Midfield calibration-based radar array plane evaluation method and system, and medium

Abstract

The invention relates to the technical field of radars, in particular to a radar array plane evaluation method and system based on midfield calibration and a medium. The method comprises the following steps: acquiring reference data in an infield microwave anechoic chamber, acquiring field detection data in an evaluation environment, comparing the acquired field detection data with the reference data, and evaluating the state of a radar array plane to be detected. According to the application, the state and performance of the digital array antenna are evaluated on the user site by using the internal monitoring network and the midfield calibration technology of the radar, a suggestion whether to carry out factory return maintenance is quickly given, the whole array surface field return maintenance and renovation are not needed, the equipment work is not influenced, and the method can be widely applied to engineering, engineering engineering and the like. The technical problems that in the prior art, the current actual use performance of a radar array cannot be visually and accurately evaluated on a user site, and the antenna array surface can only be returned to a factory for repair and maintenance according to a fixed time interval are solved.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to a radar array surface evaluation method, system and medium based on mid-field calibration. Background Art

[0002] With the continuous breakthrough development of computer technology and digital signal processing technology, especially the rapid development of monolithic microwave integrated circuit technology and optical fiber technology, a new generation of unit-level digital array radar based on phased array technology has emerged, injecting new vitality and vitality into the traditional radar field. Digital array radar integrates modern phased array theory, ultra-large-scale integrated circuits, high-speed computers, advanced solid-state devices and optoelectronic technology. Its core unit is the phased array antenna. The transmitter and receiver are distributed and integrated inside each channel. Its distributed active channel design makes the channels independent of each other. The failure of a single channel will not affect the operation of other channels, and the mission reliability is greatly improved. Compared with the traditional analog array centralized transmitter and receiver design, the mission reliability is greatly improved. The parameters of each channel of the digital active array can be configured separately. The flexibility of the system and the available redundancy margin are greatly improved, while the complexity of use is also increasing geometrically. After the factory darkroom calibration is completed, with the normal failure caused by use in harsh natural environments, the loss or failure of some components between different arrays will cause certain differences in the amplitude and phase of the received signals of different channels. Due to the composition principle of the phased array digital array, some main parameters of the antenna (such as sum and difference beam width, power aperture, antenna main-sub ratio, etc.) should not only meet the requirements of the standard during design and manufacturing, but also be maintained at an acceptable level during long-term use. Once the amplitude and phase errors between channels exceed a certain threshold, it will have a great impact on its performance. Therefore, it is necessary to regularly repair the faulty parts of the equipment in each channel of the antenna and recalibrate the compensation parameters of the whole machine. The common practice in the industry is that professional technicians return the antenna array surface to the factory for repair and maintenance at fixed use time intervals. Due to the complex composition and high professionalism of the digital array, general operators cannot make an accurate assessment of the current actual use performance of the digital array at the user's site.

[0003] The digital array radar receiver and transmitter adopt a distributed design and are integrated in the digital unit. The radar digital array undergoes strict indoor darkroom calibration and channel consistency compensation during assembly before being used by the radar system. After a long period of work on site, due to device loss or failure, there will be certain differences in amplitude and phase between different channels, resulting in a decrease in array performance. The conventional practice is to return the antenna array to the factory for repair and maintenance at fixed time intervals, repair the faulty channels and calibrate the array parameters in a microwave darkroom. This method has high requirements for the calibration location and equipment. It is impossible to make a quantitative assessment of the actual performance of the antenna array on site and give recommendations on whether it is necessary to return to the factory for repair. Summary of the invention

[0004] In order to solve the problems of the prior art and to achieve the purpose of directly evaluating the status of the radar array to be tested at the user's site without the need for the equipment to be returned to the factory for inspection by professionals, the present application provides a radar array evaluation method and system based on mid-field calibration.

[0005] In the first aspect, a radar array evaluation method based on midfield calibration is provided, which adopts the following technical solutions:

[0006] Get benchmark data:

[0007] In an indoor microwave darkroom, the amplitude and phase of the received signals of all channels of the radar array to be tested are collected and stored through an internal monitoring mode, and recorded as a first reference amplitude and a first reference phase; the internal monitoring mode means that the radio frequency signals received by all channels of the radar array to be tested are emitted by the monitoring component, and are coupled through the power division network of the radar array to be tested and then fed into the cable;

[0008] In the indoor microwave darkroom, the amplitude and phase of the received signal of all channels of the radar array to be tested are collected and stored through the external monitoring mode, which are recorded as the second reference amplitude and the second reference phase; the external monitoring mode means that the radio frequency signal received by all channels of the radar array to be tested is emitted by the monitoring component and is transmitted into space through the external monitoring antenna and then fed into the space;

[0009] Obtain on-site test data, compare it with the benchmark data, and evaluate the status of the radar array to be tested:

[0010] In the evaluation environment, the amplitude and phase of the received signals of all channels of the radar array to be tested are obtained through the internal monitoring mode, which are recorded as the first detection amplitude and the first detection phase; the first detection amplitude is compared with the first reference amplitude, and the first detection phase is compared with the first reference phase to evaluate the state of each channel of the radar array to be tested;

[0011] In the evaluation environment, the amplitude and phase of the received signals of all channels of the radar array to be tested are obtained through the external monitoring mode, which are recorded as the second detection amplitude and the second detection phase; the second detection amplitude is compared with the second reference amplitude, and the second detection phase is compared with the second reference phase to evaluate the status of the external cable array of each channel of the radar array to be tested.

