Microwave radiometer indoor calibration method and device based on multi-parameter environment simulation

Abstract

The application discloses a microwave radiometer indoor calibration method and equipment based on multi-parameter environment simulation, relates to the related technical field of microwave equipment calibration, and comprises the following steps: a controllable atmospheric environment is constructed according to a full electromagnetic wave shielding cylindrical cabin; a microwave signal is transmitted to an environment simulation cabin section through a KV wave band standard signal transmitter in a transmitting end cabin section; a microwave radiometer to be calibrated is pushed into a receiving end cabin section to perform penetration calibration test; an environment-signal coupling response function is established; an analytical correction formula under different environment conditions is used; and an anti-type training correction generation component is arranged in a calibration memory. The application solves the technical problems that in the prior art, a plurality of controllable atmospheric environment parameters cannot be simulated synchronously under laboratory conditions, it is difficult to accurately separate the environment coupling effect and the self response, and the calibration result is deviated from the real running environment, and the technical effects that the measurement precision, the calibration reliability and the environment adaptability of the microwave radiometer under a complex atmospheric environment are improved are achieved.

Description

Technical Field

[0001] This invention relates to the technical field of microwave equipment calibration, specifically to an indoor calibration method and equipment for microwave radiometers based on multi-parameter environmental simulation. Background Technology

[0002] Microwave radiometers, as highly sensitive passive microwave remote sensing devices, are widely used to receive the weak microwave signals emitted by target objects to invert key parameters such as physical temperature, humidity, and dielectric properties. With the increasing demand for quantitative remote sensing, the accuracy requirements for microwave radiometer measurements have reached unprecedented levels. Traditional microwave radiometer calibration mainly relies on field calibration or on-board cold air / blackbody two-point calibration. However, during field calibration, microwave radiometers are inevitably affected by complex and variable environmental factors such as atmospheric turbulence, rainfall, temperature changes, and surface clutter, resulting in limited calibration accuracy. While microwave anechoic chambers can shield against external electromagnetic interference, they cannot simulate the combined environmental conditions of vacuum, low temperature, and different atmospheric compositions, making it difficult for calibration results to fully reproduce the real physical field environment during on-orbit operation. Furthermore, when electromagnetic waves propagate in a non-uniform atmosphere, refraction, attenuation, and phase delay occur. The transmission effects caused by the environment are highly coupled with the radiometer's own system response, making it difficult for existing linear correction models to accurately separate these effects, thus introducing inversion errors. How to reproduce a controllable, multi-layered atmospheric environment under laboratory conditions and accurately decouple the influence of environmental factors on microwave radiation transmission is a key breakthrough that urgently needs to be made in current microwave radiation metrology.

[0003] Therefore, current technologies have technical problems such as the inability to simultaneously simulate multiple controllable atmospheric environmental parameters under laboratory conditions, difficulty in accurately separating environmental coupling effects from their own responses, and resulting in calibration results deviating from the real operating environment. Summary of the Invention

[0004] This application provides an indoor calibration method and equipment for microwave radiometers based on multi-parameter environmental simulation. This solves the technical problems in the prior art, such as the inability to simultaneously simulate multiple controllable atmospheric environmental parameters under laboratory conditions, the difficulty in accurately separating environmental coupling effects from the self-response, and the resulting deviation of calibration results from the real operating environment. This achieves the technical effect of improving the measurement accuracy, calibration reliability, and environmental adaptability of microwave radiometers in complex atmospheric environments.

[0005] This application provides an indoor calibration method for microwave radiometers based on multi-parameter environmental simulation. The method includes: constructing a controllable atmospheric environment using a fully shielded cylindrical chamber; transmitting microwave signals of preset frequency and preset amplitude to the environmental simulation chamber via a transmitting antenna using a KV-band standard signal transmitter calibrated by a third party in the transmitting section; pushing the microwave radiometer to be calibrated into the receiving section, rotating the receiving antenna to a horizontal position facing the transmitting antenna, performing a penetration calibration test, and receiving the penetrating microwave signal through the controllable atmospheric environment in the environmental simulation chamber; establishing an environment-signal coupling response function based on the microwave signal, the penetrating microwave signal, and the layered uniform field; inverting the analytical correction formula of the microwave radiometer to be calibrated under different environmental conditions, and deploying an adversarial training correction generation component in the calibration memory of the microwave radiometer to be calibrated, wherein the analytical correction formula is defined by the channel gain coefficient, the noise temperature coefficient, and the atmospheric attenuation compensation coefficient.

[0006] In a possible implementation, the cylindrical cabin is divided axially into a transmitter section, an environment simulation section, and a receiver section; wherein, the transmitter section houses a standard signal transmitter and a transmitting antenna; the environment simulation section contains a standard material cavity, which is equipped with a control unit based on temperature, humidity, and pressure, and each control unit is equipped with a standard device, thereby constructing a controllable atmospheric environment based on a layered uniform field according to the standard material cavity; the receiver section is used to house a microwave radiometer to be calibrated and a receiving antenna.

