Evaluation device and method for output brightness temperature of calibration source of microwave radiometer in vacuum environment

Abstract

The invention discloses a vacuum environment microwave radiometer calibration source output brightness temperature evaluation device which comprises a vacuum environment simulation system. The reference calibration source, the reference calibration source temperature uniformity measurement sensor group, the reference calibration source black body wedge internal longitudinal temperature sensor group, the reference calibration source black body opening surface variable temperature shielding case, the microwave radiometer and the calibrated calibration source are arranged in the vacuum environment simulation system, and the microwave radiometer can move on a multi-dimensional movement guide rail in a three-dimensional mode. The system comprises a calibrated calibration source, a calibrated calibration source temperature uniformity measurement sensor group, a calibrated calibration source black body wedge internal longitudinal temperature sensor group, and a calibrated calibration source black body opening surface variable temperature shielding case. The invention also discloses a vacuum environment microwave radiometer calibration source output brightness temperature evaluation method, which comprises calibration matrix construction and any background output brightness temperature fitting, and effectively solves the problem that the internal temperature measurement data of the existing microwave radiometer calibration source cannot effectively represent the overall output brightness temperature.

Description

Technical Field

[0001] This invention relates to the field of output brightness temperature technology for calibration sources of vacuum environment microwave radiometers, and particularly to an evaluation device and method for the output brightness temperature of calibration sources of vacuum environment microwave radiometers. Background Technology

[0002] A radiometer is a highly sensitive receiver that receives the natural radiation of an object. Although different objects have different radiation characteristics, i.e., radiation brightness temperature, the differences between them are not significant. The radiation brightness temperature of the same object under different conditions may vary to some extent, but it is usually very small. Microwave radiometers must undergo uniform, accurate, and reliable calibration. That is, the radiometer is used to receive the radiation signal from a calibration source with precisely known microwave radiation characteristics in order to accurately construct a quantitative relationship between the radiometer's electrical signal output and the received radiation brightness temperature. Only in this way can the accuracy and application value of passive remote sensing information be guaranteed.

[0003] Internationally, mainstream institutions use blackbodies (also called radiators) in their microwave radiometer calibration sources, employing a two-dimensional array structure of pyramidal or conical wedges. The blackbody consists of an inner metal substrate and an outer absorbing material. During vacuum calibration, the operating temperature of the radiometer calibration source is typically between 80K and 340K. The objects facing the calibration source blackbody include the radiometer antenna, the radiometer housing, and the heat sink of the vacuum chamber. Due to the poor thermal conductivity of the absorbing material, ranging from only 1W / (m·K) to 2W / (m·K), a temperature gradient inevitably exists on the surface of the blackbody wedges when calibrating the radiometer in a vacuum environment due to radiative heat transfer caused by the difference between the blackbody's physical temperature and the background temperature. The physical temperature of the blackbody is measured by a temperature sensor embedded within it. When a longitudinal temperature gradient exists in the wedge, the measurement value from the internal temperature sensor will not accurately reflect the physical temperature of the blackbody's surface. During typical calibration, there is a significant difference between the physical temperature of the calibration source blackbody and the background temperature. Therefore, the temperature sensor inside the calibration source blackbody alone cannot reflect the actual physical temperature of its surface, i.e., the radiative brightness temperature of the calibration source blackbody. Inaccurate assessment of the calibration source output brightness temperature will severely affect the validity of the radiometer calibration results. Summary of the Invention

[0004] The purpose of this invention is to provide an evaluation device and method for the output brightness temperature of a calibration source of a microwave radiometer in a vacuum environment. Even if there is a longitudinal temperature gradient in the blackbody wedge, the microwave radiation brightness temperature output by the blackbody at different background temperatures and different physical temperature ranges can be accurately fitted based on the measurement values ​​of the longitudinal sensor group installed inside the blackbody metal wedge and the calibration data matrix.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides an evaluation device for the output brightness temperature of a calibration source of a microwave radiometer in a vacuum environment, comprising a vacuum environment simulation system, and a reference calibration source, a reference calibration source uniformity measurement sensor group, a reference calibration source blackbody wedge internal longitudinal sensor group, a reference calibration source blackbody aperture variable temperature shield, a microwave radiometer moving in three dimensions on a multi-dimensional motion guide rail, a calibration source to be calibrated, a calibration source uniformity measurement sensor group, a calibration source blackbody wedge internal longitudinal sensor group, and a calibration source blackbody aperture variable temperature shield, all disposed within the vacuum environment simulation system.

[0007] The reference calibration source includes a reference calibration source open box and a reference calibration source blackbody housed within the reference calibration source open box. A reference calibration source uniformity measurement sensor group and a longitudinal sensor group inside the blackbody wedge are disposed on the blackbody. All sensors in the uniformity measurement sensor group are uniformly installed on the same horizontal plane inside their respective blackbody wedges. The longitudinal sensor group is installed in the central region of the blackbody, with the lowest position sensor located at the root of the wedge and the highest position sensor near the tip of the wedge. The distance between the highest and lowest position temperature sensors is greater than half the height of the blackbody wedge. The variable-temperature shielding cover at the blackbody aperture has high emissivity in the infrared band, enabling efficient thermal radiation to simulate the background temperature of the reference calibration source.

[0008] The reference source calibration source is characterized by high emissivity (typically above 0.999) and accurate temperature measurement (the average temperature value of the uniformity measurement sensor group is taken as its overall temperature). It is approximately assumed that the radiant brightness temperature of the standard calibration source is equal to its physical temperature.

[0009] The calibration source includes a calibration source open box and a calibration source blackbody housed within the calibration source open box. The calibration source uniformity measurement sensor group and the calibration source blackbody wedge internal longitudinal sensor group are disposed on the calibration source blackbody. The calibration source blackbody opening surface variable temperature shield is used to simulate the background temperature of the calibration source.