[0012] Furthermore, when collecting the first reference amplitude and the first reference phase, the method adopted is as follows: the monitoring component switches its own output switch to the internal monitoring link and sends out an excitation signal. After the excitation signal passes through the array power division network, it is coupled to the input end of each channel of the radar array to be measured with equal amplitude and phase. The digital unit of each receiving channel simultaneously converts the data sampling into a digital signal through down-conversion and analog-to-digital conversion and then sends it down, so as to obtain the first reference amplitude and first reference phase of the receiving signal of all channels of the radar array to be measured.

[0013] Furthermore, when collecting the second reference amplitude and the second reference phase, the method adopted is as follows: the monitoring component switches its own output switch to the external monitoring link and sends out an excitation signal. The excitation signal is emitted through the external monitoring antenna and spatially transmitted to the input end of each receiving channel of the radar array to be measured. The digital unit of each receiving channel simultaneously converts the data sampling into a digital signal through down-conversion and analog-to-digital conversion and then sends it down to obtain the second reference amplitude and second reference phase of the receiving signal of all channels of the radar array to be measured.

[0014] Furthermore, before collecting the second reference amplitude and the second reference phase, phase compensation is performed on each channel of the radar array to be measured, specifically as follows: phase compensation is performed on each channel of the radar array to be measured using the fixed principle of mid-field difference.

[0015] Furthermore, the first detection amplitude is compared with the first reference amplitude, and the first detection phase is compared with the first reference phase. The evaluation principle for evaluating the state of each channel of the radar array to be tested is as follows:

[0016] If any one or both of conditions A and B are met, the channel will be listed as a faulty channel:

[0017] Condition A: The first detection amplitude is at least 3dB smaller than the first reference amplitude;

[0018] Condition B: The first detection phase deviates from the first reference phase by more than 30°, and the first detection phase deviates from the average detection phase of all channels of the radar array to be tested by more than 30°.

[0019] Furthermore, the second detection amplitude is compared with the second reference amplitude, and the second detection phase is compared with the second reference phase. The evaluation principle for evaluating the state of the external cable array of each channel of the radar array to be tested is as follows:

[0020] If any one or both of conditions C and D are met, in addition to the fault channel consistent with the evaluation in claim 5, the newly added fault channel is recorded as the external cable array damaged channel:

[0021] Condition C: The second detection amplitude is at least 3dB smaller than the second reference amplitude;

[0022] Condition D: The second detection phase deviates from the second reference phase by more than 30°, and the second detection phase deviates from the average detection phase of all channels of the radar array to be tested by more than 30°.

[0023] Furthermore, when obtaining the reference data, it also includes collecting and storing the reference lobe data of the radar array to be tested in the indoor microwave darkroom through the external monitoring mode; the reference lobe data includes the maximum level Wm of the sum beam main lobe and the ratio Rm of the sum beam main lobe to the side lobe;

[0024] Acquiring on-site detection data and evaluating the state of the radar array to be tested also includes acquiring detection lobe data of the radar array to be tested in the evaluation environment through an external monitoring mode; the detection lobe data includes the maximum level Wm' of the sum beam main lobe and the ratio Rm' of the sum beam main lobe to the side lobe;

[0025] Compare the reference lobe data with the detection lobe data to evaluate the power of the radar array to be tested.

[0026] Furthermore, when obtaining the reference data, it also includes collecting and storing the reference lobe data of the radar array to be tested in an indoor microwave darkroom through an external monitoring mode; the reference lobe data also includes the 3dB beam width Em of the sum beam main lobe and the zero depth position θ of the difference beam;

[0027] Acquiring on-site detection data and evaluating the state of the radar array to be tested also includes acquiring detection lobe data of the radar array to be tested through an external monitoring mode under the evaluation environment; the detection lobe data also includes; the sum beam main lobe 3dB beam width Em', the difference beam zero depth position θ';

[0028] Compare the reference lobe data with the detection lobe data to evaluate the accuracy of the radar array to be tested.

[0029] In the second aspect, a radar array evaluation system based on midfield calibration is provided, which adopts the following technical solutions:

[0030] A radar array surface evaluation system based on midfield calibration, the system is used to implement the radar array surface evaluation method based on midfield calibration as described in the first aspect, the system comprising:

[0031] Monitoring component: used to output RF signals according to control instructions at specified times;

[0032] External monitoring antenna: used to transmit radio frequency signals and transmit them to the input end of the receiving channel of the radar array to be tested;

[0033] Digital beamforming: used to receive digital signals sent from all channels of the radar array to be tested, and select different processing methods according to the type of data detected, and then send them to the data processing and display control unit for display;

[0034] Data processing and display control: issue control instructions, receive data sent by digital beamforming, compare the received detection data with the benchmark data, output and display the evaluation results;

[0035] RF coaxial cable: used to connect the external monitoring antenna and the external monitoring output port of the monitoring component.

[0036] In a third aspect, a storage medium is provided, characterized in that: the storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps in the method described in the first aspect.