[0007] In possible implementations, the microwave signals transmitted by the standard signal transmitter at each preset frequency and preset amplitude include pure carrier mode, modulation mode, and frequency sweep mode; wherein, the pure carrier mode is used to measure channel gain and path attenuation; the modulation mode is used to measure channel bandwidth and group delay characteristics; and the frequency sweep mode is used to obtain the response curve within the frequency band.

[0008] In possible implementations, penetration calibration includes direct penetration calibration and differential penetration calibration: direct penetration calibration measures the received power after signal penetration by filling a standard material cavity with a controlled atmospheric environment; differential penetration calibration uses the received power measured under vacuum conditions of the standard material cavity as a reference, and obtains the measured value of the atmospheric absorption coefficient by differential calculation under different atmospheric environmental conditions. In differential penetration calibration, the accuracy of radiometer correction inversion is verified.

[0009] In a possible implementation, before retrieving the analytical correction formula for the microwave radiometer to be calibrated under different environmental conditions, the method further includes: determining a test frequency point; measuring the attenuation of the microwave signal emitted by the standard signal transmitter after penetrating dry air; wherein the test frequency point is a window frequency point with a known atmospheric absorption coefficient and insensitive to humidity, using dry air as the reference atmospheric environment; inferring the equivalent transmission path length of the electromagnetic wave in the standard material cavity through the microwave radiation transmission equation based on the attenuation and theoretical absorption coefficient; and writing the equivalent transmission path length as a fixed parameter into the calibration memory.

[0010] In a possible implementation, the analytical correction formula for the microwave radiometer to be calibrated under different environmental conditions is retrieved, including: using the measured values ​​based on the layered uniform field as measured environmental parameters describing the atmospheric medium characteristics; combining the measured environmental parameters with the characteristics of the transmitted signal to drive the microwave radiation transmission equation and calculate the theoretical receiving characteristics, wherein the theoretical receiving characteristics include the theoretical receiving brightness temperature; controlling a standard signal transmitter to transmit a first microwave signal, which is received by the microwave radiometer to be calibrated, and recording the measured receiving brightness temperature based on the first penetrating microwave signal; and solving the channel response characteristics of the microwave radiometer to be calibrated and the transmission effects introduced by the atmospheric environment by comparison and nonlinear least squares fitting based on the theoretical receiving characteristics and the measured receiving brightness temperature.

[0011] In a possible implementation, after solving the channel response characteristics of the microwave radiometer to be calibrated and the transmission effect introduced by the atmospheric environment, the following steps are taken: defining independent and dependent variables, wherein environmental parameters are used as independent variables and calibration coefficients are used as dependent variables, and the calibration coefficients include channel gain coefficients, noise temperature coefficients, and atmospheric attenuation compensation coefficients; using the equivalent transmission path as a constraint, performing multiple regression calculations and linear surrogate optimization iterations based on independent and dependent variables on the transmission effect to determine the analytical correction formula.

[0012] In one possible implementation, an initial analytical correction curve is determined through multiple regression analysis; the initial analytical correction curve is segmented and linearized in parallel, using trend reversal as a first type of cut point and the change exceeding the limit as a second cut point, and digitized into the analytical correction formula.

[0013] In one possible implementation, an adversarial training correction generation component is employed and deployed in the calibration memory of the microwave radiometer to be calibrated. This includes: constructing the correction generation component based on the analytical correction formula; randomly selecting a set of environmental parameter combinations not involved in the fitting process, conducting tests within a standard material cavity, determining the radiometer's measured values, and performing calculations based on the analytical correction formula; using a correction judgment component to compare the corrected values ​​with known true values, and determining incremental learning features; feeding the incremental learning features back to the correction generation component, performing optimization and iterative training of the analytical correction formula until training convergence, and determining the completed correction generation component, which is then embedded in the calibration memory.

[0014] This application also provides an electronic device, including: a memory for storing executable instructions; and a processor for executing the executable instructions stored in the memory to implement an indoor calibration method for a microwave radiometer based on multi-parameter environmental simulation.

[0015] This application proposes a method and equipment for indoor calibration of microwave radiometers based on multi-parameter environmental simulation. A controllable atmospheric environment is constructed using a fully shielded cylindrical chamber. Microwave signals are transmitted from the transmitting chamber to the simulated environment chamber via a KV-band standard signal transmitter. The microwave radiometer to be calibrated is then pushed into the receiving chamber to perform a penetration calibration test. An environment-signal coupling response function is established, and an adversarial training calibration generation component is deployed in the calibration memory using analytical correction formulas under different environmental conditions. This method solves the technical problems in existing technologies, such as the inability to simultaneously simulate multiple controllable atmospheric environmental parameters under laboratory conditions and the difficulty in accurately separating environmental coupling effects from the radiometer's own response, leading to calibration results that deviate from the actual operating environment. This achieves the technical effect of improving the measurement accuracy, calibration reliability, and environmental adaptability of microwave radiometers in complex atmospheric environments. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments of this disclosure will be briefly described below. Flowcharts are used in this application to illustrate the operations performed by the system according to the embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed precisely in sequence. Instead, various steps can be processed in reverse order or simultaneously as needed. Furthermore, other operations can be added to these processes, or one or more steps can be removed from these processes.

