Double-array-element double-frequency radar angle measurement method for suppressing phase noise based on vector averaging method

Abstract

According to the double-array-element double-frequency radar angle measurement method for restraining the phase noise based on the vector averaging method, the phase noise is effectively restrained through the vector averaging algorithm, the influence of phase cycle skipping is overcome, and compared with an existing scalar averaging method, the angle measurement precision of a double-array-element sparse cloth double-frequency radar under the low signal-to-noise ratio is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of radar measurement, and particularly relates to a dual-array-element dual-frequency radar angle measurement method for suppressing phase noise based on the vector averaging method. Background Art

[0002] Radar phase interference angle measurement is a method of obtaining the incident angle of a target by using the phase difference of the signals received by each antenna element according to the different phases 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, an integer multiple ambiguity in the phase difference measurement value will occur, resulting in an incorrect angle measurement result.

[0003] To solve the problem of phase difference measurement value ambiguity, in engineering, unambiguous angle measurement is achieved by designing long and short baselines. However, multi-baseline phase comparison angle measurement methods such as the long and short baseline method have strict requirements for the placement of antenna elements. In addition, the number of antenna elements and the number of receiving channels are relatively large, resulting in large equipment volume, weight, and power consumption. When the antenna layout space is limited and only two antenna elements can be installed, phase ambiguity can be solved by receiving signals of different frequencies.

[0004] To reduce the influence of phase noise on the correct solution of phase ambiguity, Fan Xiaobo of the University of Electronic Science and Technology proposed a dual-array-element dual-frequency search method for solving phase ambiguity and measuring angles based on the scalar averaging algorithm to reduce phase noise in his master's thesis "Research on Microwave Radar Speed and Angle Measurement for Lunar Orbit Rendezvous and Docking" in April 2013. This method suppresses the influence of phase noise by arithmetically averaging the phase difference measurement values, traverses and searches all possible values of the integer cycle ambiguity, and minimizes the cost function in the solution space to solve the phase ambiguity.

[0005] The dual-array-element dual-frequency search method for solving phase ambiguity and measuring angles based on the scalar averaging algorithm reduces the influence of noise by arithmetically averaging the phase difference measurement values. However, since the principal value interval of the phase difference measurement value is located in , when the actual phase difference value without error is in or nearby, due to the influence of noise, the phase difference measurement value will produce a modulo "cycle skipping phenomenon", that is, the measurement result jumps between and , resulting in a sharp deterioration of the angle measurement accuracy. Summary of the Invention

[0006] To solve the above problems, the present invention provides a dual-array-element dual-frequency radar angle measurement method for suppressing phase noise based on the vector averaging method, which can eliminate the influence of "cycle skipping" and effectively improve the angle measurement accuracy under low signal-to-noise ratio.

[0007] A dual-array-element dual-frequency radar angle measurement method for suppressing phase noise based on the vector averaging method, antenna element , When receiving a dual - frequency signal with a receiving frequency of the unambiguous phase estimation value is:

[0008] where is the rounding function, is the mean value of the unambiguous phase difference vector, is the measured phase value when receiving a signal with a receiving frequency of , is the frequency of the other signal in the dual - frequency signal.

[0009] Furthermore, the calculation method of the mean value of the unambiguous phase difference vector is:

[0010] where represents the th measurement value of the dual - frequency phase difference , represents the total number of times of the dual - frequency signals received in the past required for calculating , and , is the theoretical phase difference when the antenna elements , receive a signal with a receiving frequency of , is the theoretical phase difference when the antenna elements , receive a signal with a receiving frequency of , is the arctangent function.

[0011] Furthermore, the calculation method of the theoretical phase difference is:

[0012] where is the integer - cycle ambiguity value of the phase difference when the antenna elements , receive a signal with a receiving frequency of , is the theoretical value of the phase difference whose principal - value interval is in , when the antenna elements receive a signal with a receiving frequency of .

[0013] Furthermore, the calculation method of the theoretical phase difference is:

[0014] Among them, is the antenna element , The integer cycle ambiguity value of the phase difference when receiving a signal with a frequency of . is the antenna element , The theoretical value of the phase difference when receiving a signal with a frequency of in the principal value range of .

[0015] Furthermore, in the presence of phase errors, the calculation method of the estimated value of the theoretical phase difference is:

[0016] Among them, is the antenna element , The integer cycle ambiguity estimated value of the phase difference when receiving a signal with a frequency of . is the antenna element , The estimated value of the phase difference when receiving a signal with a frequency of in the principal value range of ; The calculation method of the integer cycle ambiguity estimated value is:

[0017] And the frequency satisfies:

[0018] Among them, is the rounding function, is 's measurement error, is 's measurement error.

