A robust phase ambiguity resolution method and device for sparsely distributed dual-element dual-frequency radar angle measurement

Abstract

The present invention belongs to the field of radar measurement technology, and specifically relates to a method and device for robust phase ambiguity resolution of sparse dual-element dual-frequency radar angle measurement. The specific process of the method is as follows: Step 1: at time t, slidingly store unambiguous angle estimation values ​​and sort them in ascending order. When the clustering result does not meet the requirements, continue sliding and storing data until the requirements are met, where represents the total number of set unambiguous angle estimation values; Step 2: at time t, based on the angle estimation values ​​at the current time and the previous time, determine whether the current deambiguation is correct, correct the erroneous deambiguation results, and set a flag; Step 3: Count the flag situation. If the number of errors is greater than the set probability, return to step 1 and start again. Otherwise, return to step 2 to re-determine the angle estimation value at the next time.

Description

Technical Field

[0001] The present invention belongs to the field of radar measurement technology, and in particular relates to a method and device for robust phase ambiguity resolution in angle measurement of a sparsely distributed dual-element dual-frequency radar. Background Art

[0002] Radar phase interferometry angle measurement is a method of obtaining the target incident angle based on the phase difference of the target echo received by each antenna element. In theory, the larger the antenna element spacing, the higher the angle measurement accuracy. However, when the element spacing is greater than half a wavelength, the phase difference measurement value will be Integer multiple ambiguity leads to incorrect angle measurement results.

[0003] To resolve the ambiguity of phase difference measurements, engineers design long and short baselines to achieve deambiguous angle measurement. However, multi-baseline phase comparison angle measurement methods, such as the long and short baseline method, place strict requirements on antenna element placement. Furthermore, the large number of antenna elements and receiving channels increases the size, weight, and power consumption of the equipment. When antenna layout space is limited and only two antenna elements can be installed, phase ambiguity can be resolved by receiving signals at different frequencies.

[0004] In his master's thesis, "Research and Design of a Robust Deambiguation Algorithm for Lunar Rendezvous Radar Interferometry," published in May 2014, Cui Wei of the University of Electronic Science and Technology of China proposed a dual-element, dual-frequency, or multi-frequency search algorithm for phase ambiguity resolution. This method resolves phase ambiguity by searching all possible values ​​of the integer ambiguity at different frequencies and minimizing a cost function in the solution space.

[0005] In practical applications, due to the low power of radar received signals and the influence of receiver thermal noise, the phase difference measurements between array elements contain large phase measurement errors, leading to phase deambiguation errors. Existing dual-frequency search methods have low deambiguation accuracy when phase measurement errors are large. Multi-frequency search methods can effectively improve phase deambiguation accuracy, but multiple operating frequencies increase the difficulty of radar system design. Summary of the Invention

[0006] In order to solve the above problems, the present invention proposes a method and device for robust phase ambiguity resolution of sparse dual-element dual-frequency radar angle measurement, which can effectively improve the accuracy of ambiguity resolution under low signal-to-noise ratio without increasing the operating frequency.

[0007] The technical solutions for implementing the present invention are as follows:

[0008] In a first aspect, the present invention provides a robust phase ambiguity resolution method for angle measurement of a sparse dual-element dual-frequency radar, the specific process of which is as follows:

[0009] Step 1: At the moment When the sliding storage unambiguous angle estimate And sort in ascending order to get , in the When the clustering result does not meet the requirements, continue to slide and store the unambiguous angle estimation value until the requirements are met. Indicates the total number of unambiguous angle estimates set;

[0010] Step 2: At the moment When the angle estimation value at the current moment and the previous moment is used, it is determined whether the current deambiguation is correct, the wrong deambiguation result is corrected, and the flag is set;

[0011] Step 3: Count the flags. If the number of errors is greater than the set probability, return to step 1 and start again. Otherwise, return to step 2 to re-judge the angle estimate at the next moment.

[0012] Optionally, the present invention divides the incident angle range evenly into Class ,calculate Fall into Number of class data ,remember The maximum value of , according to the Determine whether the clustering results meet the requirements.

[0013] Optionally, the clustering result of the present invention meets the requirements:

[0014] , .

[0015] Optionally, the present invention determines whether the current defuzzification is correct based on the angle estimation value at the current moment and the previous moment, specifically by calculating the absolute value of the difference between the angle estimation value at the current moment and the previous moment ,like Less than threshold , then the angle deambiguation at the current moment is considered correct, otherwise it is considered that the current deambiguation is wrong.

[0016] Optionally, the threshold of the present invention According to the maximum value of the target angle change rate Confirmation means satisfaction ,in The data update period.

