Photon device and method for simultaneously measuring Doppler frequency shift and angle of arrival

Abstract

The present invention discloses a photon device and method for simultaneously measuring Doppler frequency shift and angle of arrival, belonging to the technical field of microwave photon-assisted radar. The device is configured such that after the transmitted signal and the reference signal are combined, they enter a first dual-parallel Mach-Zehnder modulator operating in the carrier-suppressed single-sideband modulation mode to generate two positive first-order sideband signals. The two positive first-order sideband signals then enter a second dual-parallel Mach-Zehnder modulator and are modulated by the echo signal. The modulated signal output from the second dual-parallel Mach-Zehnder modulator enters a photodetector for photoelectric conversion to generate a down-converted signal. An electrical spectrum analyzer is used to compare the frequency of the down-converted signal and the reference signal to obtain the magnitude and direction of the Doppler frequency shift; monitoring the power of the frequency-converted signal can obtain the angle of arrival of the target. In the present invention, only a photodetector with a bandwidth lower than the transmitted signal frequency is used to complete the measurement of the Doppler frequency shift and the angle of arrival, reducing the requirements for the bandwidth of the photodetector.

Description

Technical Field

[0001] The present invention belongs to the field of microwave photonics technology, and particularly relates to a photon device and method for simultaneously measuring Doppler frequency shift and angle of arrival. Background Art

[0002] Measuring the Doppler frequency shift (hereinafter also simply referred to as DFS) and angle of arrival (hereinafter also simply referred to as AOA) of microwave signals can be used to determine the radial velocity and position of a target, and is widely used in radar, electronic warfare, and wireless communication systems. However, traditional electronic solutions are limited in terms of bandwidth, electromagnetic interference, and size. Fortunately, microwave photonics technology has the advantages of ultra-wideband, electromagnetic interference resistance, small size, and light weight, providing a feasible way to overcome the bottlenecks faced by electronic methods.

[0003] In recent years, photon schemes for simultaneously measuring DFS and AOA have been proposed. X. Cao et al. realized the measurement of DFS and AOA based on a two-channel photon mixer. DFS and AOA are obtained by measuring the frequency and phase difference of intermediate frequency signals from two paths. However, it is impossible to measure the angle where the direction of the echo signal is close to the normal direction of the receiving antenna. G. Li et al. used a polarization division multiplexing dual-drive Mach-Zehnder modulator to construct a two-channel microwave photon mixer to expand the detection range of AOA. C. Huang et al. proposed a scheme using a dual-parallel dual-drive Mach-Zehnder modulator and an optical filter. The optical filter is used to select the desired optical sideband signal, thereby realizing the measurement of DFS and AOA. The use of the optical filter limits the measurement bandwidth of the system.

[0004] X. Li et al. used two Mach-Zehnder modulators to divide the optical signal into two independent arms. DFS is obtained from the intermediate frequency signal. The AOA information is obtained by analyzing the phase information of the output waveforms between the two arms. However, the phase information of the two independent optical signals is easily affected by the external environment, and it is difficult to obtain a stable time-domain waveform, which poses a challenge to the subsequent waveform analysis. Summary of the Invention

[0005] The object of the present invention is to propose a photon device for simultaneously measuring Doppler frequency shift and angle of arrival in view of one of the above problems.