[0010] In some possible implementations, both the reference calibration source and the calibration source being calibrated have a blackbody aperture that is more than 10 times larger than the aperture of the radiometer antenna, and the physical temperature of the blackbody is set to vary in the range of 80K to 340K.

[0011] In some possible implementations, the uniformity measurement sensor group of the reference calibration source and the calibration source includes at least five temperature sensors installed on the same horizontal plane inside the blackbody wedge; the longitudinal sensor group inside the blackbody wedge of the reference calibration source and the calibration source includes two or more temperature sensors.

[0012] In some possible implementations, the physical temperature of the blackbody aperture variable-temperature shielding of the reference calibration source and the calibrated source is set to vary within the range of 80K to 340K, with the side facing the blackbody having an infrared emissivity of 0.95 or higher. The physical temperature difference between the reference calibration source and the blackbody aperture variable-temperature shielding is no greater than 3K. The physical temperature difference between the calibrated source and the blackbody aperture variable-temperature shielding is set according to certain step requirements, with the side facing the blackbody having an infrared emissivity of 0.95 or higher. The blackbody aperture shielding of the calibration source has an infrared emissivity of 0.95 or higher on the side facing the blackbody, thus enabling efficient thermal radiation to the blackbody. If there is a temperature difference between the aperture shielding and the blackbody, heat transfer will occur between them according to heat transfer theory. The tip of the blackbody wedge is closer to the shielding, so its temperature is significantly affected by the shielding temperature (changing towards the shielding temperature), while the temperature at the root of the wedge is minimally affected by the shielding temperature and can be ignored. Blackbody wedges will produce a certain longitudinal temperature gradient.

[0013] In some possible implementations, the reference calibration source and the variable-temperature shielding cover of the blackbody aperture of the calibration source are moved by an electrically controlled displacement stage; or, when it is inconvenient to move them, a narrow slit is reserved in the variable-temperature shielding cover for the movement of the antenna of the microwave radiometer.

[0014] Secondly, the present invention provides a method for evaluating the output brightness temperature of a calibration source for a vacuum environment microwave radiometer, utilizing the evaluation device for the output brightness temperature of a calibration source for a vacuum environment microwave radiometer described in the first aspect, comprising the following steps:

[0015] The calibration matrix is ​​constructed by using a calibration source with no surface longitudinal temperature gradient as a standard brightness temperature reference calibration source. After observing the reference calibration source, the microwave radiometer observes the temperature of the target standard source under a specific background within a very short time interval, obtaining the correspondence between the microwave radiometer temperature observation value and the values ​​of the longitudinal sensor group inside the blackbody wedge of the calibrated standard source under a specific background temperature. Then, by continuously changing the physical temperature of the reference calibration source, the physical temperature of the target standard source, and the physical temperature of the variable temperature shield at the blackbody aperture of the target standard source, a calibration matrix is ​​obtained by jointly constructing the data vectors of the longitudinal sensor group inside the blackbody wedge of the target standard source.

[0016] Arbitrary background output brightness temperature fitting: When calibrating a microwave radiometer, under the condition that the background temperature of the microwave radiometer calibration source is unknown, the output brightness temperature of the microwave radiometer calibration source is obtained based on the obtained calibration matrix interpolation fitting result and the data vector of the longitudinal sensor group inside the blackbody wedge of the calibration source at this time.

[0017] In some possible implementations, the construction of the calibration matrix specifically includes:

[0018] During the evaluation process, the reference calibration source and the variable temperature shield at the blackbody aperture of the reference calibration source are kept at close physical temperatures, with a specific temperature difference of no more than 3K. According to heat transfer theory, the temperature difference of the longitudinal sensor group inside the blackbody wedge of the reference calibration source will be ignored at this time.

[0019] Set the physical temperature of the reference calibration source and the physical temperature of the variable-temperature shield at the blackbody aperture of the reference calibration source. At this time, the variable-temperature shield at the blackbody aperture of the reference calibration source is closed at the aperture of the reference calibration source's open box. Set the physical temperature of the calibration source to be calibrated and the physical temperature of the variable-temperature shield at the blackbody aperture of the calibration source to simulate the specific background temperature of the calibration source. At this time, the variable-temperature shield at the blackbody aperture of the calibration source is closed at the aperture of the calibration source's open box. Both the reference calibration source and the calibration source to be calibrated are in a state of waiting for observation.

[0020] Remove the variable temperature shield on the aperture of the blackbody of the reference calibration source, and use a microwave radiometer to observe the standard brightness temperature of the reference calibration source. At this time, the standard brightness temperature of the reference calibration source in the working window of the microwave radiometer is the same as the physical temperature of the blackbody of the reference calibration source. Record the physical temperature of the reference calibration source at this time, which is the physical temperature of the blackbody of the reference calibration source.

