A method for evaluating local radiation intensity radio frequency electromagnetic sensitivity

Abstract

The application provides a method for evaluating local radiation intensity radio frequency electromagnetic sensitivity, which comprises the following steps: step one, analyzing electromagnetic environment coupling paths of a radar reconnaissance system; step two, analyzing strong radio frequency weak points of front door coupling; step three, according to a cable bundle injection conduction sensitivity test method, carrying out CS114 curve five sensitivity test verification on cable bundles involved in rear door coupling to obtain a threshold of rear door coupling; step four, determining the relationship between a system strong radio frequency sensitive response and a limiter front end signal; step five, determining a lower limit of a local radiation antenna receiving port field intensity; a local radiation field intensity upper limit is the smaller value of a calculation result of a field intensity of a key device damage threshold transmitted to the antenna receiving port and a preset standard; and step six, carrying out local radiation, gradually increasing the field intensity amplitude from the lower limit until the system appears sensitive. The application makes the evaluation result more accurate and more reliable.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electromagnetic compatibility evaluation of ship electronic equipment, and particularly relates to a method for evaluating local radiation strong radio frequency electromagnetic sensitivity. BACKGROUND

[0002] A radar reconnaissance system is an important component of a ship combat system and plays a decisive role in the continuous and effective exertion of the combat effectiveness of the ship. An electromagnetic environment effect directly affects the combat effectiveness of equipment, is an important index for equipment development and type examination, is the enrichment and expansion of the technical field of electromagnetic compatibility, and GJB8848-2016 'System electromagnetic environment effect test method' lists a strong radio frequency electromagnetic environment as an essential examination element. For a ship radar reconnaissance system, a test examination is generally performed according to a test frequency and field strength specified in a development general requirement or a contract, and when the development general requirement or the contract is not specified, a test examination is performed according to the data in tables 1 to 2 in GJB1389B-2022 'System electromagnetic environment effect requirement'. However, for the radar reconnaissance system, due to the complexity of the composition, the large structure, the numerous function performance parameters, and the fact that the external radio frequency electromagnetic environment sensitivity test is at the end of the development of the equipment, the bottom number of the equipment to the external radio frequency electromagnetic environment is not clear, and during the test examination process, the system may be disturbed, the performance may be degraded, or even damaged, which is destructive to a certain extent, and the development of a strong radio frequency full level irradiation has the characteristics of great risk, long time and weak implementability.

[0003] Generally, a local radiation electromagnetic sensitivity evaluation method is used to develop the design level evaluation of the external radio frequency electromagnetic environment. However, the evaluation method and the evaluation standard are still in the trial application and popularization stage, the strong radio frequency electromagnetic sensitivity evaluation research for the radar reconnaissance system is less, and currently, there are mainly two methods, one is to adopt the results of the equipment level electromagnetic radiation sensitivity (RS103) test of the radar reconnaissance system, that is, to adopt the results of the equipment level electromagnetic radiation sensitivity (RS103) test of the sub-system or each device in the electromagnetic compatibility darkroom, and to evaluate the design level of the external radio frequency electromagnetic environment of the system according to the equipment level electromagnetic radiation sensitivity test data; and the other is to evaluate the design level of the external radio frequency electromagnetic environment of the system according to the test data of a certain stage (such as system land joint debugging and testing, navigation test, mooring test, etc.) of the radar reconnaissance system, according to the test data of the external radio frequency electromagnetic environment of the radar reconnaissance system at the stage.

[0004] Although the above two evaluation methods have been applied to engineering to a certain extent, they have certain limitations and deficiencies.

[0005] (1) The first evaluation method is the result of each device or subsystem passing the external applied electric field test stress under the standard darkroom facility conditions. The standard darkroom is a shielded place affected by space and surrounding shielding body. The functional performance of the radar reconnaissance device or subsystem under the applied external electromagnetic environment cannot be verified in practice. The evaluation of the system's external radio frequency electromagnetic environment design level is based on the test results of each device or subsystem under the standard darkroom facility conditions, which may cause a large gap between the evaluation results and the actual use of the system's external radio frequency electromagnetic environment level.

[0006] (2) The second evaluation method is to use the external radio frequency electromagnetic environment test data of the ship installation or simulated installation. Although it objectively reflects the actual use of the subsystem, the data can only reflect the radar reconnaissance system's external electromagnetic environment level (sensitive or insensitive) in a specific installation environment. The electromagnetic radiation capability of the surrounding installation equipment cannot be adjusted step by step, and the problem of the subsystem's external electromagnetic environment sensitivity threshold and damage threshold cannot be answered. Therefore, the evaluation results do not have the engineering value of general application. SUMMARY

[0007] The application provides a method for evaluating the local radiation strong radio frequency electromagnetic sensitivity, which can solve the technical problems of large gap between the evaluation results and the actual results, and lack of application value of the evaluation results.