[0006] To achieve the above object, some embodiments of the present invention propose a photon device for simultaneously measuring Doppler frequency shift and angle of arrival, which includes a semiconductor laser, a first dual-parallel Mach-Zehnder modulator, a second dual-parallel Mach-Zehnder modulator, a first electrical coupler, a second electrical coupler, a 90° electrical coupler, an erbium-doped fiber amplifier, a photodetector and a signal analysis unit; the output end of the semiconductor laser is connected to the optical input port of the first dual-parallel Mach-Zehnder modulator, and the semiconductor laser is configured to generate a continuous first optical carrier, and the first optical carrier enters the first dual-parallel Mach-Zehnder modulator; the transmitted signal is divided into two paths by the first electrical coupler, one path is fed to the transmitting antenna, and the other path is input to the second electrical coupler; the transmitted signal and the reference signal enter the 90° electrical coupler after being combined by the second electrical coupler, wherein both the transmitted signal and the reference signal are single-frequency microwave signals, and the frequency of the transmitted signal is higher than the frequency of the reference signal; the two signals output from the 90° electrical coupler are respectively loaded onto the two radio frequency ports of the first dual-parallel Mach-Zehnder modulator, and the first dual-parallel Mach-Zehnder modulator is configured to perform single-sideband suppression modulation on the first optical carrier by the transmitted signal and the reference signal to obtain two positive first-order sideband signals; the output end of the first dual-parallel Mach-Zehnder modulator is connected to the input end of the erbium-doped fiber amplifier, so that the two positive first-order sideband signals generated by the first dual-parallel Mach-Zehnder modulator enter the erbium-doped fiber amplifier for power amplification; the output end of the erbium-doped fiber amplifier is connected to the optical input port of the second dual-parallel Mach-Zehnder modulator, so that the two power-amplified positive first-order sideband signals enter the second dual-parallel Mach-Zehnder modulator as the second optical carrier and the third optical carrier respectively; after the first target echo and the second target echo of the transmitted signal from the transmitting antenna are received by the first receiving antenna and the second receiving antenna respectively, they are respectively loaded onto the two radio frequency ports of the second dual-parallel Mach-Zehnder modulator for modulating the second optical carrier and the third optical carrier respectively, and the two sub-modulators of the second dual-parallel Mach-Zehnder modulator operate at the quadrature point and the main modulator operates at the maximum point; the optical output end of the second dual-parallel Mach-Zehnder modulator is connected to the photodetector, so that the optical signal output by the second dual-parallel Mach-Zehnder modulator enters the photodetector for beat frequency to generate a down-converted electrical signal; the output end of the photodetector is connected to the signal analysis unit, and the signal analysis unit is configured to obtain the magnitude and direction of the Doppler frequency shift by analyzing the frequency of the down-converted electrical signal and the frequency of the reference signal; the angle of arrival is estimated by monitoring the power of the down-converted electrical signal.

[0007] In some embodiments, the signal analysis unit is an electrical spectrum analyzer, a vector signal analyzer, an oscilloscope with FFT or a network analyzer.

[0008] In some embodiments, the photodetector is a photodiode.

[0009] In some embodiments, the first dual-parallel Mach-Zehnder modulator and the second dual-parallel Mach-Zehnder modulator each include a Y-type optical splitter, a Y-type optical coupler, two sub-modulators, and a main modulator; wherein, the two sub-modulators are intensity modulators and the main modulator is an optical phase shifter.

[0010] In some embodiments, the frequency of the reference signal can be much lower than the frequency of the transmitted signal, so as to reduce the performance requirements of subsequent devices. For example, the frequency of the reference signal is 0 to 2 GHz, such as 1 GHz or less, while the frequency of the transmitted signal is 4 to 20 GHz. The photodetector is a photodiode, and the bandwidth of the photodiode is slightly larger than the frequency range of the reference signal, such as 0 to 2.2 GHz, and the frequency responsivity is, for example, 0.8 A / W.

[0011] In some embodiments, the signal analysis unit is configured to calculate the normalized power of the down-converted electrical signal, and obtain the Doppler shift, as well as the phase difference between the first echo signal and the second echo signal, from the normalized power and the down-converted electrical signal generated by the photodetector; and then calculate the angle of arrival .

[0012] Some other embodiments of the present application propose a method for simultaneously measuring Doppler frequency shift and angle of arrival, which is implemented based on any one of the above photon devices for simultaneously measuring Doppler frequency shift and angle of arrival. The method includes the steps of: causing a semiconductor laser to generate a continuous optical carrier and enter the first dual-parallel Mach-Zehnder modulator; combining the transmitted signal and the reference signal and then entering a 90° electrical coupler; loading the two signals output by the 90° electrical coupler onto two radio frequency ports of the first dual-parallel Mach-Zehnder modulator; the first dual-parallel Mach-Zehnder modulator uses carrier-suppressed single-sideband modulation to generate two positive first-order sideband signals, and the two positive first-order sideband signals are sent to an erbium-doped fiber amplifier for power amplification; the two amplified positive first-order sides enter the second dual-parallel Mach-Zehnder modulator as two optical carriers; respectively loading the first target echo and the second target echo received by the first receiving antenna and the second receiving antenna onto the second dual-parallel Mach-Zehnder modulator for modulating the two optical carriers, wherein the two sub-modulators of the second dual-parallel Mach-Zehnder modulator operate at the quadrature point and the main modulator operates at the maximum point; sending the optical signal output by the second dual-parallel Mach-Zehnder modulator into a photodetector for beat frequency to generate a down-converted electrical signal; using the electrical spectrum analyzer to analyze the frequency of the down-converted electrical signal and the frequency of the reference signal to obtain the magnitude and direction of the Doppler frequency shift; estimating the angle of arrival by monitoring the power of the down-converted electrical signal.

