Infrared system detection probability calculation method based on Johnson criterion

Abstract

The invention provides an infrared system detection probability calculation method based on a Johnson criterion, which solves the problem that the reliability of the infrared system detection probability is low, and comprises the following steps of: 1, respectively measuring different parameter information of an infrared system in a laboratory and outdoors; step 2, calculating the detection probability of the infrared system to the first target based on the different parameter information and the Johnson criterion; 3, calculating the detection probability of the infrared system to the second target based on the different parameter information and the Johnson criterion; and 4, correcting the detection probability of the second target under any to-be-detected meteorological condition based on the detection probability of the first target under the typical meteorological condition. According to the method, actual measurement data under typical meteorological conditions are utilized, reconnaissance probability prediction of the infrared system in any weather and different reconnaissance distances is achieved based on the Johnson criterion, the problem that a traditional infrared system reconnaissance probability prediction process is seriously affected by human vision is solved, and the accuracy of a prediction result is higher by introducing the actual measurement data.

Description

Technical Field

[0001] The invention relates to the field of infrared system performance evaluation, and in particular to a method for calculating infrared system detection probability based on Johnson criterion. Background Art

[0002] The performance evaluation of infrared systems is a complex and meticulous process, which usually focuses on indicators such as resolution, sensitivity, dynamic range, linearity, noise equivalent temperature difference, detection probability, minimum resolvable temperature difference and minimum detectable temperature difference. Among them, the minimum resolvable temperature difference and the minimum detectable temperature difference are subjective evaluation indicators, which are usually obtained by the observer through human observation, reflecting the resolution and detection capabilities of the infrared system under different conditions. At present, the methods of infrared system performance evaluation are mainly divided into two categories: measurement method and model method. The measurement method is to directly measure the various performance indicators of the infrared system through actual experiments and test equipment. Although the measurement results are accurate and reliable, the test conditions are limited, the evaluation scope is limited, and the cost is huge; the model method uses computers as tools to simulate the performance of infrared imaging systems in various complex environments. Although it can simulate various complex environments, avoid tedious field tests, save time and cost, the accuracy and reliability of the model are affected by many factors and need to be continuously verified and optimized.

[0003] Detection probability refers to the probability that an infrared system can correctly detect a specific target under certain conditions. The higher the probability value, the stronger the detection capability of the infrared system, and the more accurately it can capture target information in a complex environment. The detection probability not only reflects the infrared system's ability to detect specific targets, but also directly affects the actual application effect of the infrared system. Therefore, the detection probability of a specific target is an important indicator in the evaluation of infrared system performance and the development of night vision infrared systems. Research on the detection probability of infrared systems is of great significance to the design, optimization, and application of infrared systems.

[0004] At present, the detection probability of infrared systems is mainly calculated by field testing or computational evaluation. Among them: field testing mainly selects appropriate meteorological conditions, places specific observed targets in areas with sufficient line-of-sight distance (exceeding the detection distance required by the design index), and interprets the infrared system imaging map through multiple groups of observers to statistically analyze the detection probability of the infrared system for specific targets. The advantage of the field test method is that the results are highly reliable; the limitations are that the line-of-sight distance of the test area is relatively strict, the test results are easily affected by human subjective factors, and multiple groups of observers are required to participate in the experiment, which consumes huge human and material resources. It is generally only applicable to the detection probability calculation of infrared systems for specific targets under specific backgrounds and meteorological conditions, and it is difficult to meet the actual application requirements of infrared systems working under various backgrounds and meteorological conditions and facing various targets. The computational evaluation is mainly based on the working principle of the infrared system, using the Johnson criterion or TTP (targeting task performance, referred to as TTP) criterion proposed by the US Army Night Vision Sensor Agency, to construct an infrared system imaging performance evaluation model, and realize the detection probability calculation of infrared systems for various targets under various backgrounds and meteorological conditions. The advantage of the computational evaluation method is that the calculation results are not affected by human subjective factors and consume low human and material resources; the limitation is that the credibility of the infrared system detection probability test results is low. Summary of the invention

[0005] The purpose of the present invention is to provide a method for calculating the detection probability of an infrared system based on the Johnson criterion. By using measured data under typical meteorological conditions, the reconnaissance probability prediction of the infrared system at different reconnaissance distances in any weather is realized based on the Johnson criterion. This method not only overcomes the problem that the traditional infrared system reconnaissance probability prediction process is seriously affected by human vision, but also makes the prediction result more accurate by introducing measured data.

