Photonics large-bandwidth two-dimensional arrival angle estimation device and method

Abstract

The invention provides a photonics large-bandwidth two-dimensional arrival angle estimation device and method, and belongs to the technical field of wireless radio frequency. The photonics arrival angle estimation device comprises a receiving antenna A1, a receiving antenna A2, a receiving antenna A0, a first optical domain delay matching channel, a second optical domain delay matching channel, a reference optical domain delay channel, an optical splitter, a first balance photoelectric detection unit, a second balance photoelectric detection unit and a feedback control module. According to the photonics large-bandwidth two-dimensional arrival angle estimation device and method, on the basis of coherent characteristics of received signals of adjacent antenna array elements, a pitch angle and an azimuth angle of an incoming wave signal are obtained through optical domain delay search by adopting photonics microwave signal transmission and balance detection, prior information such as frequency and bandwidth of the incoming wave signal is not needed, and the estimation accuracy is high. The antenna has the advantages of wide working frequency range, large bandwidth and high angle measurement precision.

Description

Technical Field

[0001] The invention belongs to the field of wireless radio frequency technology and relates to a photonics large-bandwidth two-dimensional arrival angle estimation device and method. Background Art

[0002] In the fields of wireless communication, radar detection, intelligent driving, etc., it is very important to obtain parameters such as the direction, distance and speed of the target object. With the rapid development of communication, radar and other technologies, signals are gradually developing in the direction of wide frequency band and large bandwidth. In different application scenarios, in addition to measuring the angle of the system echo signal, it is also necessary to measure the arrival angle of the unknown incoming wave signal. Therefore, the arrival angle measurement of large bandwidth unknown incoming wave signals is one of the key problems that must be solved in communication and radar systems.

[0003] In the prior art [1] (Chen Hao, Huang Chongjia, Erwin HW Chan. Photonic approach for measuring AOA of multiple signals with improved measurement accuracy [J]. IEEE Photonics Journal, 2020, 12 (3): 1-10), a microwave photon down-conversion method is used to down-convert the input microwave signal to an intermediate frequency, and then a low-frequency electrical spectrum analyzer is used to measure the power of the intermediate frequency signal. The angle of arrival of the incoming signal is determined based on the mapping relationship between the intermediate frequency signal power and the phase difference caused by the antenna spacing. By setting the optical modulator at different bias points, the signal arrival angle in different angle measurement ranges can be obtained. This method is only applicable to the angle of arrival measurement of single-frequency signals or narrowband signals, and requires the frequency of the incoming signal to be known, and cannot process large-bandwidth signals.

[0004] In the prior art [2] (Lin Qirui, Ma Jianxin. Photonic approach for Doppler-frequency-shift and angle-of-arrival measurement with direction unambiguity and high precision [J]. Applied Optics, 2023, 62 (6): 1447-1455), a dual-drive Mach-Zehnder modulator is used to realize the electro-optical conversion of the antenna receiving signal. The two first-order optical sidebands generated are separated by an optical filter to form two channels, and the beat frequency is detected by two identical low-speed photodetectors. The angle of arrival measurement without direction ambiguity is achieved by comparing the power of the beat frequency signals of the two channels. This method is only applicable to the angle of arrival measurement of single-frequency signals, and the frequency of the signal needs to be known. It is difficult to achieve the angle of arrival measurement of broadband unknown frequency signals.

[0005] In the prior art [3] (Tu Zhaoyang, Wen Aijun, Xiu Zhongguo, et al. Angle-of-arrivale stimulation of broadband microwave signals based on microwave photonic filtering [J]. IEEE Photonics Journal, 2017, 9 (5): 1-8), a microwave photon notch filter is constructed and the notch filtering characteristics are used to convert the time difference of the signal arriving at adjacent antennas into the change of the notch position in the output signal spectrum. This scheme can measure the arrival angle of broadband incoming wave signals. However, this scheme requires knowing the frequency and bandwidth of the incoming wave signal in advance and using a spectrum analyzer to measure the notch position. The system is relatively complex and the determination of the notch position is easily affected by system noise.