[0013] In the solution of the embodiment of the present application, by comparing the frequency of the low-frequency down-converted electrical signal output by a photodiode (also simply referred to as PD) and the reference signal frequency, the magnitude and direction of the DFS can be obtained. The role of the reference signal is to determine the direction of the DFS and realize the down-conversion of the echo signal. Monitoring the power of the down-converted electrical signal can obtain the target AOA information. Compared with the dual-channel measurement scheme using two PDs, in the single-channel measurement scheme proposed in the present application, only a single photodiode is required to complete the measurement of DFS and AOA, and the structure is simpler. In addition, the present application does not require optical filters and polarization control devices, thereby improving the measurement accuracy and stability of the system. Description of the Drawings

[0014] Figure 1 is a schematic diagram of a photon device for simultaneously measuring Doppler frequency shift and angle of arrival according to an embodiment of the present invention.

[0015] Figure 2 is a spectrogram of the output signal of the device, where the Doppler frequency shift DFS is +1 MHz.

[0016] Figure 3 is a spectrogram of the output signal of the device, where the Doppler frequency shift DFS is -1 MHz.

[0017] Figure 4 Schematic diagram of DFS and its error measured by the device according to the present application.

[0018] Figure 5 Schematic diagram of AOA and its error measured by the device according to the present application. Detailed implementation manners

[0019] To make the technical problems solved by the present invention, the technical solutions adopted and the achieved technical effects clearer, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0020] As Figure 1 shown, a photon device for simultaneously measuring Doppler frequency shift and angle of arrival proposed by an embodiment of the present invention includes a semiconductor laser 1, a first dual-parallel Mach-Zehnder modulator 2, a second dual-parallel Mach-Zehnder modulator 7, a first electrical coupler 3, a second electrical coupler 4, a 90° electrical coupler 5, an erbium-doped fiber amplifier 6, a photodiode 8, and an electrical spectrum analyzer 9.

[0021] Wherein, each of the dual-parallel Mach-Zehnder modulators includes a Y-type optical splitter, a Y-type optical coupler, two sub-modulators, and a main modulator; the two sub-modulators are intensity modulators, and the main modulator is an optical phase shifter. The first parallel Mach-Zehnder modulator 2 and the second parallel Mach-Zehnder modulator 7 each have an optical input port, two radio frequency input ports, an optical output port, and three DC bias ports.

[0022] The output end of the semiconductor laser 1 is connected to the optical input port 21 of the first dual-parallel Mach-Zehnder modulator 2; the transmitted signal TS is divided into two paths by the first electrical coupler 3, one path is fed to the transmitting antenna AT, and the other path is input to the input port of the second electrical coupler 4; the transmitted signal TS and the reference signal RS are combined by the second electrical coupler 4 and then enter the input end of the 90° electrical coupler 5; the two signals output from the 90° electrical coupler 5 are respectively loaded onto the two radio frequency input ports of the first dual-parallel Mach-Zehnder modulator 2; the optical output port 22 of the first dual-parallel Mach-Zehnder modulator 2 is connected to the input end 61 of the erbium-doped fiber amplifier 6; the output end 62 of the erbium-doped fiber amplifier 6 is connected to the optical input port 71 of the second dual-parallel Mach-Zehnder modulator 7; the first target echo ES1 received by the first receiving antenna AR1 and the second target echo ES2 received by the second receiving antenna AR2 spaced d from the first receiving antenna AR1 are respectively loaded onto the two radio frequency input ports of the second dual-parallel Mach-Zehnder modulator 7; the optical output port 72 of the second dual-parallel Mach-Zehnder modulator 7 is connected to the photodiode 8, and the output end of the photodiode 8 is connected to the electrical spectrum analyzer 9.

