisition of the device under test; and to acquire a second channel signal output by the second signal acquisition channel for signal acquisition of the device under test;

[0033] A cross-correlation calculation module, used for performing cross-correlation calculation on the first channel signal and the second channel signal to obtain a first low-frequency noise signal;

[0034] A wavelet transform module, used for performing wavelet transform on the first low-frequency noise signal to obtain a transformed first low-frequency noise signal;

[0035] The separation processing module is used to separate and process the converted first low-frequency noise signal according to the entropy value corresponding to the converted first low-frequency noise signal to obtain a second low-frequency noise signal of the device under test.

[0036] In a fourth aspect, the present application further provides a computer-readable storage medium, wherein a computer program is stored on the computer-readable storage medium, and the computer program is executed by a processor to execute the above method.

[0037] In a fifth aspect, the present application further provides a computer program product, wherein the computer program product comprises a computer program, and the computer program is executed by a processor to execute the above method.

[0038] The above-mentioned low-frequency noise measurement system includes a first signal acquisition channel, a second signal acquisition channel and a processor. The first signal acquisition channel is used to collect signals from the device under test and output a first channel signal; the second signal acquisition channel is used to collect signals from the device under test and output a second channel signal; the processor is used to perform the following steps: perform cross-correlation calculation on the first channel signal and the second channel signal to obtain a first low-frequency noise signal; perform wavelet transformation on the first low-frequency noise signal to obtain a converted first low-frequency noise signal; and perform separation processing on the converted first low-frequency noise signal according to the entropy value corresponding to the converted first low-frequency noise signal to obtain a second low-frequency noise signal of the device under test. The present application performs cross-correlation calculation on the first channel signal and the second channel signal to obtain a first low-frequency noise signal, which can suppress the influence of the noise of the noise acquisition device itself; and performs separation processing on the converted first low-frequency noise signal according to the entropy value corresponding to the first low-frequency noise signal after wavelet transformation to obtain a second low-frequency noise signal of the device under test, which can further suppress the influence of the noise of the noise acquisition device itself, and can achieve excellent noise performance in the low-frequency region, significantly improving the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 is a schematic diagram of a low-frequency noise measurement system in one embodiment;

[0041] Figure 2 is a circuit diagram of a transformer coupled amplifier in one embodiment;

[0042] Figure 3 is another circuit diagram of a transformer coupled amplifier in one embodiment;

[0043] Figure 4 is a schematic diagram of an equivalent circuit of a first transformer in an embodiment;

[0044] Figure 5 is a schematic flow chart of a method for measuring low-frequency noise in one embodiment;

[0045] Figure 6 FIG. 4 is a structural block diagram of a low-frequency noise measuring device in one embodiment. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0047] In one embodiment, a low-frequency noise measurement system includes a first signal acquisition channel, a second signal acquisition channel and a processor, which is suitable for low-frequency noise measurement of low-impedance devices, such as low-frequency noise measurement of advanced detectors with low shunt resistance characteristics, and can provide effective low-frequency noise measurement under source resistance in the range of 1 to 10Ω. The first signal acquisition channel is used to acquire signals of the device under test and output first channel signals; the second signal acquisition channel is used to acquire signals of the device under test and output second channel signals; the processor may include a data acquisition unit and a processing unit, the data acquisition unit is used to acquire the first channel signal and the second channel signal and digitize them, and transmit them to the processing unit, and the processing unit is used to perform the following steps:

[0048] The first channel signal and the second channel signal are cross-correlated to obtain a first low-frequency noise signal; the first low-frequency noise signal is wavelet transformed to obtain a transformed first low-frequency noise signal; and the transformed first low-frequency noise signal is separated and processed according to an entropy value corresponding to the transformed first low-frequency noise signal to obtain a second low-frequency noise signal of the device under test.