[0008] The application provides a method for evaluating the local radiation strong radio frequency electromagnetic sensitivity, which includes the following steps:

[0009] Step one, according to the typical functional principle such as Figure 1 , the electromagnetic environment coupling path analysis of the radar reconnaissance system is carried out. The electromagnetic environment coupling path mainly includes front door coupling and back door coupling. The front door coupling passes through the antenna, coaxial switch, filter, limiter, RF preamplifier, etc. to the reconnaissance system receiving and processing unit in turn, and the back door coupling is introduced into the internal circuit through the power line and signal line between devices.

[0010] Step two, strong radio frequency weak point analysis of the front door coupling is carried out. The front door coupling carries out test verification on the radio frequency power performance of coaxial switch, filter, limiter, and RF preamplifier through traversal method. The most sensitive key device to strong radio frequency is determined through the bearing power test.

[0011] Step three, according to GJB151B-2013 project CS114 4kHz-400MHz cable bundle injection conduction sensitivity test method, the cable bundle involved in the back door coupling carries out CS114 curve five (the most stringent requirement of the standard) sensitivity test verification, and the threshold of the back door coupling is obtained; It should be noted that the step three of the present application is to compare the front door coupling and the back door coupling, which is the most key device affecting the strong radio frequency sensitivity of the ship radar reconnaissance system.

[0012] Step four, combining the test results of steps three and four, determine that the main key device of the strong radio frequency sensitivity of the ship radar reconnaissance system is the front door coupling, and the relationship between the system strong radio frequency sensitive response and the limiter front end signal is determined according to the power threshold of the key device obtained in step three;

[0013] Step five, according to the step three, the relationship between the system strong radio frequency sensitive response and the antenna receiving port response is established, and the field intensity lower limit of the local radiation antenna receiving port is determined according to formulas (1), (2) and (3); The upper limit of the local radiation field intensity is the smaller value of the field intensity calculation result of the key device damage threshold transmitted to the antenna receiving port and the preset standard (i.e. the ship open deck external electromagnetic environment field intensity required by GJB1389B-2022 "System Electromagnetic Environment Effect Requirements");

[0014] Step six, select the working frequency band to be evaluated, use the parameter adjustable electromagnetic environment radiation source system to generate the upper and lower limit of the field intensity of the strong radio frequency signal, and carry out the local radiation (antenna receiving port) according to the method specified in GJB8848-2016, gradually increase the field intensity amplitude from the lower limit until the system appears sensitive, and the obtained sensitive threshold is the system electromagnetic strong radio frequency sensitivity evaluation threshold.

[0015] Further, the strong radio frequency weak point analysis of the front door coupling is carried out, and the strong radio frequency power performance of the coaxial switch, filter, limiter, RF preamplifier is verified by the traversal method, and the key device most sensitive to the strong radio frequency is determined by the bearing power test; including:

[0016] Specifically, according to the bearing power test of the coaxial switch, filter, limiter, RF preamplifier and the like is carried out, and the damage threshold of the device is obtained; Figure 2

[0017] Test f1-f 18 GHz, 1GHz as a step, any point frequency as test frequency, set the signal source to output the continuous wave signal of the frequency, adjust the signal source output power until the power meter reading is N1dBmW;

[0018] f1-f 18 ​GHz, with 1 GHz step, any point frequency as test frequency, set the signal source output current frequency of continuous wave signal, adjust the signal source output power until the power meter reading is N2 dBmW, with the specified power output, for a specified time (for example, 3 min);

[0019] After the test is completed, test according to the table 1 small signal index, if the test result meets the index, it is indicated that the power bearing index test is passed, if the test result does not meet the index, it is indicated that the threshold upper limit of the key device bearing power has been reached, the input power and parameters at this time are recorded;

[0020] According to the test results, the damage threshold of the limiter, coaxial switch, filter and RF preamplifier is obtained, therefore, according to the test results, the minimum damage threshold is determined as the front door coupling strong radio frequency key device;

[0021] Table 1 f1~f 18 GHz test index

[0022]

[0023] Table 1 is a table of f1~f18 GHz test index.

[0024] Further, step four, combined with the test results of step two and step three, determines that the main key device of the ship radar reconnaissance system strong radio frequency sensitivity is the front door coupling, combined with the key device power threshold obtained in step three, determines the relationship between the system strong radio frequency sensitive response and the limiter front end signal; including:

[0025] According to the response relationship between the antenna receiving port response and the key device front end signal on the radar reconnaissance system, the transfer function between the key device front end signal of the radar reconnaissance system and the antenna receiving port response is obtained, that is, the relationship between the field strength at the antenna port and the power size of the key device front end signal.

