Method and system for calculating millimeter wave imaging limit detection distance

Abstract

This invention relates to a method and system for estimating the ultimate detection range of millimeter-wave imaging, belonging to the field of millimeter-wave remote sensing and detection technology. It solves the problem of the inability to determine the ultimate detection range of millimeter-wave imaging under complex detection environments. The invention establishes a formula for the brightness-temperature difference at the target object at the ultimate distance in the current observation scenario; it selects an object with a known distance within the ultimate detection range of the millimeter-wave imaging system for detection, establishing a formula for the brightness-temperature difference at close range; it uses a millimeter-wave imaging system with the ultimate distance to be determined for close-range actual measurement, substituting the close-range brightness-temperature difference formula into the ultimate distance brightness-temperature difference formula to obtain the relationship between the brightness-temperature difference and the detection distance d; it adjusts the value of the detection distance d in the relationship between the brightness-temperature difference and the detection distance d according to a fixed step size until the brightness-temperature difference is less than or equal to the brightness-temperature sensitivity value of the millimeter-wave imaging system, thus obtaining the ultimate detection range of the millimeter-wave imaging system. This invention is used to determine the ultimate detection range of millimeter-wave imaging systems.

Description

Technical Field

[0001] This invention belongs to the field of millimeter-wave remote sensing and detection technology. Background Technology

[0002] Millimeter-wave imaging systems achieve remote sensing and detection of target objects and scenes by receiving the spontaneous or reflected millimeter-wave thermal radiation from the target material. The short wavelength of millimeter waves gives them unique advantages in imaging resolution and penetration. In various scenarios, this technology offers advantages such as all-weather, all-day operation, strong concealment, low susceptibility to clutter interference, and low power consumption. Therefore, it has been widely applied in important fields such as human security checks, sea surface target detection, medical imaging, atmospheric remote sensing, industrial inspection, and military reconnaissance.

[0003] The detection range of a millimeter-wave imaging system refers to the maximum distance at which the system can effectively detect a target object and generate a clear image. Its value is influenced by multiple factors, including transmit power, receiver sensitivity, antenna gain, atmospheric attenuation, and environmental conditions. Under ideal conditions, the detection range of millimeter-wave imaging can reach hundreds or even thousands of meters. In complex real-world scenarios, shorter detection ranges can be determined through multiple experiments. However, in applications such as sea surface target detection, longer detection ranges are required, and the conditions of the detection scenarios are complex, making it difficult to obtain realistic data in actual scenarios. In the simulation testing phase, data obtained through theoretical derivation and empirical formulas are mostly used. To make the results more realistic and accurate, a link is established between close-range measured detection data and long-range detection capability assessments under the same scenario. Accurately determining the limit detection range under complex environments remains a challenge. Existing methods typically employ multiple tests, but this method suffers from high computational cost and low efficiency in repeated trials. Furthermore, multiple tests are not suitable for some complex environments. Summary of the Invention

[0004] This invention addresses the problem of the inability to determine the limiting detection distance of millimeter-wave imaging under complex detection environments by providing a method and system for estimating the limiting detection distance of millimeter-wave imaging.

[0005] The millimeter-wave imaging limit detection distance estimation method of the present invention includes:

[0006] Step 1: Establish the formula for the brightness temperature difference at the target object at the limit detection distance under the current observation scenario;

[0007] Step 2: Select objects with known distances within the extreme detection range of the millimeter-wave imaging system for detection, and establish a formula for the brightness temperature difference of objects at close range;

[0008] Step 3: Use a millimeter-wave imaging system with the limit distance to perform close-range actual measurement, substitute the close-range brightness temperature difference formula into the limit detection distance brightness temperature difference formula, and obtain the relationship between brightness temperature difference and detection distance d;

[0009] Step 4: Adjust the value of the detection distance d in the formula relating the brightness temperature difference and the detection distance d according to a fixed step size until the brightness temperature difference is less than or equal to the brightness temperature sensitivity value of the millimeter-wave imaging system, and obtain the limit detection distance of the millimeter-wave imaging system.