[0049] The first channel signal and the second channel signal are the initial low-frequency noise signals collected from the device under test at the same time, wherein the noise collection devices of the first channel and the second channel are the same. When collecting the initial low-frequency noise of the device under test, the noise collection devices of the first channel and the second channel themselves will also generate noise, which will affect the measurement accuracy of the initial low-frequency noise. Since the noise of the noise collection device itself is independent and random in the two channels, and the initial low-frequency noise is the same in the two channels, the first channel signal and the second channel signal can be cross-correlated to obtain the first low-frequency noise signal, which can effectively suppress the noise of the noise collection device itself and improve the measurement accuracy.

[0050] Among them, the specific structure of the low-frequency noise measurement system is as follows: Figure 1 As shown, Figure 1 middle, Indicates the power supply voltage, represents the noise generated by the power supply voltage, represents the noise generated by resistor R1, represents the noise generated by resistor R2, represents the noise generated by resistor R3, Indicates the resistance R of the device under test DUT The noise generated, Indicates the first transformer The noise generated, The second transformer The noise generated, represents the noise generated by the first amplifier VA1, represents the noise generated by the input current of the first amplifier VA1, represents the noise generated by the second amplifier VA2, represents the noise generated by the input current of the second amplifier VA2, , represents the second channel signal, AAF represents anti-aliasing filter, ADC represents analog-to-digital converter, DFT represents discrete Fourier transform, Indicates matching impedance.

[0051] The first low-frequency noise signal can be represented as f(t), and the first low-frequency noise signal is subjected to wavelet transformation to obtain the transformed first low-frequency noise signal, as shown in formula (1).

[0052] (1)

[0053] Wherein, W represents the continuous expression of the first low-frequency noise signal; It is represented as one expression cycle of the first low-frequency noise signal; It is represented as the wavelet basis; t is represented as time; τ is represented as the translation in the wavelet transform; R is represented as the signal conjugate complex number; It is expressed as the effective detection threshold; t .

[0054] The size of the entropy value reflects the density of the noise signal. Therefore, the converted first low-frequency noise signal can be separated and processed according to the entropy value corresponding to the converted first low-frequency noise signal to obtain the second low-frequency noise signal of the device under test, thereby further suppressing the noise of the noise collection device itself and improving the measurement accuracy.

[0055] After obtaining the second low-frequency noise signal of the device under test, the detection performance of the second low-frequency noise signal is optimized through the zero-forcing (ZF) algorithm and the list sphere detector (LSD) algorithm to further suppress the noise of the noise collection device itself. At 1 Hz, the noise of the noise collection device itself (equivalent input background noise) is as low as 1×10 -20 V 2 / Hz. The processed second low-frequency noise signal can be displayed in the form of a chart or data and stored for subsequent analysis.

[0056] The data acquisition unit can also evaluate the second low-frequency noise signal in real time according to the real-time monitored signal-to-noise ratio (SNR), and optimize the signal processing process according to different noise models.

[0057] In this embodiment, the processor of the low-frequency noise measurement system performs cross-correlation calculation on the first channel signal and the second channel signal to obtain a first low-frequency noise signal, which can suppress the influence of the noise of the noise collection device itself; the processor of the low-frequency noise measurement system separates and processes the converted first low-frequency noise signal according to the entropy value corresponding to the first low-frequency noise signal after wavelet transformation to obtain a second low-frequency noise signal of the device under test, which can further suppress the influence of the noise of the noise collection device itself, achieve excellent noise performance in the low-frequency region (below 10 Hz), and significantly improve the measurement accuracy.

[0058] In one embodiment, the first signal acquisition channel includes a first transformer and a first amplifier, and the second signal acquisition channel includes a second transformer and a second amplifier, and the first transformer and the second transformer are the same, and the first amplifier and the second amplifier are the same.

[0059] The first signal acquisition channel may include a first transformer and a first amplifier. The first transformer is used to couple the signal of the device under test to the input terminal of the first amplifier. The first transformer coupling realizes impedance matching and noise optimization to reduce the influence of the equivalent input noise of the first amplifier. The first amplifier is used to amplify the coupled signal. The circuit diagram of the transformer-coupled amplifier is shown in FIG. Figure 2 As shown, R IN represents the resistance of the device under test, Indicates the voltage of the device under test, Represents the voltage at the output of the amplifier.