[0037] The beneficial effects of the present invention are as follows:

[0038] In the prior art, the radar antenna array is returned to the factory for repair and maintenance at fixed time intervals, and the faulty channels of the antenna array are repaired and the array parameters are calibrated in a microwave darkroom, which places high requirements on the calibration location and equipment.

[0039] This application uses the radar's own internal monitoring network and mid-field calibration technology to evaluate the status of the digital array antenna at the user's site and quickly give recommendations on whether it is necessary to return to the factory for repair. The evaluation method is cost-effective and does not require the entire array to be returned for maintenance and refurbishment, which does not affect the normal operation of the equipment.

[0040] This application can also evaluate the performance of radar array antennas, including array power and accuracy, and provide more comprehensive recommendations on whether factory repairs are necessary.

[0041] Compared with the traditional far-field measurement method, the external monitoring antenna in the mid-field measurement is closer to the array surface, which not only ensures a certain signal-to-noise ratio, but also greatly reduces the requirements for the measurement environment. At the same time, combined with the characteristics of each channel of the active phased array being independently controllable, this method can conveniently measure the quality of each channel separately, as well as the amplitude and phase characteristics of the channel, and has been widely used in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a flow chart of a radar array evaluation method based on midfield calibration of the present invention;

[0043] Figure 2 is a schematic diagram of a radar array evaluation system based on midfield calibration according to an embodiment of the present invention;

[0044] Figure 3 is a first reference amplitude distribution diagram of a 10-row*10-column array according to the first embodiment of the present invention;

[0045] Figure 4 is a first reference phase distribution diagram of a 10-row*10-column array according to the first embodiment of the present invention;

[0046] Figure 5 This is a first detection amplitude distribution diagram of a 10-row*10-column array according to the first embodiment of the present invention;

[0047] Figure 6 This is a first detection phase distribution diagram of a 10-row*10-column array according to the first embodiment of the present invention;

[0048] Figure 7 It is the azimuth and / or difference lobe pattern during calibration of the indoor microwave darkroom in the second embodiment of the present invention;

[0049] Figure 8 is the azimuth and / or difference lobe pattern during evaluation in Embodiment 2 of the present invention;

[0050] Fig. 9 It is the azimuth and / or difference lobe pattern during calibration in the indoor microwave darkroom of the third embodiment of the present invention;

[0051] Fig.10 This is the azimuth and / or difference lobe pattern during evaluation in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0052] The present invention provides a radar array assessment method based on midfield calibration. By calibrating and recording the reference data of the radar array to be measured in an indoor microwave darkroom, after the equipment has been used for a long time, an operator can directly perform maintenance tests at the user's site without the need for external additional equipment. Only relying on the internal monitoring network of the radar to be measured and the external off-site monitoring antenna at a fixed position, the state of the radar array to be measured is fully automatically assessed, and a suggestion is given as to whether it is necessary to return the radar to the factory for repair.

[0053] The midfield refers to the distance from each array of the radar array to be tested to the external monitoring antenna. All meet , where D is the electrical aperture side length of the radar array antenna to be measured, and λ is the wavelength of the radar to be measured.

[0054] The radar array evaluation method based on midfield calibration, the evaluation process is as follows Figure 1 As shown, the invention is further described below in conjunction with embodiments.

[0055] Embodiment 1:

[0056] The radar array to be tested is arranged in a square shape of 10 rows and 10 columns with a total of 100 units, and the row spacing is consistent with the column spacing. The specific steps of the radar array evaluation method based on midfield calibration are as follows:

[0057] Step 1: Obtain baseline data

[0058] The benchmark data is obtained by testing in an indoor microwave darkroom. The preparation of the indoor microwave darkroom environment is introduced in step 1-1. The benchmark data includes internal monitoring benchmark data and external monitoring benchmark data. The acquisition of internal monitoring benchmark data is introduced in step 1-2, and the acquisition of external monitoring benchmark data is introduced in step 1-3.

[0059] 1-1. Prepare the indoor microwave darkroom environment

[0060] Place the radar to be tested (usually a vehicle-mounted radar, with the cab at the front of the vehicle and the radar antenna at the rear) in a microwave darkroom or on a flat cement floor without interference. The external monitoring antenna is placed on the mounting port on the top of the cab at the head of the radar-carrying vehicle and is directly opposite the radar array to be tested, and the center position of the radar array to be tested meets the midfield requirements. If the height of the external monitoring antenna is lower than the lowest point of the radar array to be tested, it is necessary to carry a calibration pole to raise it to meet the minimum height requirement. The external monitoring antenna is fixed on the top of the calibration pole, the radar array to be tested is in a leveling state, the horizontality is within 3', the internal and external monitoring systems perform normally, and the external monitoring output port of the monitoring component is normally connected to the external monitoring antenna, and the internal monitoring output port of the monitoring component is normally connected to the monitoring network.

[0061] 1-2. Obtain internal benchmark data

[0062] In an indoor microwave darkroom, internal monitoring reference data of all channels of the radar array to be tested, including amplitude and phase, are collected and stored through an internal monitoring mode, which are recorded as a first reference amplitude and a first reference phase; the internal monitoring mode means that the radio frequency signal received by all channels of the radar array to be tested is emitted by the monitoring component and is coupled through the power division network of the radar array to be tested and then fed into the cable.