[0010] Furthermore, in this invention, in step one, the formula for the extreme distance brightness temperature difference under the current observation scenario is:

[0011]

[0012] Where θ1 and θ2 are the 3dB beamwidths of the detector antenna in the E and H planes, respectively, ΔT is the brightness temperature difference of the object received at the detector, and T B-obj0 To detect the original brightness temperature of an object, T B-bac0 The background original brightness temperature of the detected object is given by S, where α is the atmospheric radiation attenuation rate between the detected object and the detector. A Let d be the projected area of ​​the object, and d be the distance from the object to the detector.

[0013] Furthermore, in this invention, in step two, the formula for the brightness temperature difference of an object at close range includes the formula for the brightness temperature difference when the projected area of ​​the detector antenna beam is smaller than that of the target object and the formula for the brightness temperature difference when the projected area of ​​the beam is greater than or equal to that of the target object.

[0014] In this embodiment, the two scenarios are the brightness temperature difference when the detector antenna beam projection area is smaller than the target object and the brightness temperature difference when the beam projection area is greater than or equal to the target object. Either scenario is selected for measurement based on the actual measurement conditions.

[0015] Furthermore, in this invention, the formula for the original brightness temperature difference of the object when the beam projection area is smaller than the target object is:

[0016] T B-bac0 -T B-obj0 =ΔT1·α1

[0017] Where α1 is the atmospheric attenuation rate between the object and the detector when the beam projection area is smaller than the target object area, and ΔT1 is the measured brightness temperature difference between the target and the background at the detector when the beam area is smaller than the target object area.

[0018] Furthermore, in this invention, the formula for the original brightness temperature difference of the object when the beam projection area is greater than or equal to the target object is:

[0019] T B-bac0 -T B-obj0=ΔT2·α2·[π·d0 2 ·tan(θ1 / 2)·tan(θ2 / 2)] / S A

[0020] Where α2 is the atmospheric attenuation rate between the object and the detector when the beam projection area is larger than the target object area, d0 is the measurement distance when measured at close range, and ΔT2 is the brightness temperature difference when the beam diameter is larger than the target object diameter.

[0021] Furthermore, in this invention, the relationship between the brightness temperature difference and the detection distance d in step three includes:

[0022] When the beam projection area is smaller than the target object projection area, the relationship is:

[0023]

[0024] When the beam projection area is larger than the target object projection area, the relationship is:

[0025]

[0026] Furthermore, in step four of this invention, the MPM atmospheric model is used to adjust the value of the detection distance d in the formula relating the brightness temperature difference and the detection distance d at fixed step sizes until the brightness temperature difference ΔT is less than or equal to the brightness temperature sensitivity value ΔT of the millimeter-wave imaging system. sys The obtained detection distance d is the limit detection distance of the millimeter-wave imaging system.

[0027] A millimeter-wave imaging limit detection range estimation system includes:

[0028] The module for establishing the extreme distance brightness temperature difference formula is used to establish the extreme distance brightness temperature difference formula under the current observation scenario.

[0029] The module for establishing the formula for the brightness temperature difference of objects at close range is used to select two objects with known distances within the extreme detection range of the millimeter-wave imaging system for detection, and to establish a formula for the brightness temperature difference of objects at close range using the detection parameters.

[0030] The module for establishing the relationship between brightness temperature difference and detection distance is used to substitute the formula for brightness temperature difference at close range into the formula for brightness temperature difference at extreme distance to obtain the relationship between brightness temperature difference and detection distance d.

[0031] The limit detection distance calculation module uses the MPM atmospheric model to adjust the value of the detection distance d in the relationship between brightness temperature difference and detection distance d at a fixed step size until the brightness temperature difference is less than the temperature-brightness difference sensitivity value of the millimeter-wave imaging system, thereby obtaining the limit detection distance of the millimeter-wave imaging system.

[0032] This invention utilizes close-range measured brightness temperature data, ensuring computational accuracy while avoiding the need for repeated complex inter-area ray tracing calculations required by traditional methods. It only requires calculating the atmospheric attenuation rate between the object and the detector. By completely eliminating inter-area ray tracing iterations, the computational load is reduced by three orders of magnitude compared to traditional methods, from several hours to tens of seconds. This effectively improves the accuracy of determining the ultimate detection range of millimeter-wave imaging in complex detection environments. Attached Figure Description

[0033] Figure 1 This is a flowchart of the method described in this invention;

[0034] Figure 2 This is a schematic diagram of a millimeter-wave imaging observation scenario involved in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of a millimeter-wave imaging model at close range when the beam is smaller than the target object, as described in an embodiment of the present invention.

