Test calibration method and device for non-polarized electrode

Abstract

The invention discloses a test calibration method and device for a non-polarized electrode. The method comprises the following steps: constructing a standard electric field test environment; synchronously acquiring response signals of the measured electrode and the reference electrode; calculating performance parameters such as direct current drift, range, long-term stability and noise power spectral density of the measured electrode; and comparing the parameters with corresponding parameters of the reference electrode to finish calibration. The device comprises a standard electric field generation system, a data acquisition and measurement system and an environment control and guarantee system. According to the invention, multi-parameter, high-precision and traceable systematic testing and calibration of the non-polarized electrode are realized.

Description

Technical Field

[0001] This invention belongs to the field of geophysical electrical exploration technology, and particularly relates to a testing and calibration method and apparatus for a non-polarizable electrode. Background Technology

[0002] Non-polarizable electrodes are key sensors used in geophysical electrical exploration to measure weak natural electric field signals on the Earth's surface. Their performance directly determines the quality and reliability of data collected by exploration methods such as magnetotellurics (MT) and controlled-source magnetotellurics (CSAMT).

[0003] Currently, the industry's performance evaluation of non-polarizable electrodes mainly relies on field comparative tests or simple indoor DC potential tests. These traditional methods have significant technical limitations and shortcomings: First, the testing environment is uncontrollable. Field environments are complex and variable, and factors such as electromagnetic interference, temperature fluctuations, and uneven soil media are difficult to isolate, seriously affecting the accuracy, repeatability, and comparability of test results, and making it impossible to establish a stable and traceable laboratory calibration system. Second, the evaluation dimensions are limited. Existing methods can usually only measure the static DC potential or range of the electrode, making it difficult to systematically and quantitatively evaluate its key performance parameters such as background noise characteristics, long-term time-domain stability, and dynamic range fluctuations over a wide frequency band. Third, there is a lack of traceable standard benchmarks. Existing tests are mostly relative comparisons between electrodes, lacking a known, stable, and accurately reproducible "standard electric field" as an absolute benchmark, making it impossible to achieve absolute value calibration and value transfer of performance parameters. In addition, existing technologies are relatively fragmented and have not formed an integrated and systematic testing platform that covers everything from excitation sources and signal acquisition to environmental control. The testing process relies on manual operation and is susceptible to interference, resulting in low efficiency and difficulty in meeting the requirements for high-precision and repeatable metrological calibration.

[0004] Therefore, there is an urgent need in this field to develop a one-stop testing and calibration method and device that can perform multi-parameter, high-precision, and traceable testing on non-polarized electrodes under controlled experimental conditions, so as to improve the scientificity and reliability of electrode performance evaluation. Summary of the Invention

[0005] This invention proposes a testing and calibration method and apparatus for non-polarized electrodes to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides a method for testing and calibrating a non-polarizable electrode, comprising the following steps:

[0007] Construct a standard electric field testing environment;

[0008] Based on the standard electric field test environment, the response signals of the electrode under test and the reference electrode are acquired synchronously.

[0009] Calculate the performance parameters of the electrode under test based on the response signal;

[0010] The performance parameters of the electrode under test are compared with the performance parameters of the corresponding reference electrode to complete the calibration of the electrode under test.

[0011] Optionally, the steps for constructing the standard electric field test environment include:

[0012] Provide test media and excitation electrodes;

[0013] A known current is applied to the excitation electrode to establish a standard electric field in the test medium.

[0014] Optionally, in the step of providing the test medium and the excitation electrode, the test medium is an electrolyte, and the excitation electrode is a pair of large-area electrodes.

[0015] Optionally, in the step of synchronously acquiring the response signals of the electrode under test and the reference electrode, a multi-channel synchronous measurement device is used for data acquisition.

[0016] Optionally, the multi-channel synchronous measurement device includes at least two of the following: a digital multimeter, a dynamic signal analyzer, and a multi-channel noise analyzer.

[0017] Optionally, the steps for calculating the performance parameters of the electrode under test include:

[0018] Based on the response signal, extract the DC potential information;

[0019] Based on the DC potential information, calculate the DC drift and range parameters;

[0020] The DC drift and range parameters are used as performance parameters for comparison.

[0021] Optionally, the steps for calculating the performance parameters of the electrode under test may also include:

[0022] Based on the response signal, a time-domain analysis is performed to assess long-term stability, and a frequency-domain transformation is performed to calculate the noise power spectral density.

[0023] The present invention also provides a testing and calibration apparatus for a non-polarizable electrode, used to implement the method, comprising:

[0024] A standard electric field generation system is used to generate a standard electric field in a test medium.

[0025] A data acquisition and measurement system is used to simultaneously acquire the response signals of the electrode under test and the reference electrode in the standard electric field.