[0063] The method for obtaining the first reference amplitude and the first reference phase is as follows:

[0064] In the indoor microwave darkroom, start the automatic array calibration. The radar to be tested receives the array calibration test instruction and performs internal monitoring control of the whole array reception at a certain frequency point. The control monitoring component switches its own output switch to the internal monitoring link and sends out the excitation signal of the measured frequency point when the required time arrives. After the signal is divided by the internal monitoring network, it is coupled to the input end of each receiving channel of the radar array to be tested with equal amplitude and phase. Each receiving channel collects RF data at the same time. After the analog data sampling is converted into digital signals through down-conversion, analog-to-digital conversion and other processes, it is simultaneously sent to the digital beamforming equipment through optical fiber. The digital beamforming converts the optical fiber data into network data and then sends it down. The digital beamforming does not synthesize the signal. In one test, the amplitude A1-A100 (recorded as the first reference amplitude) and phase θ1-θ100 (recorded as the first reference phase) of all channels of the radar array to be tested in the internal monitoring mode can be obtained simultaneously. The first reference amplitude and the first reference phase of the received signals of all channels are counted and the data is stored. When obtaining the benchmark data in the indoor microwave darkroom, the monitoring amplitude distribution is as follows: Figure 3 As shown, the monitoring phase distribution is Figure 4 shown.

[0065] 1-3. Obtain external benchmark data

[0066] First, phase compensation of each channel of the radar array to be tested is performed as follows:

[0067] The phase compensation of each channel of the radar array to be tested is performed by using the principle of fixed mid-field distance difference: first, obtain the straight-line distance from the fixed external monitoring antenna array surface to each array of the radar array to be tested, the method is as follows: due to the known array arrangement rules and the row and column spacing between each array, the arrangement with the center of the array as point (0, 0), each antenna unit has a coordinate point in this coordinate system, which is recorded as point A, and the coordinates are (x, y). During the mid-field calibration of the external monitoring, the projection coordinates of the external monitoring antenna (recorded as point C) to the plane where the array is located are (x0, y0) (recorded as point B), and the distance between point B and point C, that is, the vertical distance of the projection of the external monitoring antenna, is z0. The values ​​of x0, y0, and z0 are all obtained by the calibration of the total station; any point A can be connected to point B to form an oblique line, and the length of the oblique line can be obtained from the geometric relationship. Points A, B, and C are a new right triangle, and the hypotenuse AC of the right triangle can be obtained by the following formula:

[0068]

[0069]

[0070] C1 is the standard mid-range difference phase, which is a matrix file formed according to the fixed position of the antenna unit. (From the above formula, it can be seen that the value obtained is modulo 360, where the length unit is mm and the frequency f unit is MHz, is the wavelength of the radar to be tested, and the final unit of the phase is °). Load the C1 file into each channel of the radar array to be tested for self-compensation. At this time, after the phase compensation of each channel of the radar array to be tested, the phase of the signal received from the external monitoring antenna should be consistent.

[0071] Then, the internal monitoring reference data of all channels of the radar array to be tested, including amplitude and phase, are collected and stored through the external monitoring mode, which is recorded as the second reference amplitude and the second reference phase; the external monitoring mode means that the radio frequency signal received by all channels of the radar array to be tested is emitted by the monitoring component and is transmitted into space through the external monitoring antenna and then fed into the space.

[0072] The method for obtaining the second reference amplitude and the second reference phase is as follows:

[0073] In the indoor microwave darkroom, start the external monitoring mode. The radar to be tested receives the external monitoring instruction of the array and performs external monitoring control of the whole array at a certain frequency. At this time, the monitoring component will switch its own output switch to the external monitoring link and send out the excitation signal of the measured frequency when the required time arrives. The signal is transmitted through the external monitoring antenna and transmitted to the input end of each receiving channel of the radar array to be tested. Each receiving channel collects RF data at the same time. After the analog data sampling is converted into digital signals through down-conversion, analog-to-digital conversion and other processes, it is simultaneously sent to the digital beam forming device through optical fiber. The digital beam forming converts the optical fiber data into network data and then sends it down (without synthesis). In one test, the amplitude A1-A100 (recorded as the second reference amplitude) and θ1-θ100 (recorded as the second reference phase) of all channels of the radar array to be tested in the external monitoring mode can be obtained at the same time. The second reference amplitude and second reference phase of the received signals of all channels are counted and the data is stored.

[0074] Step 2: Obtain on-site test data, compare it with the benchmark data, and evaluate the status of the radar array to be tested:

[0075] After the radar has been used for a long time, the radar needs to be evaluated for its status after the startup time or when the threshold described in the maintenance manual is reached. The specific steps are as follows:

[0076] 2-1. Prepare the evaluation environment

[0077] Place the radar to be tested in an open area without external interference: the radar to be tested can be directly set up on a flat concrete ground, or it can be carried by a radar vehicle; when carried by a radar vehicle, the radar array to be tested is usually located at the rear of the radar vehicle.