[0023] The transmitted signal TS and the reference signal RS are combined by a 90° electrical coupler 5 and then enter the first dual-parallel Mach-Zehnder modulator 2. The first dual-parallel Mach-Zehnder modulator 2 operates in the optical carrier suppression single-sideband modulation mode, and two positive first (+1) order sideband signals are generated by modulating the first optical carrier with the transmitted signal TS and the reference signal RS respectively. These two positive first order sideband signals are amplified in power by an erbium-doped fiber amplifier 6, that is, after power compensation, they enter the second dual-parallel Mach-Zehnder modulator 7, and are modulated by the first echo signal ES1 and the second echo signal ES2 respectively in the second dual-parallel Mach-Zehnder modulator 7. The two sub-modulators of the second dual-parallel Mach-Zehnder modulator 7 are biased at the quadrature point, while its main modulator is biased at the maximum point. The modulated optical field signal output by the second dual-parallel Mach-Zehnder modulator 7 enters a photodiode 8 for photoelectric conversion to generate a down-converted electrical signal. By comparing the frequency of the down-converted electrical signal and the reference signal RS, an electrical spectrum analyzer 9 can obtain the magnitude and direction of the Doppler frequency shift (DFS). Monitoring the power of the down-converted electrical signal can obtain the angle of arrival (AOA) information of the target.

[0024] The frequency of the reference signal in this application can be much lower than the frequency of the transmitted signal, so as to reduce the performance requirements of subsequent devices. For example, the frequency of the reference signal is 0~2 GHz, such as 1 GHz and below, while the frequency of the transmitted signal is 4~20 GHz. The bandwidth of the photodiode is slightly larger than the frequency range of the reference signal, such as 0~2.2 GHz, and the frequency responsivity is, for example, 0.8 A / W. In addition to the photodiode 8, other devices can also be selected as the photodetector.

[0025] The principle of the photon device for simultaneously measuring the Doppler frequency shift and the angle of arrival of the present invention is as follows:

[0026] The transmitted signal TS, the reference signal RS, the first echo signal ES1 and the second echo signal ES2 can be expressed as:

[0027] (1)

[0028] Where V t is the amplitude of the transmitted signal TS, f t is the frequency of the transmitted signal TS, V r is the amplitude of the reference signal RS, f r is the frequency of the reference signal RS, V e is the amplitude of the first echo signal ES1 and the second echo signal ES2, fe are the frequencies of the first echo signal ES1 and the second echo signal ES2, φ is the phase difference between the first echo signal ES1 and the second echo signal ES2; t represents any moment on the time axis of the signal, which is a continuous variable and is used to describe the instantaneous value of the signal at different time points.

[0029] The first optical carrier CW1 emitted by the semiconductor laser 1 enters the first dual-parallel Mach-Zehnder modulator 2; among them, after the transmitted signal TS and the reference signal RS are combined, they are injected into the first dual-parallel Mach-Zehnder modulator 2 through a 90° electrical coupler 5, and the output optical field of the first dual-parallel Mach-Zehnder modulator 2 is expressed as:

[0030] (2)

[0031] where E0 is the amplitude of the first optical carrier, f0 is the frequency of the first optical carrier, β t =π V t / 2 V π and β r =π V r / 2 V π are the modulation coefficients of the transmitted signal and the reference signal respectively. J n (.) is n the Bessel function of the first kind of order.

[0032] The two positive first-order sideband x signals generated by modulating the first optical carrier CW1 in the first dual-parallel Mach-Zehnder modulator 2 are power-compensated by an erbium-doped fiber amplifier 6 with a gain of G and enter the two sub-modulators of the second dual-parallel Mach-Zehnder modulator 7 as the second optical carrier CW2 and the third optical carrier CW3 respectively. The second optical carrier CW2 and the third optical carrier CW3 are modulated by the first echo signal ES1 and the second echo signal ES2 respectively. The two sub-modulators and the main modulator of the second dual-parallel Mach-Zehnder modulator 7 work at the orthogonality point and the maximum point respectively, and the output optical field of the second dual-parallel Mach-Zehnder modulator 7 is expressed as:

[0033] (3)

[0034] wherein β e =π V e / 2 V π is the modulation coefficient of the echo signal, G and is the gain of the erbium-doped fiber amplifier 6.

[0035] The down-converted electrical signal generated by the photodiode 8 is:

[0036] (4)

[0037] wherein, the Doppler frequency shift is ; R and is the responsivity of the photodiode.