[0017] Figure 1 This is a schematic diagram of the indoor calibration method for a microwave radiometer based on multi-parameter environmental simulation, provided in an embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0019] Explanation of reference numerals in the attached drawings: Input device 401, processor 402, memory 403, output device 404. Detailed Implementation

[0020] To further illustrate the technical means and effects adopted by the present invention in order to achieve the intended purpose, the following detailed description is provided in conjunction with the accompanying drawings and preferred embodiments, based on the specific implementation methods, structures, features and effects of the present invention.

[0021] This application provides an indoor calibration method for microwave radiometers based on multi-parameter environmental simulation, such as... Figure 1 As shown, the method includes: Step S100: Construct a controllable atmospheric environment based on a cylindrical cabin that is fully shielded from electromagnetic waves.

[0022] Step S100 further includes dividing the cylindrical cabin axially into a transmitter section, an environment simulation section, and a receiver section; wherein, the transmitter section houses a standard signal transmitter and a transmitting antenna; the environment simulation section contains a standard material cavity, which is equipped with a control unit based on temperature, humidity, and pressure, and each control unit is equipped with a standard device, thereby constructing a controllable atmospheric environment based on a layered uniform field according to the standard material cavity; the receiver section is used to house a microwave radiometer to be calibrated and a receiving antenna.

[0023] Preferably, the fully electromagnetically shielded cylindrical chamber refers to a cylindrical, enclosed cavity structure made of electromagnetic shielding material. This structure blocks electromagnetic waves from entering the cavity and prevents leakage, ensuring that microwave measurements performed within the chamber are not interfered with by external electromagnetic interference. A controllable atmospheric environment is constructed within the cylindrical chamber, including setting and adjusting atmospheric parameters such as gas composition, temperature, humidity, and air pressure to achieve the specific conditions required for the experiment. The cylindrical chamber is axially divided into a transmitting section, an environmental simulation section, and a receiving section. The transmitting section is the first independent compartment along the axial direction, housing a standard signal transmitter and a transmitting antenna. The standard signal transmitter is an instrument capable of generating microwave signals, whose frequency and power amplitude are calibrated by a higher-level metrology institution. The transmitting antenna is a device connected to the output of the standard signal transmitter, used to convert the microwave signals generated by the transmitter into electromagnetic waves that propagate in space and radiate them into the environmental simulation section.

[0024] Preferably, the environmental simulation chamber refers to an independent intermediate section divided along the axial direction of the cylindrical chamber, located between the transmitter and receiver sections. It contains a standard material cavity to generate and maintain a specific atmospheric environment. The standard material cavity is a container with a defined geometry and volume installed inside the environmental simulation chamber to hold the controlled atmospheric medium. It is equipped with temperature, humidity, and pressure-based control units, i.e., actuators connected to the standard material cavity, used to change the physical state within the cavity. The temperature control unit raises or lowers the gas temperature within the standard material cavity, the humidity control unit increases or decreases the water vapor content within the standard material cavity, and the pressure control unit increases or decreases the gas pressure within the standard material cavity. Each control unit is equipped with a standard instrument, which is an installed measuring instrument used to monitor and provide real-time feedback of the actual temperature, humidity, and pressure values ​​after control, ensuring the accuracy of environmental parameters. A controllable atmospheric environment based on a layered uniform field is constructed using the standard material cavity. This means that the gas within the standard material cavity is divided into several layers in the vertical or horizontal direction through the control units, with uniform temperature, humidity, and pressure distribution within each layer.

[0025] Preferably, the receiving section refers to the independent end compartment of the cylindrical body along the axial direction, used to house the microwave radiometer to be calibrated and the receiving antenna. The microwave radiometer to be calibrated is a microwave radiation receiving device whose measurement performance indicators such as gain and noise figure need to be determined. The receiving antenna is a device connected to the input end of the microwave radiometer to be calibrated, used to receive electromagnetic wave signals propagated from the environmental simulation section. During calibration testing, the antenna is mechanically rotated to point in the direction of the transmitting antenna.

[0026] In step S200, at the transmitting end section, a microwave signal with a preset frequency and preset amplitude is transmitted to the environmental simulation section via a transmitting antenna through a KV band standard signal transmitter calibrated by a third party.

[0027] Step S200 further includes the standard signal transmitter transmitting microwave signals at various preset frequency points and preset amplitudes, including pure carrier mode, modulation mode and frequency sweep mode; wherein, the pure carrier mode is used to measure channel gain and path attenuation; the modulation mode is used to measure channel bandwidth and group delay characteristics; and the frequency sweep mode is used to obtain the response curve within the frequency band.

