A two-dimensional high-precision angle measurement method and device based on minimum-scale sparse L array

Abstract

The present invention provides a two-dimensional, high-precision angle measurement method and device based on a minimally sparsely spaced L-array, belonging to the field of radar measurement technology. The method specifically involves: L-array construction: using three antenna elements sparsely spaced to form an L-array with an element spacing of , where the spacing is greater than half the wavelength of the received signal; two-dimensional angle measurement: using the constructed L-array to receive echo signals with carrier frequencies of and , constructing a virtual baseline using dual-frequency phase difference, and resolving phase difference ambiguity to obtain high-precision, unambiguous angle measurement results in both pitch and azimuth directions.

Description

Technical Field

[0001] The present invention provides a two-dimensional high-precision angle measurement method and device based on a minimum-scale sparsely distributed L array, belonging to the technical field of radar measurement. Background Art

[0002] Signal arrival angle measurement methods include phase comparison angle measurement, beamforming angle measurement, and multiple signal classification (MUSIC) angle measurement. 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, phase difference measurement values ​​will appear. Integer multiple ambiguity leads to incorrect angle measurement results.

[0003] In order to solve the ambiguity problem of phase difference measurement, the engineering design of long and short baselines constructs a virtual baseline smaller than half a wavelength to obtain an unambiguous phase difference, thereby achieving phase ambiguity-free angle measurement. At least three antenna array elements are required to achieve one-dimensional high-precision unambiguous angle measurement using long and short baselines, such as Figure 1 To achieve two-dimensional high-precision and unambiguous angle measurement, at least five antenna array elements are required, as shown in Figure 2 As shown in (a) and (b).

[0004] The use of long and short multi-baselines to achieve two-dimensional unambiguous angle measurement has strict requirements on the placement of antennas, and requires a large number of antenna array elements, which occupies a large amount of space-based platform resources such as volume, weight, and power consumption. Summary of the Invention

[0005] In order to meet the requirements of space-based radar with high measurement accuracy and low resource cost, the present invention discloses a two-dimensional high-precision angle measurement method and device based on a minimum-scale sparse L-array. It only uses three sparse antenna array elements and receives dual-frequency echoes to resolve phase ambiguity, thereby achieving two-dimensional high-precision and unambiguous angle measurement.

[0006] The technical solutions for implementing the present invention are as follows:

[0007] In a first aspect, the present invention provides a two-dimensional high-precision angle measurement method based on a minimum-scale sparse L array, the specific process of which is as follows:

[0008] L array construction: Use 3 antenna array elements sparsely spaced with an array element spacing of The L matrix, Greater than half the wavelength of the received signal;

[0009] Two-dimensional angle measurement: The constructed L array receives the carrier frequency and The echo signal is transmitted, and a virtual baseline is constructed through the dual-frequency phase difference and the phase difference ambiguity is resolved to obtain high-precision and unambiguous angle measurement results in the pitch and azimuth directions respectively.

[0010] Optionally, the present invention provides three antenna array elements: antenna array element a, b, and c, wherein antenna array element a is located at the right-angle vertex of the L array, and antenna array element b and antenna array element c are respectively located on the two vertical arms of the L array and are 1 / 4 of the distance from antenna array element a. .

[0011] Optionally, the present invention provides , for any frequency , the array element spacing The following formula must also be satisfied:

[0012]

[0013] in, is the speed of light, Represents variance.