[0006] The technical solution for achieving the purpose of the present invention is as follows:

[0007] The present invention provides a method for calculating detection probability of an infrared system based on the Johnson criterion, comprising:

[0008] Step 1: Measure different parameter information of the infrared system in the laboratory and outdoors respectively;

[0009] Step 2: calculating the detection probability of the infrared system for the first target based on the different parameter information and the Johnson criterion;

[0010] Step 3: calculating the detection probability of the infrared system for the second target based on the different parameter information and the Johnson criterion;

[0011] Step 4: Based on the detection probability of the first target under typical meteorological conditions, the detection probability of the second target under any meteorological conditions to be measured is corrected.

[0012] In a possible implementation of the present invention, step one includes:

[0013] The minimum resolvable temperature difference of the laboratory measurement infrared system;

[0014] Outdoor measurement of the projection area of ​​the first target and the second target in the observation direction;

[0015] Measure the target-background temperature difference between the first target and the background under typical meteorological conditions;

[0016] Measure the zero line-of-sight temperature difference between the second target and the background.

[0017] In a possible implementation of the present invention, the laboratory measures the minimum resolvable temperature difference of the infrared system, including: measuring the minimum resolvable temperature difference of the infrared system using a standard measurement system in the laboratory to obtain a spatial frequency and temperature difference curve of the infrared system;

[0018] The outdoor measurement of the projection areas of the first target and the second target in the observation direction includes: outdoor measurement of the projection area A of the first target in the observation direction and the projection area B of the second target in the observation direction.

[0019] In a possible implementation of the present invention, measuring the target-background temperature difference between the first target and the background under typical meteorological conditions includes: measuring the target-background temperature difference ΔT between the first target and the background at the observation distance under typical meteorological conditions. A-det ;

[0020] The measuring of the zero-line-of-sight temperature difference between the second target and the background comprises: measuring the zero-line-of-sight temperature difference ΔT between the second target and the background at zero line-of-sight B-0 .

[0021] In a possible implementation of the present invention, the different parameter information of step 1 includes: the minimum resolvable temperature difference of the infrared system, the target-background temperature difference between the first target and the background, and the projection area A of the first target in the observation direction;

[0022] The second step comprises:

[0023] The spatial frequency of the first target is calculated based on the minimum resolvable temperature difference and the target-background temperature difference, the number of equivalent stripes of the first target is calculated in combination with the projection area and spatial frequency of the first target, and the detection probability of the infrared system for the first target is determined based on the Johnson criterion.

[0024] In a possible implementation of the present invention, the step 2 is specifically as follows:

[0025] Based on the measured target-background temperature difference ΔT of the first target A-det , according to ΔTA-det =MRTD(f), back-calculate the spatial frequency f of the first target A , denoted as f A =MRTD -1 (ΔT A-det ), combined with the projection area A, the target equivalent strip number N of the first target is calculated by formula (1) A ;

[0026]

[0027] In formula (1), f A represents the spatial frequency of the first target, A represents the projection area of ​​the first target in the observation direction, and R A Indicates the distance between the infrared system and the first target;

[0028] According to formula (2), the detection, recognition and identification probabilities at a certain detection distance are determined as follows:

[0029]

[0030] In formula (2), N 50 It represents the number of strip cycles at 50% detection, recognition and identification probability, determined by the empirical value of Johnson criterion, N A Indicates the target equivalent band number of the first target, E A is the coefficient; P A It represents the probability of detection, recognition and identification of the target by the infrared system, according to different N 50 Sure.