[0028] Preferably, in the transmitting section, a KV-band standard signal transmitter capable of generating microwave signals in the 18GHz to 27GHz frequency range transmits microwave signals with preset frequencies and preset amplitudes to the environmental simulation section via a transmitting antenna. Specifically, this standard signal transmitter is tested and calibrated by a metrology institution independent of the equipment manufacturer and user, and its output signal's frequency accuracy, power amplitude accuracy, and other indicators are traceable to metrology standards, serving as a signal source with known values ​​during calibration. The preset frequency refers to the specific frequency value of the microwave signal output by the standard signal transmitter, and the preset amplitude refers to the specified frequency value of the standard signal. The specific power level of the microwave signal output by the transmitter; the microwave signals transmitted by the standard signal transmitter at each preset frequency and preset amplitude include pure carrier mode, modulation mode and frequency sweep mode. Among them, pure carrier mode means that the standard signal transmitter only outputs a continuous wave of a single frequency without any modulation of that frequency, that is, without any added modulation signal. It is used to measure channel gain, that is, by comparing the signal power received by the radiometer with the known transmission power of the transmitter, the amplification factor of the signal of the entire transmission channel is calculated, as well as path attenuation, that is, by measuring the amount of power reduction of the signal from the transmitting antenna to the receiving antenna due to atmospheric absorption, diffusion and other factors.

[0029] Preferably, the modulation mode refers to the transmitter adding a known modulation signal to the carrier wave, such as varying the amplitude or frequency according to a specific pattern. This is used to measure channel bandwidth, i.e., by analyzing the radiometer's response to different frequency components in the modulation signal, the effective frequency range of the receiving channel can be determined. It also measures group delay characteristics, i.e., by analyzing the relationship between the delay time of the modulation signal's envelope after passing through the transmission channel and the frequency, the consistency of the channel's time delay for different frequency components can be determined. The frequency sweep mode refers to the transmitter output signal frequency continuously varying and scanning between a set start frequency and a set end frequency while maintaining a constant output amplitude. This is used to obtain the response curve within the frequency band. During the frequency sweep, the response amplitude at the output of the microwave radiometer to be calibrated is continuously recorded, thus obtaining a continuous curve showing the gain or attenuation characteristics of the radiometer and transmission channel at various frequency points throughout the entire set frequency range.

[0030] Step S300: Push the microwave radiometer to be calibrated into the receiving compartment, turn the receiving antenna to a horizontal position facing the transmitting antenna, perform a penetration calibration test, and receive the penetration microwave signal through the controlled atmospheric environment in the environmental simulation compartment.

[0031] Step S300 further includes penetration calibration, which includes direct penetration calibration and differential penetration calibration: direct penetration calibration measures the received power after signal penetration by filling the standard material cavity with a controlled atmospheric environment; differential penetration calibration uses the received power measured by the standard material cavity under vacuum conditions as a reference, and obtains the measured value of the atmospheric absorption coefficient by differential calculation through measurements under different atmospheric environmental conditions, wherein differential penetration calibration performs accuracy verification of radiometer correction inversion.

[0032] Preferably, the microwave radiometer to be calibrated is brought into the receiving chamber of the cylindrical cabin by a mechanical transfer device and fixed in the working position. A mechanical rotation mechanism changes the orientation of the receiving antenna connected to the microwave radiometer to be calibrated, aligning its axis with the transmitting antenna located in the transmitting section in the horizontal plane, ensuring that the main beam center axes of the two antennas coincide. Then, a penetration calibration test is performed to obtain the penetrating microwave signal through the controlled atmospheric environment within the environmental simulation chamber. That is, the microwave signal emitted by the transmitting antenna completely passes through the internal space of the environmental simulation chamber located between the transmitting and receiving ends, and is ultimately captured by the receiving antenna and its characteristics are measured by the microwave radiometer to be calibrated. Penetration calibration includes direct penetration calibration and differential penetration calibration. In direct penetration calibration, with the standard material cavity filled with a controlled atmospheric environment, a standard signal transmitter is turned on to emit a microwave signal, and the microwave radiometer to be calibrated measures the signal after it penetrates the gas medium and reaches the receiving end. Power value; Differential penetration calibration involves evacuating the air from a standard material cavity to create a vacuum. The received microwave signal power is measured and recorded under this vacuum. Subsequently, multiple controllable atmospheric environments with different conditions are established within the standard material cavity, and the received microwave signal power is measured and recorded under each condition. The power values ​​measured under each atmospheric environment condition are then compared with the reference power value measured under vacuum to calculate the power difference. Based on the power difference and the known transmission signal frequency and equivalent transmission path length, the actual absorption coefficient of the microwave under that atmospheric environment is deduced using physical formulas. Differential penetration calibration verifies the accuracy of the radiometer calibration inversion, including comparing the measured atmospheric absorption coefficient calculated by differential penetration calibration with the predicted absorption coefficient calculated based on a theoretical model, to determine the accuracy of the inversion calculation results of the microwave radiometer under calibration.