[0021] The microwave radiometer is moved away from the reference calibration source, and then the variable-temperature shield at the blackbody aperture of the reference calibration source is moved back to the blackbody aperture. The physical temperature of the reference calibration source and the physical temperature of the variable-temperature shield at the blackbody aperture are changed in steps, and the system is once again in a state of waiting for observation. Then, the variable-temperature shield at the blackbody aperture of the calibration source is removed. Since the variable-temperature shield has just left the blackbody aperture of the calibration source, the physical temperature field on the surface of the blackbody of the calibration source will change slowly. The microwave radiometer is used to observe the calibration source within a finite time. Physical temperature can characterize the output brightness temperature of the calibration source under a specific background temperature; record the physical temperature of the blackbody of the calibration source, the physical temperature of the variable temperature shield at the aperture of the blackbody of the calibration source, and the values ​​of the longitudinal sensor group inside the wedge of the blackbody of the calibration source; the physical temperature of the reference calibration source is the standard brightness temperature, the physical temperature of the calibration source, the physical temperature of the variable temperature shield at the aperture of the blackbody of the calibration source, and the data vector of the longitudinal sensor group inside the wedge of the blackbody of the calibration source, to construct a four-dimensional calibration dataset under the first round of temperature combination;

[0022] The microwave radiometer is moved away from the calibration source, and then the variable temperature shield on the blackbody aperture of the calibration source is moved back to the blackbody aperture of the calibration source. The physical temperature of the calibration source and the physical temperature of the variable temperature shield on the blackbody aperture of the calibration source are changed in a certain step, and the meter is put back into the waiting observation state.

[0023] Repeat the above process to construct the four-dimensional calibration dataset for the next round of temperature combinations;

[0024] By selecting different combinations of physical temperatures of the reference calibration source, the physical temperature of the calibration source, and the physical temperature of the variable temperature shield at the blackbody aperture of the calibration source, the data vectors of the longitudinal sensor group inside the blackbody wedge of the calibration source under each case, and the four-dimensional calibration dataset under multiple temperature combinations are combined to form a calibration data matrix.

[0025] By fitting the calibration data matrix vector, the output brightness temperature of the calibration source under different background temperatures within the operating temperature range is obtained, thus completing the evaluation of the output brightness temperature of the calibration source of the microwave radiometer.

[0026] In some possible implementations, the arbitrary background output brightness temperature fitting specifically includes:

[0027] Linear interpolation fitting is used to fit the output brightness temperature under any background temperature. The vector formed by the longitudinal sensor array inside the blackbody wedge of the reference calibration source is read when the calibrated source is in a specific working scenario. Let this vector have N elements, i.e., p = N, and be expressed as a vector [k1', k2', k3', ..., k N '];

[0028] In calibration matrix T G In the search, the relationship between [k1',k2',k3',...,k] is... N Let T be two sets of vectors with the minimum and second minimum vector distances, respectively. G (min1) and T G (min2), specifically represented by the symbol T G (k1,k2,k3,...,k N ') and T G (kk1,kk2,kk3,...,kk N );

[0029] In k1 and kk1, k2 and kk2, k3 and kk3...kk N Insert l points at equal intervals between them, and add T G (min1) and T G (min2) yields a total of l+2 fitted vectors. Among these fitted vectors, the search continues to find vectors that fit within [k1',k2',k3',...,k... N The vector group with the minimum vector distance is assumed to be the q-th vector (1≤q≤l+2).

[0030] Reading and T G (min1) and T G (min2) The calibration value T of the associated calibration source. C (i,j) and TC (i,j+1), and generate l points at equal intervals between the two calibration values, and select the qth fitting point as the output brightness temperature of the calibration source in this specific working scenario.

[0031] Thirdly, the present invention provides an electronic device, comprising:

[0032] At least one processor, at least one memory, and a communication interface; wherein,

[0033] The processor, memory, and communication interface communicate with each other;

[0034] The memory stores program instructions that can be executed by the processor, which invokes the program instructions to perform the method described in the second aspect.

[0035] Fourthly, the present invention provides a non-transitory computer-readable storage medium storing computer instructions that cause a computer to perform the method described in the second aspect.

[0036] The present invention provides an evaluation device and method for the output brightness temperature of a calibration source of a microwave radiometer in a vacuum environment. This device and method utilize the physical temperatures of the reference calibration source, the calibrated calibration source, and the variable-temperature shielding cover at the blackbody aperture of the calibrated calibration source under measurement conditions. The data vectors from the longitudinal sensor group inside the blackbody wedge of the calibrated calibration source under each condition are combined with the physical temperatures of the reference calibration source, the calibrated calibration source, and the variable-temperature shielding cover at the blackbody aperture to form a calibration data matrix. By fitting the matrix vectors, the output brightness temperature of the calibrated calibration source under different background conditions within the operating temperature range is given, thus completing the evaluation of the output brightness temperature of the calibrated microwave radiometer. This solves the problem in the prior art where the measurement results of the internal sensors of the microwave radiometer calibration source cannot reflect the surface temperature of the blackbody when facing a background environment that differs from the physical temperature of the blackbody, especially the problem of measuring the output brightness temperature of a blackbody calibration source using a periodic array structure in a vacuum environment. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the evaluation method of the present invention;

[0038] Figure 2 This is a schematic diagram of the open box of the reference / calibrated standard source and the blackbody of the reference / calibrated standard source in Example 1;

[0039] Figure 3 A schematic diagram showing the opening and closing of the variable temperature shield at the aperture of the blackbody, used as a reference / calibrated source;

[0040] Figure 4This is a schematic diagram of the installation of the reference / calibrated standard source uniformity measurement sensor and the longitudinal sensor group inside the blackbody wedge of the reference / calibrated standard source. The sensor group is used to emphasize the relationship between the longitudinally installed multiple sensors.