[0014] Optionally, the present invention can be used for any carrier frequency , The following conditions must be met:

[0015]

[0016] Optionally, the specific process of the two-dimensional angle measurement of the present invention is as follows:

[0017] Step 1: Extract antenna elements a and b The phase of the received signal at the frequency , and calculate the antenna array elements a and b at Phase difference of the received signal at the frequency ;

[0018] Step 2: Utilize Phase Difference , calculate the virtual baseline The corresponding unambiguous phase difference ;

[0019] Step 3: Calculation Phase integer ambiguity value under frequency :

[0020]

[0021] in, , The main value interval is The phase difference measurement value, express Phase error; Indicates rounding;

[0022] but No ambiguity in frequency phase difference for:

[0023]

[0024] Step 4: Calculate the horizontal angle of incidence estimate :

[0025]

[0026] Step 5: Extract antenna elements a and c The phase difference of the received signal at the frequency is obtained by following steps 1 to 4 to obtain the vertical incidence angle estimation result. ;

[0027] Step 6: Calculate the pitch angle estimation result And the azimuth estimation results , thus achieving two-dimensional high-precision angle measurement;

[0028] .

[0029] In a second aspect, the present invention provides a two-dimensional high-precision angle measurement device based on a minimum-scale sparsely distributed L array, comprising: an L array and a two-dimensional angle measurement module;

[0030] The L array includes three antenna elements, and the three antenna elements are sparsely distributed with an element spacing of The L-type Greater than half the wavelength of the received signal;

[0031] The two-dimensional angle measurement module uses the L array to receive the carrier frequency and The echo signal is transmitted, and a virtual baseline is constructed through the dual-frequency phase difference and the phase difference ambiguity is resolved to obtain high-precision and unambiguous angle measurement results in the pitch and azimuth directions respectively.

[0032] Beneficial effects:

[0033] First, the method of the present invention uses only three sparsely distributed antenna elements, and resolves phase ambiguity by receiving dual-frequency echoes to achieve two-dimensional high-precision and unambiguous angle measurement. Compared with the multi-baseline angle measurement method based on five antenna elements, it reduces two antenna elements. It has the advantages of easy layout of space platform antennas in actual engineering, light weight, low power consumption and high precision.

[0034] Second, the present invention considers the influencing factors in actual engineering and constrains the arrangement of the sparse L array and the array element spacing. The conditions constrain the carrier frequency and The satisfaction of the conditions can ensure the accurate measurement of two-dimensional unambiguous angles by three sparsely distributed antenna elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] 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.

[0036] Figure 1 Schematic diagram of a linear array consisting of three antenna elements;

[0037] Figure 2 (a) is a schematic diagram of a "cross array" composed of 5 antenna elements, and (b) is a schematic diagram of an "L array" composed of 5 antenna elements;

[0038] Figure 3 Schematic diagram of an "L array" composed of three antenna elements of the present invention, as well as a schematic diagram of the relationship between the horizontal incidence angle, vertical incidence angle, azimuth angle, elevation angle and target position coordinates in the antenna array coordinate system;

[0039] Figure 4 Schematic diagram of the relationship between the horizontally sparse array composed of antenna elements a and b and the incident angle;

[0040] Figure 5 (a) is the estimated value of the pitch angle at different incident angles by the method of the present invention, (b) is the estimated value of the angle at different incident azimuth angles;

[0041] Figure 6 is the RMSE of the angle estimation error of the method of the present invention and the multi-baseline angle measurement method based on 5 antenna array elements under different standard deviations;

[0042] Figure 7 This is a flow chart of the angle measurement method of the present invention. DETAILED DESCRIPTION

[0043] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0044] 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.

[0045] 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.

[0046] The embodiment of the present application proposes a two-dimensional high-precision angle measurement method based on a minimum-scale sparse L array. The method includes two parts:

[0047] L array construction: Use 3 antenna array elements sparsely spaced with an array element spacing of The L matrix, Greater than half the wavelength of the received signal;

[0048] Two-dimensional angle measurement: The constructed L array receives the carrier frequency and The echo signal is transmitted, and a virtual baseline is constructed through the dual-frequency phase difference and the phase difference ambiguity is resolved to obtain high-precision and unambiguous angle measurement results in the pitch and azimuth directions respectively.