[0033] Step S400: Based on the microwave signal, the penetrating microwave signal and the layered uniform field, establish the environment-signal coupling response function. By inverting the analytical correction formula of the microwave radiometer to be calibrated under different environmental conditions, use an adversarial training correction generation component and deploy it in the calibration memory of the microwave radiometer to be calibrated. The analytical correction formula is defined by the channel gain coefficient, the noise temperature coefficient and the atmospheric attenuation compensation coefficient.

[0034] Preferably, an environment-signal coupling response function is established using the parameter distribution of each layer of the layered uniform field as input and the amplitude attenuation or phase change of the transmitted microwave signal compared to the original microwave signal as output. This function is used to quantitatively describe the specific impact of a particular atmospheric environment on microwave signal transmission. Then, based on the original microwave signal and the measured transmitted microwave signal, inversion is performed to derive and determine the parameters of the characteristic of the microwave radiometer to be calibrated, generating analytical correction formulas under different environmental conditions. The analytical correction formulas are defined by the channel gain coefficient, the noise temperature coefficient, and the atmospheric attenuation compensation coefficient. They can calculate the correction amount to be applied to the measured value of the microwave radiometer to be calibrated based on the current environmental parameters such as temperature, humidity, and pressure. The channel gain coefficient is used to correct the deviation of the signal amplification factor of the receiving link of the microwave radiometer to be calibrated, the noise temperature coefficient is used to correct the deviation of the noise power generated by the internal circuit of the microwave radiometer to be calibrated as a function of the environment, and the atmospheric attenuation compensation coefficient is used to correct the signal attenuation caused by the absorption of microwave energy by atmospheric gases.

[0035] Preferably, an adversarial training correction generation component is used. This component receives real-time environmental parameters as input, runs an analytical correction formula, and outputs a specific correction value. Specifically, using a set of known environmental parameters, the correction generation component calculates the correction value, applies the calculated correction value to new measured data, and compares the application result with a higher-level reference standard. Based on the deviation characteristics of the comparison result, the parameters inside the correction generation component are adjusted in reverse, such as adjusting the specific values ​​of the gain coefficient and noise temperature coefficient. This process is repeated until the deviation is controlled within a preset threshold. Finally, the correction generation component is deployed in the calibration memory of the microwave radiometer to be calibrated. The calibration memory refers to a non-volatile memory chip on the hardware circuit board of the microwave radiometer to be calibrated used to store calibration data. That is, the correction generation component is written into the calibration memory chip in the form of data or code. The microwave radiometer to be calibrated can directly call the contents of the memory for real-time correction during actual operation.

[0036] Furthermore, step S400 also includes determining a test frequency point and measuring the attenuation of the microwave signal emitted by the standard signal transmitter after penetrating dry air. The test frequency point is a window frequency point with a known atmospheric absorption coefficient and insensitive to humidity, using dry air as the reference atmospheric environment. Based on the attenuation and theoretical absorption coefficient, the equivalent transmission path length of the electromagnetic wave in the standard material cavity is inferred by inverse reasoning through the microwave radiation transmission equation. The equivalent transmission path length is written into the calibration memory as a fixed parameter.

[0037] Preferably, before starting the measurement, a specific frequency value is selected from the microwave band as the working frequency for this test. The gas medium state inside the standard material cavity is set to dry air without water vapor through the control unit. At a window frequency with a known atmospheric absorption coefficient that is insensitive to humidity (where the atmospheric absorption coefficient refers to the absorption rate of microwave energy by a gas per unit distance, and there are generally accepted precise theoretical values ​​or experimental data available), the absorption of microwaves by dry air is dominant at this frequency, and the effect of changes in water vapor content on the total absorption is negligible. Then, with the standard material cavity filled with dry air, the standard signal transmitter is turned on to output the microwave signal at the selected test frequency, which is received by the microwave radiometer to be calibrated. The power values ​​of the transmitted and received signals are recorded, and the difference between the two is calculated to determine the attenuation. The measured attenuation is then... As a known result, the theoretical absorption coefficient of dry air at this frequency is used as a known parameter and substituted into the microwave radiative transfer equation for inverse calculation. The microwave radiative transfer equation describes the relationship between energy attenuation and path length when electromagnetic waves propagate in a medium, thereby estimating and determining the equivalent transmission path length, which represents the electromagnetic wave propagation distance required to produce the measured attenuation under the assumption of a homogeneous medium. Finally, the equivalent path length value calculated by inverse calculation is used as a fixed parameter and stored in the non-volatile memory chip inside the microwave radiometer to be calibrated. Since the axial length of the standard material cavity is not the actual transmission path, a path loss-based correction is performed on it, that is, the deviation between the actual path and the geometric path caused by factors such as antenna near-field effect, multipath reflection, and beam divergence is corrected in all actual calibration calculations to ensure the inversion accuracy of indicators such as atmospheric absorption coefficient.