[0026] Environmental control and assurance systems are used to provide a controlled physical environment for the testing process.

[0027] Optionally, the standard electric field generating system includes: a container for holding an electrolyte, a pair of excitation electrodes immersed in the electrolyte, and a high-precision constant current source connected to the excitation electrodes.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] This invention achieves a comprehensive, accurate, and traceable evaluation of the performance of non-polarizable electrodes by constructing an integrated testing platform and a systematic calibration method. Its technical advantages are mainly reflected in the following aspects: Firstly, through the collaborative operation of a standard electric field generation system and a high-precision measurement system, it achieves high signal-to-noise ratio acquisition of the electrode's multi-dimensional response in a stable, known electric field for the first time in a laboratory setting, providing a reliable benchmark for performance quantification. Secondly, based on multi-channel synchronous acquisition and signal processing technology, it can simultaneously perform one-stop analysis of multiple static and dynamic parameters of the electrode, such as DC drift, long-term stability, and noise spectrum, breaking through the limitation of single-dimensional testing in traditional methods. Thirdly, through a triple environmental protection system, it effectively isolates electromagnetic, vibration, and temperature interference, significantly improving the accuracy and repeatability of weak signal measurements. Fourthly, it uses a metrologically traceable reference electrode as a comparison benchmark, ensuring the traceability and value transferability of test results, providing a reliable metrological basis for electrode R&D screening, quality control, and field applications. Overall, this invention constructs a complete, systematic, and highly interference-resistant electrode performance calibration system, significantly improving the scientific rigor, consistency, and engineering applicability of test results. Attached Figure Description

[0030] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0031] Figure 1 This is a schematic diagram of the device according to an embodiment of the present invention;

[0032] In the diagram: 1. Electromagnetic shielding room; 2. Vibration isolation table; 3. Precision temperature control system; 4. Constant current source; 5. Excitation electrode; 6. Solution pool; 7. Measured non-polarized electrode; 8. Reference electrode; 9. Digital multimeter; 10. Dynamic signal analyzer; 11. Data processing and analysis platform. Detailed Implementation

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0035] Example 1

[0036] This embodiment provides a method for testing and calibrating a non-polarizable electrode, including the following steps:

[0037] Construct a standard electric field testing environment;

[0038] Based on the standard electric field test environment, the response signals of the electrode under test and the reference electrode are acquired synchronously.

[0039] Calculate the performance parameters of the electrode under test based on the response signal;

[0040] The performance parameters of the electrode under test are compared with the performance parameters of the corresponding reference electrode to complete the calibration of the electrode under test.

[0041] The specific implementation process is as follows:

[0042] S1: Environment Setup and System Initialization: Start the environmental control and protection system to ensure that the test environment is in a state of electromagnetic shielding, vibration isolation and constant temperature; place the test medium in the container and install the excitation electrode, the non-polarized electrode under test 7 and the reference electrode 8;

[0043] S2: Standard electric field establishment: A precisely known and stable current I is applied to the excitation electrode through a high-precision constant current source 4 to establish a uniform and stable standard electric field E in the test medium;

[0044] S3: Multi-parameter synchronous data acquisition: Using a data acquisition and measurement system, the potential difference signal between the measured electrode pair and the reference electrode pair under the action of a standard electric field is acquired synchronously.

[0045] S4: Signal Processing and Performance Parameter Calculation: Process the acquired signals and calculate various performance parameters of the non-polarizable electrode, including:

[0046] Based on the DC potential measurement, calculate the DC drift and range of the electrode;

[0047] The long-term stability of the electrode is evaluated based on the time-domain signal.

[0048] Based on frequency domain spectrum analysis, the noise power spectral density of the electrode is calculated;

[0049] S5: Calibration and Comparison: Compare the calculated performance parameters of the electrode under test with the parameters of the reference electrode to complete the calibration and performance evaluation of the non-polarized electrode under test.

[0050] The data processing methods designed are shown in Table 1.

[0051] Table 1

[0052]

[0053] The performance parameters of the non-polarizable electrode are calculated as follows: Assume the sampling frequency of the measurement system is f. s The number of points in a single data segment is N.

[0054] (1) DC drift and range;

[0055] DC potential: For a data sequence V[n] of a certain electrode channel within a time period T, its DC potential V DC for:

[0056]

[0057] Range: The DC potential difference between two measured electrodes (e.g., A and B) at the same time t. The average value over the time period T is expressed as:

[0058] V AB =V DC,A -V DC,B ;

[0059] DC drift: typically defined as the rate of change of DC potential over time. It is determined by linearly fitting different time intervals (e.g., V per hour). DC The value is obtained. Let the time series be ti, and the corresponding DC potential be V. DC (t i The fitted straight line is V. fit (t) = a·t + b.