[0060] In practical applications, since only very low DC voltage can exist at the input end of the first transformer, when the first transformer is used during the biasing of the device under test, a coupling capacitor is required to prevent the DC component from reaching the bridge. At this time, the circuit diagram of the transformer-coupled amplifier is as follows: Figure 3 shown.

[0061] Assume that the device under test (DUT) is a pure resistor R IN , voltage noise source IN represents the low-frequency noise signal of the device under test to be amplified and analyzed. The equivalent circuit of the first transformer is as follows Figure 4 As shown, the winding resistance R p and R s In the equivalent circuit, C1 and C2 represent parasitic capacitance, L Mis the magnetizing inductance, R P and R S is the parasitic resistance caused by the primary and secondary windings, T ID is an ideal transformer with a turns ratio (gain) of n, so:

[0062] (2)

[0063] in and They are ideal transformer T ID The voltages at the primary and secondary ports, and They are transformer T ID Currents in the primary and secondary ports. Real transformers can only approximate the desired performance of an ideal transformer within a limited frequency interval.

[0064] At low frequencies, the magnetizing inductance essentially shorts out the low frequency noise signal from the device under test, preventing it from reaching the input of the amplifier. At higher frequencies, the parasitic capacitances C1 and C2 are responsible for the resonance phenomenon and ultimately short out the low frequency noise signal from the device under test before it reaches the amplifier. The parasitic capacitance is usually negligible because it is small. Assuming that the first amplifier VA has a large input impedance, the low frequency noise signal of the device under test can be estimated. IN and the input voltage of the first amplifier VA The transfer function H T As shown in formula (3).

[0065] (3)

[0066] in IN is the low-frequency noise signal of the device under test, is the input voltage of the first amplifier VA, s is the Laplace transfer variable, is the induction time constant, magnetizing inductance and the primary winding resistance are the parameters of the first transformer, is the resistance of the device under test. Equation (3) clearly shows that the lower frequency inflection point depends on the value of the source impedance, while the parameters of the first transformer ( and ) sets the lowest achievable frequency inflection point (for ≪ ). At 2π ≫( + ) frequency, the gain becomes a constant equal to the turns ratio n. In this case, the loading effect of the first transformer on the source impedance can be assumed to be negligible ( There is no obvious voltage drop on the surface). It can be calculated in is a constant ( The total contribution of all other noise sources within the frequency range of , as shown in formula (4).

[0067] (4)

[0068] in, represents the winding resistance R of the first transformer p The noise generated, represents the winding resistance R of the first transformer s The noise generated, represents the noise generated by the first amplifier, represents the noise generated by the input current of the first amplifier, is the resistance of the device under test.

[0069] The first amplifier can be an ultra-low noise amplifier. The main task of the first amplifier is to amplify the signal coupled by the first transformer while maintaining extremely low self-noise. The noise performance of the amplifier directly affects the overall noise level of the low-frequency noise system. The equivalent input noise voltage (En) of the first amplifier should be as low as possible, usually requiring Below; the first amplifier should have sufficient bandwidth and gain to cover the required measurement frequency range (usually below 1Hz) and amplify the low-frequency noise signal of the device under test to a level that the processor can handle.

[0070] If Dividing by the gain n, we can get the overall equivalent input background noise within the first transformer passband The overall equivalent input background noise can be Directly related to the noise to be measured For comparison, as shown in formula (5).

[0071] (5)

[0072] in, represents the winding resistance R of the first transformer p The noise generated, represents the winding resistance R of the first transformer s The noise generated, represents the noise generated by the first amplifier, represents the noise generated by the input current of the first amplifier, is the resistance of the device under test.

[0073] It is also possible to calculate the equivalent input background noise when the device under test is directly connected to the input of the first amplifier VA , as shown in formula (6).