[0036] Figure 4 This is a schematic diagram of a millimeter-wave imaging model at close range when the beam is larger than the target object, as described in an embodiment of the present invention.

[0037] Figure 5 This is a diagram illustrating the calculation of ship area in an embodiment of the present invention;

[0038] Figure 6 This is a close-range (2km) sea surface brightness temperature diagram from the ship's disembarkation point in this embodiment of the invention.

[0039] Figure 7 This is the apparent brightness temperature diagram of the critical distance antenna in this embodiment of the invention;

[0040] Figure 8 This is a noisy image of the critical distance in an embodiment of the present invention;

[0041] Figure 9 This is the brightness temperature change curve at the critical distance in the embodiments of the present invention;

[0042] Figure 10 This is a schematic diagram of the system described in this invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0044] Specific implementation method one: Refer to Figure 1 This embodiment specifically describes the method for estimating the ultimate detection distance of millimeter-wave imaging, which includes:

[0045] Step 1: Establish the formula for the brightness temperature difference at the target object at the limit detection distance under the current observation scenario;

[0046] Step 2: Select objects with known distances within the extreme detection range of the millimeter-wave imaging system for detection, and establish a formula for the brightness temperature difference of objects at close range;

[0047] Step 3: Use a millimeter-wave imaging system with the limit distance to perform close-range actual measurement, substitute the close-range brightness temperature difference formula into the limit detection distance brightness temperature difference formula, and obtain the relationship between brightness temperature difference and detection distance d;

[0048] Step 4: Adjust the value of the detection distance d in the formula relating the brightness temperature difference and the detection distance d according to a fixed step size until the brightness temperature difference is less than or equal to the brightness temperature sensitivity value of the millimeter-wave imaging system, and obtain the limit detection distance of the millimeter-wave imaging system.

[0049] This invention rapidly derives the system's limit distance using brightness temperature data at close range through iteration. This not only ensures imaging quality but also provides a scientific basis for system design, promotes technical standardization, enhances comparability between different systems, and fosters technical exchange and cooperation within the industry. Furthermore, detection distance assessment helps in the rational configuration of components during system integration, reducing costs, and predicting system performance under different environmental conditions. This provides optimal solutions for diverse application scenarios, thereby driving the widespread application and continuous advancement of millimeter-wave imaging technology in multiple fields such as security, traffic monitoring, and medical imaging. The "close range" referred to in this invention refers to the object that millimeter-wave imaging can detect in actual measurements. The detection distance is determined based on the actual detection environment. The invention utilizes close-range detection data to obtain brightness temperature difference formulas when the detector antenna beam projection area is smaller than the target object and when the beam projection area is greater than or equal to the target object.

[0050] Furthermore, in this invention, in step one, the formula for the extreme distance brightness temperature difference under the current observation scenario is:

[0051]

[0052] Where θ1 and θ2 are the 3dB beamwidths of the detector antenna in the E and H planes, respectively, ΔT is the brightness temperature difference of the object received at the detector, and T B-obj0 To detect the original brightness temperature of an object, T B-bac0 The background original brightness temperature of the detected object is given by S, where α is the atmospheric radiation attenuation rate between the detected object and the detector. ALet d be the projected area of ​​the object, and d be the distance from the object to the detector.

[0053] Furthermore, in this invention, in step two, the formula for the brightness temperature difference of an object at close range includes the formula for the brightness temperature difference when the projected area of ​​the detector antenna beam is smaller than that of the target object and the formula for the brightness temperature difference when the projected area of ​​the beam is greater than or equal to that of the target object.

[0054] This embodiment presents two scenarios: a brightness temperature difference formula when the detector antenna beam projection area is smaller than the target object, and a brightness temperature difference formula when the beam projection area is greater than or equal to the target object. Either scenario is selected for measurement based on the actual measurement conditions.

[0055] Furthermore, in this invention, the formula for the original brightness temperature difference of the object when the beam projection area is smaller than the target object is:

[0056] T B-bac0 -T B-obj0 =ΔT1·α1

[0057] Where α1 is the atmospheric attenuation rate between the object and the detector when the beam projection area is smaller than the target object area, and ΔT1 is the measured brightness temperature difference between the target and the background at the detector when the beam area is smaller than the target object area.