[0006] The above technology provides an optional solution to the problem of arrival angle estimation, but it usually requires prior information such as the frequency of the incoming signal. In addition, in terms of bandwidth signal processing, it is limited by its working principle and system complexity, and it is difficult to meet the requirements for effective measurement of the arrival angle of large bandwidth unknown signals in practical applications. Summary of the invention

[0007] The present invention provides a photonic two-dimensional arrival angle estimation device and method for large-bandwidth unknown incoming wave signals, which effectively solves the limitations of the arrival angle measurement method in the background technology that the prior information such as the signal frequency needs to be known in advance, it is difficult to measure large-bandwidth signals, and the system complexity is high. It can effectively estimate the arrival angle of large-bandwidth signals and meet the needs in actual application scenarios.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A photonics large-bandwidth two-dimensional arrival angle estimation device comprises a receiving antenna A1, a receiving antenna A2, a receiving antenna A0, a first light domain delay matching channel, a second light domain delay matching channel, a reference light domain delay channel, an optical splitter, a first balanced photoelectric detection unit, a second balanced photoelectric detection unit, and a feedback control module.

[0010] The receiving antenna A1 is an adjacent array element of the receiving antenna A0 in the horizontal direction, and the receiving antenna A2 is an adjacent array element of the receiving antenna A0 in the vertical direction.

[0011] The first optical domain delay matching channel comprises a first laser light source, a first electro-optical conversion unit, and a first optical domain adjustable delay unit, which are connected in sequence by optical fibers or optical waveguides.

[0012] The second optical domain delay matching channel comprises a second laser light source, a second electro-optical conversion unit, and a second optical domain adjustable delay unit, which are connected in sequence by optical fibers or optical waveguides.

[0013] The optical domain reference delay channel includes a third laser light source, a third electro-optical conversion unit, and an optical domain fixed delay unit, which are connected in sequence by optical fiber or optical waveguide; the delay time of the fixed delay unit is greater than the maximum time difference generated by the interval between adjacent antenna array elements.

[0014] The receiving antenna A1 and the first electro-optical conversion unit are connected in sequence through cables or microstrip lines; the receiving antenna A2 and the second electro-optical conversion unit are connected in sequence through cables or microstrip lines; the receiving antenna A0 and the third electro-optical conversion unit are connected in sequence through cables or microstrip lines.

[0015] The optical splitter includes an input port and two output ports, and has the function of dividing the output of the optical domain reference delay channel into two paths; the input port of the optical splitter is connected to the output port of the optical domain reference delay channel; the two output ports of the optical splitter are respectively transmitted to the lower port of the first balanced photoelectric detection unit and the upper port of the second balanced photoelectric detection unit;

[0016] The first optical domain delay matching channel is connected to the upper port of the first balanced detection unit; the second optical domain delay matching channel is connected to the lower port of the second balanced detection unit;

[0017] The feedback control module includes a radio frequency power monitoring unit and a signal analysis and control unit;

[0018] The first balanced detection unit has the function of performing photoelectric conversion on the optical microwave signals output by the first optical domain adjustable delay channel and the optical domain reference delay channel to output electrical signals and subtract them; the electrical signal output by the first balanced detection unit is transmitted to the RF power monitoring unit in the feedback control module.

[0019] The second balanced detection unit has the function of performing photoelectric conversion on the optical microwave signals output by the second optical domain adjustable delay channel and the optical domain reference delay channel to output electrical signals and subtract them; the electrical signals of the second balanced detection unit are transmitted to the RF power monitoring unit in the feedback control module.

[0020] The first balance detection unit, the second balance detection unit and the feedback control analysis module are connected via cables or microstrip lines.

[0021] The feedback control module outputs a control signal of the delay change amount, which is transmitted to the first light domain adjustable delay unit and the second light domain adjustable delay unit respectively, forming a feedback control loop.

[0022] The above-mentioned photonic large-bandwidth two-dimensional arrival angle estimation device implements a method for two-dimensional arrival angle estimation, and the steps are as follows:

[0023] In the first step, the microwave signal received by the receiving antenna A1 is modulated onto the optical carrier emitted by the first laser light source via the first electro-optical conversion unit; the microwave signal received by the receiving antenna A2 is modulated onto the optical carrier emitted by the second laser light source via the second electro-optical conversion unit; the microwave signal received by the receiving antenna A0 is modulated onto the optical carrier emitted by the third laser light source via the third electro-optical conversion unit.