[0038] The normalized power P of the down-converted electrical signal is obtained from formula (4) as

[0039] (5)

[0040] Therefore, the Doppler frequency shift and the phase difference between the first echo signal ES1 and the second echo signal ES2 are obtained from formulas (4) and (5), and then the angle of arrival (AOA) is calculated by combining with formula (6).

[0041] (6)

[0042] The electrical spectrum analyzer 9 is used as a signal analysis unit to obtain the Doppler frequency shift and the angle of arrival. By configuring the electrical spectrum analyzer 9 according to the above principle, the required Doppler frequency shift and angle of arrival can be obtained. It should be understood that in addition to the electrical spectrum analyzer 9, a vector signal analyzer, an oscilloscope with fast Fourier transform (FFT), or a network analyzer can also be used as the signal analysis unit to calculate the Doppler frequency shift and the angle of arrival .

[0043] In some embodiments, the first dual-parallel Mach-Zehnder modulator and the second dual-parallel Mach-Zehnder modulator each include a Y-type optical splitter, a Y-type optical coupler, two sub-modulators, and a main modulator; wherein, the two sub-modulators are intensity modulators and the main modulator is an optical phase shifter.

[0044] To verify that the present invention can simultaneously measure the Doppler frequency shift and the angle of arrival, the following is a description of the experimental verification.

[0045] In the experiment, the wavelength of the continuous optical carrier output by the semiconductor laser 1 was set to 1548.934 nm, and the power was 13 dBm. The transmitted signal, reference signal, first echo signal ES1, and second echo signal ES2 were generated by a signal source. The frequency of the transmitted signal was set to 18 GHz, and the power was 12 dBm; the frequency of the reference signal was 1 GHz, and the power was 10 dBm; the frequency of the first echo signal was set to 18.001 GHz, and the power was 10 dBm, and the frequency of the second echo signal was set to 17.999 GHz, and the power was 10 dBm. An electrical phase shifter was used to adjust the phase difference between the first echo signal ES1 and the second echo signal ES2.

[0046] Figure 2 The spectrum measured when the echo signal was set to 18.001 GHz was shown. It could be seen that the down-converted electrical signal was generated at 1.001 GHz, which was greater than the frequency of the reference signal, indicating that the DFS was +1 MHz. Similarly, when the echo signal became 17.999 GHz, as Figure 3 shown, the down-converted electrical signal was located at 0.999 GHz, which was lower than 1 GHz, indicating that the DFS was -1 MHz, and the spurious suppression ratio was still higher than 36 dB.

[0047] The DFS and error measured by the device at different frequencies were further studied. During the measurement, the resolution bandwidth of the electrical spectrum analyzer (ESA) 9 was set to 1 Hz, the video bandwidth was set to 1 Hz, and the span was set to 80 Hz. As Figure 4 shown, when the reference signal was set to 1 GHz, the measured DFS result was very close to the theoretical value. The DFS error measured by the device of the present invention fluctuated within a small range of ±0.1 Hz.

[0048] Figure 5 The experimental and theoretical results of the AOA were shown. It could be seen that the designed device achieved AOA measurement from 0° to 90°. The AOA measurement error of the device proposed by the present invention was within ±1.2°.

[0049] In the solution proposed in the embodiment of the present application, only a photodiode (PD) was required to complete the measurement of DFS and AOA, reducing the requirements for the PD bandwidth. At the same time, optical filters and polarization control devices were not required, improving the measurement stability of the system.