[0060] Drift rate D is the slope a, and its unit is μV / h or mV / day:

[0061] D=a;

[0062] Drift amount: The total change over a specific time period ΔT, such as the drift amount over 24 hours.

[0063] ΔV 24h =V DC (tend)−V DC (tstart);

[0064] (2) Long-term stability;

[0065] Long-term stability is usually characterized by statistics on the magnitude of fluctuations.

[0066] Standard deviation: For a voltage fluctuation sequence V[n] after removing the long-term trend (or within a short period of time), its standard deviation is... Directly reflects stability:

[0067] ;

[0068] Where μ is The mean is usually close to 0.

[0069] Allan variance: A more professional assessment of the stability of frequency standards. For a DC potential sequence VDC(k) sampled at equal intervals, its overlap Allan variance is calculated as follows:

[0070] ;

[0071] in It is the relevant time, and M is the length. The number of data segments.

[0072] (3) Power spectral density;

[0073] This is a key indicator for evaluating electrode background noise.

[0074] One-sided power spectral density:

[0075] Perform an FFT on each windowed data segment x[n] to obtain the complex spectrum X[k], k=0,1,...,N / 2.

[0076] Calculate the PSD estimate P of this data segment. seg [k]:

[0077] ;

[0078] Formula explanation: It is a periodogram; multiplying by 2 is used to convert the two-sided spectrum to a one-sided spectrum (ignoring negative frequencies); dividing by It normalizes energy to frequency resolution. The power spectrum is obtained by dividing by S. w It is the window function correction factor; for the Hanning window, S w ≈0.375, this step is crucial, as it corrects for power loss caused by windowing and ensures accurate PSD amplitude.

[0079] Average power spectral density:

[0080] The Pseg[k] values ​​from the M data segments are averaged to obtain the final smoothed PSD estimate:

[0081] .

[0082] This embodiment uses a dynamic signal analyzer or a multi-channel noise analyzer to perform multi-channel coherent analysis in order to separate and quantify the noise originating from the electrode under test itself and the inherent noise of the environment and system.

[0083] like Figure 1 As shown, this embodiment also provides a testing and calibration device for a non-polarized electrode, used to implement the method, including:

[0084] A standard electric field generation system is used to generate a standard electric field in a test medium.

[0085] A data acquisition and measurement system is used to simultaneously acquire the response signals of the measured non-polarized electrode 7 and the reference electrode 8 in the standard electric field.

[0086] Environmental control and assurance systems are used to provide a controlled physical environment for the testing process.

[0087] The standard electric field generation system, serving as the testing benchmark, employs a constant current source method. A known current (I) with pA-level accuracy and extremely low noise, generated by a high-performance constant current source, is applied through a pair of large-area excitation electrodes made of inert material (such as a platinum-titanium mesh) in a standard electrolyte-filled cell. Based on the known conductivity (σ) of the medium and Ohm's law (J=σE), a uniform, stable, and precisely known standard electric field (E) can be calculated and generated within the cell.

[0088] The data acquisition and measurement system, serving as the platform's "sensors" and "brain," employs a multi-instrument collaborative measurement architecture. It includes:

[0089] Electrode array: at least one non-polarized electrode to be tested and a pair of reference electrodes traceable by the National Institute of Metrology, which are precisely fixed in a uniform field region along the electric field direction, and the spacing L is precisely measured.

[0090] The measurement equipment array integrates a digital multimeter (for high-precision DC potential and stability measurements), a dynamic signal analyzer 10, and a data processing and analysis platform 11 (for multi-channel synchronous acquisition, spectrum analysis, and precise quantization of noise power spectral density PSD). The system features an input impedance >10 GΩ, nanovolt (nV) level resolution, and extremely low noise floor, and effectively separates signal from noise using coherent analysis techniques.

[0091] Among them, the environmental control and protection system: as a prerequisite for high-precision measurement, this system ensures a pure testing environment through triple isolation:

[0092] Electromagnetic shielding: The entire platform is placed in electromagnetic shielding room 1, which completely isolates the power frequency (50 / 60 Hz) and other external electromagnetic interference.

[0093] Vibration isolation: The test cell is supported by a vibration isolation platform 2 to eliminate the disturbance of mechanical vibration to the electrode-electrolyte interface.

[0094] Precision temperature control: The ambient and solution temperature fluctuations are controlled within ±0.5°C to stabilize the electrode potential and dielectric conductivity.

[0095] The following example illustrates the calibration of a certain type of Ag-AgCl nonpolar electrode:

[0096] 1. Preparation:

[0097] Prepare a 0.1 mol / L high-purity NaCl electrolyte and inject it into a PVC solution tank 6.