[0078] An external monitoring antenna is installed on the vehicle carrying the external monitoring antenna: the front of the vehicle carrying the external monitoring antenna is facing the radar array to be tested, and the position of the center of the radar array to be tested meets the midfield requirements. A calibration pole is installed at the front of the vehicle carrying the external monitoring antenna, which is the farthest from the radar array to be tested. The installation interface of the calibration pole should be higher than the lowest point of the radar array to be tested. The external monitoring antenna is fixed on the top of the calibration pole, and the external monitoring antenna and the radar array to be tested are in a leveling state, with a horizontality of less than 3'. The topological connection between the equipment must be exactly the same as that in the indoor microwave darkroom, and the three-dimensional distance from the external monitoring antenna to the center of the radar array to be tested remains unchanged.

[0079] The internal and external monitoring systems are connected normally. The external monitoring output port of the monitoring component is connected normally to the external monitoring antenna, and the internal monitoring output port of the monitoring component is connected normally to the monitoring network.

[0080] 2-2. Evaluate the status of each channel of the radar array to be tested

[0081] In the evaluation environment, the amplitude and phase of the received signal of all channels of the radar array to be tested are obtained through the internal monitoring mode, which are recorded as the first detection amplitude and the first detection phase; the internal monitoring mode means that the radio frequency signal received by all channels of the radar array to be tested is emitted by the monitoring component, and is coupled through the power division network of the radar array to be tested and then fed into the cable; the first detection amplitude is compared with the first reference amplitude, and the first detection phase is compared with the first reference phase to evaluate the channel state of the radar array to be tested; the details are as follows:

[0082] Start the array assessment. The radar to be tested receives the array assessment test instruction and performs internal monitoring control of the entire array at a certain frequency. The control monitoring component sends an excitation signal. After the common signal passes through the array power division network, it is coupled to the input end of each receiving channel of the radar array to be tested with equal amplitude and phase. The digital unit of each receiving channel simultaneously converts the data sampling into a digital signal through down-conversion, analog-to-digital conversion and other processes and then sends it down. At the same time, the amplitude (recorded as the first detection amplitude) and phase (recorded as the first detection phase) of all channels of the radar array to be tested in the internal monitoring mode are obtained, and the first detection amplitude of the received signal of each channel of the radar array to be tested is compared with the first reference amplitude one by one, and the first detection phase is compared with the first reference phase one by one. If any one or both of conditions A and B are met, the channel fault channel can be:

[0083] Condition A: The first detection amplitude is at least 3dB smaller than the first reference amplitude;

[0084] Condition B: The first detection phase deviates from the first reference phase by more than 30°, and the first detection phase deviates from the average detection phase of all channels of the entire array by more than 30°.

[0085] In this embodiment, the amplitude distribution during evaluation is as follows Figure 5 As shown, the phase distribution is Figure 6 As shown, there are 16 channels with abnormal amplitude and phase.

[0086] 2-3. Evaluate the status of the external cable array of each channel of the radar array to be tested

[0087] In the evaluation environment, the amplitude and phase of the received signal of all channels of the radar array to be tested are obtained through the external monitoring mode, which are recorded as the second detection amplitude and the second detection phase; the external monitoring mode means that the radio frequency signal received by all channels of the radar array to be tested is transmitted by the monitoring component, and is transmitted to the space through the external monitoring antenna and then fed in; the second detection amplitude is compared with the second reference amplitude, and the second detection phase is compared with the second reference phase to evaluate the external cable array status of each channel of the radar array to be tested. The details are as follows:

[0088] First, perform phase compensation on each channel of the radar array to be tested: load the C1 file into each channel of the radar array to be tested for self-compensation. At this time, after phase compensation on each channel of the radar array to be tested, the phase of the signal received from the external monitoring antenna should remain consistent.

[0089] Then, start the external monitoring instruction to perform external monitoring control of the entire array reception at a certain frequency point. In one test, the second detection amplitude and second detection phase of all channels of the radar array to be tested in the external monitoring mode are obtained simultaneously. The second detection amplitude of the received signal of each channel of the radar array to be tested is compared with the second reference amplitude one by one, and the second detection phase is compared with the second reference phase one by one. If any one or two of conditions C and D are met, except for the channel consistent with the fault detected in step 2-2, the newly added faulty channel is recorded as the damaged channel of the external cable array and saved.

[0090] Condition C: The second detection amplitude is at least 3dB smaller than the second reference amplitude;

[0091] Condition D: The second detection phase deviates from the second reference phase by more than 30°, and the second detection phase deviates from the average detection phase of all channels of the entire array by more than 30°.

[0092] According to this embodiment, 16 channels are damaged ( Figure 5 The dark blocks in the middle are the specific locations), and 0 cables were damaged.

[0093] Embodiment 2:

[0094] On the basis of the implementation of step 1, when acquiring the external reference data, the reference lobe related data is also acquired. The details are as follows:

[0095] In the indoor microwave darkroom, when collecting and storing the external monitoring reference data of all channels of the radar array to be tested through the external monitoring mode, it also includes collecting the reference lobe related data. By starting the lobe test function, the radar control system controls the monitoring component to switch its own output switch to the external monitoring link, and sends the excitation signal of the measured frequency point at the specified time. The signal is transmitted through the external monitoring antenna and spatially transmitted to the input end of each receiving channel of the radar array to be tested (because the optical path difference from each array to the external monitoring antenna under the mid-field condition has been compensated respectively in steps 1-3, the antenna directional diagram has been focused to the far-field condition), and each receiving channel of the radar array to be tested collects RF data at the same time, and converts the analog data sampling into digital signals through down-conversion, analog-to-digital conversion and other processes, and then sends them to the digital beam forming device through optical fiber at the same time. The digital beam forming weights the data of each channel according to the actual position of each array in the entire array (the same source data is multiplied by the azimuth sum weight and azimuth difference weight respectively), and multiplied by the current frame azimuth and elevation pointing angle, and then the synthesized sum beam data and difference beam data are sent down through the network. During the lobe scanning process under this condition, the beam azimuth pointing starts from the azimuth angle of -45° calibrated by the external monitoring antenna relative to the center of the array, with a step of 1°. The beam pitch pointing is always fixed to the pitch angle of the external detection antenna relative to the center of the array. Two data are obtained and saved each time, and then switched to the next angle until the lobe scanning ends at the azimuth angle of 45°. The two data include one sum beam data and one difference beam data. When obtaining the reference data in the indoor microwave darkroom, the azimuth and / or difference beam lobe pattern is as follows: Figure 7 After the scan is completed, the data of the maximum level Wm of the sum beam main lobe and the ratio Rm of the sum beam main lobe to the side lobe are obtained and saved.

[0096] The method for obtaining the maximum level Wm of the sum beam main lobe is: traverse the entire sum beam data and take the maximum value.

[0097] The method for obtaining the ratio Rm of the sum beam main lobe to the side lobe is as follows: after the main lobe envelope of the sum beam is removed, the remaining data is traversed and the maximum is taken, and then the value is subtracted from the main lobe maximum level to obtain the ratio of the sum beam main lobe to the side lobe.

[0098] When obtaining on-site detection data and evaluating the state of the radar array to be tested, it also includes obtaining the detection lobe data of the radar array to be tested through the external monitoring mode under the evaluation environment; the detection lobe data includes the maximum level Wm' of the sum beam main lobe (which needs to be normalized with the reference lobe amplitude, the method is to subtract the reference lobe and amplitude maximum value from the measurement results of each lobe pointing point), and the ratio Rm' of the sum beam main lobe to the side lobe. The azimuth and / or difference beam pattern during evaluation is as follows: Figure 8 As shown, the detection lobe data is compared with the reference lobe data to evaluate the power of the radar array to be tested. The detection lobe data is compared with the reference lobe data to evaluate the power of the radar array to be tested. The evaluation principles are as follows:

[0099] Wm-Wm'<1dB and Rm-Rm'<3dB, which means the radar array power to be tested is normal;

[0100] 1dB≤Wm-Wm'≤3dB and Rm-Rm'<5dB, it is recorded that the radar array to be tested has good power and can be operated at a reduced rating;

[0101] If Wm-Wm'>3dB or Rm-Rm'>5dB, it means the radar array power influence exceeds the index and cannot be used normally.

[0102] This radar is designed with a margin of about 1.2dB. Therefore, when the array loss is less than this value, the radar performance can still meet the index requirements. When the loss is less than 3dB, without considering additional losses (such as weather, humidity, etc.), the radar can meet the user's minimum usage requirements and is marked as derating. When the loss is greater than 3dB, the user's minimum requirements cannot be met. Therefore, this parameter needs to be adjusted according to actual conditions. The threshold taken in this embodiment is only an example.

[0103] According to this embodiment, 16 channels are damaged ( Figure 5 The dark blocks in the middle are the specific locations), 0 cables are damaged, and the array power is shown to be good (Wm-Wm'=2.6dB, Rm-Rm'=4dB).

[0104] Embodiment three:

[0105] On the basis of implementing step 2, when acquiring the external reference data, other reference lobe related data are also acquired. The details are as follows:

[0106] In the indoor microwave darkroom, when the external monitoring reference data of all channels of the radar array to be tested are collected and stored through the external monitoring mode, the collected reference lobe related data also includes: the 3dB beam width Em of the sum beam main lobe, the zero depth position θ of the difference beam, and when the reference data is obtained in the indoor microwave darkroom, the azimuth and / or difference beam directivity diagram is as follows: Fig. 9 After the scan is completed, the data of the sum beam main lobe 3dB beam width Em and the difference beam zero depth position θ are obtained and saved.

[0107] The method for obtaining the 3dB beam width Em of the sum beam main lobe is as follows: find the first position where the subtraction is equal to 3dB to the left and right of the extracted maximum value of the sum beam main lobe envelope, and subtract the azimuth scanning angles corresponding to the two positions to obtain the 3dB beam width of the sum beam main lobe.

[0108] The method for obtaining the zero depth position θ of the difference beam is as follows: within the azimuth angle corresponding to the main lobe area of ​​the beam, find the minimum value of the difference beam, which is the zero depth position θ of the difference beam.

[0109] When obtaining on-site detection data and evaluating the state of the radar array to be tested, it also includes obtaining the detection lobe data of the radar array to be tested through the external monitoring mode under the evaluation environment, including the 3dB beam width Em' of the sum beam main lobe and the zero depth position θ' of the difference beam. The azimuth and / or difference beam directivity diagram during evaluation is as follows: Fig.10 shown.