[0049] The following is a detailed description of the specific implementation process of each of the above parts:

[0050] like Figure 3 As shown in the figure, the minimum scale sparse L array antenna element arrangement is constructed, antenna element a is located at the origin, antenna element b is located at d from the origin on the Y axis, and antenna element c is located at d from the origin on the Z axis. The sparse array composed of antenna elements a and b measures the horizontal incident angle. , the sparse array composed of antennas a and c measures the vertical incidence angle Pitch angle , azimuth The relationship diagram of the target position coordinates in the antenna array coordinate system is shown in Figure 3 If the target is known The distance from the origin O of the coordinate system is , then the vertical angle of incidence , horizontal angle of incidence Satisfy the following formula:

[0051] (1)

[0052] The pitch angle and azimuth The calculation formula is as follows:

[0053] (2)

[0054] like Figure 4 As shown, the following process is derived 、 as well as Requirements to be met:

[0055] Antenna elements a and b form a horizontally sparse array, which receives dual-frequency signals. The received signal frequencies are 、 ,in , and the corresponding wavelengths are 、 , the distance between elements a and b is . is the horizontal angle of incidence.

[0056] When the received signal frequency is When the phase difference between antenna elements a and b receiving signals is for

[0057] (3)

[0058] in, is the speed of light, is the integer cycle ambiguity value of the phase difference, The main value interval is The phase difference measurement value.

[0059] Similarly, when the received signal frequency is When the phase difference between antenna elements a and b receiving signals is for

[0060] (4)

[0061] in, Indicates phase difference In frequency The equivalent baseline under is the integer cycle ambiguity value of the phase difference, The main value interval is The phase difference measurement value.

[0062] Defining a virtual baseline for

[0063] (5)

[0064] According to formula (5), we can deduce 、 Frequency difference meets

[0065] (6)

[0066] The corresponding unambiguous phase difference is

[0067] (7)

[0068] Substituting formula (5) into formula (7) we get

[0069] (8)

[0070] Differentiating Equation (3) and Equation (4), we can obtain

[0071] (9)

[0072] Where, , They are Generally speaking, the signal frequency and baseline length can be determined, that is, , ,but The measurement error It can be expressed as

[0073] (10)

[0074] It can be seen from formula (10) that when When fixed, the larger the frequency is, the The smaller it is, the better. No ambiguity phase difference To solve .

[0075] According to the unambiguous phase difference, the frequency can be obtained Lower phase integer fuzzy number for

[0076] (11)

[0077] Where, Indicates rounding.

[0078] In actual engineering, the influence of thermal noise will cause phase measurement errors. 、 Respectively 、 The phase error, and , Therefore, the phase ambiguity solution considering the phase error is expressed as

[0079] (12)

[0080] To obtain the correct integer week fuzzy value , requiring that the second half of formula (12) has no effect on rounding, that is, it must satisfy

[0081] (13)

[0082] Arranged:

[0083] (14)

[0084] Assuming the channel phase measurement accuracy is comparable, and are independent of each other and have a mean of 0 and a variance of Gaussian distribution, then The mean is 0 and the variance is Gaussian distribution, The variance of , it is assumed that the maximum error will not exceed 3 times the standard deviation, that is , after substituting into formula (14), we get:

[0085] (15)

[0086] because , if formula (15) holds, then it must satisfy:

[0087] (16)

[0088] The solution is:

[0089] (17)

[0090] Explanation of the above formula and Standard deviation Equation (17) needs to be satisfied to ensure unambiguous angle measurement.

[0091] In summary, frequency The following conditions must be met:

[0092] (18)

[0093] If any given , so that there exists If formula (18) is satisfied, then the following conditions must also be satisfied:

[0094] (19)

[0095] The solution is The following conditions must be met:

[0096] (20)

[0097] The angle measurement accuracy of the method of the present invention is deduced below. According to formula (10), The measurement error It can be expressed as

[0098] (twenty one)

[0099] Guaranteed integer fuzzy value Under the correct premise, The standard deviation is equal to The standard deviation of Assuming that the channel phase measurement accuracy is similar, according to formula (21), It can be expressed as:

[0100] (twenty two)

[0101] Known pitch angle , azimuth According to formula (2), 、 Taking the differential, we get:

[0102] (twenty three)

[0103] in, for error.

