Angle measurement method for dual-element dual-frequency radar based on vector averaging method to suppress phase noise

Abstract

The present invention provides a dual-element dual-frequency radar angle measurement method based on vector averaging to suppress phase noise. The vector averaging algorithm is used to effectively suppress phase noise and overcome the influence of phase "cycle jumps". Compared with the existing scalar averaging method, the present invention greatly improves the angle measurement accuracy of the dual-element sparsely distributed dual-frequency radar under low signal-to-noise ratio.

Description

Technical Field

[0001] The present invention belongs to the field of radar measurement technology, and in particular relates to a dual-element dual-frequency radar angle measurement method based on a vector averaging method to suppress phase noise. Background Art

[0002] Radar phase interferometry angle measurement uses the phase difference of the received signals from each antenna element to determine the target's angle of incidence. Theoretically, greater spacing between antenna elements improves angle measurement accuracy. However, when the spacing is greater than half a wavelength, integer multiples of the phase difference measurements become ambiguous, leading to erroneous angle measurements.

[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] To minimize the impact of phase noise on accurate phase ambiguity resolution, Fan Xiaobo of the University of Electronic Science and Technology of China proposed a dual-element, dual-frequency search method for phase ambiguity resolution in his master's thesis, "Research on Lunar Orbit Rendezvous and Docking Microwave Radar Velocimetry and Angle Measurement," published in April 2013. This method uses a scalar averaging algorithm to reduce phase noise and suppress the effects of phase noise. It then searches through all possible values ​​of the integer ambiguity, minimizing a cost function in the solution space to resolve the phase ambiguity.

[0005] The dual-element dual-frequency search phase ambiguity measurement method based on the scalar averaging algorithm reduces the influence of noise by performing arithmetic averaging on the phase difference measurement values. However, since the main value interval of the phase difference measurement value is located in , when the actual phase difference without error is or When the phase difference measurement value is affected by noise, it will produce distorted The "skip phenomenon" of the measurement results is and The jump between the two causes a sharp deterioration in the angle measurement accuracy. Summary of the Invention

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

[0007] A dual-element dual-frequency radar angle measurement method based on vector averaging to suppress phase noise, antenna array element 、 Receive dual-frequency signals, and the receiving frequency is The unambiguous phase estimate of the signal for:

[0008]

[0009] in, is the rounding function, is the mean of the unambiguous phase difference vector, The receiving frequency is The measured value of the phase of the signal is is the frequency of the other signal in the dual-frequency signal.

[0010] Furthermore, the unambiguous phase difference vector mean The calculation method is:

[0011]

[0012] in, Indicates the dual-frequency phase difference No. The measured value, Represents calculation The total number of dual-frequency signals that need to be received in the past, and , Antenna array element 、 The receiving frequency is The theoretical phase difference of the signal is, Antenna array element 、 The receiving frequency is The theoretical phase difference of the signal is, is the inverse tangent function.

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

[0014]

[0015] in, Antenna array element 、 The receiving frequency is The ambiguity value of the phase difference of the signal is an integer number of cycles, Antenna array element 、 The receiving frequency is The main value interval of the signal is The theoretical value of the phase difference.

[0016] Furthermore, the theoretical phase difference The calculation method is:

[0017]

[0018] in, Antenna array element 、 The receiving frequency is The ambiguity value of the phase difference of the signal is an integer number of cycles, Antenna array element 、 The receiving frequency is The main value interval of the signal is The theoretical value of the phase difference.

[0019] Furthermore, in the presence of phase error, the theoretical phase difference The estimated value of is calculated as:

[0020]

[0021] in, Antenna array element 、 The receiving frequency is The integer cycle ambiguity estimate of the phase difference of the signal, Antenna array element 、 The receiving frequency is The main value interval of the signal is The estimated phase difference of

[0022] Integer week ambiguity estimate The calculation method is:

[0023]

[0024] And frequency satisfy:

[0025]

[0026] in, is the rounding function, for The measurement error, for measurement error.

[0027] Furthermore, the unambiguous estimate of the target incident angle for:

[0028]

[0029] in, is the speed of light, Antenna array element 、 spacing.

[0030] Furthermore, the frequency Satisfies the following relationship:

[0031]

[0032] in, is the speed of light, Antenna array element 、 spacing.

[0033] Furthermore, the antenna array element 、 The spacing between them satisfies:

[0034]

[0035] in, 、 Antenna array elements 、 The received frequency is 、 The wavelength of the signal.