[0098] The excitation electrode 5, the non-polarized electrode under test 7, and the reference electrode 8 with metrological traceability are arranged as follows: Figure 1 Install as shown. Ensure the electrode pairs are aligned along the direction of the electric field and accurately measure the electrode spacing L = 10.00 cm.

[0099] Close the door of the electromagnetic shielding room 1, start the precision temperature control system 3, and stabilize the ambient temperature at 25.0±0.2°C.

[0100] 2. Establish a standard electric field:

[0101] A high-precision constant current source 4 is activated to apply a stable DC current of I = 1.000 mA to the excitation electrode 5. The solution conductivity σ is measured to be 1.05 S / m. According to the formula E = J / σ ≈ (I / A) / σ (where A is the effective cross-sectional area through which the current flows), the standard electric field strength E in the uniform field region is calculated to be approximately 0.1 mV / m.

[0102] 3. Data Collection:

[0103] The digital multimeter 9 continuously monitors the DC potential difference of the electrode pair under test for 24 hours to assess its DC stability and drift.

[0104] Simultaneously, the dynamic signal analyzer 10 synchronously acquires the potential difference signal between the tested electrode pair and the reference electrode pair within the 0.01Hz-1kHz frequency band. The analyzer is configured to perform multiple averaging operations to reduce random noise.

[0105] 4. Data processing and calibration, which is achieved through the data processing and analysis platform 11 (data sources are shown in Table 2):

[0106] DC performance: The initial range of the electrode under test was calculated to be 0.8mV from the data of the digital multimeter, and the drift was less than 0.1mV after 24 hours.

[0107] Noise performance: The time-domain data acquired by the dynamic signal analyzer was subjected to FFT transformation to obtain the noise voltage power spectral density (PSD) of the tested electrode and the reference electrode. At 1 Hz, the noise PSD of the tested electrode was 10. -16 V² / Hz, while the reference electrode is 5 × 10⁻⁶. -17 V² / Hz. Coherence analysis confirmed that the difference mainly originated from the electrode under test itself.

[0108] Calibration conclusion: Based on the above data, this batch of Ag-AgCl non-polarized electrodes has good DC performance, but its noise level near 1Hz is about 3dB higher than that of the reference electrode, so it should be used with caution in subsequent high-frequency MT detection.

[0109] Table 2

[0110]

[0111] As can be seen from this embodiment, the present invention can accurately and quantitatively evaluate the comprehensive performance of non-polarizable electrodes, providing a reliable metrological basis for electrode research and development, production screening and field application.

[0112] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for testing and calibrating a non-polarizable electrode, characterized in that, Includes the following steps: Construct a standard electric field testing environment; Based on the standard electric field test environment, the response signals of the electrode under test and the reference electrode are acquired synchronously. Calculate the performance parameters of the electrode under test based on the response signal; The performance parameters of the electrode under test are compared with the performance parameters of the corresponding reference electrode to complete the calibration of the electrode under test.

2. The method according to claim 1, characterized in that, The steps for constructing a standard electric field testing environment include: Provide test media and excitation electrodes; A known current is applied to the excitation electrode to establish a standard electric field in the test medium.

3. The method according to claim 2, characterized in that, In the step of providing the test medium and the excitation electrode, the test medium is an electrolyte, and the excitation electrode is a pair of large-area electrodes.

4. The method according to claim 1, characterized in that, In the step of synchronously acquiring the response signals of the electrode under test and the reference electrode, a multi-channel synchronous measurement device is used for data acquisition.

5. The method according to claim 4, characterized in that, The multi-channel synchronous measurement device includes at least two of the following: a digital multimeter, a dynamic signal analyzer, and a multi-channel noise analyzer.

6. The method according to claim 1, characterized in that, The step of calculating at least one performance parameter of the electrode under test includes: Based on the response signal, extract the DC potential information; Based on the DC potential information, calculate the DC drift and range parameters; The DC drift and range parameters are used as performance parameters for comparison.

7. The method according to claim 6, characterized in that, The steps for calculating the performance parameters of the electrode under test also include: Based on the response signal, a time-domain analysis is performed to assess long-term stability, and a frequency-domain transformation is performed to calculate the noise power spectral density.

8. A testing and calibration apparatus for a non-polarizable electrode, used to implement the method as described in any one of claims 1-7, characterized in that, include: A standard electric field generation system is used to generate a standard electric field in a test medium. A data acquisition and measurement system is used to simultaneously acquire the response signals of the electrode under test and the reference electrode in the standard electric field. Environmental control and assurance systems are used to provide a controlled physical environment for the testing process.

9. The apparatus according to claim 8, characterized in that, The standard electric field generating system includes: a container for holding an electrolyte, a pair of excitation electrodes immersed in the electrolyte, and a high-precision constant current source connected to the excitation electrodes.

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