[0041] In the figure, 01-the open box of the reference / calibrated source, 02-the blackbody (pyramid wedge array structure) of the reference / calibrated source, 021-the metal substrate, 022-the pyramid (or cone) wedge array structure made of microwave absorbing material, 1-the reference calibration source, 2-the uniformity measurement sensor of the reference calibration source, 3-the longitudinal sensor group inside the wedge of the reference calibration source blackbody, 4-the variable temperature shield of the aperture of the reference calibration source blackbody, 5-the calibrated source, 6-the uniformity measurement sensor of the calibrated source, 7-the longitudinal sensor group inside the wedge of the calibrated source blackbody, 8-the variable temperature shield of the aperture of the calibrated source blackbody, 9-the microwave radiometer, 10-the vacuum environment simulation system. Detailed Implementation

[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. At the same time, in the description of the embodiments of this application, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0043] Example 1

[0044] This embodiment provides an evaluation device for the output brightness temperature of a calibration source for a microwave radiometer in a vacuum environment, such as... Figure 1 As shown, it includes a vacuum environment simulation system, and a reference calibration source, a reference calibration source uniformity measurement sensor group, a reference calibration source blackbody wedge internal longitudinal sensor group, a reference calibration source blackbody aperture variable temperature shield, a microwave radiometer that can move in three dimensions on a multi-dimensional motion guide rail, a calibration source to be calibrated, a calibration source uniformity measurement sensor group, a calibration source blackbody wedge internal longitudinal sensor group, and a calibration source blackbody aperture variable temperature shield.

[0045] Both the reference calibration source and the calibration source being calibrated have a blackbody aperture of 300 mm or more, and the physical temperature of the blackbody is set to vary within the range of 80 K to 340 K, which is a typical value commonly used in actual use.

[0046] The uniformity measurement sensor group for the reference and calibrated sources includes at least five temperature sensors (five in this embodiment), evenly installed on the same horizontal plane inside the wedges of each blackbody. The average of their temperature measurements is used as the temperature of the reference calibration source. The longitudinal sensor group inside the wedges of the blackbody for both the reference and calibrated sources includes two or more temperature sensors (three in this embodiment). Their temperature measurements form a vector (a directional data set consisting of three data points arranged sequentially in the longitudinal direction), used to characterize the temperature gradient inside the blackbody of the reference / calibrated source caused by the difference between the ambient temperature and the operating temperature. The operating temperature refers to its set temperature.

[0047] The reference calibration source includes a reference calibration source open box and a reference calibration source blackbody housed within the reference calibration source open box. A reference calibration source uniformity measurement sensor group and a longitudinal sensor group inside the reference calibration source blackbody wedge are mounted on the reference calibration source blackbody. A variable temperature shield on the aperture of the reference calibration source blackbody is used to simulate the background temperature of the reference calibration source.

[0048] The calibration source includes a calibration source open box and a calibration source blackbody contained within the calibration source open box. A calibration source uniformity measurement sensor group and a calibration source blackbody wedge internal longitudinal sensor group are set on the calibration source blackbody. A variable temperature shield on the calibration source blackbody opening is used to simulate the background temperature of the calibration source.

[0049] The open box of the reference / calibrated source and the blackbody of the reference / calibrated source included within the open box, such as Figure 2 As shown, the reference / calibrated blackbody includes a pyramid (or cone) wedge array structure made of a metal matrix and absorbing material. In this embodiment, it is a pyramid structure. The reference / calibrated blackbody uniformity measurement sensor (group) and the longitudinal sensor (group) inside the blackbody wedge of the reference / calibrated blackbody are set on the pyramid structure.

[0050] The variable temperature shield at the blackbody aperture of the reference calibration source can vary the physical temperature of the shield within the range of 80K to 340K, and has an infrared emissivity of over 0.95. The physical temperature difference between the variable temperature shield and the reference calibration source is no more than 3K.

[0051] The variable temperature shield at the aperture of the blackbody being calibrated can vary the physical temperature of the shield within the range of 80K to 340K, and the side facing the blackbody has an infrared emissivity of over 0.95.

[0052] The reference calibration source and the blackbody aperture variable temperature shield of the calibration source are moved by an electrically controlled displacement stage; or, when it is inconvenient to move them, a narrow slit is reserved on the variable temperature shield for the movement of the microwave radiometer antenna.

[0053] The microwave radiometer has a sensitivity better than 0.1K.

[0054] The radiometer's multidimensional motion guide rail has three degrees of freedom of motion capability.

[0055] During the evaluation process, the reference calibration source and its blackbody aperture variable-temperature shield are kept at approximately the same physical temperature, with a difference of no more than 3K. According to heat transfer theory, the temperature difference of the longitudinal sensor group inside the blackbody wedge of the reference calibration source is negligible at this temperature. When the reference calibration source blackbody aperture variable-temperature shield is closed at the aperture of the reference calibration source's open box, i.e., the blackbody aperture, it is in a state of waiting for observation. See [link to relevant documentation]. Figure 1 State 1 on the left: When the variable-temperature shielding cover of the blackbody aperture of the calibration source is closed on the aperture of the calibration source opening box, i.e., the aperture of the reference calibration source blackbody, the surface physical temperature difference between the calibration source and the blackbody of the calibration source is set according to a certain step, and the system is in a waiting-for-observation state. See [link to relevant documentation]. Figure 1 State 1 on the right side;

[0056] When the variable-temperature shielding cover at the aperture of the blackbody of the reference calibration source is removed from the aperture of the reference calibration source housing (i.e., the blackbody aperture), the physical temperature field of the corresponding blackbody surface will slowly change. If a microwave radiometer is used to observe the temperature within a finite time, this indicates the standard brightness temperature of the reference calibration source at the same background temperature. (See [reference]). Figure 1 State 2 on the left side; the limited time is generally within 10 seconds, but in some cases it can exceed 10 seconds.

[0057] When the variable-temperature shield at the aperture of the blackbody being calibrated is removed from the aperture of the blackbody opening, the physical temperature field of the corresponding surface of the blackbody will change slowly. If a microwave radiometer is used to observe the temperature within a finite time, the physical temperature of the blackbody at the specific background temperature, i.e., the physical temperature of the variable-temperature shield at the aperture of the blackbody, is represented by the data vector of the longitudinal sensor array inside the wedge of the blackbody. (See [reference needed]). Figure 1 State 3 on the right side of the middle.

