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

Abstract

The present invention relates to a method and device for measuring angles in a sparse dual-element phase comparison and dual-frequency phase ambiguity resolution radar, belonging to the field of radar measurement technology. The specific process of the method is as follows: Step 1: The sparse dual-element array performs dual-channel phase comparison measurement at dual carrier frequencies to obtain the phase difference between the array elements, and then obtains the ambiguity coefficient containing the phase error; Based on the ambiguity coefficient, the constraint conditions for the dual frequency and carrier values ​​are determined; Step 2: Under the constraint conditions determined in Step 1, the radar signal operating frequency is selected, and a virtual short baseline is constructed based on the dual-element phase difference at different frequencies; Step 3: Based on the virtual baseline ambiguity resolution method, an unambiguous and high-precision one-dimensional angle measurement angle is calculated.

Description

Technical Field

[0001] The present invention relates to a sparse dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method and device, belonging to the technical field of radar measurement. Background Art

[0002] In recent years, research on high-precision angle measurement using dual-element sparse arrays has attracted widespread attention from scholars both domestically and internationally. A dual-element sparse array is a minimal antenna array consisting of two elements with a spacing greater than half a wavelength. This array can improve angle measurement performance and reduce mutual coupling between elements by increasing the spacing between elements, while reducing platform installation space, weight, power consumption, and cost.

[0003] However, when the element spacing is greater than half a wavelength, phase ambiguity will occur. The larger the element spacing, the more phase ambiguity there is, and the more difficult it is to accurately resolve the ambiguity. Due to the limitation to the dual-element minimum antenna array scenario, multi-element interferometer deambiguation methods such as the long-short baseline method, the staggered baseline method, and the stereo baseline method are not applicable. For the dual-element scenario, in 2013, Fan Xiaobo proposed a method for deambiguation by exhaustively enumerating ambiguity numbers under dual frequencies in the "Research on Lunar Orbit Rendezvous and Docking Microwave Radar Velocimetry"; in 2022, Ma Dingkun et al. published the "Frequency Domain Deambiguation Interferometer Direction Finding Method" and proposed a frequency domain phase ambiguity resolution method, which uses the carrier phase continuity characteristics and the principle of fixed baseline-changing signal wavelength ratio to resolve phase ambiguity; however, none of the existing studies have given the frequency selection principles and frequency selection range.

[0004] Existing related research has not yet delved into the frequency selection principles and frequency selection range, and therefore has not been able to form a complete radar angle measurement method in the sparsely distributed dual-element scenario. Summary of the Invention

[0005] The purpose of the present invention is to propose a sparse dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method and device. Considering the existence of phase measurement errors, the frequency selection constraint conditions for successful dual-frequency ambiguity resolution are calculated, thereby ensuring that the sparse dual-element array can achieve accurate angle measurement.

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

[0007] In the first aspect, the present invention provides a sparse dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method, the specific process of which is as follows:

[0008] Step 1: sparsely spaced dual array elements at dual carrier frequencies and The dual-channel phase comparison measurement is performed to obtain the phase difference between the array elements, and then the ambiguity coefficient containing the phase error is obtained; according to the ambiguity coefficient, the dual frequency is determined and The constraints on the carrier value;

[0009] Step 2: Under the constraints determined in step 1, the radar signal operating frequency is selected, and a virtual short baseline is constructed according to the phase difference of the two array elements at different frequencies;

[0010] Step 3: Based on the virtual baseline deambiguation method, the unambiguous and high-precision one-dimensional angle measurement is calculated.

[0011] Optionally, the specific process of obtaining the phase difference between array elements and the ambiguity coefficient including the phase error in step 1 of the present invention is as follows:

[0012] The sparsely spaced dual-element array is used for dual-channel phase comparison measurement under two transmission frequency conditions, and the phase difference between the elements is obtained as follows: and ;

[0013]

[0014] in, and Respectively and There is no phase measurement error in the part, and and It means and The phase measurement error part in ;

[0015] The ambiguity coefficient including the phase error is:

[0016]

[0017] in, Indicates rounding calculation. is the baseline length, is a virtual short baseline, , .

[0018] Optionally, the step 1 of the present invention determines the dual frequency according to the phase difference between the array elements and the ambiguity coefficient. and The specific process of the carrier value constraint is as follows:

[0019] according to Combined with the fact that the fuzzy coefficient of the phase error must have no effect on the rounding calculation, we can get

[0020]

[0021] The maximum measurement error of the phase difference between the two channels is expressed as ;

[0022] Determine dual frequency and The constraints on the carrier value are:

[0023] .