[0024] In the second step, the optical microwave signal output by the first electro-optical conversion unit is transmitted to the first optical domain adjustable delay unit; the optical microwave signal output by the second electro-optical conversion unit is transmitted to the second optical domain adjustable delay unit; and the optical microwave signal output by the third electro-optical conversion unit is transmitted to the optical domain fixed delay unit.

[0025] The optical microwave signal output by the first optical domain delay matching channel and the optical microwave signal output by the optical domain reference delay channel enter the upper and lower optical input ports of the first balanced detection unit respectively, and undergo photoelectric conversion and differential combination in the balanced detection unit; the optical microwave signal output by the second optical domain delay matching channel and the optical microwave signal output by the optical domain reference delay channel are output to the lower and upper optical input ports of the second balanced detection unit, and undergo photoelectric conversion and differential combination in the balanced detection unit.

[0026] In the third step, the RF power monitoring unit in the feedback control module monitors the signal power output by the first balanced detection unit and the second balanced detection unit, and outputs a control signal through the signal analysis and control unit to adjust the delay change of the first optical domain delay adjustment unit and the second optical domain delay adjustment unit respectively.

[0027] In the fourth step, the first optical domain adjustable delay unit scans the delay time of the optical microwave signal output by the first electro-optical conversion unit, and searches for the delay change τ1 corresponding to the minimum output power of the first balanced detection unit; the second optical domain adjustable delay unit scans the delay time of the optical microwave signal output by the second electro-optical conversion unit, and searches for the delay change τ2 corresponding to the minimum output power of the second balanced detection unit.

[0028] Step 5: The delay change τ1 of the first light domain delay adjustable unit, the delay change τ2 of the second light domain delay adjustable unit, and the delay T of the light domain fixed delay unit are calculated. D The difference is

[0029]

[0030] Where α and β are the incident angles of the incoming wave signal in the x-axis direction and the y-axis direction respectively; according to formulas (1) and (2), the incident angles α and β are calculated from the values ​​of Δτ1 and Δτ2; the incident angles α and β and the elevation angle γ and azimuth angle θ of the incoming wave signal satisfy the relationship of formulas (3) and (4):

[0031]

[0032] The signal analysis and control unit in the feedback control module outputs a control signal of the delay change to the first light domain adjustable delay unit and the second light domain adjustable delay unit respectively according to the RF power value output by the RF power monitoring unit and the control algorithm; the system calculates the incident angles α and β by formulas (1) and (2) according to the delay change τ1 of the first light domain adjustable delay unit and the delay change τ2 of the second light domain adjustable delay unit corresponding to the minimum RF power value, and further calculates the pitch angle γ and azimuth angle θ of the incoming wave signal by formulas (3) and (4).

[0033] The beneficial effects of the present invention are:

[0034] (1) Based on the coherent characteristics of the signals received by adjacent antenna array elements, the present invention obtains the two-dimensional arrival angle of the unknown signal through optical domain delay search, without requiring prior information such as the frequency and bandwidth of the incoming signal.

[0035] (2) The present invention adopts photonic microwave signal transmission and balanced detection method to realize the estimation of the two-dimensional arrival angle of unknown incoming wave signal, which has the advantages of wide working frequency band, large bandwidth and high angle measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural diagram of the photonic two-dimensional arrival angle estimation device of the present invention.

[0037] Figure 2 3 is a distribution diagram of two-dimensional antenna array elements in an embodiment of the present invention.

[0038] Figure 3 It is a curve diagram showing the relationship between the power value of the RF signal output by the first balanced detection unit and the delay change τ1 of the first optical domain adjustable delay unit.

[0039] Figure 4 It is a curve diagram showing the relationship between the power value of the RF signal output by the second balanced detection unit and the delay change τ2 of the second optical domain adjustable delay unit.

[0040] Figure 5 It is the relationship between the positive and negative values ​​of the delay time difference Δτ1 and Δτ2 and the quadrant position of the incoming wave signal source.

[0041] Figure 6 It is a diagram showing the relationship between the azimuth and elevation angles of the incoming signal in the angle measurement space. DETAILED DESCRIPTION

[0042] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0043] The present invention discloses a photonics large-bandwidth two-dimensional arrival angle estimation device, comprising a receiving antenna A1, a receiving antenna A2, a receiving antenna A0, a first light domain delay matching channel, a second light domain delay matching channel, a reference light domain delay channel, an optical splitter, a first balanced photoelectric detection unit, a second balanced photoelectric detection unit, and a feedback control module;

[0044] The receiving antenna A1 is an adjacent array element of the receiving antenna A0 in the horizontal direction, and the receiving antenna A2 is an adjacent array element of the receiving antenna A0 in the vertical direction.