[0017] Optionally, the error-corrected defuzzification result of the present invention is:

[0018] Assume that the phase ambiguity number estimation result at the previous moment is ,calculate , ;

[0019]

[0020] According to the Calculate the corresponding incident angle estimation result for:

[0021]

[0022] in, Indicates the phase difference measurement value at the current moment, is the wavelength of the signal transmitted by the sparsely distributed dual array element, Indicates the array element spacing;

[0023] Take the closest angle of Corresponding The phase ambiguity correction result at the current moment ,Right now

[0024] .

[0025] Optionally, if the angle deambiguation is correct at the current moment, the present invention sets the flag to 1, otherwise it sets the flag to 0, and stores the data flag in a data file of length In the array, after each angle deblurring is completed, the probability of counting the number of errors in the array ,like , then the current situation is considered to be beyond the error correction capability of the finite memory algorithm, and return to step 1, otherwise return to step 2.

[0026] In a second aspect, the present invention provides a sparse dual-element dual-frequency radar angle measurement robust phase ambiguity resolution device, comprising: an unambiguous angle estimation module, a ambiguity resolution judgment correction module, and a reset module;

[0027] The unambiguous angle estimation module is used to estimate the angle at time When the sliding storage unambiguous angle estimate And sort in ascending order to get , in the When the clustering result does not meet the requirements, continue to slide and store the unambiguous angle estimation value until the requirements are met. Indicates the total number of unambiguous angle estimates set;

[0028] The defuzzification judgment correction module is used to When the angle estimation value at the current moment and the previous moment is used, it is determined whether the current deambiguation is correct, the wrong deambiguation result is corrected, and the flag is set;

[0029] The reset module is used to count the flags. If the number of errors is greater than the set probability, the unambiguous angle estimation module is controlled to start re-execution. Otherwise, the deambiguation judgment correction module is controlled to re-judge the angle estimation value at the next moment.

[0030] Beneficial effects:

[0031] First, the present invention proposes a robust phase ambiguity resolution method for sparse dual-element dual-frequency radar angle measurement, which can accurately identify and correct outliers in the phase ambiguity resolution process, and greatly improves the accuracy of ambiguity resolution under low signal-to-noise ratio compared with the existing dual-frequency search method.

[0032] Second, compared with the existing multi-frequency search method, the present invention does not need to increase the number of frequency points, which is more conducive to the implementation of radar system engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 Schematic diagram of the dual-element dual-frequency angle measurement principle.

[0035] Figure 2 Flowchart of the finite memory outlier elimination algorithm.

[0036] Figure 3 The following is a comparison chart of the correct deambiguation probability of this method and the existing method under different signal-to-noise ratios. DETAILED DESCRIPTION

[0037] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0038] It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments may be combined with each other; and, based on the embodiments in this disclosure, all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of this disclosure.

[0039] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on this disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0040] like Figure 1 As shown, for the use of sparse dual antenna array elements 、 Receive dual-frequency signals, the receiving signal frequencies are 、 ,in , and the corresponding wavelengths are 、 , array element 、 The spacing is , is the target incident angle.

[0041] When the received signal frequency is When the antenna array element 、 Phase difference of received signal for

[0042] (1)

[0043] in, is the integer cycle ambiguity value of the phase difference, The main value interval is The phase difference measurement value, subscript 1 indicates that the received signal frequency is .

[0044] Similarly, when the received signal frequency is When the phase difference for

[0045] (2)

[0046] Combining equations (1) and (2) yields

[0047] (3)

[0048] Right now

[0049] (4)

[0050] From formula (1) and (2), we can see that 、 The value ranges are

[0051] (5)

[0052] (6)

[0053] In actual engineering, the phase measurement error will be caused by the influence of thermal noise. The phase difference measurement value including the phase measurement error is recorded as 、

[0054] Substituting all integer values ​​within the range of formula (5) into formula (4), we can obtain Solution space ,Right now:

[0055] (7)

[0056] Constructing the cost function in the solution space ,Right now

[0057] (8)

[0058] in, is the rounding function. The value in the solution space that minimizes the cost function within the range of formula (6) is the phase ambiguity number estimation result

[0059] (9)

[0060] Substituting equation (9) into equation (2) yields the incident angle estimation result: for

[0061] (10)

[0062] When the target is far away, the signal-to-noise ratio of the received signal is low. 、 When there is a large phase measurement error, the phase ambiguity number estimation result is wrong.