[0058] Example 2

[0059] This embodiment provides a method for evaluating the output brightness temperature of a calibration source for a vacuum environment microwave radiometer. It utilizes the evaluation device for the output brightness temperature of a calibration source for a vacuum environment microwave radiometer as described in Embodiment 1, and includes two steps: a calibration matrix construction step and an arbitrary background output brightness temperature fitting step.

[0060] The calibration matrix construction steps are as follows: A calibration source without a surface longitudinal temperature gradient is constructed as a standard brightness temperature reference calibration source. After observing the reference calibration source, the microwave radiometer observes the temperature of the target standard source under a specific background within a very short time interval, obtaining the correspondence between the microwave radiometer temperature observation value and the values ​​of the longitudinal sensor group inside the blackbody wedge of the target standard source under a specific background temperature. Then, by continuously changing the physical temperature of the reference calibration source, the physical temperature of the target standard source, and the physical temperature of the variable temperature shield at the blackbody aperture of the target standard source, a calibration matrix is ​​obtained by jointly constructing the data vectors of the longitudinal sensor group inside the blackbody wedge of the target standard source. During the evaluation process, the reference calibration source and the variable temperature shield at the blackbody aperture of the reference calibration source are always kept at close physical temperatures, with a specific temperature difference not exceeding 3K. According to heat transfer theory, the temperature difference of the longitudinal sensor group inside the blackbody wedge of the reference calibration source will be ignored at this time. The average of the temperature values ​​obtained from all the uniformity measurement sensor groups of the reference calibration source is taken as the physical temperature of the reference calibration source, i.e., the standard brightness temperature of the reference calibration source. In the microwave band, radiated brightness temperature = physical temperature × emissivity. For an ideal blackbody, the emissivity is 1, therefore the radiated brightness temperature of an ideal blackbody is exactly equal to its physical temperature. Practical standard calibration sources are typically designed with high emissivity (usually above 0.999) and accurate temperature measurement (averaging from multiple points to represent its overall temperature), meaning: the output brightness temperature of the standard calibration source = the physical temperature of the standard calibration source + a small correction term. Within a specific brightness temperature uncertainty requirement range, this small correction term can be ignored, and the radiated brightness temperature of the standard calibration source is considered equal to its physical temperature.

[0061] Step S1: Set the physical temperature of the reference calibration source to between 80K and 340K. Use the average value of the uniformity measurement sensor of the reference calibration source as a reference to determine whether the set temperature has been reached. If there is a difference between the two, the set value of the physical temperature of the reference calibration source can be fine-tuned to make them more consistent. Set in 10K increments, and set 80K as T. R1 The remaining temperature points are T in order. R2 ... T Rn Set the physical temperature of the variable temperature shield at the blackbody aperture of the reference calibration source to be consistent with the physical temperature of the reference calibration source. Usually, an error within 3K will not affect the evaluation results. At this time, the variable temperature shield at the blackbody aperture of the reference calibration source is closed at the aperture of the reference calibration source's open box.

[0062] Step S2: Read the temperature sensor values ​​of each temperature sensor in the longitudinal sensor group inside the blackbody wedge of the reference calibration source. When the deviation between the sensors exceeds 10 mK, the sensors should be recalibrated. If the deviation does not exceed 10 mK, the reference calibration source is considered to be a calibration source without longitudinal temperature gradient, and the next step can be continued.

[0063] Step S3: Set the physical temperature of both the calibration source and the variable temperature shield at the blackbody aperture of the calibration source to 80K. Use the average value of the uniformity measurement sensor of the calibration source as a reference for whether the set value has been achieved. If there is a difference between the two, the set value of the physical temperature of the calibration source can be finely adjusted to make them more consistent. Let the physical temperature value of the calibration source at 80K be T. DUT1 In subsequent steps, the temperature is increased in 10K increments until it reaches 340K, with the remaining temperature points being T. DUT2 ... T DUTn ;

[0064] Step S4: Read the temperature values ​​of each temperature sensor in the longitudinal sensor group inside the blackbody wedge of the calibration source. When the deviation between the sensors exceeds 10 mK, the sensors should be recalibrated; when it does not exceed 10 mK, the requirement is met, and continue to the next step. Because in step S3, the physical temperature of the calibration source and the variable temperature shield at the blackbody aperture of the calibration source are set to be the same, theoretically there is no longitudinal temperature gradient. Therefore, in this step S4, when the values ​​measured by each sensor in the longitudinal sensor group do not exceed 10 mK, it is considered that there is no longitudinal temperature gradient.

[0065] Step S5: Set the physical temperature of the variable temperature shield at the blackbody aperture of the calibration source to be calibrated to be 10K higher than the physical temperature of the calibration source, to be 90K, in order to simulate the specific background temperature of the calibration source. At this time, the variable temperature shield at the blackbody aperture of the calibration source is closed at the aperture of the open box of the calibration source.

[0066] Both the reference calibration source and the calibration source being calibrated are in a state of waiting for observation; that is, waiting for radiometer observation. The radiometer observes the brightness temperature, not the temperature.

[0067] Step S6: After the temperatures of the reference calibration source and the calibration source being calibrated have stabilized, remove the variable temperature shield on the blackbody aperture of the reference calibration source and use a microwave radiometer to observe the radiation brightness temperature of the reference calibration source. Since there is almost no temperature difference between the blackbody and the background, the radiation brightness temperature of the reference calibration source in the working window of the microwave radiometer is consistent with the physical temperature of the blackbody of the reference calibration source.