[0045] The first optical domain delay matching channel comprises a first laser light source, a first electro-optical conversion unit, and a first optical domain adjustable delay unit, which are connected in sequence by optical fibers or optical waveguides;

[0046] The second optical domain delay matching channel comprises a second laser light source, a second electro-optical conversion unit, and a second optical domain adjustable delay unit, which are sequentially connected by optical fibers or optical waveguides;

[0047] The optical domain reference delay channel includes a third laser light source, a third electro-optical conversion unit, and an optical domain fixed delay unit, which are sequentially connected by optical fibers or optical waveguides, and the delay time of the fixed delay unit is greater than the maximum time difference generated by the interval between adjacent antenna array elements;

[0048] The receiving antenna A1 and the first electro-optical conversion unit are connected in sequence through a cable or a microstrip line; the receiving antenna A2 and the second electro-optical conversion unit are connected in sequence through a cable or a microstrip line; the receiving antenna A0 and the third electro-optical conversion unit are connected in sequence through a cable or a microstrip line;

[0049] The optical splitter includes an input port and two output ports, and has the function of dividing the output of the optical domain reference delay channel into two paths; the input port of the optical splitter is connected to the output port of the optical domain reference delay channel; the two output ports of the optical splitter are respectively transmitted to the lower port of the first balanced photoelectric detection unit and the upper port of the second balanced photoelectric detection unit.

[0050] The first optical domain delay matching channel is connected to the upper port of the first balanced detection unit; the second optical domain delay matching channel is connected to the lower port of the second balanced detection unit;

[0051] The feedback control module includes a radio frequency power monitoring unit and a signal analysis and control unit.

[0052] The first balanced detection unit has the function of performing photoelectric conversion on the optical microwave signals output by the first optical domain adjustable delay channel and the optical domain reference delay channel to output electrical signals and subtract them. The electrical signals output by the first balanced detection unit are transmitted to the RF power monitoring unit in the feedback control module;

[0053] The second balanced detection unit has the function of performing photoelectric conversion on the optical microwave signals output by the second optical domain adjustable delay channel and the optical domain reference delay channel to output electrical signals and subtract them. The electrical signals of the second balanced detection unit are transmitted to the RF power monitoring unit in the feedback control module;

[0054] The first balance detection unit, the second balance detection unit and the feedback control analysis module are connected via cables or microstrip lines;

[0055] The feedback control analysis module outputs a control signal of the delay change amount to the first light domain adjustable delay unit and the second light domain adjustable delay unit respectively, forming a feedback control loop.

[0056] Example

[0057] Figure 2 It is a distribution diagram of two-dimensional antenna array elements. Antenna A1 is the adjacent element of antenna A0 in the horizontal direction, and antenna A2 is the adjacent element of antenna A0 in the vertical direction. The distance between the elements is d = 7.5 cm. There is a spatial incoming wave signal with a center frequency of 2 GHz and a bandwidth of 600 MHz. Its azimuth angle θ is -61.4° and its elevation angle γ is 24.4°. Figure 1It is a structural diagram of a photonic two-dimensional arrival angle estimation device. The microwave signal received by the receiving antenna A1 is modulated onto the light wave emitted by the first laser light source via the first electro-optical conversion unit; the microwave signal received by the receiving antenna A2 is modulated onto the light wave emitted by the second laser light source via the second electro-optical conversion unit; the microwave signal received by the receiving antenna A0 is modulated onto the light wave emitted by the third laser light source via the third electro-optical conversion unit.

[0058] The optical microwave signal output by the first electro-optical conversion unit is transmitted to the first optical domain adjustable delay unit; the optical microwave signal output by the second electro-optical conversion unit is transmitted to the second optical domain adjustable delay unit; the optical microwave signal output by the third electro-optical conversion unit is transmitted to the optical domain fixed delay unit, and the delay amount T of the optical domain fixed delay unit is D =250ps;

[0059] The optical microwave signal output by the first optical domain delay matching channel and the optical microwave signal output by the optical domain reference delay channel enter the upper and lower optical input ports of the first balanced detection unit respectively, and undergo photoelectric conversion and differential combination in the balanced detection unit; the optical microwave signal output by the second optical domain delay matching channel and the optical microwave signal output by the optical domain reference delay channel are output to the lower and upper optical input ports of the second balanced detection unit, and undergo photoelectric conversion and differential combination in the balanced detection unit.