[0036] Beneficial effects:

[0037] The present invention provides a dual-element dual-frequency radar angle measurement method based on vector averaging to suppress phase noise. The vector averaging algorithm is used to effectively suppress phase noise and overcome the influence of phase "cycle jumps". Compared with the existing scalar averaging method, the present invention greatly improves the angle measurement accuracy of the dual-element sparsely distributed dual-frequency radar under low signal-to-noise ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the dual-element dual-frequency angle measurement principle.

[0039] Figure 2 This is a comparison chart of the deblurring accuracy between the present invention and the scalar averaging method at different incident angles.

[0040] Figure 3 This is a comparison diagram of the root mean square error of angle measurement between the present invention and the scalar averaging method when the incident angle is 0°.

[0041] Figure 4 This is a comparison diagram of the angle measurement root mean square error between the present invention and the scalar averaging method when the incident angle is 30°. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0043] This paper proposes a dual-frequency angle measurement method using a sparse dual-element array to suppress phase noise and eliminate the effect of "cycle skipping" using a vector averaging algorithm. The specific contents are as follows:

[0044] like Figure 1 As shown, the present invention uses sparsely distributed dual antenna array elements 、 Time-sharing dual-frequency signal reception, the receiving signal frequencies are 、 ,in , and the corresponding wavelengths are 、 , array element 、 The spacing is , is the target incident angle.

[0045] When the received signal frequency is When the antenna array element 、 Phase difference of received signal for

[0046] (1)

[0047] in, is the speed of light, Antenna array element 、 The receiving frequency is The ambiguity value of the phase difference of the signal is an integer number of cycles, Antenna array element 、 The receiving frequency is The main value interval of the signal is The theoretical value of the phase difference, subscript 1 indicates that the received signal frequency is .

[0048] When the received signal frequency is When , the theoretical phase difference can be obtained by the same logic for

[0049] (2)

[0050] in, Antenna array element 、 The receiving frequency is The ambiguity value of the phase difference of the signal is an integer number of cycles, Antenna array element 、 The receiving frequency is The main value interval of the signal is Theoretical value of phase difference

[0051] make ,consider There is no phase ambiguity, that is, it satisfies:

[0052] (3)

[0053] Therefore the frequency The following relationship should be satisfied:

[0054] (4)

[0055] Phase estimate after deambiguation for

[0056] (5)

[0057] In actual engineering, thermal noise can cause phase measurement errors. When the phase measurement error exceeds a certain range, it can lead to errors in the deambiguation process. The following analyzes the impact of phase measurement error on deambiguation.

[0058] After considering the phase measurement error, equation (5) can be expressed as

[0059] (6)

[0060] in, The receiving frequency is The unambiguous phase estimation value of the signal, the measured value of the dual-frequency phase difference , the receiving frequency is The measured value of the signal phase , 、 They are and The phase measurement error, Antenna array element 、 The receiving frequency is Therefore, the integer cycle ambiguity estimate of the phase difference considering the phase measurement error is The phase ambiguity solution result is expressed as

[0061] (7)

[0062] To obtain the correct integer week fuzzy value , requiring that the second half of formula (7) has no effect on rounding, that is, it must satisfy

[0063] (8)

[0064] Assuming the channel phase measurement accuracy is the same, the single channel phase noise is statistically independent with a mean of 0 and a variance of Gaussian white noise, that is ,but , , according to formula (8) we can get

[0065] (9)

[0066] When the target is far away, the received signal-to-noise ratio is low, resulting in the single-channel phase noise not meeting the condition of formula (9), and the phase ambiguity resolution result is wrong.

[0067] From formula (7), we can see that The measurement error Magnified In order to suppress the influence of phase noise and phase "jump", the vector mean filtering method is used, that is, the vector conduct Point vector average. Unambiguous phase difference vector mean The calculation formula is:

[0068] (10)

[0069] in, Indicates the dual-frequency phase difference No. The measured value, Represents calculation The total number of dual-frequency signals that need to be received at the past moment, that is, the present invention uses the average of the measurement values ​​of the past N moments as the unambiguous phase difference vector mean at the current moment; at the same time, , Antenna array element 、 The receiving frequency is The theoretical phase difference of the signal is, Antenna array element 、 The receiving frequency is The theoretical phase difference of the signal is, is the inverse tangent function.