[0031] In a possible implementation of the present invention, the different parameter information of step 1 includes: a zero-viewing-distance temperature difference between the second target and the background, and a projection area of ​​the second target in the observation direction;

[0032] The step three comprises:

[0033] The apparent temperature difference of the infrared system for the second target at the observation distance is obtained according to the zero-line-of-sight temperature difference, the spatial frequency of the second target is calculated based on the apparent temperature difference, the number of equivalent stripes of the second target is calculated in combination with the projection area and the spatial frequency of the second target, and the detection probability of the infrared system for the second target is determined based on the Johnson criterion.

[0034] In a possible implementation of the present invention, the step three is specifically:

[0035] Based on MODTRAN software (atmospheric transmittance calculation software), the transmittance τ of the infrared system to the second target at the observation distance under the test conditions is calculated. atm , based on the zero-line-of-sight temperature difference ΔT between the second target and the background B-0The apparent temperature difference ΔT of the infrared system to the second target at the observation distance is obtained by formula (3): B-det ;

[0036] ΔT B-det =ΔT B-0 ×t atm Formula (3)

[0037] In formula (3), τ atm Indicates the transmittance of the infrared system to the second target at the observation distance, ΔT B-0 Indicates the zero-line-of-sight temperature difference between the second target and the background, ΔT B-det represents the apparent temperature difference of the infrared system to the second target at the observation distance;

[0038] According to ΔT B-det =MRTD(f), inversely calculate the spatial frequency f of the second target B , denoted as f B =

[0039] MRTD -1 (ΔT B-det );

[0040] Combined with the projection area B of the second target in the observation direction, the equivalent strip number N of the second target is calculated by formula (4): B ;

[0041]

[0042] In formula (4), N B represents the number of equivalent stripes of the second target, f B represents the spatial frequency of the second target, B represents the projection area of ​​the second target in the observation direction, and R B Indicates the distance between the infrared system and the second target;

[0043] According to the Johnson criterion, the detection, recognition and identification probability of the infrared system at a certain detection distance is determined by formula (5):

[0044]

[0045] In formula (5), N 50 The number of strip cycles at 50% detection, recognition and identification probability is determined by the empirical value of Johnson criterion, N B Indicates the number of equivalent stripes of the second target, E B Represents the coefficient, P B It represents the probability of detection, recognition and identification of the target by the infrared system, according to different N 50 Sure.

[0046] In a possible implementation of the present invention, the step 4 includes:

[0047] Under different weather conditions, the performance change of the infrared system is expressed as formula (6):

[0048]

[0049] In formula (6), P A represents the probability of detection, recognition, and identification calculated based on the Johnson criterion according to the target parameters measured under typical weather conditions, P B N represents the probability of detection, recognition and identification of the target by the infrared system under any weather conditions; A Indicates the number of target equivalent stripes for the first target, N B Indicates the number of equivalent stripes of the second target.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] The present invention utilizes measured data under typical meteorological conditions and realizes the prediction of reconnaissance probability of infrared system at different reconnaissance distances in any weather based on Johnson criterion. It not only overcomes the problem that the reconnaissance probability prediction process of traditional infrared system is seriously affected by human vision, but also makes the prediction result more accurate by introducing measured data. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 A flow chart of a method for calculating detection probability of an infrared system based on Johnson criterion provided by the present invention;

[0053] Figure 2 A schematic diagram of the minimum resolvable temperature difference MRTD curve of the infrared system provided by the present invention;

[0054] Figure 3 A calculation flow chart of a method for calculating detection probability of an infrared system based on Johnson criterion provided by the present invention in practical application;

[0055] Figure 4 This is a table of different parameter information acquisition methods for the infrared system provided by the present invention. DETAILED DESCRIPTION

[0056] The present invention is described in detail below in conjunction with the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these embodiments are all within the scope of protection of the present invention.