[0058] Furthermore, in this invention, the formula for the original brightness temperature difference of the object when the beam projection area is greater than or equal to the target object is:

[0059] T B-bac0 -T B-obj0 =ΔT2·α2·[π·d0 2 ·tan(θ1 / 2)·tan(θ2 / 2)] / S A

[0060] Where α2 is the atmospheric attenuation rate between the object and the detector when the beam projection area is larger than the target object area, d0 is the measurement distance when measured at close range, and ΔT2 is the brightness temperature difference when the beam diameter is larger than the target object diameter.

[0061] Furthermore, in this invention, the relationship between the brightness temperature difference and the detection distance d in step three includes:

[0062] When the beam diameter is smaller than the target object diameter, the relationship is:

[0063]

[0064] When the beam diameter is larger than the target object diameter, the relationship is:

[0065]

[0066] Furthermore, in step four of this invention, the MPM atmospheric model is used to adjust the value of the detection distance d in the formula relating the brightness temperature difference and the detection distance d at fixed step sizes until the brightness temperature difference ΔT is less than or equal to the brightness temperature sensitivity value ΔT of the millimeter-wave imaging system. sys The detection distance d obtained at this time is the limit detection distance of the millimeter-wave imaging system.

[0067] A millimeter-wave imaging limit detection range estimation system includes:

[0068] Module 1 for establishing the formula for the extreme distance brightness temperature difference is used to establish the formula for the extreme distance brightness temperature difference under the current observation scenario.

[0069] Module 2 for establishing the formula for the brightness temperature difference of objects at close range is used to select two objects with known distances within the extreme detection range of the millimeter-wave imaging system for detection, and to establish the formula for the brightness temperature difference of objects at close range using the detection parameters.

[0070] Module 3, which establishes the relationship between brightness temperature difference and detection distance, is used to substitute the near-distance brightness temperature difference formula into the extreme-distance brightness temperature difference formula to obtain the relationship between brightness temperature difference and detection distance d.

[0071] The limit detection distance calculation module 4 uses the MPM atmospheric model to adjust the value of the detection distance d in the relationship between the brightness temperature difference and the detection distance d at a fixed step size until the brightness temperature difference is less than the temperature-brightness difference sensitivity value of the millimeter-wave imaging system, thereby obtaining the limit detection distance of the millimeter-wave imaging system.

[0072] In an exemplary embodiment of the present invention, an equivalent method for extrapolating millimeter-wave imaging detection range is provided. This method applies the brightness-temperature difference measured at close range to the MPM atmospheric model and iterates via computer to obtain the maximum detection range, eliminating a significant portion of the image simulation process and greatly reducing simulation time. Please refer to... Figure 2 In this exemplary embodiment, the millimeter-wave imaging equivalent extrapolation method includes the following steps:

[0073] Step S1: Obtain the area of ​​the observed target object and the brightness temperature calculation formula for long-distance observation scenarios, and simplify the model as follows. Figure 2 Considering background weighting and atmospheric radiation, the relationship between the original brightness temperature difference at the target object and the measured brightness temperature difference at the radiometer is obtained.

[0074] Step S2: Discuss two cases to obtain the formula for brightness temperature difference at close range, and obtain the original brightness temperature difference at the target location from the measured brightness temperature difference at close range.

[0075] Step S3: Substitute the original brightness temperature difference into the brightness temperature difference calculation formula of the observation scene to obtain the relationship between the brightness temperature difference and the detection distance d.

[0076] Step S4: Take the initial value of d as the initial detection distance for close range, continuously increase d to iterate the value of ΔT, and compare it with the sensitivity K. As d increases, ΔT decreases. When the value of ΔT is less than the sensitivity K, the corresponding d is the farthest detection distance.

[0077] The above method can quickly predict and calculate the maximum detection distance of millimeter-wave imaging. Compared with the method of predicting the maximum detection distance by generating simulated images, this method uses the brightness temperature difference within the near range of the system's detection range to incorporate the brightness temperature difference at the limit distance, and calculates the brightness temperature difference value instead of image generation. This significantly reduces the amount of calculation required for image generation pixels and the calculation time, and improves prediction efficiency.