[0074] (6)

[0075] When comparing equation (6) with equation (5), if is the main source of noise, then the use of the first transformer is obviously more advantageous. In addition, the equivalent input voltage noise of the first amplifier is reduced (measured in power spectral density as n 2 The benefit of increasing the equivalent input current noise of the first amplifier and increasing the noise source from the first transformer winding resistance is at the expense of increasing the equivalent input current noise of the first amplifier and increasing the noise source from the first transformer winding resistance. The second signal acquisition channel includes a second transformer and a second amplifier, and the first transformer and the second transformer are the same, and the first amplifier and the second amplifier are the same.

[0076] In one embodiment, the primary winding resistance of the first transformer is less than 10Ω, and the magnetizing inductance of the first transformer is greater than 1H.

[0077] The primary winding resistance and magnetizing inductance of the first transformer are key factors affecting the measurement performance. The smaller the primary winding resistance, the larger the magnetizing inductance, and the lower the noise introduced by the first transformer. In this embodiment, three transformers of different models are used for testing to show the influence of the primary winding resistance and the characteristic magnetizing inductance on the measurement results, as shown in Table 1.

[0078] Table 1 Specifications of the low noise impedance matching transformer used

[0079] The smaller the primary winding resistance of the first transformer, the lower the thermal noise introduced by the first transformer. As shown in Table 1, when selecting the first transformer, it is best to select a model with a primary winding resistance less than 10Ω. High magnetizing inductance helps the first transformer maintain high impedance in the low-frequency region, so that the low-frequency noise signal of the device under test can be effectively coupled to the first amplifier. Ideally, a first transformer with a magnetizing inductance greater than 1H is selected.

[0080] In this embodiment, selecting a first transformer with a primary winding resistance less than 10Ω and a magnetizing inductance greater than 1H can reduce the thermal noise introduced by the first transformer and maintain high impedance, so that the low-frequency noise signal of the device under test can be effectively coupled to the first amplifier.

[0081] In one of the embodiments, when the processor performs cross-correlation calculation on the first channel signal and the second channel signal to obtain the first low-frequency noise signal, the specific steps are as follows: obtain multiple signal pairs based on the first channel signal and the second channel signal; obtain multiple cross-spectra corresponding to the multiple signal pairs based on the multiple signal pairs; perform mean processing on the multiple cross-spectra to obtain the first low-frequency noise signal.

[0082] Assuming the voltage gain of the transformer-coupled amplifier is constant, the first channel signal is , the formula is shown in formula (7), the second channel signal is , the formula is shown in formula (8).

[0083] (7)

[0084] (8)

[0085] Where A=nG, A is the total voltage gain of the transformer coupled amplifier circuit, G is the first amplifier From the first transformer output gain, or the second amplifier From the second transformer output Here it is assumed that R1 and R2 are much larger than R3 and , so it can be ignored and Typically, and It is a Junction Field-Effect Transistor (JFET) input amplifier, so the input current noise source and The contribution of can also be neglected.

[0086] Although and right and The contribution is the same, but and Only for Contribute, too. and Only for In other words, in the analysis and When, from and The contributions of the first and second channel signals are completely correlated, while the remaining noise sources produce completely uncorrelated contributions between the channels. In this case, the cross spectrum between the two channels contains only the contributions from the correlated noise sources, while the noise contributions due to the uncorrelated contributions are completely rejected. While this is correct in principle, in actual cross-correlation measurements, the cross-correlation calculation of the first channel signal and the second channel signal can be performed by utilizing the properties of the Discrete Fourier Transform (DFT) combined with an improved periodogram method, where the degree to which the contribution of the uncorrelated noise sources is reduced relative to the correlated noise sources depends on the measurement time.

[0087] Specifically, the data stream of the first channel signal and the second channel signal is divided into signal pairs of length N to obtain a plurality of signal pairs; a plurality of cross-spectra corresponding to each of the plurality of signal pairs are obtained according to the plurality of signal pairs; and the plurality of cross-spectra are averaged to obtain uncorrelated noise suppression to obtain a first low-frequency noise signal. The reduction in the contribution of the uncorrelated noise to the estimated cross-spectra is inversely proportional to the reciprocal of the mean number M.