[0057] See also Figure 1 The embodiment of the present invention provides a method for calculating the detection probability of an infrared system based on the Johnson criterion, comprising the following steps:

[0058] Step 1: Measure different parameter information of the infrared system in the laboratory and outdoors.

[0059] Specifically, step one of the embodiment of the present invention includes: measuring the minimum resolvable temperature difference of the infrared system in the laboratory; measuring the projection area of ​​the first target and the second target in the observation direction outdoors; measuring the target-background temperature difference between the first target and the background under typical meteorological conditions; and measuring the zero-line-of-sight temperature difference between the second target and the background.

[0060] In the process of calculating the detection probability of the infrared system, the embodiment of the present invention comprehensively utilizes the laboratory partial performance measured data of the infrared system and the outdoor field performance test data, thereby improving the calculation accuracy of the detection probability of the infrared system. The minimum resolvable temperature difference in the embodiment of the present invention is the measurement of the standard target in the laboratory by a standard instrument (the instrument is calibrated in the laboratory), the target background temperature difference refers to the measurement of the outdoor environment when the line of sight distance is far, and the zero line of sight temperature difference has no requirements for indoor and outdoor and is determined according to the actual situation.

[0061] More specifically, the laboratory measurement of the minimum resolvable temperature difference of the infrared system in the embodiment of the present invention includes: measuring the minimum resolvable temperature difference of the infrared system in the laboratory using a standard measurement system to obtain a spatial frequency and temperature difference curve of the infrared system, such as Figure 2 More specifically, the outdoor measurement of the projection areas of the first target and the second target in the observation direction in the embodiment of the present invention includes: outdoor measurement of the projection area A of the first target and the projection area B of the second target in the observation direction.

[0062] More specifically, the above-mentioned measuring the target-background temperature difference between the first target and the background under typical meteorological conditions in the embodiment of the present invention includes: measuring the target-background temperature difference ΔT between the first target and the background at the observation distance under typical meteorological conditions. A-det More specifically, the above-mentioned measurement of the zero-line-of-sight temperature difference between the second target and the background in the embodiment of the present invention includes: measuring the zero-line-of-sight temperature difference ΔT between the second target and the background at zero line-of-sight B-0 .

[0063] Step 2: Calculate the detection probability of the infrared system for the first target based on different parameter information and Johnson criterion.

[0064] The different parameter information used in step 1 in step 2 of the embodiment of the present invention includes: the minimum resolvable temperature difference of the infrared system, the target-background temperature difference between the first target and the background, and the projection area A of the first target in the observation direction.

[0065] Specifically, step two includes: solving the spatial frequency of the first target based on the minimum resolvable temperature difference and the target-background temperature difference, calculating the equivalent band number of the first target in combination with the projection area and spatial frequency of the first target, and determining the detection probability of the infrared system for the first target based on the Johnson criterion.

[0066] The embodiment of the present invention uses the measured spatial frequency temperature difference curve of the infrared system to solve the spatial frequency of the target based on the measured target background temperature difference; specifically, the spatial frequency and temperature difference curve are used to read the spatial frequency value on the curve based on the temperature difference value, and the spatial frequency value is calculated according to ΔT A-det =MRTD(f), back-calculate the spatial frequency f of the first target A , denoted as f A =MRTD -1 (ΔT A-det ).

[0067] More specifically, step 2 of the embodiment of the present invention is as follows:

[0068] Based on the measured target-background temperature difference ΔT of the first target A-det , according to ΔT A-det =MRTD(f), back-calculate the spatial frequency f of the first target A , denoted as f A =MRTD -1 (ΔT A-det ), combined with the projection area A, the target equivalent strip number N of the first target is calculated by formula (1) A ;

[0069]

[0070] In formula (1), f A represents the spatial frequency of the first target, A represents the projection area of ​​the first target in the observation direction, and R A Indicates the distance between the infrared system and the first target;

[0071] According to formula (2), the detection, recognition and identification probabilities at a certain detection distance are determined as follows:

[0072]

[0073] In formula (2), N 50 It represents the number of strip cycles at 50% detection, recognition and identification probability, determined by the empirical value of Johnson criterion, N A Indicates the target equivalent band number of the first target, E A Represents coefficient; P A Indicates the probability of detection, recognition and identification of the target by the infrared system, according to different N 50 OK. When N 50When the number of stripe cycles at 50% recognition probability is taken, P A Represents the probability of recognition.