[0024] Optionally, the present invention selects a carrier frequency according to the constraint condition. ,get The value of should meet the conditions:

[0025] .

[0026] Optionally, the present invention selects the carrier frequency and The value of should meet the conditions to determine the working frequency , construct the virtual baseline as:

[0027] .

[0028] Optionally, step three of the present invention is based on a virtual baseline defuzzification method to calculate an unambiguous high-precision one-dimensional angle measurement angle, specifically:

[0029] Calculate the fuzzy parameters of the physical long baseline based on the phase difference obtained by dual-channel phase comparison measurement ,

[0030]

[0031] in, 、 Respectively expressed in 、 The phase difference between the two array elements obtained by dual-channel phase comparison measurement under frequency conditions is ;

[0032] Fuzzy parameters based on physical long baseline , thereby solving the unambiguous high-precision one-dimensional angle measurement :

[0033]

[0034] in, Represents the speed of light.

[0035] In a second aspect, the present invention provides a sparse dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement device, comprising a sparse dual-element array, a constraint condition calculation module, a virtual short baseline construction module, and a one-dimensional angle measurement module;

[0036] Constraint calculation module, using sparse dual array elements at dual carrier frequencies and The dual-channel phase comparison measurement is performed to obtain the phase difference between the array elements, and then the ambiguity coefficient containing the phase error is obtained; according to the ambiguity coefficient, the dual frequency is determined and The constraints on the carrier value;

[0037] A virtual short baseline construction module selects a radar signal operating frequency based on the constraint conditions and constructs a virtual short baseline according to the dual-element phase difference at different frequencies;

[0038] The one-dimensional angle measurement module calculates the unambiguous and high-precision one-dimensional angle measurement angle based on the virtual baseline deambiguation method.

[0039] Beneficial effects:

[0040] First, a sparse dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method is proposed. Based on the principle of virtual short baseline deambiguation and the influence mechanism of phase measurement error on ambiguity coefficient estimation, a dual-frequency selection interval for successful deambiguation under the influence of phase measurement error is derived. The dual-frequency phase ambiguity is resolved and high-precision one-dimensional angle measurement is achieved, thus forming a dual-frequency deambiguation radar angle measurement method when resources are strongly constrained in sparse dual-element scenarios.

[0041] Second, the sparsely distributed dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method proposed in the present invention can achieve unambiguous and high-precision one-dimensional angle measurement using dual array elements and dual frequencies, and analyzes and derives the frequency selection range for phase ambiguity resolution, providing a theoretical basis for the engineering application of this method to meet the engineering needs of unambiguous and high-precision angle measurement under strong resource constraints such as installation space, weight, power consumption, and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] 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.

[0043] Figure 1 Schematic diagram of a dual-element sparse array structure;

[0044] Figure 2 Generate a schematic diagram for the virtual baseline;

[0045] Figure 3 for When , the relationship between the angle measurement accuracy and decorrelation frequency after deambiguation;

[0046] Figure 4 for The relationship between the probability of successful defuzzification and decorrelation frequency when ;

[0047] Figure 5 for When , the relationship between the angle measurement accuracy and decorrelation frequency after deambiguation;

[0048] Figure 6 for The relationship between the success probability of defuzzification and the decorrelation frequency when . DETAILED DESCRIPTION

[0049] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0050] 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.

[0051] 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.

[0052] The present invention utilizes the different phase differences between the dual array elements under dual frequencies to form an unambiguous virtual short baseline. Based on the principle of virtual short baseline deambiguation and the influence mechanism of phase measurement error on fuzzy number estimation, the present invention further theoretically analyzes the dual-frequency selection interval for successful deambiguation under the influence of phase measurement error, thereby obtaining the optimal dual-frequency working system. With a relatively low resource cost, the present invention realizes unambiguous high-precision one-dimensional angle measurement, providing a new idea for high-precision angle measurement under strong resource constraints such as installation space, weight, power consumption, and cost.

[0053] The embodiment of the present application provides a sparse dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method, and the specific process is as follows:

[0054] Step 1: Sparsely spaced dual array elements at dual carrier frequencies and The dual-channel phase comparison measurement is performed to obtain the phase difference between the array elements, and then the ambiguity coefficient containing the phase error is obtained; based on the ambiguity coefficient, the constraint conditions of the dual frequency and carrier values ​​are determined;

[0055] The following deduces the principle of selecting the dual-frequency deambiguation frequency under the condition of limited frequency difference and determines the value range of the dual frequency

[0056] like Figure 1 As shown, a sparse array is an array with an array element spacing greater than half a wavelength. For far-field signals, a two-element sparse array is considered, and the number of array elements is 2. Assume that the one-dimensional angle of the far-field space target radar echo is , .