[0088] In this embodiment, a plurality of signal pairs are obtained according to the first channel signal and the second channel signal; and a relatively accurate first low-frequency noise signal can be obtained by performing mean value processing on a plurality of cross-spectra corresponding to each of the plurality of signal pairs.

[0089] In one of the embodiments, when the processor obtains multiple cross-spectra corresponding to each of the multiple signal pairs based on multiple signal pairs, the specific steps are as follows: performing discrete Fourier transform on the multiple signal pairs to obtain multiple signal transformation pairs; and obtaining multiple cross-spectra corresponding to each of the multiple signal pairs based on the multiple signal transformation pairs.

[0090] Discrete Fourier transform is performed on multiple signal pairs to obtain multiple signal transformation pairs.

[0091] According to multiple signal transformation pairs, multiple cross-spectrums corresponding to the multiple signal pairs are obtained, where the discrete frequencies The calculation formula of is shown in formula (9).

[0092] (9)

[0093] in Discrete frequency, is the sampling frequency, parameter Usually called resolution bandwidth, it indicates the lowest frequency other than 0 at which the crossover spectrum can be obtained. The estimated value of .

[0094] In this embodiment, discrete Fourier transform is performed on multiple signal pairs to obtain multiple signal transformation pairs; based on the multiple signal transformation pairs, multiple cross-spectra corresponding to each of the multiple signal pairs are obtained to obtain a first low-frequency noise signal.

[0095] In one of the embodiments, when the processor separates the converted first low-frequency noise signal according to the entropy value corresponding to the converted first low-frequency noise signal to obtain the second low-frequency noise signal of the device under test, the specific steps are as follows: obtaining a white noise signal according to the minimum entropy value corresponding to the converted first low-frequency noise signal; separating the white noise signal from the converted first low-frequency noise signal to obtain the second low-frequency noise signal of the device under test.

[0096] The low-frequency noise detection process can be regarded as a probability distribution sequence, and the entropy value corresponding to the converted first low-frequency noise signal can be obtained by calculation. The entropy value corresponding to the converted first low-frequency noise signal reflects the density of the first low-frequency noise signal, and the serialization degree of the converted first low-frequency noise signal distribution can be extracted, and the converted first low-frequency noise signals at different levels can be separated and processed.

[0097] Specifically, the minimum entropy value corresponding to the converted first low-frequency noise signal can be used as a white noise signal. The white noise signal is separated from the converted first low-frequency noise signal, high-frequency coefficients at different levels in the first low-frequency noise signal from which the white noise signal is separated are subjected to threshold quantization processing, the processed low-frequency noise signal is reconstructed, and the reconstructed low-frequency noise signal is used as the second low-frequency noise signal of the device under test.

[0098] In this embodiment, a white noise signal is obtained according to the minimum entropy value corresponding to the converted first low-frequency noise signal; the white noise signal is separated from the converted first low-frequency noise signal to obtain a second low-frequency noise signal of the device under test, which can further suppress the influence of the noise of the noise acquisition device itself, achieve excellent noise performance in the low-frequency region, and significantly improve the measurement accuracy.

[0099] In one embodiment, a method for measuring low-frequency noise is provided, and the method is applied to a low-frequency noise measurement system, wherein the low-frequency noise measurement system includes a first signal acquisition channel, a second signal acquisition channel, and a processor. This embodiment can be executed by a processor of the low-frequency noise measurement system, and the processor can obtain the first channel signal and the second channel signal, and then obtain the second low-frequency noise signal of the device under test. In this embodiment, the method includes Figure 5 The steps shown are:

[0100] Step S501: obtaining a first channel signal output by a first signal acquisition channel for signal acquisition of a device under test.

[0101] The processor of the low-frequency noise measurement system can obtain, from the first signal acquisition channel, a first channel signal output by the first signal acquisition channel for signal acquisition of the device under test.

[0102] Step S502: obtaining a second channel signal output by a second signal acquisition channel for acquiring signals from a device under test.

[0103] The processor of the low-frequency noise measurement system can obtain, from the second signal acquisition channel, a second channel signal output by the second signal acquisition channel for signal acquisition of the device under test.