[0110] Compare the detection lobe data with the reference lobe data (where △θ=θ-θ') to evaluate the accuracy of the radar array to be tested. The evaluation principles are as follows:

[0111] -0.05°<△θ<+0.05° and Em-Em'<1dB, which means the accuracy of the radar to be tested is normal;

[0112] -0.1°≤△θ≤+0.1° and Em-Em'<2dB, which means the radar under test has good accuracy and operates at a reduced rating;

[0113] If △θ>+0.1°, or △θ<-0.1° or Em-Em'>2dB, it means that the accuracy of the radar under test exceeds the accuracy index requirement of the user and cannot meet normal use.

[0114] According to this embodiment, 16 channels are damaged ( Figure 5 The dark blocks in the middle are the specific locations), 0 cables are damaged, the array power is shown as good (Wm-Wm'=2.6dB, Rm-Rm'=4dB), and the accuracy is shown as normal (△θ=0.02°, Em-Em'=0.3dB).

[0115] The selection of the angle deviation threshold is related to the angle measurement accuracy required by the radar user and needs to be adjusted according to actual usage. The threshold used in this embodiment is only used as an example.

[0116] The present invention also provides a radar array assessment system based on mid-field calibration, including a monitoring component, an external monitoring antenna, a digital beam forming, a data processing and display control, and a radio frequency coaxial cable. Figure 2 shown.

[0117] The monitoring component is the core equipment of the radar array evaluation system based on midfield calibration. Its main function is to receive the control instructions and timing of the radar control system, and output the required RF signal at the specified time according to the control instruction requirements (specified detection link, detection frequency, signal time width, signal bandwidth). When the radar under test receives the internal monitoring instruction, the monitoring component switches its output switch to the internal monitoring network and sends out the excitation signal of the measured frequency at the specified time; when the radar under test receives the external monitoring instruction, the monitoring component switches its output switch to the external monitoring link and sends out the excitation signal of the measured frequency at the specified time. In the internal monitoring mode, the excitation signal is coupled to the input end of each receiving channel of the radar array under test with equal amplitude and phase after being divided by the internal monitoring network. The radar array channel under test collects RF data at the same time, and converts the analog data sampling into digital signals through down-conversion, analog-to-digital conversion and other processes, and sends them to digital beamforming. In the external monitoring mode, the excitation signal is emitted through the external monitoring antenna and transmitted spatially to the input end of each receiving channel of the radar array to be tested. Each receiving channel collects RF data at the same time, and converts the analog data samples into digital signals through processes such as down-conversion and analog-to-digital conversion, and then sends them to digital beamforming.

[0118] The external monitoring antenna is used to transmit the radio frequency signal and transmit it spatially to the input end of the receiving channel of the radar array to be tested.

[0119] Digital beamforming is used to receive digital signals sent from all channels of the radar array to be tested, and select different processing methods according to the type of data detected, and then send them to the data processing and display control unit for data display. Among them, when detecting the amplitude and phase of the received signals of all channels of the radar array to be tested, the digital beamforming does not perform synthesis operations on the received digital signals, and directly sends the digital signals to the data processing and display control unit for data display. When detecting lobe-related data, the digital beamforming performs weighting and other processing on the received digital signals, synthesizes the sum beam data and the difference beam data, and then sends them to the data processing and display control unit for data display.

[0120] Data processing and display control are used to receive the data sent by digital beamforming, compare the received detection data with the benchmark data, and output the evaluation results for intuitive display.

[0121] The radio frequency coaxial cable is used for the external monitoring antenna and the external monitoring output port of the monitoring component.

[0122] By acquiring benchmark data in a microwave darkroom and then acquiring field detection data in an evaluation environment, the acquired field detection data is compared with the benchmark data to evaluate the state of the radar array to be tested, thereby realizing a radar array evaluation method based on mid-field calibration.

[0123] The present invention also provides a storage medium storing one or more programs, wherein the one or more programs can be executed by one or more processors to implement the steps in the radar array assessment method based on mid-field calibration.

[0124] Although the present invention has been disclosed as above with preferred embodiments, the embodiments are not intended to limit the present invention. Any equivalent changes or modifications made without departing from the spirit and scope of the present invention also belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the content defined by the claims of this application.

Claims

1. A radar array evaluation method based on mid-field calibration, characterized in that: The steps include: Get benchmark data: In the indoor microwave darkroom, the amplitude and phase of the received signals of all channels of the radar array to be tested are collected and stored through the internal monitoring mode, and recorded as the first reference amplitude and the first reference phase; The internal monitoring mode means that the radio frequency signals received by all channels of the radar array to be tested are emitted by the monitoring component and are coupled through the power division network of the radar array to be tested and then fed into the cable; In the indoor microwave darkroom, the amplitude and phase of the received signal of all channels of the radar array to be tested are collected and stored through the external monitoring mode, which are recorded as the second reference amplitude and the second reference phase; the external monitoring mode means that the radio frequency signal received by all channels of the radar array to be tested is emitted by the monitoring component and is transmitted into space through the external monitoring antenna and then fed into the space; Obtain on-site test data, compare it with the benchmark data, and evaluate the status of the radar array to be tested: In the evaluation environment, the amplitude and phase of the received signals of all channels of the radar array to be tested are obtained through the internal monitoring mode, which are recorded as the first detection amplitude and the first detection phase; the first detection amplitude is compared with the first reference amplitude, and the first detection phase is compared with the first reference phase to evaluate the state of each channel of the radar array to be tested; In the evaluation environment, the amplitude and phase of the received signals of all channels of the radar array to be tested are obtained through the external monitoring mode, which are recorded as the second detection amplitude and the second detection phase; the second detection amplitude is compared with the second reference amplitude, and the second detection phase is compared with the second reference phase to evaluate the status of the external cable array of each channel of the radar array to be tested.