[0063] In order to reduce the error probability of the phase ambiguity number estimation result and improve the measurement accuracy of the incident angle, the angle value output by formula (10) is subjected to limited memory error correction processing to assist in phase ambiguity resolution. The embodiment of the present application proposes a dual-element dual-frequency radar angle measurement phase ambiguity resolution method. This method uses limited memory to identify and correct the ambiguity resolution error value, effectively improving the ambiguity resolution accuracy under low signal-to-noise ratio without increasing the operating frequency, and assisting the sparse dual-element dual-frequency radar in robust phase ambiguity resolution. The specific process is as follows:

[0064] Step 1: At the moment When the sliding storage unambiguous angle estimate And sort in ascending order to get , in the When the clustering result does not meet the requirements, continue to slide and store the unambiguous angle estimation value until the requirements are met. Indicates the total number of unambiguous angle estimates set;

[0065] Step 2: At the moment When the angle estimation value at the current moment and the previous moment is used, it is determined whether the current deambiguation is correct, the wrong deambiguation result is corrected, and the flag is set;

[0066] Step 3: Count the flags. If the number of errors is greater than the set probability, return to step 1 and start again. Otherwise, return to step 2 to re-judge the angle estimate at the next moment.

[0067] like Figure 2 As shown, the above process is described in detail below. The specific contents are as follows:

[0068] Step 1: Initialize clustering.

[0069] If the initial value of the finite memory algorithm is wrong, the error correction algorithm will continue to make mistakes for a period of time until the correct initial value can be obtained. In order to improve the reliability of the initial value of the finite memory algorithm, the data clustering method can be used to provide the initial value for the finite memory algorithm.

[0070] At the moment When , the unambiguous angle estimation value obtained in the sliding storage formula (10) is , Represents the total number of unambiguous angle estimation values ​​set, and sorts the data in ascending order to obtain

[0071] (11)

[0072] Uniformly divide the classes within the range of incident angles , here the number of categories Adjustable.

[0073] At the moment When calculating Fall into Number of class data ,remember The maximum value of .like ,in , then take the The average value of the class is used as the clustering result; otherwise, continue sliding the stored data until an initial value that meets the conditions is obtained.

[0074] Step 2: Outlier identification and error correction.

[0075] At the moment When comparing the angle estimate at the current moment Angle estimate with the previous moment ,make

[0076] (12)

[0077] if Less than threshold , then the angle defuzzification at the current moment is considered correct; otherwise, the angle defuzzification at the current moment is considered wrong and needs to be corrected. Considering that the target angle will not change suddenly, the threshold According to the maximum value of the target angle change rate Confirmation means satisfaction ,in The data update period.

[0078] If the angle estimate at the current moment is When a sudden change occurs, the phase ambiguity number estimation result at the current moment is Error correction is required, and the phase ambiguity estimation result at the previous moment is is the correct value, to correct ,make

[0079] (13)

[0080] According to formula (10), Corresponding incident angle estimation results for

[0081] (14)

[0082] Take the closest angle of Corresponding The phase ambiguity correction result at the current moment ,Right now

[0083] (15)

[0084] Step 3: Record the error correction process in the limited memory process. If the angle deambiguation is correct at the current moment, set the flag to 1, otherwise set the flag to 0. Store the data flag in a file with a length of In the array, after each angle calculation is completed, the probability of counting the number of errors in the array .like , then the current situation is considered to be beyond the error correction capability of the current algorithm, and the memory should be reset and restarted.

[0085] This embodiment provides a sparse dual-element dual-frequency radar angle measurement robust phase ambiguity resolution device, comprising: an unambiguous angle estimation module, a ambiguity resolution judgment correction module, and a reset module;

[0086] The unambiguous angle estimation module is used to estimate the angle at time When the sliding storage unambiguous angle estimate And sort in ascending order to get , in the When the clustering result does not meet the requirements, continue to slide and store the unambiguous angle estimation value until the requirements are met. Indicates the total number of unambiguous angle estimates set;

[0087] The defuzzification judgment correction module is used to When the angle estimation value at the current moment and the previous moment is used, it is determined whether the current deambiguation is correct, the wrong deambiguation result is corrected, and the flag is set;

[0088] The reset module is used to count the flags. If the number of errors is greater than the set probability, the unambiguous angle estimation module is controlled to start re-execution. Otherwise, the deambiguation judgment correction module is controlled to re-judge the angle estimation value at the next moment.

[0089] In order to verify the effectiveness of the present invention, the following simulation experiments are carried out:

[0090] In this example, the interferometer system simulation parameters are as follows: antenna array element spacing , signal frequency , , setting the channel phase noise to statistically independent zero-mean Gaussian white noise. The target moves at a constant angular velocity of 1° / s within the range of -60° to +60°. The phase deambiguation accuracy of the present invention is compared with that of the existing dual-element dual-frequency, triple-frequency, quad-frequency, and penta-frequency deambiguation methods. The results are as follows: Figure 3 As shown in the figure, this method significantly improves the accuracy of phase deambiguation compared to the existing dual-frequency search deambiguation method. Using three-, four-, and five-frequency search deambiguation methods can effectively improve the accuracy of phase deambiguation. When the signal-to-noise ratio (SNR) is greater than 2dB, the accuracy of three-frequency search deambiguation is lower than that of the present invention. When the SNR is greater than 4dB, this method is comparable to the five-frequency search deambiguation method.