[0074] The above detection probability of the embodiment of the present invention refers to the probability of the optoelectronic system finding the target, the recognition probability refers to the probability of the optoelectronic system detecting the target and recognizing the target, and the identification probability refers to the probability of the optoelectronic system detecting the target, recognizing and identifying the target. The detection probability, recognition probability and identification probability are all related to N A The target equivalent cycle number is relevant.

[0075] Step 3: Calculate the detection probability of the infrared system for the second target based on different parameter information and Johnson criterion.

[0076] Among them, the different parameter information used in step 1 in the above step 3 of the embodiment of the present invention includes: the zero-line-of-sight temperature difference between the second target and the background, and the projection area of ​​the second target in the observation direction. The zero-line-of-sight temperature difference in the embodiment of the present invention refers to the zero-distance detection between the infrared system and the target without interference from distance and meteorological conditions.

[0077] Specifically, the above step three of the embodiment of the present invention includes: obtaining the apparent temperature difference of the infrared system to the second target at the observation distance according to the zero line-of-sight temperature difference, calculating the spatial frequency of the second target based on the apparent temperature difference, calculating the equivalent number of stripes of the second target in combination with the projection area and spatial frequency of the second target, and determining the detection probability of the infrared system to the second target based on the Johnson criterion.

[0078] More specifically, the above step three of the embodiment of the present invention is specifically:

[0079] Based on MODTRAN software (atmospheric transmittance calculation software (MODTRAN)), the transmittance τ of the infrared system to the second target at the observation distance under the test conditions is calculated. atm , based on the zero-line-of-sight temperature difference ΔT between the second target and the background B-0 The apparent temperature difference ΔT of the infrared system to the second target at the observation distance is obtained by formula (3): B-det ;

[0080] ΔT B-det =ΔT B-0 ×t atm Formula (3)

[0081] In formula (3), τ atm Indicates the transmittance of the infrared system to the second target at the observation distance, ΔT B-0 Indicates the zero-line-of-sight temperature difference between the second target and the background, ΔT B-det represents the apparent temperature difference of the infrared system to the second target at the observation distance;

[0082] According to ΔT B-det=MRTD(f), inversely calculate the spatial frequency f of the second target B , denoted as f B =MRTD -1 (ΔT B-det );

[0083] Combined with the projection area B of the second target in the observation direction, the equivalent strip number N of the second target is calculated by formula (4): B ;

[0084]

[0085] In formula (4), N B represents the number of equivalent stripes of the second target, f B represents the spatial frequency of the second target, B represents the projection area of ​​the second target in the observation direction, and R B Indicates the distance between the infrared system and the second target;

[0086] According to the Johnson criterion, the detection, recognition and identification probability of the infrared system at a certain detection distance is determined by formula (5):

[0087]

[0088] In formula (5), N 50 It represents the number of strip cycles at 50% detection, recognition and identification probability, determined by the empirical value of Johnson criterion, N B Indicates the number of equivalent stripes of the second target, E B Represents the coefficient, P B Indicates the probability of detection, recognition and identification of the target by the infrared system, according to different N 50 Sure.

[0089] It should be pointed out that the conditions to be measured in the embodiment of the present invention refer to the actual environmental conditions between the infrared system and the target to be measured. The embodiment of the present invention corrects any meteorological conditions to be measured based on typical meteorological conditions, and the detection probability of the infrared system for the first target calculated based on the measurement data of the typical meteorological conditions is used as a known condition to correct the detection probability of the second target under any meteorological condition, so that the probability calculation result is more accurate.

[0090] Step 4: Based on the detection probability of the first target under typical meteorological conditions, the detection probability of the second target under any meteorological conditions to be tested is corrected.