[0019] Furthermore, the unambiguous estimated value of the target incident angle is:

[0020] Among them, is the speed of light, is the spacing between the antenna elements , .

[0021] Furthermore, the frequency satisfies the following relationship:

[0022] Among them, is the speed of light, is the antenna array element 、 spacing.

[0023] Furthermore, the spacing between the antenna array elements 、 satisfies:

[0024] Among them, 、 are respectively the wavelengths corresponding to the signals received by the antenna array elements 、 with frequencies of 、 。

[0025] Beneficial effects: The present invention provides a dual-array-element dual-frequency radar angle measurement method for suppressing phase noise based on the vector averaging method, which effectively suppresses phase noise and overcomes the influence of phase "cycle skipping" through the vector averaging algorithm. Compared with the existing scalar averaging method, the present invention greatly improves the angle measurement accuracy of the dual-array-element sparse dual-frequency radar under low signal-to-noise ratio. Description of the drawings

[0026] Figure 1 is a schematic diagram of the dual-array-element dual-frequency angle measurement principle.

[0027] Figure 2 is a comparison chart of the ambiguity resolution correct rate between the present invention and the scalar averaging method under different incident angles.

[0028] Figure 3 is a comparison chart of the root mean square error of angle measurement between the present invention and the scalar averaging method when the incident angle is 0°.

[0029] Figure 4 is a comparison chart of the root mean square error of angle measurement between the present invention and the scalar averaging method when the incident angle is 30°. Specific implementation manners

[0030] In order to enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application.

[0031] The present invention proposes a method for using sparse dual-array-element dual-frequency angle measurement to suppress phase noise and eliminate the influence of "cycle skipping" by the vector averaging algorithm. The specific content is as follows: As Figure 1 shown, the present invention uses sparse dual antenna array elements , Receive dual - frequency signals in a time - sharing manner, and the received signal frequencies are respectively , , where , and the corresponding wavelengths are respectively , . The element , spacing is , is the target incident angle.

[0032] When the received signal frequency is , the phase difference , of the received signals by antenna elements is (1) where is the speed of light, is the integer - cycle ambiguity value of the phase difference when antenna elements , receive signals with a frequency of , is the theoretical value of the phase difference in the principal value range of , when antenna elements receive signals with a frequency of . The subscript 1 indicates that the received signal frequency is .

[0033] When the received signal frequency is , similarly, the theoretical phase difference is (2) where is the integer - cycle ambiguity value of the phase difference when antenna elements , receive signals with a frequency of , is the theoretical value of the phase difference in the principal value range of , when antenna elements receive signals with a frequency of Let , considering without phase ambiguity, that is, satisfying: (3) Therefore, the frequency should satisfy the following relationship: (4) ​Phase estimation value after ambiguity resolution is (5) In practical engineering, phase measurement errors are generated due to thermal noise. When the phase measurement error exceeds a certain range, the ambiguity resolution process will go wrong. The following analyzes the influence of phase measurement errors on ambiguity resolution.

[0034] After considering the phase measurement error, Equation (5) can be expressed as (6) where is the unambiguous phase estimation value when receiving a signal with a receiving frequency of , the measured value of the dual-frequency phase difference , the measured phase value when receiving a signal with a receiving frequency of , , and are respectively and phase measurement errors, is the integer cycle ambiguity estimation value of the phase difference when the antenna array element , receives a signal with a receiving frequency of . Therefore, the phase ambiguity resolution result of the integer cycle ambiguity estimation value considering the phase measurement error is expressed as (7) To obtain the correct integer cycle ambiguity value , it is required that the latter part of Equation (7) has no influence on rounding, that is, it must satisfy (8) Assume that the channel phase measurement accuracies are equivalent, and the single-channel phase noise is statistically independent Gaussian white noise with a mean of 0 and a variance of , that is , then , , and according to Equation (8), we can get (9) When the target distance is far, the low signal-to-noise ratio of the received signal causes the single-channel phase noise not to satisfy the condition of Equation (9), and the phase ambiguity resolution result goes wrong.

[0035] It can be seen from Equation (7) that the measurement error of is amplified by times. To suppress the influence of phase noise and phase "cycle skipping", the method of vector mean filtering is adopted, that is, for the vector perform Point vector averaging. Unambiguous phase difference vector mean The calculation formula is as follows: (10) Wherein, represents the th measurement value of the dual-frequency phase difference, represents the total number of times of the dual-frequency signals received in the past required for calculation , that is, in the present invention, the measurements of the past N moments are averaged to be used as the unambiguous phase difference vector mean at the current moment; at the same time, , is the theoretical phase difference when the antenna array element , receives a signal with a frequency of , is the theoretical phase difference when the antenna array element , receives a signal with a frequency of , is the arctangent function.