[0057] Assume that At time t, the output signal of array element 1 is The output signal of element 2 is Can be expressed as:

[0058] (1)

[0059] in, and Represent the thermal noise of the output signals of array element 1 and array element 2 respectively, is the radar echo signal, It represents the time difference between the radar echo signal reaching array element 1 and array element 2. Assuming that the incoming signal travels at the speed of light Propagation, time difference It can be expressed as:

[0060] (2)

[0061] Where, Represents the geometric spacing between two array elements (also called baseline length). Assume that the carrier frequency of the incoming signal is , and its corresponding wavelength is , then the carrier phase difference of the received signals of the two array elements is It can be expressed as:

[0062] (3)

[0063] According to the definition of sparse array, if the distance between two array elements is greater than half wavelength, that is, , the actual phase difference Phase difference measured by comparing with the dual channels of the array (The main value interval is )difference The relationship between the phase ambiguity of the whole cycle is:

[0064] (4)

[0065] in, is the fuzzy coefficient of the phase difference, Indicates no phase ambiguity, A non-zero integer indicates the presence of phase ambiguity.

[0066] like Figure 1 As shown, assuming that the radar transmit carrier frequency is The signal has a wavelength of , the target angle is At this time, the actual phase difference between the two antenna elements receiving the radar echo is It can be expressed as

[0067] (5)

[0068] in, It represents the phase difference obtained by comparing the signals of the dual-element receiving channel (i.e., dual-channel) using phase measurement. Indicates the corresponding baseline length The fuzzy coefficient of , we can get

[0069] (6)

[0070] To assist in deambiguation, the radar transmit carrier frequency is The signal has a wavelength of ,definition is the equivalent baseline length. Under this equivalent baseline length, the actual phase difference of the radar echo received by the two channels is It can be expressed as

[0071] (7)

[0072] in, Indicates the corresponding equivalent baseline length obtained by dual-channel phase comparison measurement The phase difference, Indicates the corresponding equivalent baseline length The fuzzy coefficient.

[0073] The non-negative phase difference is obtained by the following formula :

[0074] (8)

[0075] in, Defined as a virtual short baseline.

[0076] According to formula (8), when the virtual short baseline satisfies ,but That is, it meets the conditions for single-value angle measurement without phase ambiguity.

[0077] From this we can get

[0078] (9)

[0079] According to formula (5) and formula (8), the fuzzy coefficient can be derived for:

[0080] (10)

[0081] Substituting equation (10) into equation (5), we can get the baseline length The following unambiguous high-precision one-dimensional angle measurement solution:

[0082] (11)

[0083] In actual engineering, considering the existence of phase measurement error, the phase difference between array elements obtained by dual-channel phase comparison measurement under two transmission frequency conditions is and can be rewritten as:

[0084] (12)

[0085] in, and Respectively and There is no phase measurement error in the part, and and It means and The phase measurement error part in .

[0086] Then the frequency and The unambiguous phase difference estimation between the two array elements under the condition can be expressed as

[0087] (13)

[0088] Virtual short baseline The corresponding phase difference can be expressed as:

[0089] (14)

[0090] in, express There is no phase measurement error in the part, and express Phase measurement error part.

[0091] According to the fuzzy coefficient formula shown in formula (10), the fuzzy coefficient including the phase error is:

[0092] (15)

[0093] in, Indicates rounding calculation.

[0094] Comparing Equation (12) and Equation (15), to obtain the correct fuzzy coefficient value, it is necessary to ensure that the right half of Equation (15) has no effect on the rounding calculation, that is, the following conditions need to be met:

[0095] (16)

[0096] Considering the consistent channel measurement accuracy, and The measurement error can be expressed as ( represents the maximum measurement error of the phase difference between channels), then under extreme conditions, , we can get the following inequality:

[0097] (17)

[0098] The standard deviation of the dual-channel phase difference measurement caused by thermal noise It can be calculated by the following formula:

[0099] (18)

[0100] Under different carrier frequencies, the maximum measurement error of the phase difference between the two channels can be approximately expressed as , then and Substituting into formula (17) we can get:

[0101] (19)

[0102] In summary, The value of should satisfy:

[0103] (20)

[0104] Step 2: Construct a virtual short baseline based on the phase difference of the two array elements at different frequencies

[0105] The present invention utilizes two different frequencies to construct a virtual baseline, realizes phase ambiguity resolution, and obtains an unambiguous and high-precision one-dimensional angle measurement result.