[0091] The detection probability of the first target in the embodiment of the present invention is corrected. The detection probability of the second target under any meteorological conditions to be measured is changed by the weather conditions. The performance of the infrared system changes (the performance is reflected in the detection, recognition and identification probability of the target). The first target and the second target are observed by the same infrared system, and the detection probability of the first target P is calculated.A System parameters and results can be measured and calculated, the second goal P B Calculation time P A Can be seen as P B correction factor.

[0092] Furthermore, step 4 of the embodiment of the present invention includes:

[0093] Under different weather conditions, the performance change of the infrared system is expressed as formula (6):

[0094]

[0095] In formula (6), P A represents the probability of detection, recognition, and identification calculated based on the Johnson criterion according to the target parameters measured under typical weather conditions, P B N represents the probability of detection, recognition and identification of the target by the infrared system under any weather conditions; A Indicates the number of target equivalent stripes for the first target, N B Indicates the number of equivalent stripes of the second target.

[0096] In the embodiment of the present invention, the detection probability of the first target is calculated based on the measured data and can be used as a known condition; the environmental condition of the second target is arbitrary, wherein the calculation result of the first target can be used as a correction of the second target.

[0097] In practical application, please refer to Figure 3 A method for estimating detection probability of an infrared system based on the Johnson criterion comprises: (1) measuring the MRTD of the infrared system in the laboratory and measuring the observation area of ​​the first target and the second target in the projection direction outdoors; (2) measuring the target-background temperature difference between the first target and the background under typical meteorological conditions; and measuring the zero-line-of-sight temperature difference between the second target and the background; (3) resolving the spatial frequency and the number of target equivalent strips based on the MRTD and the target-background temperature difference of the first target, and calculating the detection probability of the infrared system for the first target based on the Johnson criterion; (4) calculating the apparent temperature difference of the second target under the observation distance under the test condition based on the MODTRAN software, resolving the spatial frequency and the number of target equivalent strips based on the MRTD, and calculating the detection probability of the second target by the infrared system; and (5) correcting the detection probability of the second target under any test meteorological condition based on the detection probability of the first target under typical meteorological conditions.

[0098] The basic principles of the embodiments of the present invention are as follows:

[0099] The distance from the infrared system to the target is R, and the minimum resolvable temperature difference of the infrared system is MRTD(f).

[0100] (1) Weather condition a:

[0101] For a typical observation target, the projection area of ​​the target in the observation direction is A. Due to the attenuation factor of the atmosphere, the temperature difference between the target and the background reaching the infrared system is ΔT. A-det ;

[0102] According to ΔT A-det =MRTD(f), inverse calculation of spatial frequency f A , denoted as f A =MRTD -1 (ΔT A-det );

[0103] Combined with the target area A, calculate the target equivalent strip number N A ;

[0104]

[0105] Determine the detection, recognition, and identification probabilities at a certain detection distance according to the Johnson criterion:

[0106]

[0107] In formula (2), N 50 It refers to the number of strip cycles when the probability of detection, recognition and identification is 50%.

[0108] (2) Weather condition b:

[0109] For a certain observation target, the target's projection area in the observation direction is B. Due to the influence of atmospheric attenuation factors, the temperature difference between the target and the background reaching the infrared system is ΔT. B-det , which can be expressed as:

[0110] ΔT B-det =ΔT B-0 ·τ atm Formula (3)

[0111] In formula (3), ΔT B-0 represents the average temperature difference between the zero-line-of-sight target and the background, τ atm represents the atmospheric transmittance;

[0112] According to ΔT B-det =MRTD(f), inverse calculation of spatial frequency f B , denoted as f B =MRTD -1 (ΔT B-det );

[0113] Combined with the target area, calculate the target equivalent band number N B ;

[0114]

[0115] Determine the detection, recognition, and identification probabilities at a certain detection distance according to the Johnson criterion:

[0116]

[0117] In formula (5), N 50 It refers to the number of strip cycles when the probability of detection, recognition and identification is 50%.