[0078] Examples of ship detection methods in specific sea surface scenarios;

[0079] Using a cargo ship on the sea as the target object and an infinitely large, calm sea surface as the detection background, the initial imaging distance is 2 kilometers. First, the relationship between the original brightness temperature difference at the target object and the measured brightness temperature difference at the radiometer is obtained.

[0080] Next, the projected area of ​​the ship on the sea surface was measured to be 1.5024e+04m. 2 At a detection range of 2 kilometers, the beam projection area is 3.798e+06m². 2 Since the area is smaller than the projected area of ​​the target object, the formula for the original brightness temperature difference between the ship and the sea surface at a detection distance of 2 kilometers is T. B-bac0 -T B-obj0 =ΔT1·α1, and the atmospheric attenuation coefficient α1 is calculated to be 1.3014 according to the atmospheric MPM model. Using the ray tracing algorithm, the target brightness temperature of the ship on the sea surface is calculated. The target brightness temperature prediction parameters are shown in Table 1 below. The ship-sea surface brightness temperature prediction results are as follows: Figure 6 As shown.

[0081] Table 1:

[0082]

[0083]

[0084] Based on the budget results, the original brightness temperature difference is T. B-bac0 -T B-obj0 =61.7721, ΔT=47.4670, greater than sensitivity 0.3. According to step S3, the formula for the brightness temperature difference at any distance d is:

[0085] The detection distance d starts from an initial value of 2 km and increases by 1 km each time. The value of ΔT at the corresponding d is calculated using the near-range brightness temperature difference formula and compared with the sensitivity K = 0.3. When ΔT is greater than K, d is incremented by 1, and a new ΔT value is calculated. As d increases, ΔT continuously decreases. When d is 154 km, ΔT is 0.30042; when d is 155 km, ΔT is 0.2966, which is less than 0.3. Therefore, 154 km is the critical distance, i.e., the farthest detection distance.

[0086] Figure 7 This is the apparent brightness temperature map of the antenna at the critical distance (154km) in an embodiment of the present invention. It can be seen from the map that the brightness temperatures of the ship and the sea surface are very close at 154km, but the ship's position can still be distinguished. Due to the presence of system noise, the system noise is added to the apparent brightness temperature map, and the result is as follows. Figure 8 As shown, the difference in brightness temperature between the ship and the sea surface is difficult to distinguish with the naked eye.

[0087] Furthermore, in Figure 8 The ship-sea surface brightness temperature difference analysis was performed by selecting a horizontal line at the ship's location. The results are as follows: Figure 9 As shown in the figure, the smooth curve represents the sea surface brightness temperature, while the bulge represents the ship's brightness temperature. The figure shows ΔT as 0.395K, which is close to 0.3K, demonstrating the feasibility of this equivalent calculation method.

[0088] The detection range of the millimeter-wave imaging system described in this invention directly affects its imaging quality and application effectiveness. The evaluation method can identify the system's performance characteristics under different environmental and target conditions, providing a scientific basis for system design and optimization. Millimeter-wave technology, due to its strong penetration and good anti-interference capabilities, is widely used in security, traffic monitoring, medical imaging, and other fields. Researching detection range evaluation methods can clarify its applicability and limitations in different application scenarios, promoting its application in new fields. This invention establishes a unified standard for evaluating the detection range of millimeter-wave imaging systems, facilitating scientific comparisons between different systems, promoting technical exchange and cooperation within the industry, and driving technological progress. Understanding the detection range of millimeter-wave imaging helps in the rational configuration of modules and components during system integration and design, ensuring optimal performance in target detection and imaging, and reducing development and implementation costs. Millimeter-wave imaging systems may operate under different environmental conditions; the detection range evaluation method can help researchers understand and predict the system's performance under various climate, weather, and lighting conditions, facilitating the selection of the optimal solution for different application scenarios.

[0089] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A method for estimating the ultimate detection distance of millimeter-wave imaging, characterized in that, include: Step 1: Establish the formula for the brightness temperature difference at the target object at the limit detection distance under the current observation scenario; Step 2: Select objects with known distances within the extreme detection range of the millimeter-wave imaging system for detection, and establish a formula for the brightness temperature difference of objects at close range; Step 3: Use a millimeter-wave imaging system with the limit distance to perform close-range actual measurement, substitute the close-range brightness temperature difference formula into the limit detection distance brightness temperature difference formula, and obtain the relationship between brightness temperature difference and detection distance d; Step 4: Adjust the value of the detection distance d in the formula relating the brightness temperature difference and the detection distance d according to a fixed step size until the brightness temperature difference is less than or equal to the brightness temperature sensitivity value of the millimeter-wave imaging system, and obtain the limit detection distance of the millimeter-wave imaging system.