[0026] Further, step five, according to the following method, determine the lower limit of the field strength of the local radiation antenna receiving port:

[0027] AF = 20 log f - G - 29.78 (1)

[0028] AF = 20 log (E0 / V0) (2)

[0029] V0 = P0 + L T (3)

[0030] Wherein, G is the antenna gain, unit dB; AF is the key port receiving antenna antenna coefficient, unit dB / m; E0 is the local radiation field strength, unit V / m; V0 is the key port antenna output voltage, unit V; P0 is the system strong RF response corresponding to the key device front-end signal power, unit dBm; L T L is the transfer function between the key device front-end signal and the key port response, unit dB; wherein, L T L = L1 + L2; wherein, L1 represents the radome attenuation, unit dB; L2 represents the link loss between the key device limiter front-end to the key port (receiving antenna), unit dB.

[0031] The application effectively solves the problems of not being able to answer the system external electromagnetic environment sensitivity threshold, damage threshold and not having the value of engineering application by using the parameter-adjustable electromagnetic environment radiation source system through the local radiation method.

[0032] Meanwhile, the evaluation method also uses the combination of system key device performance indicators and the like, so that the evaluation result is obtained under the equivalent use environment, the evaluation result is more accurate and has higher reliability, and the problem of large deviation between the previous evaluation result and the actual use result is solved. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 A typical functional electromagnetic environment coupling path analysis diagram of a radar reconnaissance system is provided for the embodiments of the application;

[0034] Figure 2 A power endurance test test block diagram is provided for the embodiments of the application;

[0035] Figure 3 A local radiation implementation schematic diagram of the electromagnetic environment radiation source system is provided for the embodiments of the application. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the application more clear, the embodiments of the application will be further described in detail below with reference to the drawings.

[0037] The application proposes a method based on local radiation, combines the two evaluation methods, fully utilizes the parameter-adjustable electromagnetic environment radiation source system, combines the subsystem key device performance indicators, carries out the subsystem external RF electromagnetic sensitivity evaluation, makes the subsystem external RF electromagnetic sensitivity evaluation result closer to the actual use state, and has more application value, so as to achieve the purpose of more accurate evaluation result and wider application range.

[0038] Firstly, according to the following formula, the local radiation field strength E0 is calculated: Figure 1The key port is the port directly facing the potential radio frequency hazard. According to the composition and working principle of the ship radar reconnaissance system, the strong radio frequency key port of the radar reconnaissance system is determined as the antenna seat (composed of antennas, switches, filters, limiters, radio frequency power amplifiers, etc.) of different frequency bands located on the deck of the ship.

[0039] In the second step, the power withstand test of all microwave devices (switches, filters, limiters, radio frequency power amplifiers, etc.) in the determined system key port antenna seat is carried out, and the main characterization parameter is the power withstand capability to determine the most sensitive key device under strong radio frequency.

[0040] Specifically, according to Figure 2 As shown, the power threshold test of microwave devices such as switches, filters, limiters, and radio frequency power amplifiers is carried out, and the test frequency band f1-f 18 GHz is selected with 1GHz step; any point frequency is the test frequency, and the signal source outputs the continuous wave signal and the pulse signal with pulse width of 1us and repetition period of 1ms at the frequency. After completing the test in the above steps, the small signal index is tested according to Table 2, if the test result meets the index, it means that the power withstand index test is passed, if the test result does not meet the index, it means that the upper threshold of the microwave device power withstand has been reached, and the input power and parameters at this time are recorded. The test results show that the limiter is the most sensitive key device under strong radio frequency, and the upper threshold is reached first.

[0041] Table 2: Microwave device power threshold test record

[0042]

[0043] In the third step, according to the threshold test results, the signal input power in front of the limiter has an upper threshold, when the signal input power in front of the limiter is greater than P0, the radar reconnaissance system will have sensitive (video signal delay, not meeting linear update, etc.) response.

[0044] In the fourth step, as shown in Figure 1 After the antenna branch receives the signal, it enters the limiter through the switch and filter, and there is link loss and antenna cover attenuation on the coupling path. According to the different frequency bands, the transfer function L T between the signal in front of the limiter and the antenna seat port response of the radar reconnaissance system key device is calculated.

[0045] Specifically, according to the known antenna gain, the field strength lower limit of the key port of local radiation is determined according to formulas (1), (2), (3), and the field strength upper limit of local radiation is the smaller one of the field strength calculated by transferring the damage threshold of the key device to the field strength at the key port and the external electromagnetic environment field strength of the open deck of the ship required by GJB1389B-2022 “System Electromagnetic Environment Effect Requirements”, as shown in Table 3.