[0118] (3) Analysis of infrared system performance changes under different weather conditions:

[0119]

[0120] Assume A condition (measurement calculation P A The data of the environmental conditions (i.e. typical environmental conditions) are measured data, then the B condition (measurement and calculation of P B Under the environmental conditions (i.e., any environmental conditions), the parameters are obtained in the prediction process of infrared system reconnaissance probability based on John's criterion using measured data as follows Figure 4 shown.

[0121] The embodiment of the present invention is based on the Johnson criterion and utilizes the infrared system performance test data under typical environmental conditions to realize the prediction of reconnaissance probability at different reconnaissance distances in any weather. Specifically, the minimum resolvable temperature difference MRTD of the infrared system, the target-background temperature difference between the target and the background under typical weather conditions, and the projected area of ​​the target in the observation direction are measured in the laboratory, and the detection, recognition and identification probability of the infrared system for the target is calculated based on the Johnson criterion; the zero-line-of-sight temperature difference of any target background is measured, and the atmospheric transmittance of the observation distance is calculated using MODTRAN software to obtain the target apparent temperature difference to solve the target equivalent strip number, and the target detection, recognition and identification probability under any meteorological conditions is predicted based on the target detection, recognition and identification probability under typical meteorological conditions. The method of the present invention utilizes measured data under typical meteorological conditions to realize the prediction of the reconnaissance probability of the infrared system based on the Johnson criterion, which can not only overcome the problem that the traditional infrared system reconnaissance probability prediction process is seriously affected by human vision, but also make the prediction result more accurate by introducing measured data.

[0122] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

[0123] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0124] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for calculating detection probability of an infrared system based on Johnson criterion, characterized in that: include: Step 1: Measure different parameter information of the infrared system in the laboratory and outdoors respectively; Step 2: calculating the detection probability of the infrared system for the first target based on the different parameter information and the Johnson criterion; Step 3: calculating the detection probability of the infrared system for the second target based on the different parameter information and the Johnson criterion; Step 4: Based on the detection probability of the first target under typical meteorological conditions, the detection probability of the second target under any meteorological conditions to be measured is corrected.

2. The method for calculating the detection probability of an infrared system based on the Johnson criterion according to claim 1, characterized in that: The step one comprises: The minimum resolvable temperature difference of the laboratory measurement infrared system; Outdoor measurement of the projection area of ​​the first target and the second target in the observation direction; Measure the target-background temperature difference between the first target and the background under typical meteorological conditions; Measure the zero line-of-sight temperature difference between the second target and the background.

3. The method for calculating detection probability of an infrared system based on Johnson criterion according to claim 2, characterized in that: The laboratory measures the minimum resolvable temperature difference of the infrared system, including: measuring the minimum resolvable temperature difference of the infrared system using a standard measurement system in the laboratory to obtain a spatial frequency and temperature difference curve of the infrared system; The outdoor measurement of the projection areas of the first target and the second target in the observation direction includes: outdoor measurement of the projection area A of the first target in the observation direction and the projection area B of the second target in the observation direction.

4. The method for calculating detection probability of an infrared system based on Johnson criterion according to claim 2, characterized in that: The measuring of the target-background temperature difference between the first target and the background under typical meteorological conditions comprises: measuring the target-background temperature difference ΔT between the first target and the background at the observation distance under typical meteorological conditions A-det ; The measuring of the zero-line-of-sight temperature difference between the second target and the background comprises: measuring the zero-line-of-sight temperature difference ΔT between the second target and the background at zero line-of-sight B-0 .

5. The method for calculating detection probability of an infrared system based on Johnson criterion according to claim 1, characterized in that: The different parameter information of step one includes: the minimum resolvable temperature difference of the infrared system, the target-background temperature difference between the first target and the background, and the projection area A of the first target in the observation direction; The second step comprises: The spatial frequency of the first target is calculated based on the minimum resolvable temperature difference and the target-background temperature difference, the number of equivalent stripes of the first target is calculated in combination with the projection area and spatial frequency of the first target, and the detection probability of the infrared system for the first target is determined based on the Johnson criterion.