[0038] Furthermore, step S400 also includes using the measured values ​​based on the layered uniform field as measured environmental parameters describing the atmospheric medium characteristics; combining the measured environmental parameters with the characteristics of the transmitted signal to drive the microwave radiative transfer equation and calculate the theoretical receiving characteristics, wherein the theoretical receiving characteristics include the theoretical receiving brightness temperature; controlling a standard signal transmitter to transmit a first microwave signal, which is received by the microwave radiometer to be calibrated, and recording the measured receiving brightness temperature based on the first penetrating microwave signal; and, based on the theoretical receiving characteristics and the measured receiving brightness temperature, solving the channel response characteristics of the microwave radiometer to be calibrated and the transmission effect introduced by the atmospheric environment by comparison and nonlinear least squares fitting.

[0039] Preferably, the values ​​read in real time by the standard instrument installed on the standard material cavity are used as quantitative input data describing the current atmospheric state. Specifically, this includes the temperature, humidity, and pressure values ​​of each atmospheric layer. The measured environmental parameters and known transmitted signal characteristics are substituted into the microwave radiative transfer equation to perform forward calculations, determining the signal state that the receiver should measure under ideal conditions, as well as the received signal intensity value expressed in brightness temperature, calculated based on the current atmospheric state and transmission path, i.e., the theoretical received brightness temperature. While maintaining a layered uniform field state in the standard material cavity, the standard signal transmitter is activated to emit a first microwave signal with a specific frequency and amplitude. This signal penetrates the atmospheric environment and is received by the microwave to be calibrated. The radiometer receives the signal and records its measurement results, which are then determined as the measured received brightness temperature. The theoretical received brightness temperature is then compared with the measured brightness temperature to determine the difference between the two. A nonlinear least-squares fitting method is used, and by repeatedly adjusting the parameters to be determined, the sum of squares of the differences between the theoretical and measured values ​​is minimized. This allows for the calculation of the channel response characteristics of the microwave radiometer to be calibrated. This involves understanding the combined influence of the radiometer's own hardware, such as amplifiers, mixers, and filters, on the signal amplitude and phase, manifested as deviations in parameters such as gain and bandwidth, as well as the transmission effects introduced by the atmospheric environment—the additional attenuation of the signal during propagation due to atmospheric absorption and refraction.

[0040] Furthermore, step S400 also includes defining independent and dependent variables, wherein environmental parameters are used as independent variables and calibration coefficients are used as dependent variables, and the calibration coefficients include channel gain coefficients, noise temperature coefficients, and atmospheric attenuation compensation coefficients; and using the equivalent transmission path as a constraint, performing multiple regression calculations and linear surrogate optimization iterations based on independent and dependent variables on the transmission effect to determine the analytical correction formula.

[0041] Preferably, environmental parameters are used as independent variables, and calibration coefficients such as channel gain coefficient, noise temperature coefficient, and atmospheric attenuation compensation coefficient are used as dependent variables. The equivalent transmission path is used as a constraint in the calculation process. The transmission effect introduced by the separated atmospheric environment is taken as the analysis object. Multiple regression analysis is used to establish a mathematical relationship between the dependent variable and multiple independent variables. The calibration coefficients that accurately describe the transmission effect under different environmental parameters are solved. When solving complex nonlinear relationships, a simplified linear surrogate model is first constructed to replace the original problem for rapid calculation. The calculation-verification-correction cycle is repeated. The parameters of the linear surrogate model are adjusted in each cycle to gradually approximate the real physical relationship. Finally, the analytical correction formula is determined, and a quantitative relationship is established between environmental parameters such as temperature, humidity, and pressure and calibration coefficients such as channel gain coefficient, noise temperature coefficient, and atmospheric attenuation compensation coefficient.

[0042] Furthermore, step S400 also includes determining an initial analytical correction curve through multiple regression calculation; using trend reversal as a first type of cut point and exceeding the limit of change as a second cut point, the initial analytical correction curve is segmented and linearized in parallel to be integrated and digitized into the analytical correction formula.

[0043] Preferably, multiple regression is used to fit and solve the environmental parameters and corresponding calibration coefficients based on measured data points to determine an initial analytical calibration curve, which describes the continuous relationship between the calibration coefficients and environmental parameters across the entire range of environmental parameter variations. Then, specific points on the initial analytical calibration curve where the curve slope changes significantly are identified and marked as trend inflection points. These trend inflection points are used as a type of cut point to divide the curve into different segments. Next, specific points on the initial analytical calibration curve where the numerical change of the calibration coefficient exceeds a preset threshold are identified and marked as exceeding the limit. These exceeding the limit are used as a second cut point to divide the curve into different segments. Then, each independent segment is linearized, that is, a straight line segment approximates the original curve segment within each segment. After linearizing all segments, these straight line segments are combined according to the original segment order to form a complete, piecewise continuous set of linear functions. Finally, this is converted into a data structure that can be directly stored and retrieved in digital circuits, typically containing the start and end ranges of each segment and corresponding parameters such as the slope and intercept of the straight line. This ultimately becomes the analytical calibration formula used for calculation during the actual operation of the microwave radiometer to be calibrated.