[0104] Substituting equations (21) and (22) into equation (23), we can obtain the angular measurement accuracy of the pitch angle and azimuth angle:

[0105] (twenty four)

[0106] like Figure 7 As shown, the specific steps for achieving high-precision angle measurement based on the above minimum-scale sparse L array are as follows:

[0107] Step 1: Extract antenna elements a and b ( ) The phase of the received signal at the frequency , calculate the antenna elements a and b at The phase difference of the received signal :

[0108] (25)

[0109] Step 2: Utilize Phase Difference , calculate the virtual baseline The corresponding unambiguous phase difference :

[0110] (26)

[0111] Step 3: Obtain Phase integer ambiguity value under frequency :

[0112] (27)

[0113] but No ambiguity in frequency phase difference for:

[0114] (28)

[0115] Step 4: Calculate the horizontal angle of incidence estimate :

[0116] (29)

[0117] Step 5: Extract antenna elements a and c Repeat steps 1 to 4 to get the vertical angle of incidence estimation result. .

[0118] Step 6: Calculate the pitch angle estimation result And the azimuth estimation results :

[0119] (30)

[0120] Furthermore, the embodiment of the present application provides a two-dimensional high-precision angle measurement device based on a minimum-scale sparse L array, comprising: an L array and a two-dimensional angle measurement module;

[0121] The L array includes three antenna elements, and the three antenna elements are sparsely distributed with an element spacing of The L-type Greater than half the wavelength of the received signal;

[0122] The two-dimensional angle measurement module uses the L array to receive the carrier frequency and The echo signal is transmitted, and a virtual baseline is constructed through the dual-frequency phase difference and the phase difference ambiguity is resolved to obtain high-precision and unambiguous angle measurement results in the pitch and azimuth directions respectively.

[0123] The present invention uses Matlab software to verify the above-mentioned two-dimensional high-precision angle measurement method based on the minimum-scale sparse L array.

[0124] (1) An L-shaped array consisting of three antenna elements is used to measure the angle of a narrowband radiation source. The array configuration is as follows: Figure 1 As shown. Radar angle measurement transmit and receive signal frequency , the standard deviation of the channel phase difference error , select the one that satisfies formula (18) (20) and They are 0.056m and 12.67GHz respectively. Corresponding wavelength ,at this time It is about 4.7 times of half wavelength, and the range of the pitch angle and azimuth angle is -85°~+85°. The estimated value of the incident angle is obtained by the method of the present invention. Figure 5 As shown in (a) and (b).

[0125] (2) Compare the angle measurement performance of the method of the present invention with that of the multi-baseline angle measurement method based on 5 antenna array elements.

[0126] Parameters of this method Same as (1); Multi-baseline angle measurement method based on 5 antenna elements Radar angle measurement receiving signal frequency , , , The standard deviation of the channel phase difference error is 4 and 5 times the half wavelength respectively. The incident elevation angle is 60° and the azimuth angle is -60°. The standard deviation is 0.1°~6.0°, and the root mean square error (RMSE) of the estimated value under different standard deviations is calculated through 500 Monte Carlo simulations as the evaluation indicator:

[0127] (31)

[0128] Where L is the number of Monte Carlo experiments, is the true value of the pitch angle and azimuth angle, is the pitch angle, azimuth angle The estimated value of the simulation.

[0129] Comparing the RMSE of the two methods, such as Figure 6 As shown, the two methods have similar performance.