[0068] Step S7: Move the microwave radiometer away from the reference calibration source, and then move the variable temperature shield at the blackbody aperture of the reference calibration source back to the blackbody aperture of the reference calibration source. Change the physical temperature of the reference calibration source and the physical temperature of the variable temperature shield at the blackbody aperture of the reference calibration source in a certain step, and put it back into the waiting observation state.

[0069] Then remove the variable temperature shield from the blackbody aperture of the calibration source. Since the variable temperature shield has just left the blackbody aperture of the calibration source, the physical temperature field on the surface of the blackbody of the calibration source will change slowly. By observing the physical temperature of the calibration source with a microwave radiometer within a limited time (tens of seconds), the output brightness temperature of the calibration source under a specific background temperature can be characterized.

[0070] The microwave radiometer is moved to the calibration source using a multi-dimensional motion guide rail for observation, and the calibration value T of the output brightness temperature of the calibration source at a specific background temperature is obtained. C (i,j); When the physical temperature of the calibration source is 80K and the physical temperature of the variable temperature shield at the blackbody aperture of the calibration source is 80K±3K, T C (i,j) is T C (1,1), i=1, j=1, j increases sequentially when the physical temperature of the variable temperature shield at the blackbody aperture of the calibration source is changed, and i increases sequentially when the physical temperature of the calibration source is changed.

[0071] Step S8: Record the physical temperature of the calibration source at this time, i.e., the physical temperature of the blackbody of the calibration source, the physical temperature of the variable temperature shield at the aperture of the blackbody of the calibration source, and the temperature sensor values ​​of each temperature sensor in the longitudinal sensor group inside the wedge of the blackbody of the calibration source. The temperature sensor values ​​of each temperature sensor in the longitudinal sensor group inside the wedge of the blackbody of the calibration source constitute a new vector T. G ,i,j(k1,k2,…,k p ), the vector and T C (i,j) association, usually p takes 2 or 3, in this embodiment it takes 3; when there is a certain difference in physical temperature between the calibration source and the variable temperature shield of the blackbody aperture of the calibration source, the values ​​of each temperature sensor in the longitudinal sensor group inside the blackbody wedge of the calibration source will be pulled apart by a certain temperature gradient, and this temperature gradient vector can accurately express the background temperature interference faced.

[0072] The first round of temperature combination-based four-dimensional calibration dataset is constructed by referencing the physical temperature of the calibration source (i.e., the standard brightness temperature), the physical temperature of the calibration source, the physical temperature of the variable temperature shield at the aperture of the calibration source blackbody, and the data vector of the longitudinal sensor group inside the wedge of the calibration source blackbody.

[0073] The microwave radiometer is moved away from the calibration source, and then the variable temperature shield at the blackbody aperture of the calibration source is moved back to the blackbody aperture of the calibration source. The physical temperature of the calibration source and the physical temperature of the variable temperature shield at the blackbody aperture of the calibration source are changed in 10K increments, and the meter is once again in the waiting observation state.

[0074] Step S9: Repeat steps S3-S8 above to construct the four-dimensional calibration dataset under the next round of temperature combination until the physical temperature of the calibration source and the physical temperature of the variable temperature shield at the blackbody aperture of the calibration source reach 340K.

[0075] By selecting different combinations of physical temperatures of the reference calibration source, the physical temperature of the calibration source, and the physical temperature of the variable temperature shield at the blackbody aperture of the calibration source, the data vectors of the longitudinal sensor group inside the blackbody wedge of the calibration source under each case, and the four-dimensional calibration dataset under multiple temperature combinations are combined to form a calibration data matrix.

[0076] Step S10: Increase the physical temperature of the reference calibration source by 10K. The physical temperature of the variable-temperature shield at the blackbody aperture of the reference calibration source should match the set physical temperature of the reference radiation source. Repeat steps S2-S9. When the physical temperature of the reference calibration source reaches 330K, the calibration data matrix T is complete. G The construction of.

[0077] Arbitrary Background Output Brightness Temperature Fitting Steps: During microwave radiometer calibration, under the condition that the background temperature of the calibration source is unknown, the output brightness temperature of the microwave radiometer calibration source is obtained based on the interpolation fitting results of the obtained calibration matrix, and according to the data vector of the longitudinal sensor group inside the blackbody wedge of the calibration source at this time, within the operating temperature range. This completes the evaluation of the output brightness temperature of the calibration source of the microwave radiometer. In summary, in practical work, the background radiation faced by the calibration source will not exactly match the radiation effect at the physical temperature point set by the variable temperature shield on the blackbody aperture of the calibration source. Therefore, arbitrary background (unknown background temperature) output brightness temperature fitting is required. The specific implementation steps are as follows:

[0078] In step Q1, when constructing the calibration data matrix, it is assumed that the physical temperature of the variable temperature shield at the blackbody aperture of the reference calibration source can cover the entire range of background radiation brightness temperature that can be formed during the calibration of the microwave radiometer in a vacuum environment. Therefore, linear interpolation fitting will be used to fit the output brightness temperature under any background.

[0079] Step Q2: Read the vector formed by the longitudinal sensor group inside the blackbody wedge of the reference calibration source when the calibration source is in a specific working scenario. In this embodiment, the vector is set to have 3 elements, i.e., p=3, and is expressed as a vector in the form of [k1',k2',k3'].

[0080] Step Q3, in calibration matrix T G In the search, two pairs of vectors with the minimum and second-minimum vector distances to [k1',k2',k3'] are denoted as T. G (min1) and T G(min2), specifically represented by the symbol T G (k1,k2,k3) and T G (kk1,kk2,kk3);

[0081] Step Q4: Insert l points at equal intervals between k1 and kk1, k2 and kk2, and k3 and kk3, and add T. G (min1) and T G (min2) yields a total of l+2 fitted vectors. Among these fitted vectors, we continue searching for the set of vectors with the minimum vector distance to [k1',k2',k3'], assuming it is the q-th vector (1≤q≤l+2);

[0082] Step Q5, Read and T G (min1) and T G (min2) The calibration value T of the associated calibration source. C (i,j) and T C (i,j+1), and generate l points at equal intervals between the two calibration values, and select the qth fitting point as the output brightness temperature of the calibration source in this specific working scenario.