[0044] Furthermore, step S400 also includes: constructing a calibration generation component according to the analytical calibration formula; randomly selecting a set of environmental parameter combinations that were not involved in the fitting, conducting tests in a standard material cavity, determining the measured values ​​of the radiometer and performing calculations based on the analytical calibration formula; performing a judgment between the calibration value and the known true value according to the calibration judgment component to determine the incremental learning features; feeding the incremental learning features back to the calibration generation component, performing optimization and iterative training of the analytical calibration formula until the training converges, determining the completed calibration generation component, and embedding it in the calibration memory.

[0045] Preferably, the analytical correction formula is encapsulated to construct a correction generation component, which can output corresponding calibration coefficients based on the input real-time environmental parameters. Specifically, a set of environmental parameter combinations not involved in the fitting is randomly selected from all possible environmental parameter values, including temperature, humidity, and pressure. Testing is conducted within a standard material chamber. That is, the atmospheric environment within the standard material chamber is actually set to the environmental parameter combination state through a control unit, and a complete signal transmission and reception test procedure is executed. Under this test state, the original output value actually measured by the microwave radiometer to be calibrated is recorded to determine the radiometer's measured value. Simultaneously, the current environmental parameters are input into the correction generation component to perform calculations based on the analytical correction formula, calculate and determine the corresponding calibration coefficients, and apply them to the radiometer's measured value. A correction judgment component is used to compare the corrected value with the known true value. The correction judgment component is a functional module used for comparison and evaluation. The known true value is the accurate measurement value obtained through a standard signal transmitter and differential penetration calibration under this test state. The calibration generator compares the corrected value output by the calibration generator with the known true value, calculates the deviation value and deviation characteristics between the two, such as the direction, magnitude, and variation pattern of the deviation, and then extracts incremental learning features that the calibration generator can use to improve its own performance. Then, the extracted deviation feature information is passed as input to the calibration generator, so that it knows the difference between its current output and the true value. Then, the optimization and iterative training of the analytical calibration formula is performed. That is, the calibration generator automatically adjusts the parameters of the analytical calibration formula stored in its internal storage according to the received incremental learning features, such as adjusting the segment interval, modifying the slope or intercept of the line, and repeating the cycle of randomly selecting new parameters-testing-judging-feedback-adjusting until the deviation value fed back by the calibration judgment component is continuously stable within the pre-set allowable error range and no longer significantly improves with further iterations. The calibration generator is then determined to be completed. Finally, the calibration generator is written into the non-volatile memory chip on the microwave radiometer hardware to be calibrated in the form of binary code.

[0046] Figure 2 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention, showing a block diagram of an exemplary electronic device suitable for implementing the embodiments of the present invention. Figure 2 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of the embodiments of the present invention. This electronic device is in the form of a general-purpose computing device, and its components may include, but are not limited to, an input device 401, a processor 402, a memory 403, and an output device 404. The processor 402 may be one or more; the memory 403 may include a computer-readable medium and at least one program product having a set (at least one) of program modules configured to perform the functions of the embodiments of this application.

[0047] The memory 403 shown in this embodiment of the invention can be any combination of one or more computer-readable media. The computer-readable storage media can be, but is not limited to, infrared, semiconductor systems, devices or components, or any combination thereof, used to store software programs, computer-executable programs and modules, such as the program instructions / modules corresponding to the microwave radiometer indoor calibration method based on multi-parameter environment simulation in this embodiment of the invention. The processor 402 executes various functional applications and data processing of the computer device by running the software programs, instructions and modules stored in the memory 403, thereby realizing the above-mentioned microwave radiometer indoor calibration method based on multi-parameter environment simulation.

[0048] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A microwave radiometer indoor calibration method based on multi-parameter environmental simulation, characterized in that, The method includes: A controllable atmospheric environment is constructed based on a cylindrical cabin that is fully shielded from electromagnetic waves; In the transmitting section, microwave signals with preset frequency and preset amplitude are transmitted to the environmental simulation section via a transmitting antenna through a KV band standard signal transmitter calibrated by a third party. Push the microwave radiometer to be calibrated into the receiving compartment, turn the receiving antenna to a horizontal position facing the transmitting antenna, perform a penetration calibration test, and receive the penetration microwave signal through the controlled atmospheric environment in the environmental simulation compartment. Based on the microwave signal, the penetrating microwave signal, and the layered uniform field, an environment-signal coupling response function is established. By inverting the analytical correction formula of the microwave radiometer to be calibrated under different environmental conditions, an adversarial training correction generation component is deployed in the calibration memory of the microwave radiometer to be calibrated. The analytical correction formula is defined by the channel gain coefficient, the noise temperature coefficient, and the atmospheric attenuation compensation coefficient.