2. The method for estimating the ultimate detection distance of millimeter-wave imaging according to claim 1, characterized in that, In step one, the formula for the extreme distance brightness temperature difference under the current observation scenario is: Where θ1 and θ2 are the 3dB beamwidths of the detector antenna in the E and H planes, respectively, ΔT is the brightness temperature difference of the object received at the detector, and T B-obj0 To detect the original brightness temperature of an object, T B-bac0 The background original brightness temperature of the detected object is given by S, where α is the atmospheric radiation attenuation rate between the detected object and the detector. A Let d be the projected area of ​​the object, and d be the distance from the object to the detector.

3. The method for estimating the ultimate detection distance of millimeter-wave imaging according to claim 2, characterized in that, In step two, the formulas for the brightness temperature difference of an object at close range include the formulas for the brightness temperature difference when the projected area of ​​the detector antenna beam is smaller than that of the target object and the formulas for the brightness temperature difference when the projected area of ​​the beam is greater than or equal to that of the target object.

4. The method for estimating the ultimate detection distance of millimeter-wave imaging according to claim 3, characterized in that, The formula for the original brightness temperature difference of an object when the beam projection area is smaller than the target object is: T B-bac0 -T B-obj0 =ΔT1·α1 Where α1 is the atmospheric attenuation rate between the object and the detector when the beam projection area is smaller than the target object area, and ΔT1 is the measured brightness temperature difference between the target and the background at the detector when the beam area is smaller than the target object area.

5. The method for estimating the ultimate detection distance of millimeter-wave imaging according to claim 3 or 4, characterized in that, The formula for the original brightness temperature difference of an object when the beam projection area is greater than or equal to the target object is: T B-bac0 -T B-obj0 =ΔT2·α2·[π·d0 2 ·tan(θ1 / 2)·tan(θ2 / 2)] / S A Where α2 is the atmospheric attenuation rate between the object and the detector when the beam projection area is larger than the target object area, d0 is the measurement distance when measured at close range, and ΔT2 is the brightness temperature difference when the beam diameter is larger than the target object diameter.

6. The method for estimating the ultimate detection distance of millimeter-wave imaging according to claim 5, characterized in that, In step three, the relationship between the brightness temperature difference and the detection distance d includes: When the beam diameter is smaller than the target object diameter, the relationship is: When the beam diameter is larger than the target object diameter, the relationship is:

7. The method for estimating the ultimate detection distance of millimeter-wave imaging according to claim 6, characterized in that, In step four, the MPM atmospheric model is used to adjust the value of the detection distance d in the formula relating brightness temperature difference and detection distance d at fixed step sizes until the brightness temperature difference ΔT is less than or equal to the brightness temperature sensitivity value ΔT of the millimeter-wave imaging system. sys The obtained detection distance d is the limit detection distance of the millimeter-wave imaging system.

8. A millimeter-wave imaging limit detection distance estimation system, characterized in that, include: The limit distance brightness temperature difference formula establishment module (1) is used to establish the limit distance brightness temperature difference formula under the current observation scenario; The module for establishing the formula for the brightness temperature difference of objects at close range (2) is used to select two objects with known distance within the limit detection range of the millimeter-wave imaging system for detection, and to establish the formula for the brightness temperature difference of objects at close range using the detection parameters. The module (3) for establishing the relationship between brightness temperature difference and detection distance is used to substitute the formula for brightness temperature difference at close range into the formula for brightness temperature difference at extreme distance to obtain the relationship between brightness temperature difference and detection distance d. The limit detection distance calculation module (4) uses the MPM atmospheric model to adjust the value of the detection distance d in the relationship between the brightness temperature difference and the detection distance d according to a fixed step size until the brightness temperature difference is less than the temperature-brightness difference sensitivity value of the millimeter-wave imaging system, and obtains the limit detection distance of the millimeter-wave imaging system.

Images