[0083] Example 3

[0084] This invention provides an electronic device, comprising:

[0085] At least one processor, at least one memory, and a communication interface; wherein,

[0086] The processor, memory, and communication interface communicate with each other;

[0087] The memory stores program instructions that can be executed by the processor, which calls the program instructions to execute the method of Embodiment 2.

[0088] Example 4

[0089] This embodiment provides a non-transitory computer-readable storage medium that stores computer instructions, which cause the computer to execute the method of Embodiment 2.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An evaluation device for the output brightness temperature of a calibration source of a microwave radiometer in a vacuum environment, characterized in that, It includes a vacuum environment simulation system, and a reference calibration source, a reference calibration source uniformity measurement sensor group, a reference calibration source blackbody wedge internal longitudinal sensor group, a reference calibration source blackbody aperture variable temperature shield, a microwave radiometer that moves in three dimensions on a multi-dimensional motion guide rail, a calibration source to be calibrated, a calibration source uniformity measurement sensor group, a calibration source blackbody wedge internal longitudinal sensor group, and a calibration source blackbody aperture variable temperature shield, all set within the vacuum environment simulation system. The reference calibration source includes a reference calibration source open box, and a reference calibration source blackbody and a temperature control device housed within the reference calibration source open box. The reference calibration source uniformity measurement sensor group and the reference calibration source blackbody wedge internal longitudinal sensor group are disposed on the reference calibration source blackbody. The reference calibration source blackbody aperture variable temperature shield is used to simulate the background temperature of the reference calibration source. The calibration source includes a calibration source open box, a calibration source blackbody and a temperature control device housed within the calibration source open box, a calibration source uniformity measurement sensor group and a longitudinal sensor group inside the calibration source blackbody wedge are disposed on the calibration source blackbody, and a variable temperature shield at the aperture of the calibration source blackbody is used to simulate the background temperature of the calibration source.

2. The evaluation device for the output brightness temperature of a vacuum environment microwave radiometer calibration source according to claim 1, characterized in that, Both the reference calibration source and the calibration source being calibrated have a blackbody aperture that is more than 10 times larger than the aperture of the radiometer antenna, and the physical temperature of the blackbody is set to vary within the range of 80K to 340K.

3. The evaluation device for the output brightness temperature of a vacuum environment microwave radiometer calibration source according to claim 1 or 2, characterized in that, The uniformity measurement sensor group of the reference calibration source and the calibration source includes no fewer than five temperature sensors, which are evenly installed on the same horizontal plane inside the blackbody wedge of each source; the longitudinal sensor group inside the blackbody wedge of the reference calibration source and the calibration source includes two or more temperature sensors, which are installed in the central region of the blackbody, with the lowest sensor located at the root of the wedge and the highest sensor close to the tip of the wedge, and the distance between the highest and lowest temperature sensors is greater than half the height of the blackbody wedge.

4. The evaluation device for the output brightness temperature of a vacuum environment microwave radiometer calibration source according to claim 3, characterized in that, The physical temperature of the variable-temperature shields on the blackbody apertures of the reference calibration source and the calibration source being calibrated is set to vary within the range of 80K to 340K. The side of the variable-temperature shield facing the blackbody has an infrared emissivity of 0.95 or higher. The physical temperature difference between the reference calibration source and the variable-temperature shield on the blackbody aperture of the reference calibration source is no greater than 3K. The physical temperature difference between the calibration source and the variable-temperature shield on the blackbody aperture of the calibration source being calibrated is set according to a certain step requirement. The side of the variable-temperature shield facing the blackbody has an infrared emissivity of 0.95 or higher.

5. The evaluation device for the output brightness temperature of a vacuum environment microwave radiometer calibration source according to claim 1, characterized in that, The reference calibration source and the blackbody aperture variable temperature shield of the calibration source are moved by an electrically controlled displacement stage; or, when it is inconvenient to move them, a narrow slit is reserved on the variable temperature shield for the movement of the microwave radiometer's antenna.

6. A method for evaluating the output brightness temperature of a calibration source for a vacuum environment microwave radiometer, using the evaluation apparatus for the output brightness temperature of a calibration source for a vacuum environment microwave radiometer as described in any one of claims 1-5, characterized in that... Includes the following steps: The calibration matrix is ​​constructed by using a calibration source with no surface longitudinal temperature gradient as a standard brightness temperature reference calibration source. After observing the reference calibration source, the microwave radiometer observes the temperature of the target standard source under a specific background within a very short time interval, obtaining the correspondence between the microwave radiometer temperature observation value and the values ​​of the longitudinal sensor group inside the blackbody wedge of the calibrated standard source under a specific background temperature. Then, by continuously changing the physical temperature of the reference calibration source, the physical temperature of the target standard source, and the physical temperature of the variable temperature shield at the blackbody aperture of the target standard source, a calibration matrix is ​​obtained by jointly constructing the data vectors of the longitudinal sensor group inside the blackbody wedge of the target standard source. Arbitrary background output brightness temperature fitting: When calibrating a microwave radiometer, under the condition that the background temperature of the microwave radiometer calibration source is unknown, the output brightness temperature of the microwave radiometer calibration source is obtained based on the obtained calibration matrix interpolation fitting result and the data vector of the longitudinal sensor group inside the blackbody wedge of the calibration source at this time.