[0050] Some other embodiments of the present application further provide a method for simultaneously measuring Doppler frequency shift and angle of arrival, which is implemented based on the above-mentioned photon device for simultaneously measuring Doppler frequency shift and angle of arrival. The method includes the steps of: causing the continuous optical carrier generated by the semiconductor laser 1 to enter the first dual-parallel Mach-Zehnder modulator 2; combining the transmitted signal and the reference signal and then entering the 90° electrical coupler 5; respectively loading the two signals output by the 90° electrical coupler 5 onto the two radio frequency ports of the first dual-parallel Mach-Zehnder modulator 2; the first dual-parallel Mach-Zehnder modulator 2 uses carrier-suppressed single-sideband modulation to generate two positive first-order sideband signals; sending the two positive first-order sideband signals into the erbium-doped fiber amplifier 6 for power amplification; using the two amplified positive first-order sideband signals as two optical carriers and respectively sending them into the second dual-parallel Mach-Zehnder modulator 7; respectively loading the target echoes received by the two receiving antennas onto the second dual-parallel Mach-Zehnder modulator 7 for modulating the two optical carriers; the two sub-modulators of the second dual-parallel Mach-Zehnder modulator 7 operate at the quadrature point, and the main modulator operates at the maximum point; sending the optical signal output by the second dual-parallel Mach-Zehnder modulator 7 into the photodiode 8 for beat frequency to generate a down-converted electrical signal; using an electrical spectrum analyzer 9 to analyze the frequency of the down-converted electrical signal and the frequency of the reference signal to obtain the magnitude and direction of the Doppler frequency shift; estimating the angle of arrival by monitoring the power of the down-converted electrical signal.

[0051] In summary, the present invention proposes a photon device and method for simultaneously measuring DFS and AOA. In this solution, only a low-frequency PD of 1 GHz is required to complete the measurement of DFS and AOA, reducing the requirement for the PD bandwidth. At the same time, optical filters and polarization control devices are not required, improving the measurement stability of the system. The designed measurement scheme is expected to be applied in fields such as radar and electronic warfare.

[0052] As described above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope described in the present invention, according to the technical solution of the present invention and its inventive concept, makes an equivalent replacement or change, and should be covered by the protection scope of the present invention.

Claims

1. A photon device for simultaneously measuring Doppler shift and angle of arrival, characterized in that: It includes a semiconductor laser, a first double parallel Mach-Zehnder modulator, a second double parallel Mach-Zehnder modulator, a first electric coupler, a second electric coupler, a 90° electric coupler, an erbium-doped fiber amplifier, a photodetector and a signal analysis unit; The output end of the semiconductor laser is connected to the optical input port of the first dual parallel Mach-Zehnder modulator, and the semiconductor laser is configured to generate a continuous first optical carrier, and the first optical carrier enters the first dual parallel Mach-Zehnder modulator; The transmitting signal is divided into two paths through the first electrical coupler, one path is fed to the transmitting antenna, and the other path is input to the second electrical coupler; the transmitting signal and the reference signal are combined through the second electrical coupler and enter the 90° electrical coupler, wherein the transmitting signal and the reference signal are both single-frequency microwave signals, and the frequency of the reference signal is lower than the frequency of the transmitting signal; the two signals output from the 90° electrical coupler are respectively loaded to the two RF ports of the first dual parallel Mach-Zehnder modulator, and the first dual parallel Mach-Zehnder modulator is configured to suppress single sideband modulation of the first optical carrier by the transmitting signal and the reference signal to obtain two positive first-order sideband signals; The output end of the first dual parallel Mach-Zehnder modulator is connected to the input end of the erbium-doped fiber amplifier, and the erbium-doped fiber amplifier is configured to power amplify the two positive first-order sideband signals generated by the first dual parallel Mach-Zehnder modulator; The output end of the erbium-doped fiber amplifier is connected to the optical input port of the second dual-parallel Mach-Zehnder modulator, so that the two positive first-order sideband signals after power amplification enter the second dual-parallel Mach-Zehnder modulator as the second optical carrier and the third optical carrier respectively; The first receiving antenna and the second receiving antenna are configured to receive the first target echo and the second target echo of the transmission signal from the transmitting antenna respectively, and then load them to the two radio frequency ports of the second dual parallel Mach-Zehnder modulator respectively for modulating the second optical carrier and the third optical carrier respectively, wherein the two sub-modulators of the second dual parallel Mach-Zehnder modulator operate at the orthogonal point, and the main modulator operates at the maximum point; The optical output end of the second dual parallel Mach-Zehnder modulator is connected to a photodetector, and the photodetector is configured to perform a beat frequency operation on the optical signal output by the second dual parallel Mach-Zehnder modulator to generate a down-converted electrical signal; The output end of the photodetector is connected to the signal analysis unit, and the signal analysis unit is configured to obtain the magnitude and direction of the Doppler frequency shift by analyzing the frequency of the down-converted electrical signal and the frequency of the reference signal; and estimate the arrival angle by monitoring the power of the down-converted electrical signal.