[0106] According to step 1, the operating frequencies of the signals are determined to be 、 , the phase differences between the two array elements are

[0107] (twenty one)

[0108] Due to the limitation of the frequency difference of the transmitted signal due to practical factors, the phase difference is calculated To construct a virtual short baseline,

[0109] (twenty two)

[0110] in, .

[0111] Phase difference Equivalent to the frequency Under the condition, the length is The phase difference of the virtual baseline is as follows: Figure 2 As shown, , .

[0112] Step 3: Based on the virtual baseline defuzzification method, calculate the unambiguous and high-precision one-dimensional angle measurement

[0113] First, the fuzzy parameters of the physical long baseline are calculated based on the phase difference obtained by the dual-channel phase comparison measurement. According to equations (5) and (8), the fuzzy parameters can be deduced as satisfy:

[0114] (twenty three)

[0115] in, 、 Respectively expressed in 、 The phase difference between the two array elements obtained by dual-channel phase comparison measurement under frequency conditions is .

[0116] Next, the physical long baseline is defuzzified based on the virtual short baseline to obtain the physical long baseline. The corresponding unambiguous phase difference , thereby solving the unambiguous and high-precision one-dimensional angle measurement:

[0117] (twenty four)

[0118] The embodiment of the present application provides a sparse dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement device, comprising a sparse dual-element array, a constraint condition calculation module, a virtual short baseline construction module, and a one-dimensional angle measurement module;

[0119] Constraint calculation module, using sparse dual array elements at dual carrier frequencies and The dual-channel phase comparison measurement is performed to obtain the phase difference between the array elements, and then the ambiguity coefficient containing the phase error is obtained; according to the ambiguity coefficient, the dual frequency is determined and The constraints on the carrier value;

[0120] A virtual short baseline construction module selects a radar signal operating frequency based on the constraint conditions and constructs a virtual short baseline according to the dual-element phase difference at different frequencies;

[0121] The one-dimensional angle measurement module calculates the unambiguous and high-precision one-dimensional angle measurement angle based on the virtual baseline deambiguation method.

[0122] Based on the theoretical derivation model above, the MATLAB tool is used to analyze the angle measurement performance of the proposed sparse dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method. First, the correctness of the selected range of the deduced phase ambiguity frequency is verified. The simulation parameters are set as follows:

[0123] ①Original transmission frequency GHz;

[0124] ②Signal propagation speed m / s;

[0125] ③Dual array element spacing ;

[0126] ④ Assume that the far-field target arrival direction angle is ;

[0127] ⑤The number of Monte Carlo simulations is 300;

[0128] ⑥The signal-to-noise ratio is selected as SNR=30dB, 40dB.

[0129] The root mean square error (RMSE) of the one-dimensional angle measurement is used as the evaluation parameter of the estimation accuracy. When the signal-to-noise ratio is 30dB and 40dB respectively, the root mean square error of the angle after defuzzification is The relationship between the ratios is as follows Figure 3 As shown, the corresponding defuzzification success probability is The relationship between the ratios is as follows Figure 4 shown.

[0130] From the simulation results, it can be seen that when or ,Right now or When , the root mean square error of the direction of arrival angle after deambiguation increases sharply, and the deambiguation success rate drops significantly, matching the theoretical boundary. The vertical lines in the figure represent the frequency ratio boundaries under different signal-to-noise ratio conditions. and frequency ratio boundary , the simulation results show that when When , the deambiguation success rate will also drop significantly due to the influence of phase error.

[0131] To further verify the conclusion, the dual array element spacing in the simulation parameters is changed to , the other conditions remain unchanged, when the signal-to-noise ratio is 30dB and 40dB respectively, the angle root mean square error after defuzzification is The relationship between the ratios is as follows Figure 5 As shown, the corresponding defuzzification success probability is The relationship between the ratios is as follows Figure 6 shown.

[0132] From the simulation results, it can be seen that when or When or When , the ambiguity cannot be successfully resolved; when When , the deambiguation success rate will also drop significantly due to the influence of phase error.

[0133] In summary, the theoretical boundary of the defuzzification frequency selected in this application is consistent with the simulation results.