7. The method for evaluating the output brightness temperature of a vacuum environment microwave radiometer calibration source according to claim 6, characterized in that, The construction of the calibration matrix specifically includes: During the evaluation process, the reference calibration source and the variable temperature shield at the blackbody aperture of the reference calibration source are kept at close physical temperatures, with the specific temperature difference not exceeding the set temperature. According to the heat transfer theory, the temperature difference of the longitudinal sensor group inside the blackbody wedge of the reference calibration source will be ignored at this time. Set the physical temperature of the reference calibration source and the physical temperature of the variable-temperature shield at the blackbody aperture of the reference calibration source. At this time, the variable-temperature shield at the blackbody aperture of the reference calibration source is closed at the aperture of the open box of the calibration source being calibrated. Set the physical temperature of the calibration source being calibrated and the physical temperature of the variable-temperature shield at the blackbody aperture of the calibration source to simulate the specific background temperature of the calibration source being calibrated. At this time, the variable-temperature shield at the blackbody aperture of the calibration source is closed at the aperture of the open box of the calibration source being calibrated. Both the reference calibration source and the calibration source being calibrated are in a state of waiting for observation. Remove the variable temperature shield on the aperture of the blackbody of the reference calibration source, and use a microwave radiometer to observe the standard brightness temperature of the reference calibration source. At this time, the standard brightness temperature of the reference calibration source in the working window of the microwave radiometer is the same as the physical temperature of the reference calibration source. Record the physical temperature of the reference calibration source at this time, which is the physical temperature of the blackbody of the reference calibration source. The microwave radiometer is moved away from the reference calibration source, and then the variable-temperature shielding cover at the blackbody aperture of the reference calibration source is moved back to the blackbody aperture. The physical temperature of the reference calibration source and the physical temperature of the variable-temperature shielding cover at the blackbody aperture are changed in steps, and the system is put back into an observation state. Then, the variable-temperature shielding cover at the blackbody aperture of the calibration source is removed. The physical temperature field on the surface of the blackbody of the calibration source will change slowly. By observing the physical temperature of the calibration source with the microwave radiometer within a finite time, the specific background temperature can be characterized. The output brightness temperature of the calibration source at a given temperature is recorded; the physical temperature of the calibration source at this time is recorded, namely the physical temperature of the blackbody of the calibration source, the physical temperature of the variable temperature shield at the aperture of the blackbody of the calibration source, and the value of the longitudinal sensor group inside the wedge of the blackbody of the calibration source; the physical temperature of the reference calibration source (i.e., the standard brightness temperature), the physical temperature of the calibration source, the physical temperature of the variable temperature shield at the aperture of the blackbody of the calibration source, and the data vector of the longitudinal sensor group inside the wedge of the blackbody of the calibration source are used to construct a four-dimensional calibration dataset under the first round of temperature combinations; The microwave radiometer is moved away from the calibration source, and then the variable temperature shield on the blackbody aperture of the calibration source is moved back to the blackbody aperture of the calibration source. The physical temperature of the calibration source and the physical temperature of the variable temperature shield on the blackbody aperture of the calibration source are changed in a certain step, and the meter is put back into the waiting observation state. Repeat the above process to construct the four-dimensional calibration dataset for the next round of temperature combinations; By selecting different combinations of physical temperatures of the reference calibration source, the physical temperature of the calibration source, and the physical temperature of the variable temperature shield at the blackbody aperture of the calibration source, the data vectors of the longitudinal sensor group inside the blackbody wedge of the calibration source under each case, and the four-dimensional calibration dataset under multiple temperature combinations are combined to form a calibration data matrix. By fitting the calibration data matrix vector, the output brightness temperature of the calibration source under different background temperatures within the operating temperature range is obtained, thus completing the evaluation of the output brightness temperature of the calibration source of the microwave radiometer.

8. The method for evaluating the output brightness temperature of a vacuum environment microwave radiometer calibration source according to claim 6, characterized in that, The arbitrary background output brightness temperature fitting specifically includes: Linear interpolation fitting is used to fit the output brightness temperature under any background temperature. The vector formed by the longitudinal sensor array inside the blackbody wedge of the reference calibration source is read when the calibrated source is in a specific working scenario. Let this vector have N elements, i.e., p = N, and be expressed as a vector [k1', k2', k3', ..., k N ']; In calibration matrix T G In the search, the relationship between [k1',k2',k3',...,k] is... N Let T be two sets of vectors with the minimum and second minimum vector distances, respectively. G (min1) and T G (min2), specifically represented by the symbol T G (k1,k2,k3,...,k N ') and T G (kk1,kk2,kk3,...,kk N ); In k1 and kk1, k2 and kk2, k3 and kk3...kk N Insert l points at equal intervals between them, and add T G (min1) and T G (min2) yields a total of l+2 fitted vectors. Among these fitted vectors, the search continues to find vectors that fit within [k1',k2',k3',...,k... N The vector group with the minimum vector distance is assumed to be the q-th vector (1≤q≤l+2). Reading and T G (min1) and T G (min2) The calibration value T of the associated calibration source. C (i,j) and T C (i,j+1), and generate l points at equal intervals between the two calibration values, and select the qth fitting point as the output brightness temperature of the calibration source under this specific working scenario; when the physical temperature of the calibration source is changed, i increases sequentially, and when the physical temperature of the variable temperature shield of the blackbody aperture of the calibration source is changed, j increases sequentially.

9. An electronic device, characterized in that, include: At least one processor, at least one memory, and a communication interface; wherein, The processor, memory, and communication interface communicate with each other; The memory stores program instructions that can be executed by the processor, which invokes the program instructions to perform the method described in any one of claims 6 to 8.

10. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer instructions that cause the computer to perform the method described in any one of claims 6 to 8.

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