2. The photon device for simultaneously measuring Doppler shift and arrival angle according to claim 1, characterized in that: The signal analysis unit is an electric spectrum analyzer, a vector signal analyzer, an oscilloscope with FFT or a network analyzer.

3. The photon device for simultaneously measuring Doppler shift and arrival angle according to claim 1, characterized in that: The photodetector is a photodiode.

4. The photon device for simultaneously measuring Doppler shift and arrival angle according to claim 1, characterized in that: The first dual parallel Mach-Zehnder modulator and the second dual parallel Mach-Zehnder modulator respectively include a Y-type optical beam splitter, a Y-type optical coupler, two sub-modulators and a main modulator; wherein the two sub-modulators are intensity modulators and the main modulator is an optical phase shifter.

5. The photon device for simultaneously measuring Doppler shift and arrival angle according to claim 4, characterized in that: The frequency of the reference signal is 0-2 GHz, and the frequency of the transmission signal is 4-20 GHz.

6. The photon device for simultaneously measuring Doppler frequency shift and arrival angle according to claim 4, characterized in that: The photodetector is a photodiode, and the bandwidth of the photodiode is 0-2.2 GHz.

7. The photon device for simultaneously measuring Doppler frequency shift and arrival angle according to claim 6, characterized in that: The signal analysis unit is configured to The normalized power P of the down-converted electrical signal is calculated, and the Doppler frequency shift and the phase difference between the first echo signal and the second echo signal are obtained from the normalized power P and the down-converted electrical signal generated by the photodiode; wherein the down-converted electrical signal i is expressed as: ； in, , the Doppler shift is ，R is the photodiode responsivity; in, is the output light field of the second dual parallel Mach-Zehnder modulator, expressed as: ； in β e =π V e / 2 V π is the modulation coefficient of the first echo signal and the second echo signal, G is the gain of the erbium-doped fiber amplifier; V π yes The voltage required to cause a phase difference of π; E0 is the amplitude of the first optical carrier, f0 is the frequency of the first optical carrier, β t =π V t / 2 V π and β r =π V r / 2 V π are the modulation coefficients of the transmit signal and the reference signal respectively; J n (.)yes n Bessel function of the first kind; Among them, the transmission signal Number TS, reference signal RS, first echo signal ES1 and second echo signal ES2 surface Shown as: ； in V t is the amplitude of the transmit signal TS, f t is the frequency of the transmitted signal TS, V r is the amplitude of the reference signal RS, f r is the frequency of the reference signal RS, V e is the amplitude of the first echo signal ES1 and the second echo signal ES2, f e is the frequency of the first echo signal ES1 and the second echo signal ES2, φ is the phase difference between the first echo signal ES1 and the second echo signal ES2; t represents any time; According to The angle of arrival is calculated.

8. A photon method for simultaneously measuring Doppler frequency shift and arrival angle, using the photon device for simultaneously measuring Doppler frequency shift and arrival angle according to any one of claims 1 to 7, characterized in that: The method comprises the steps of: The semiconductor laser generates a continuous optical carrier and enters the first dual parallel Mach-Zehnder modulator; the transmission signal and the reference signal are combined and enter the 90° electrical coupler; the two signals output by the 90° electrical coupler are respectively loaded into the two radio frequency ports of the first dual parallel Mach-Zehnder modulator; the first dual parallel Mach-Zehnder modulator uses carrier suppressed single sideband modulation to generate two positive first-order sideband signals, and the two positive first-order sideband signals are sent to the erbium-doped fiber amplifier for power amplification; the two amplified positive first-order sides enter the second dual parallel Mach-Zehnder modulator as two optical carriers; the first receiving antenna The first target echo and the second target echo received by the second receiving antenna are respectively loaded into the second dual parallel Mach-Zehnder modulator for modulating the two optical carriers, wherein the two sub-modulators of the second dual parallel Mach-Zehnder modulator operate at the orthogonal point, and the main modulator operates at the maximum point; the optical signal output by the second dual parallel Mach-Zehnder modulator is sent to the photodetector for beat frequency to generate a down-converted electrical signal; the signal analysis unit is used to analyze the frequency of the down-converted electrical signal and the frequency of the reference signal to obtain the size and direction of the Doppler frequency shift; and the arrival angle is estimated by monitoring the power of the down-converted electrical signal.

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