2. The microwave radiometer indoor calibration method based on multi-parameter environmental simulation as described in claim 1, characterized in that, The cylindrical cabin is divided into a transmitter section, an environmental simulation section and a receiver section along the axial direction. The transmitting section houses a standard signal transmitter and transmitting antenna; the environmental simulation section contains a standard material cavity, which is equipped with a control unit based on temperature, humidity and pressure, and each control unit is equipped with a standard device to construct a controllable atmospheric environment based on a layered uniform field; the receiving section houses a microwave radiometer to be calibrated and a receiving antenna.

3. The microwave radiometer indoor calibration method based on multi-parameter environmental simulation as described in claim 1, characterized in that, The microwave signals transmitted by the standard signal transmitter at each preset frequency and preset amplitude include pure carrier mode, modulation mode and frequency sweep mode; The pure carrier mode is used to measure channel gain and path attenuation; the modulation mode is used to measure channel bandwidth and group delay characteristics; and the frequency sweep mode is used to obtain the response curve within the frequency band.

4. The microwave radiometer indoor calibration method based on multi-parameter environmental simulation as described in claim 1, characterized in that, Penetration calibration includes direct penetration calibration and differential penetration calibration: Among them, direct penetration calibration measures the received power of the signal after penetration by filling the standard material cavity with a controlled atmospheric environment. Differential penetration calibration uses the received power measured under vacuum conditions in a standard material cavity as a benchmark. By measuring under different atmospheric environmental conditions, the measured value of the atmospheric absorption coefficient is obtained through differential calculation. The differential penetration calibration performs accuracy verification of radiometer correction inversion.

5. The microwave radiometer indoor calibration method based on multi-parameter environmental simulation as described in claim 2, characterized in that, Before inverting the analytical correction formula for the microwave radiometer to be calibrated under different environmental conditions, the method further includes: Determine the test frequency point and measure the attenuation of the microwave signal emitted by the standard signal transmitter after passing through dry air. The test frequency point is a window frequency point with a known atmospheric absorption coefficient and insensitive to humidity, using dry air as the reference atmospheric environment. Based on the attenuation and theoretical absorption coefficient, the equivalent transmission path length of electromagnetic waves in the standard material cavity is inferred by inverse reasoning through the microwave radiation transmission equation. The equivalent transmission path length is written into the calibration memory as a fixed parameter.

6. The microwave radiometer indoor calibration method based on multi-parameter environmental simulation as described in claim 5, characterized in that, The analytical correction formulas for retrieving the microwave radiometer to be calibrated under different environmental conditions include: The measured values ​​based on the layered uniform field are used as measured environmental parameters describing the characteristics of the atmospheric medium. By combining measured environmental parameters and transmitted signal characteristics, the microwave radiation transmission equation is driven to calculate the theoretical receiving characteristics, which include the theoretical receiving brightness temperature. The control standard signal transmitter transmits the first microwave signal, which is received by the microwave radiometer to be calibrated, and the measured received brightness temperature based on the first penetrating microwave signal is recorded. Based on the theoretical receiving characteristics and the measured receiving brightness temperature, the channel response characteristics and transmission effects introduced by the atmospheric environment of the microwave radiometer to be calibrated are calculated by comparison and nonlinear least squares fitting.

7. The microwave radiometer indoor calibration method based on multi-parameter environmental simulation as described in claim 6, characterized in that, After calculating the channel response characteristics of the microwave radiometer to be calibrated and the transmission effects introduced by the atmospheric environment, the following steps are taken: Define independent and dependent variables, where environmental parameters are the independent variables and calibration coefficients are the dependent variables. The calibration coefficients include channel gain coefficient, noise temperature coefficient, and atmospheric attenuation compensation coefficient. Using the equivalent transmission path as a constraint, the transmission effect is subjected to multiple regression analysis and linear surrogate optimization iteration based on independent and dependent variables to determine the analytical correction formula.

8. The microwave radiometer indoor calibration method based on multi-parameter environmental simulation as described in claim 7, characterized in that, The initial analytical correction curve is determined by solving the multiple regression problem; Using trend reversal as a first-class cut point and exceeding the limit of change as a second-class cut point, the initial analytical correction curve is segmented and linearized in parallel, and digitized into the analytical correction formula.

9. The microwave radiometer indoor calibration method based on multi-parameter environmental simulation as described in claim 8, characterized in that, An adversarial training and correction generation component is employed and deployed in the calibration memory of the microwave radiometer to be calibrated, including: Based on the analytical correction formula, a correction generation component is constructed; By randomly selecting a set of environmental parameter combinations that were not involved in the fitting, testing was conducted in a standard material cavity to determine the measured values ​​of the radiometer and to perform calculations based on the analytical correction formula. The correction value was then compared with the known true value by the correction judgment component to determine the incremental learning features. The incrementally learned features are fed back to the calibration generation component, and the optimization and iterative training of the analytical calibration formula are performed until the training converges. The completed calibration generation component is then embedded in the calibration memory.

10. An electronic device, characterized in that, The electronic device includes: Memory, used to store executable instructions; The processor, when executing executable instructions stored in the memory, implements the microwave radiometer indoor calibration method based on multi-parameter environmental simulation as described in any one of claims 1-9.

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