[0134] 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 sparsely distributed dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method, characterized in that: The specific process is: Step 1: sparsely spaced dual array elements at dual carrier frequencies and The dual-channel phase comparison measurement is performed to obtain the phase difference between the array elements, and then the ambiguity coefficient containing the phase error is obtained; according to the ambiguity coefficient, the dual frequency is determined and The constraints on the carrier value; Step 2: Under the constraints determined in step 1, the radar signal operating frequency is selected, and a virtual baseline is constructed according to the phase difference of the two array elements at different frequencies; Step 3: Based on the virtual baseline deambiguation method, the unambiguous and high-precision one-dimensional angle measurement is calculated.

2. The sparse dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method according to claim 1 is characterized in that: The specific process of obtaining the phase difference between array elements and the ambiguity coefficient including the phase error in step 1 is as follows: The sparsely spaced dual-element array is used for dual-channel phase comparison measurement under two transmission frequency conditions, and the phase difference between the elements is obtained as follows: and ; in, and Respectively and There is no phase measurement error in the part, and and It means and The phase measurement error part in ; The ambiguity coefficient including the phase error is: in, Indicates rounding calculation. is the baseline length, is the virtual baseline, , .

3. The sparse dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method according to claim 2 is characterized in that: The first step determines the dual frequency according to the phase difference between the array elements and the ambiguity coefficient. and The specific process of the carrier value constraint is as follows: according to Combined with the fuzzy coefficient containing the phase error It must have no effect on the rounding calculation, so we can get The maximum measurement error of the phase difference between the two channels is expressed as ; Determine dual frequency and The constraints on the carrier value are: 。 4. The sparsely distributed dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method according to claim 3 is characterized in that: According to the constraints, at the selected carrier frequency ,get The value of should meet the conditions: in, Represents the speed of light.

5. The sparsely distributed dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method according to claim 4 is characterized in that: According to the selected carrier frequency and The value of should meet the conditions to determine the working frequency , construct the virtual baseline as: 。 6. The sparsely distributed dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement method according to claim 5 is characterized in that: The third step is based on the virtual baseline defuzzification method to calculate the unambiguous high-precision one-dimensional angle measurement angle, specifically: Calculate the fuzzy coefficient including the phase error based on the phase difference obtained by dual-channel phase comparison measurement , in, 、 Respectively expressed in 、 The phase difference between the two array elements obtained by dual-channel phase comparison measurement under frequency conditions is ; Based on the fuzzy coefficient including phase error , thereby solving the unambiguous high-precision one-dimensional angle measurement : 。 7. A sparsely distributed dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement device, characterized in that: It includes sparse dual array elements, constraint calculation module, virtual baseline construction module and one-dimensional angle measurement module; Constraint calculation module, using sparse dual array elements at dual carrier frequencies and The dual-channel phase comparison measurement is performed to obtain the phase difference between the array elements, and then the ambiguity coefficient containing the phase error is obtained; according to the ambiguity coefficient, the dual frequency is determined and The constraints on the carrier value; A virtual baseline construction module selects a radar signal operating frequency based on the constraint conditions and constructs a virtual baseline according to the dual-element phase difference at different frequencies; The one-dimensional angle measurement module calculates the unambiguous and high-precision one-dimensional angle measurement angle based on the virtual baseline deambiguation method.

8. The sparsely distributed dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement device according to claim 7 is characterized in that: The specific process of the constraint condition calculation module obtaining the phase difference between array elements and the fuzzy coefficient including the phase error is as follows: The sparsely spaced dual-element array is used for dual-channel phase comparison measurement under two transmission frequency conditions, and the phase difference between the elements is obtained as follows: and ; in, and Respectively and There is no phase measurement error in the part, and and It means and The phase measurement error part in ; The ambiguity coefficient including the phase error is: in, Indicates rounding calculation. is the baseline length, is the virtual baseline, , .

9. The sparsely distributed dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement device according to claim 8, characterized in that: The constraint condition calculation module determines the dual frequency according to the phase difference between the array elements and the fuzzy coefficient. and The specific process of the carrier value constraint is as follows: according to Combined with the fact that the fuzzy coefficient of the phase error must have no effect on the rounding calculation, we can get The maximum measurement error of the phase difference between the two channels is expressed as ; Determine dual frequency and The constraints on the carrier value are: 。 10. The sparsely distributed dual-element phase comparison and dual-frequency phase ambiguity resolution radar angle measurement device according to claim 9, characterized in that: The constraint condition calculation module selects the carrier frequency according to the constraint condition. ,get The value of should meet the conditions: in, Represents the speed of light.

Images