[0104] Step S503: perform cross-correlation calculation on the first channel signal and the second channel signal to obtain a first low-frequency noise signal.

[0105] When collecting the initial low-frequency noise of the device under test, the noise collection devices of the first channel and the second channel will also generate noise, which will affect the measurement accuracy of the initial low-frequency noise. Since the noise of the noise collection device itself is independent and random in the two channels, and the initial low-frequency noise is the same in the two channels, the first channel signal and the second channel signal can be cross-correlated to obtain the first low-frequency noise signal, which can effectively suppress the noise of the noise collection device itself and improve the measurement accuracy.

[0106] Step S504: performing wavelet transformation on the first low-frequency noise signal to obtain a transformed first low-frequency noise signal.

[0107] The first low-frequency noise signal can be represented as f(t), and the first low-frequency noise signal is subjected to wavelet transformation to obtain the transformed first low-frequency noise signal, as shown in formula (1).

[0108] (1)

[0109] Wherein, W represents the continuous expression of the first low-frequency noise signal; It is represented as one expression cycle of the first low-frequency noise signal; It is represented by the wavelet basis; R is represented by the signal conjugate complex number; It is indicated as the effective detection threshold.

[0110] Step S505 , performing separation processing on the converted first low-frequency noise signal according to the entropy value corresponding to the converted first low-frequency noise signal to obtain a second low-frequency noise signal of the device under test.

[0111] The size of the entropy value reflects the density of the noise signal. Therefore, the converted first low-frequency noise signal can be separated and processed according to the entropy value corresponding to the converted first low-frequency noise signal to obtain the second low-frequency noise signal of the device under test, thereby further suppressing the noise of the noise collection device itself and improving the measurement accuracy.

[0112] In the above-mentioned low-frequency noise measurement method, the first channel signal and the second channel signal are cross-correlated and calculated to obtain the first low-frequency noise signal, which can suppress the influence of the noise of the noise collection device itself; according to the entropy value corresponding to the first low-frequency noise signal after wavelet transformation, the converted first low-frequency noise signal is separated and processed to obtain the second low-frequency noise signal of the device under test, which can further suppress the influence of the noise of the noise collection device itself, achieve excellent noise performance in the low-frequency region, and significantly improve the measurement accuracy.

[0113] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0114] Based on the same inventive concept, the embodiment of the present application also provides a low-frequency noise measuring device for implementing the low-frequency noise measuring method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in the embodiments of one or more low-frequency noise measuring devices provided below can refer to the limitations of the low-frequency noise measuring method above, and will not be repeated here.

[0115] In an exemplary embodiment, Figure 6 As shown, a low-frequency noise measurement device is provided, and the device is applied to a low-frequency noise measurement system, and the low-frequency noise measurement system includes a first signal acquisition channel, a second signal acquisition channel and a processor, wherein:

[0116] The channel signal acquisition module 601 is used to acquire the first channel signal of the device under test when the first signal acquisition channel acquires and outputs the signal; and acquire the second channel signal of the device under test when the second signal acquisition channel acquires and outputs the signal;

[0117] A cross-correlation calculation module 602, configured to perform cross-correlation calculation on the first channel signal and the second channel signal to obtain a first low-frequency noise signal;

[0118] A wavelet transform module 603, configured to perform wavelet transform on the first low-frequency noise signal to obtain a transformed first low-frequency noise signal;

[0119] The separation processing module 604 is used to separate the converted first low-frequency noise signal according to the entropy value corresponding to the converted first low-frequency noise signal to obtain a second low-frequency noise signal of the device under test.

[0120] Each module in the above-mentioned low-frequency noise measurement device can be implemented in whole or in part by software, hardware and a combination thereof. Each of the above-mentioned modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to each of the above modules.

[0121] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0122] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0123] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0124] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., but are not limited to this.