[0060] The RF power monitoring unit in the feedback control and analysis module monitors the signal power output by the first balanced detection unit and the second balanced detection unit, and outputs a control signal through the signal analysis and control unit to adjust the delay change of the first optical domain delay adjustment unit and the second optical domain delay adjustment unit respectively.

[0061] The first light domain adjustable delay unit performs delay time scanning search, and the delay search step is 3ps. The relationship between the output power of the first balanced detection unit corresponding to the delay scanning amount is as follows: Figure 3 As shown, from Figure 3 It can be seen that the delay change corresponding to the minimum output power value is τ1 = 474ps; the second optical domain adjustable delay unit performs delay time scanning search, the delay search step is 3ps, and the output power relationship of the second balanced detection unit corresponding to the delay scanning amount is as follows Figure 4 As shown, from Figure 4 It can be seen that the delay change corresponding to the minimum output power value is τ2 = 99ps. The delay changes τ1 and τ2 are related to the delay of the optical domain fixed delay unit T D The differences between them are Δτ1 = 224 ps and Δτ2 = -151 ps respectively. The incident angles α and β of the incoming signal in the x-axis and y-axis directions are calculated according to the following formulas (5) and (6):

[0062]

[0063] We get α = 63.6°, β = -37.2°. Figure 5 The positional relationship between the delay time differences Δτ1 and Δτ2 and the quadrant in which the incoming wave signal source is located can be used to determine that the incoming wave signal is located in the fourth quadrant.

[0064] Further, according to formulas (7) and (8), the elevation angle γ and azimuth angle θ of the incoming signal are calculated:

[0065]

[0066] The calculated pitch angle γ = 24.2°, which is 0.2° away from the actual pitch angle of the incoming wave, and the azimuth angle θ = -60.8°, which is 0.6° away from the actual azimuth angle of the incoming wave. Based on the pitch angle and azimuth angle, we can know the position of the incoming wave signal source in space. Figure 6 shown.

Claims

1. A photonics large bandwidth two-dimensional arrival angle estimation device, characterized in that: The photonics large-bandwidth two-dimensional arrival angle estimation device comprises a receiving antenna A1, a receiving antenna A2, a receiving antenna A0, a first light domain delay matching channel, a second light domain delay matching channel, a reference light domain delay channel, an optical splitter, a first balanced photoelectric detection unit, a second balanced photoelectric detection unit, and a feedback control module; The receiving antenna A1 is an adjacent array element of the receiving antenna A0 in the horizontal direction, and the receiving antenna A2 is an adjacent array element of the receiving antenna A0 in the vertical direction; The first optical domain delay matching channel comprises a first laser light source, a first electro-optical conversion unit, and a first optical domain adjustable delay unit, which are connected in sequence by optical fibers or optical waveguides; The second optical domain delay matching channel comprises a second laser light source, a second electro-optical conversion unit, and a second optical domain adjustable delay unit, which are sequentially connected by optical fibers or optical waveguides; The optical domain reference delay channel includes a third laser light source, a third electro-optical conversion unit, and an optical domain fixed delay unit, which are connected in sequence by optical fibers or optical waveguides; the delay time of the fixed delay unit is greater than the maximum time difference generated by the intervals between adjacent antenna array elements; The receiving antenna A1 and the first electro-optical conversion unit are connected in sequence through a cable or a microstrip line; the receiving antenna A2 and the second electro-optical conversion unit are connected in sequence through a cable or a microstrip line; the receiving antenna A0 and the third electro-optical conversion unit are connected in sequence through a cable or a microstrip line; The optical splitter includes an input port and two output ports, and has the function of dividing the output of the optical domain reference delay channel into two paths; the input port of the optical splitter is connected to the output port of the optical domain reference delay channel; the two output ports of the optical splitter are respectively transmitted to the lower port of the first balanced photoelectric detection unit and the upper port of the second balanced photoelectric detection unit; The first optical domain delay matching channel is connected to the upper port of the first balanced detection unit; the second optical domain delay matching channel is connected to the lower port of the second balanced detection unit; The feedback control module includes a radio frequency power monitoring unit and a signal analysis and control unit; The first balanced detection unit has the function of performing photoelectric conversion on the optical microwave signals output by the first optical domain adjustable delay channel and the optical domain reference delay channel to output electrical signals and subtracting them; the electrical signals output by the first balanced detection unit are transmitted to the RF power monitoring unit in the feedback control module; The second balanced detection unit has the function of performing photoelectric conversion on the optical microwave signals output by the second optical domain adjustable delay channel and the optical domain reference delay channel, outputting electrical signals and subtracting them; the electrical signals of the second balanced detection unit are transmitted to the RF power monitoring unit in the feedback control module; The first balance detection unit, the second balance detection unit and the feedback control analysis module are connected via cables or microstrip lines; The feedback control module outputs a control signal of the delay change amount, which is transmitted to the first light domain adjustable delay unit and the second light domain adjustable delay unit respectively, forming a feedback control loop.