6. The method for calculating detection probability of an infrared system based on Johnson criterion according to claim 5, characterized in that: The step 2 is specifically as follows: Based on the measured target-background temperature difference ΔT of the first target A-det , according to ΔT A-det =MRTD(f), back-calculate the spatial frequency f of the first target A , denoted as f A =MRTD -1 (ΔT A-det ), combined with the projection area A, the target equivalent strip number N of the first target is calculated by formula (1) A ; In formula (1), f A represents the spatial frequency of the first target, A represents the projection area of ​​the first target in the observation direction, and R A Indicates the distance between the infrared system and the first target; According to formula (2), the detection, recognition and identification probabilities at a certain detection distance are determined as follows: In formula (2), N 50 It represents the number of strip cycles at 50% detection, recognition and identification probability, determined by the empirical value of Johnson criterion, N A Indicates the target equivalent band number of the first target, E A is the coefficient; P A It represents the probability of detection, recognition and identification calculated based on the Johnson criterion according to the target parameters measured under typical weather conditions.

7. The method for calculating detection probability of an infrared system based on Johnson criterion according to claim 1, characterized in that: The different parameter information of step 1 includes: the zero-viewing-distance temperature difference between the second target and the background, and the projection area of ​​the second target in the observation direction; The step three comprises: The apparent temperature difference of the infrared system to the second target at the observation distance is obtained according to the zero-line-of-sight temperature difference, the spatial frequency of the second target is calculated based on the apparent temperature difference, the number of equivalent stripes of the second target is calculated in combination with the projection area and the spatial frequency of the second target, and the detection probability of the infrared system to the second target is determined based on the Johnson criterion.

8. The method for calculating detection probability of an infrared system based on Johnson criterion according to claim 7, characterized in that: The step three is specifically as follows: Based on the atmospheric transmittance calculation software (MODTRAN), the transmittance τ of the infrared system to the second target at the observation distance under the test conditions is calculated. atm , based on the zero-line-of-sight temperature difference ΔT between the second target and the background B-0 The apparent temperature difference ΔT of the infrared system to the second target at the observation distance is obtained by formula (3): B-det ; ΔT B-det =ΔT B-0 ×t atm Formula (3) In formula (3), τ atm Indicates the transmittance of the infrared system to the second target at the observation distance, ΔT B-0 Indicates the zero-line-of-sight temperature difference between the second target and the background, ΔT B-det represents the apparent temperature difference of the infrared system to the second target at the observation distance; According to ΔT B-det =MRTD(f), inversely calculate the spatial frequency f of the second target B , denoted as f B =MRTD -1 (ΔT B-det ); Combined with the projection area B of the second target in the observation direction, the equivalent strip number N of the second target is calculated by formula (4): B ; In formula (4), N B represents the number of equivalent stripes of the second target, f B represents the spatial frequency of the second target, B represents the projection area of ​​the second target in the observation direction, and R B Indicates the distance between the infrared system and the second target; According to the Johnson criterion, the detection, recognition and identification probability of the infrared system at a certain detection distance is determined by formula (5): In formula (5), N 50 The number of strip cycles at 50% detection, recognition and identification probability is determined by the empirical value of Johnson criterion, N B Indicates the number of equivalent stripes of the second target, E B Represents the coefficient.

9. The method for calculating detection probability of an infrared system based on Johnson criterion according to claim 1, characterized in that: The fourth step comprises: Under different weather conditions, the performance change of the infrared system is expressed as formula (6): In formula (6), P A represents the probability of detection, recognition, and identification calculated based on the Johnson criterion according to the target parameters measured under typical weather conditions, P B N represents the probability of detection, recognition and identification of the target by the infrared system under any weather conditions; A Indicates the number of target equivalent stripes for the first target, N B Indicates the number of equivalent stripes of the second target.

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