[0036] Therefore, the final unambiguous phase estimation value is (11) The unambiguous estimation value of the target incident angle is (12) Furthermore, to verify the effectiveness of the present invention, the following simulation experiments are carried out: In this example, the simulation parameters of the interferometer system are as follows: the antenna array element spacing , the signal frequency , , satisfying . The channel phase noise is set to statistically independent zero-mean Gaussian white noise.

[0037] When the standard deviation of the channel phase noise is 20°, 10,000 Monte Carlo simulations are carried out for each angle in the range of -60° to 60°, and the deblurring correct rate of the present invention is compared with the existing method based on scalar averaging. The results are as Figure 2 shown. It can be seen that the deblurring performance of the scalar averaging method deteriorates seriously at some angles, while the present invention can achieve a deblurring correct rate of more than 90% in the range of -60° to 60°.

[0038] Set different standard deviations of channel phase noise, and conduct 10,000 Monte Carlo simulations respectively when the target incident angles are 0° and 30°. Compare the root mean square error of angle measurement between the present invention and the existing method based on scalar averaging. The results are as Figure 3 , Figure 4 shown. It can be seen from Figure 3 that when the incident angle is 0°, the phase corresponding to this angle is not likely to have "phase wrap", so the angle measurement accuracies of the two methods are roughly equivalent; it can be seen from Figure 4 that when the incident angle is 30°, the phase corresponding to this angle is close to , and is likely to have "phase wrap". Therefore, the angle measurement performance of the scalar averaging method deteriorates severely, while the present method can still obtain good angle measurement accuracy.

[0039] The above results show that compared with the existing scalar averaging method, the vector averaging method used in the present invention effectively suppresses the influence of "phase wrap", and greatly improves the correct rate of phase ambiguity resolution and the angle measurement accuracy.

[0040] Certainly, the present invention may also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can of course make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the appended claims of the present invention.

Claims

1. A dual-element dual-frequency radar angle measurement method for suppressing phase noise based on the vector averaging method, characterized in that Antenna element and receive dual - frequency signals, and when receiving signals with a frequency of the unambiguous phase estimation value is as follows: Among them, is the rounding function, is the non-fuzzy phase difference vector mean, is the actual measured value of the phase when receiving a signal with a frequency of , is the frequency of another signal in the dual-frequency signal.

2. A dual-element dual-frequency radar angle measurement method for suppressing phase noise based on the vector averaging method, characterized in that, Mean value of non-blurred phase difference vector The calculation method is as follows: Among them, represents the th measurement value of the dual-frequency phase difference, represents the total number of times of the dual-frequency signals received in the past required for calculation, and , is the theoretical phase difference when the antenna array element , receives a signal with a frequency of , is the theoretical phase difference when the antenna array element , receives a signal with a frequency of , is the arctangent function.

3. A dual-array dual-frequency radar angle measurement method for suppressing phase noise based on the vector averaging method, characterized in that, Theoretical phase difference The calculation method is as follows: Among them, is the antenna element , is the integer cycle ambiguity value of the phase difference when receiving a signal with a frequency of . is the antenna element , is the theoretical value of the phase difference in the principal value range when receiving a signal with a frequency of in .

4. A dual-element dual-frequency radar angle measurement method for suppressing phase noise based on the vector averaging method according to claim 2, characterized in that Theoretical phase difference The calculation method is as follows: Among them, is the antenna element , when receiving a signal with a frequency of the integer cycle ambiguity value of the phase difference, is the antenna element , when receiving a signal with a frequency of the principal value interval of the phase difference in the theoretical value of the phase difference.

5. A dual-element dual-frequency radar angle measurement method for suppressing phase noise based on the vector averaging method, characterized in that, In the presence of phase error, the calculation method for the estimated value of the theoretical phase difference is as follows: Among them, is the antenna element , is the integer cycle ambiguity estimation value of the phase difference when receiving a signal with a frequency of ; is the antenna element , is the phase difference estimation value in the principal value interval when receiving a signal with a frequency of in ; Integer cycle ambiguity estimate value The calculation method is as follows: and the frequency satisfies: Among them, is the rounding function, is the measurement error of is the measurement error of 6. A dual-element dual-frequency radar angle measurement method for suppressing phase noise based on the vector averaging method, characterized in that Unambiguous estimated value of the target incident angle is: Among them, is the speed of light, is the spacing between antenna elements , .

7. A dual-element dual-frequency radar angle measurement method for suppressing phase noise based on the vector averaging method, characterized in that, Frequency Satisfies the following relationship: Among them, is the speed of light, is the spacing between antenna elements , .

8. A dual-element dual-frequency radar angle measurement method for suppressing phase noise based on the vector averaging method, characterized in that Antenna element and The spacing therebetween satisfies: Among them, , are respectively the , wavelengths corresponding to the signals received by the antenna elements at frequencies of , .

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