[0091] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A robust phase ambiguity resolution method for sparse dual-element dual-frequency radar angle measurement, characterized in that: The specific process is: Step 1: At the moment When the sliding storage unambiguous angle estimate And sort in ascending order to get , in the When the clustering result does not meet the requirements, continue to slide and store the unambiguous angle estimation value until the requirements are met. Indicates the total number of unambiguous angle estimates set; Step 2: At the moment When the angle estimation value at the current moment and the previous moment is used, it is determined whether the current deambiguation is correct, the wrong deambiguation result is corrected, and the flag is set; Step 3: Count the flags. If the number of errors is greater than the set probability, return to step 1 and start again. Otherwise, return to step 2 to re-judge the angle estimate at the next moment. The defuzzification result of the error correction is: Assume that the phase ambiguity number estimation result at the previous moment is ,calculate , ; According to the Calculate the corresponding incident angle estimation result for: in, Indicates the phase difference measurement value at the current moment, is the wavelength of the signal transmitted by the sparsely distributed dual array element, Indicates the array element spacing; Take the closest angle of Corresponding The phase ambiguity correction result at the current moment ,Right now 。 2. The robust phase ambiguity resolution method for sparse dual-element dual-frequency radar angle measurement according to claim 1 is characterized in that: The method of judging whether the current defuzzification is correct is based on the angle estimation value at the current moment and the previous moment, specifically: calculating the absolute value of the difference between the angle estimation value at the current moment and the previous moment ,like Less than the set threshold , then the angle deambiguation at the current moment is considered correct, otherwise it is considered that the current deambiguation is wrong.

3. The robust phase ambiguity resolution method for sparse dual-element dual-frequency radar angle measurement according to claim 1 is characterized in that: Divide the incident angle range evenly Class ,calculate Fall into Number of class data ,remember The maximum value of , according to the Determine whether the clustering results meet the requirements.

4. The robust phase ambiguity resolution method for sparse dual-element dual-frequency radar angle measurement according to claim 3 is characterized in that: The clustering results meet the requirements when: ， 。 5. The robust phase ambiguity resolution method for sparse dual-element dual-frequency radar angle measurement according to claim 2, characterized in that: The threshold According to the maximum value of the target angle change rate Confirmation means satisfaction ,in The data update period.

6. The robust phase ambiguity resolution method for sparse dual-element dual-frequency radar angle measurement according to claim 1, characterized in that: If the angle defuzzification is correct at the current moment, the flag is set to 1, otherwise it is set to 0 and the flag is stored in the length In the array, after each angle deblurring is completed, the probability of counting the number of errors in the array ,like , then the current situation is considered to be beyond the error correction capability of the finite memory algorithm, and return to step 1, otherwise return to step 2.

7. A sparse dual-element dual-frequency radar angle measurement robust phase ambiguity resolution device, characterized in that: include: Unambiguous angle estimation module, deambiguation judgment correction module and reset module; The unambiguous angle estimation module is used to estimate the angle at time When the sliding storage unambiguous angle estimate And sort in ascending order to get , in the When the clustering result does not meet the requirements, continue to slide and store the unambiguous angle estimation value until the requirements are met. Indicates the total number of unambiguous angle estimates set; The defuzzification judgment correction module is used to When the angle estimation value at the current moment and the previous moment is used, it is determined whether the current deambiguation is correct, the wrong deambiguation result is corrected, and the flag is set; The reset module is used to count the flags. If the number of errors is greater than the set probability, the unambiguous angle estimation module is controlled to start re-execution. Otherwise, the deambiguation judgment correction module is controlled to re-judge the angle estimation value at the next moment. The defuzzification result of the error correction is: Assume that the phase ambiguity number estimation result at the previous moment is ,calculate , ; According to the Calculate the corresponding incident angle estimation result for: in, Indicates the phase difference measurement value at the current moment, is the wavelength of the signal transmitted by the sparsely distributed dual array element, Indicates the array element spacing; Take the closest angle of Corresponding The phase ambiguity correction result at the current moment ,Right now 。 8. The sparse dual-element dual-frequency radar angle measurement robust phase ambiguity resolution device according to claim 7, characterized in that: The method of judging whether the current defuzzification is correct is based on the angle estimation value at the current moment and the previous moment, specifically: calculating the absolute value of the difference between the angle estimation value at the current moment and the previous moment ,like Less than threshold , then the angle deambiguation at the current moment is considered correct, otherwise it is considered that the current deambiguation is wrong.

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