[0125] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0126] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A low frequency noise measurement system, characterized in that: The system comprises: a first signal acquisition channel, a second signal acquisition channel and a processor; The first signal acquisition channel is used to acquire the signal of the device under test and output a first channel signal; The second signal acquisition channel is used to acquire the signal of the device under test and output a second channel signal; The processor is used to perform the following steps: Performing cross-correlation calculation on the first channel signal and the second channel signal to obtain a first low-frequency noise signal; Performing wavelet transformation on the first low-frequency noise signal to obtain a transformed first low-frequency noise signal; According to the entropy value corresponding to the converted first low-frequency noise signal, the converted first low-frequency noise signal is separated and processed to obtain a second low-frequency noise signal of the device under test.

2. The system according to claim 1, characterized in that The first signal acquisition channel includes a first transformer and a first amplifier, and the second signal acquisition channel includes a second transformer and a second amplifier, and the first transformer is the same as the second transformer, and the first amplifier is the same as the second amplifier.

3. The system according to claim 2, characterized in that The primary winding resistance of the first transformer is less than 10Ω, and the magnetizing inductance of the first transformer is greater than 1H.

4. The system according to claim 1, characterized in that When the processor performs cross-correlation calculation on the first channel signal and the second channel signal to obtain the first low-frequency noise signal, the method specifically includes: Obtaining a plurality of signal pairs according to the first channel signal and the second channel signal; According to the plurality of signal pairs, a plurality of cross-spectrums corresponding to the plurality of signal pairs are obtained; The plurality of cross-spectra are averaged to obtain a first low-frequency noise signal.

5. The system according to claim 4, characterized in that When the processor obtains, according to the plurality of signal pairs, a plurality of cross-spectrums corresponding to the plurality of signal pairs, the method specifically includes: Performing discrete Fourier transform on the multiple signal pairs to obtain multiple signal transformation pairs; According to the plurality of signal transformation pairs, a plurality of cross-spectrums corresponding to the plurality of signal pairs are obtained.

6. The system according to claim 1, characterized in that When the processor performs separation processing on the converted first low-frequency noise signal according to the entropy value corresponding to the converted first low-frequency noise signal to obtain the second low-frequency noise signal of the device under test, the method specifically includes: Obtaining a white noise signal according to the minimum entropy value corresponding to the converted first low-frequency noise signal; The white noise signal is separated from the converted first low-frequency noise signal to obtain a second low-frequency noise signal of the device under test.

7. A method for measuring low-frequency noise, characterized in that: The method is applied to a low-frequency noise measurement system, which includes a first signal acquisition channel, a second signal acquisition channel and a processor; The method is executed by a processor and comprises the following steps: Acquire a first channel signal output by the first signal acquisition channel for signal acquisition of the device under test; Acquire a second channel signal output by the second signal acquisition channel for signal acquisition of the device under test; Performing cross-correlation calculation on the first channel signal and the second channel signal to obtain a first low-frequency noise signal; Performing wavelet transformation on the first low-frequency noise signal to obtain a transformed first low-frequency noise signal; According to the entropy value corresponding to the converted first low-frequency noise signal, the converted first low-frequency noise signal is separated and processed to obtain a second low-frequency noise signal of the device under test.

8. A low-frequency noise measuring device, characterized in that: The device is applied to a low-frequency noise measurement system, which includes a first signal acquisition channel, a second signal acquisition channel and a processor; the device includes: A channel signal acquisition module is used to acquire a first channel signal output by the first signal acquisition channel for signal acquisition of the device under test; and to acquire a second channel signal output by the second signal acquisition channel for signal acquisition of the device under test; A cross-correlation calculation module, used for performing cross-correlation calculation on the first channel signal and the second channel signal to obtain a first low-frequency noise signal; A wavelet conversion module, used for performing wavelet conversion on the first low-frequency noise signal to obtain a converted first low-frequency noise signal; The separation processing module is used to separate and process the converted first low-frequency noise signal according to the entropy value corresponding to the converted first low-frequency noise signal to obtain a second low-frequency noise signal of the device under test.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the system according to any one of claims 1 to 6 are implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the system according to any one of claims 1 to 6 are implemented.

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