[0070] Therefore, the final unambiguous phase estimate for

[0071] (11)

[0072] Unambiguous estimate of the target incident angle for

[0073] (12)

[0074] Furthermore, in order to verify the effectiveness of the present invention, the following simulation experiments were conducted:

[0075] In this example, the interferometer system simulation parameters are as follows: antenna array element spacing , signal frequency , ,satisfy Set the channel phase noise to statistically independent zero-mean Gaussian white noise.

[0076] When the channel phase noise standard deviation is 20°, 10,000 Monte Carlo simulations are performed for each angle in the range of -60° to 60° to compare the deambiguation accuracy of the present invention with that of the existing method based on scalar averaging. The results are as follows: Figure 2 As shown in the figure, it can be seen that the deambiguation performance of the scalar averaging method deteriorates seriously at some angles, while the present invention can achieve a deambiguation accuracy of more than 90% in the range of -60° to 60°.

[0077] Setting different channel phase noise standard deviations, and performing 10,000 Monte Carlo simulations at target incident angles of 0° and 30°, respectively, the angle measurement root mean square error of the present invention is compared with that of the existing method based on scalar averaging. The results are shown in Figure 2. Figure 3 、 Figure 4 As shown. Figure 3 It can be seen that when the incident angle is 0°, the phase corresponding to this angle is not prone to "cycle jump", so the angle measurement accuracy of the two methods is roughly the same; Figure 4 It can be seen that when the incident angle is 30°, the phase corresponding to this angle is close to , “cycle skipping” is prone to occur, so the angular measurement performance of the scalar averaging method deteriorates seriously, while this method can still achieve good angular measurement accuracy.

[0078] 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 "cycle jump" and greatly improves the accuracy of phase deambiguation and angle measurement accuracy.

[0079] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may of course make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A dual-element dual-frequency radar angle measurement method based on vector averaging to suppress phase noise, characterized in that: Antenna array elements 、 Receive dual-frequency signals, and the receiving frequency is The unambiguous phase estimate of the signal for: in, is the rounding function, is the mean of the unambiguous phase difference vector, The receiving frequency is The measured value of the phase of the signal is is the frequency of the other signal in the dual-frequency signal; Unambiguous phase difference vector mean The calculation method is: in, Indicates the dual-frequency phase difference No. The measured value, Represents calculation The total number of dual-frequency signals that need to be received in the past, and , Antenna array element 、 The receiving frequency is The theoretical phase difference of the signal is, Antenna array element 、 The receiving frequency is The theoretical phase difference of the signal is, is the inverse tangent function.

2. The dual-element dual-frequency radar angle measurement method based on vector averaging to suppress phase noise according to claim 1, characterized in that: Theoretical phase difference The calculation method is: in, Antenna array element 、 The receiving frequency is The ambiguity value of the phase difference of the signal is an integer number of cycles, Antenna array element 、 The receiving frequency is The main value interval of the signal is The theoretical value of the phase difference.

3. The dual-element dual-frequency radar angle measurement method for suppressing phase noise based on vector averaging as claimed in claim 1, characterized in that: Theoretical phase difference The calculation method is: in, Antenna array element 、 The receiving frequency is The ambiguity value of the phase difference of the signal is an integer number of cycles, Antenna array element 、 The receiving frequency is The main value interval of the signal is The theoretical value of the phase difference.

4. The dual-element dual-frequency radar angle measurement method based on vector averaging to suppress phase noise as claimed in claim 3, characterized in that: In the presence of phase error, the theoretical phase difference The estimated value of is calculated as: in, Antenna array element 、 The receiving frequency is The integer cycle ambiguity estimate of the phase difference of the signal, Antenna array element 、 The receiving frequency is The main value interval of the signal is The estimated phase difference of Integer week ambiguity estimate The calculation method is: And frequency satisfy: in, is the rounding function, for The measurement error, for measurement error.

5. The dual-element dual-frequency radar angle measurement method based on vector averaging to suppress phase noise as claimed in claim 1, characterized in that: Unambiguous estimate of the target incident angle for: in, is the speed of light, Antenna array element 、 spacing.

6. The dual-element dual-frequency radar angle measurement method based on vector averaging to suppress phase noise as claimed in claim 1, characterized in that: frequency Satisfies the following relationship: in, is the speed of light, Antenna array element 、 spacing.

7. The dual-element dual-frequency radar angle measurement method based on vector averaging to suppress phase noise as claimed in claim 1, characterized in that: Antenna array elements 、 The spacing between them satisfies: in, 、 Antenna array elements 、 The received frequency is 、 The wavelength of the signal.

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