[0130] 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 two-dimensional high-precision angle measurement method based on a minimum-scale sparse L-array, characterized in that: The specific process is: L array construction: Use 3 antenna array elements sparsely spaced with an array element spacing of The L matrix, Greater than half the wavelength of the received signal; suppose there are three antenna elements: antenna elements a, b, and c, where antenna element a is located at the right-angled vertex of the L array, and antenna elements b and c are located on the two vertical arms of the L array, and are both 1 / 4 of the distance from antenna element a. ; Two-dimensional angle measurement: The constructed L array receives the carrier frequency and The echo signal is used to construct a virtual baseline through dual-frequency phase difference and resolve the phase difference ambiguity to obtain high-precision and unambiguous angle measurement results in pitch and azimuth directions respectively; The specific process of the two-dimensional angle measurement is as follows: Step 1: Extract antenna elements a and b The phase of the received signal at the frequency , and calculate the antenna array elements a and b at Phase difference of the received signal at the frequency ; Step 2: Utilize Phase Difference , calculate the virtual baseline The corresponding unambiguous phase difference ; Step 3: Calculation Phase integer ambiguity value under frequency : in, , The main value interval is The phase difference measurement value, express Phase error; Indicates rounding; but No ambiguity in frequency phase difference for: Step 4: Calculate the horizontal angle of incidence estimate : Step 5: Extract antenna elements a and c The phase difference of the received signal at the frequency is obtained by following steps 1 to 4 to obtain the vertical incidence angle estimation result. ; Step 6: Calculate the pitch angle estimation result And the azimuth estimation results , thus achieving two-dimensional high-precision angle measurement; 。 2. The two-dimensional high-precision angle measurement method based on the minimum-scale sparse L-matrix according to claim 1, characterized in that: set up , for any frequency , the array element spacing The following formula must also be satisfied: in, is the speed of light, Represents variance.

3. The two-dimensional high-precision angle measurement method based on the minimum-scale sparse L-matrix according to claim 2, characterized in that: For any carrier frequency , The following conditions must be met: 。 4. A two-dimensional high-precision angle measurement device based on a minimum-scale sparse L-array, characterized in that: include: L array and two-dimensional angle measurement module; The L array includes three antenna elements, and the three antenna elements are sparsely distributed with an element spacing of The L-type Greater than half the wavelength of the received signal; suppose there are three antenna elements: antenna element a, b, and c, where antenna element a is located at the vertex of the L-shaped right angle, and antenna element b and antenna element c are located on the two vertical arms of the L-shaped, and are both 1 / 4 of the distance from antenna element a. ; The two-dimensional angle measurement module uses the L array to receive the carrier frequency and The echo signal is used to construct a virtual baseline through dual-frequency phase difference and resolve the phase difference ambiguity to obtain high-precision and unambiguous angle measurement results in pitch and azimuth directions respectively; The specific angle measurement process of the two-dimensional angle measurement module is as follows: Step 1: Extract antenna elements a and b The phase of the received signal at the frequency , and calculate the antenna array elements a and b at Phase difference of the received signal at the frequency ; Step 2: Utilize Phase Difference , calculate the virtual baseline The corresponding unambiguous phase difference ; Step 3: Calculation Phase integer ambiguity value under frequency : in, , The main value interval is The phase difference measurement value, express Phase error; Indicates rounding; but No ambiguity in frequency phase difference for: Step 4: Calculate the horizontal angle of incidence estimate : Step 5: Extract antenna elements a and c The phase difference of the received signal at the frequency is obtained by following steps 1 to 4 to obtain the vertical incidence angle estimation result. ; Step 6: Calculate the pitch angle estimation result And the azimuth estimation results , thus achieving two-dimensional high-precision angle measurement; 。 5. The two-dimensional high-precision angle measurement device based on the minimum-scale sparse L-matrix according to claim 4, characterized in that: set up , for any frequency , the array element spacing The following formula must also be satisfied: in, is the speed of light, Represents variance.

6. The two-dimensional high-precision angle measurement device based on the minimum-scale sparse L-matrix according to claim 5, characterized in that: For any carrier frequency , The following conditions must be met: 。

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