2. The method for realizing two-dimensional angle of arrival estimation by the photonic large bandwidth two-dimensional angle of arrival estimation device according to claim 1 is characterized in that Here are the steps: In the first step, the microwave signal received by the receiving antenna A1 is modulated onto the optical carrier emitted by the first laser light source via the first electro-optical conversion unit; the microwave signal received by the receiving antenna A2 is modulated onto the optical carrier emitted by the second laser light source via the second electro-optical conversion unit; the microwave signal received by the receiving antenna A0 is modulated onto the optical carrier emitted by the third laser light source via the third electro-optical conversion unit; In the second step, the optical microwave signal output by the first electro-optical conversion unit is transmitted to the first optical domain adjustable delay unit; the optical microwave signal output by the second electro-optical conversion unit is transmitted to the second optical domain adjustable delay unit; The optical microwave signal output by the third electro-optical conversion unit is transmitted to the optical domain fixed delay unit; The optical microwave signal output by the first optical domain delay matching channel and the optical microwave signal output by the optical domain reference delay channel enter the upper and lower optical input ports of the first balanced detection unit respectively, and undergo photoelectric conversion and differential combination in the balanced detection unit; The optical microwave signal output by the second optical domain delay matching channel and the optical microwave signal output by the optical domain reference delay channel are output to the lower and upper optical input ports of the second balanced detection unit, and are subjected to photoelectric conversion and differential combination in the balanced detection unit; In the third step, the RF power monitoring unit in the feedback control module monitors the signal power output by the first balance detection unit and the second balance detection unit, and outputs a control signal through the signal analysis and control unit to adjust the delay change of the first light domain delay adjustment unit and the second light domain delay adjustment unit respectively; In the fourth step, the first optical domain adjustable delay unit scans the delay time of the optical microwave signal output by the first electro-optical conversion unit, and searches for the delay change τ1 corresponding to the minimum output power of the first balanced detection unit; the second optical domain adjustable delay unit scans the delay time of the optical microwave signal output by the second electro-optical conversion unit, and searches for the delay change τ2 corresponding to the minimum output power of the second balanced detection unit; Step 5: The delay change τ1 of the first light domain delay adjustable unit, the delay change τ2 of the second light domain delay adjustable unit, and the delay T of the light domain fixed delay unit are calculated. D The difference is Where α and β are the incident angles of the incoming wave signal in the x-axis direction and the y-axis direction respectively; according to formulas (1) and (2), the incident angles α and β are calculated from the values ​​of Δτ1 and Δτ2; the incident angles α and β and the elevation angle γ and azimuth angle θ of the incoming wave signal satisfy the relationship of formulas (3) and (4): The signal analysis and control unit in the feedback control module outputs a control signal of the delay change to the first light domain adjustable delay unit and the second light domain adjustable delay unit respectively according to the RF power value output by the RF power monitoring unit and the control algorithm; the system calculates the incident angles α and β by formulas (1) and (2) according to the delay change τ1 of the first light domain adjustable delay unit and the delay change τ2 of the second light domain adjustable delay unit corresponding to the minimum RF power value, and further calculates the pitch angle γ and azimuth angle θ of the incoming wave signal by formulas (3) and (4).

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