2. The radar array assessment method based on mid-field calibration according to claim 1, characterized in that: When collecting the first reference amplitude and the first reference phase, the method used is as follows: The monitoring component switches its own output switch to the internal monitoring link and sends out an excitation signal. After passing through the array power division network, the excitation signal is coupled to the input end of each channel of the radar array to be tested with equal amplitude and phase. The digital unit of each receiving channel simultaneously converts the data sampling into a digital signal through down-conversion and analog-to-digital conversion and then sends it down to obtain the first reference amplitude and first reference phase of the receiving signal of all channels of the radar array to be tested.

3. The radar array assessment method based on mid-field calibration according to claim 2 is characterized in that: When collecting the second reference amplitude and the second reference phase, the method used is as follows: The monitoring component switches its output switch to the external monitoring link and sends out an excitation signal. The excitation signal is emitted through the external monitoring antenna and transmitted spatially to the input end of each receiving channel of the radar array to be tested. The digital unit of each receiving channel simultaneously converts the data sampling into a digital signal through down-conversion and analog-to-digital conversion and then sends it down to obtain the second reference amplitude and second reference phase of the receiving signals of all channels of the radar array to be tested.

4. The radar array assessment method based on mid-field calibration according to claim 3 is characterized in that: Before collecting the second reference amplitude and the second reference phase, phase compensation is performed on each channel of the radar array to be measured, specifically as follows: phase compensation is performed on each channel of the radar array to be measured using the fixed principle of mid-field difference.

5. The radar array assessment method based on mid-field calibration according to claim 1, characterized in that: The first detection amplitude is compared with the first reference amplitude, and the first detection phase is compared with the first reference phase. The evaluation principles for evaluating the status of each channel of the radar array to be tested are as follows: If any one or both of conditions A and B are met, the channel will be listed as a faulty channel: Condition A: The first detection amplitude is at least 3dB smaller than the first reference amplitude; Condition B: The first detection phase deviates from the first reference phase by more than 30°, and the first detection phase deviates from the average detection phase of all channels of the radar array to be tested by more than 30°.

6. The radar array assessment method based on mid-field calibration according to claim 5 is characterized in that: The second detection amplitude is compared with the second reference amplitude, and the second detection phase is compared with the second reference phase. The evaluation principle for evaluating the status of the external cable array of each channel of the radar array to be tested is as follows: If any one or both of conditions C and D are met, in addition to the fault channel consistent with the evaluation in claim 5, the newly added fault channel is recorded as the external cable array damaged channel: Condition C: The second detection amplitude is at least 3dB smaller than the second reference amplitude; Condition D: The second detection phase deviates from the second reference phase by more than 30°, and the second detection phase deviates from the average detection phase of all channels of the radar array to be tested by more than 30°.

7. The radar array assessment method based on mid-field calibration according to claim 1, characterized in that: Acquiring the reference data also includes collecting and storing the reference lobe data of the radar array to be tested in the indoor microwave darkroom through the external monitoring mode; the reference lobe data includes the maximum level Wm of the sum beam main lobe and the ratio Rm of the sum beam main lobe to the side lobe; Acquiring on-site detection data and evaluating the state of the radar array to be tested also includes acquiring detection lobe data of the radar array to be tested in the evaluation environment through an external monitoring mode; the detection lobe data includes the maximum level Wm' of the sum beam main lobe and the ratio Rm' of the sum beam main lobe to the side lobe; Compare the reference lobe data with the detection lobe data to evaluate the power of the radar array to be tested.

8. The radar array assessment method based on mid-field calibration according to claim 7 is characterized in that: When obtaining the reference data, it also includes collecting and storing the reference lobe data of the radar array to be tested in an indoor microwave darkroom through an external monitoring mode; the reference lobe data also includes the 3dB beam width Em of the sum beam main lobe and the zero depth position θ of the difference beam; Acquiring on-site detection data and evaluating the state of the radar array to be tested also includes acquiring detection lobe data of the radar array to be tested through an external monitoring mode under the evaluation environment; the detection lobe data also includes; the sum beam main lobe 3dB beam width Em', the difference beam zero depth position θ'; Compare the reference lobe data with the detection lobe data to evaluate the accuracy of the radar array to be tested.

9. A radar array assessment system based on midfield calibration, the system being used to implement the radar array assessment method based on midfield calibration as claimed in claim 1, the system comprising: Monitoring component: used to output RF signals according to control instructions at specified times; External monitoring antenna: used to transmit radio frequency signals and transmit them to the input end of the receiving channel of the radar array to be tested; Digital beamforming: used to receive digital signals sent from all channels of the radar array to be tested, and select different processing methods according to the type of data detected, and then send them to the data processing and display control unit for display; Data processing and display control: issue control instructions, receive data sent by digital beamforming, compare the received detection data with the benchmark data, output and display the evaluation results; RF coaxial cable: used to connect the external monitoring antenna and the external monitoring output port of the monitoring component.

10. A storage medium, characterized in that: The storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps in the method as claimed in any one of claims 1-8.

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