[0046] Table 3 Local radiation field strength upper and lower limits

[0047]

[0048]

[0049] In the fifth step, according to the field strength upper and lower limits shown in Table 3, the working frequency band to be evaluated is selected, the parameter-adjustable electromagnetic environment radiation source system is used, and the local radiation (antenna pedestal) is carried out according to the method specified in GJB8848-2016. The field strength amplitude is gradually increased from the lower limit until the system appears sensitive, and the obtained sensitive threshold is the system electromagnetic strong radio frequency sensitivity evaluation threshold. If the system still does not appear sensitive until the field strength upper limit, the highest field strength is recorded.

[0050] The above-described embodiments of the present application do not constitute a limitation on the protection scope of the present application.

Claims

1. A method for evaluating based on local radiated RF electromagnetic sensitivity, characterized in that, The method comprises: Step one, analyze the electromagnetic environment coupling path of the radar reconnaissance system, the electromagnetic environment coupling path is front door coupling and back door coupling; wherein the front door coupling passes through the antenna, coaxial switch, filter, amplitude limiter and RF preamplifier in turn to reach the reconnaissance system receiving and processing branch, and the back door coupling is introduced into the internal circuit through the power line and signal line penetrating between devices; Step two, analyze the strong radio frequency weak point of the front door coupling, the front door coupling respectively tests and verifies the radio frequency power performance of the coaxial switch, filter, amplitude limiter and RF preamplifier through the traversal method, and determines the key device most sensitive to the strong radio frequency through the bearing power test; Step three, according to the cable bundle injection conduction sensitivity test method, the CS114 curve five sensitivity test verification is carried out on the cable bundle involved in the back door coupling to obtain the threshold of the back door coupling; Step four, determine that the main strong radio frequency sensitivity of the shipborne radar reconnaissance system is the key device in the front door coupling, and determine the relationship between the system strong radio frequency sensitive response and the front end signal of the amplitude limiter in combination with the key device power threshold obtained in step three; Step five, according to the key device established in step three, the relationship between the system strong radio frequency sensitive response and the antenna receiving port response is established, and the lower limit of the local radiation antenna receiving port field strength is determined; the upper limit of the local radiation field strength is the smaller value of the calculated result of the field strength of the key device damage threshold transmitted to the antenna receiving port and the preset standard; Step six, select the working frequency band to be evaluated, generate the field strength upper and lower limit strong radio frequency signal, carry out local radiation, and gradually increase the field strength amplitude from the lower limit until the system appears sensitive, and the obtained sensitive threshold is the system electromagnetic strong radio frequency sensitivity evaluation threshold.

2. The method of claim 1, wherein, The strong radio frequency weak point of the front door coupling is analyzed, the front door coupling respectively tests and verifies the radio frequency power performance of the coaxial switch, filter, amplitude limiter and RF preamplifier through the traversal method, and determines the key device most sensitive to the strong radio frequency through the bearing power test; It comprises: Specifically, the bearing power test is carried out on the coaxial switch, filter, amplitude limiter and RF preamplifier, and the damage threshold of the device is obtained; Test time draw f1~f 18 GHz, 1GHz step, any point frequency as test frequency, set the signal source output the frequency of continuous wave signal, adjust the signal source output power until the power meter reading is N1dBmW; f1~f 18 GHz, with 1 GHz as a step, any point frequency as a test frequency, setting the signal source to output a continuous wave signal of the current frequency, adjusting the signal source output power until the power meter reading is N2 dBmW, using the specified power output of the power amplifier for a specified duration. After the test is completed, if the test result meets the index, it indicates that the bearing power index test is passed, if the test result does not meet the index, it indicates that the upper limit of the key device bearing power threshold has been reached, and the input power and parameters at this time are recorded; According to the test result, the damage threshold of the amplitude limiter, coaxial switch, filter and RF preamplifier is obtained, therefore, according to the test result, the damage threshold of the minimum is determined as the front door coupling strong radio frequency key device.

3. The method of claim 1, wherein, Step four, determine that the main strong radio frequency sensitivity of the shipborne radar reconnaissance system is the key device in the front door coupling, and determine the relationship between the system strong radio frequency sensitive response and the front end signal of the amplitude limiter in combination with the key device power threshold obtained in step three; it comprises: According to the response relationship between the antenna receiving port response and the front end signal of the key device on the radar reconnaissance system, the transfer function between the key device front end signal and the antenna receiving port response of the radar reconnaissance system is obtained, that is, the relationship between the field strength size at the antenna port and the power size of the key device front end signal.

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