A single-channel direction-finding system based on optical single-sideband modulation and its implementation method

Abstract

The present invention discloses a single-channel direction-finding system based on optical single-sideband modulation and an implementation method, belonging to the field of radio frequency signal processing technology. The system solves the problem that existing single-channel direction-finding technology cannot achieve broadband, high-probability, and real-time direction-finding in electronic reconnaissance equipment when the received radio frequency signal has frequency hopping, short duration, and uncertain arrival and end times. The system includes N antennas for receiving N radio frequency signals, a multi-channel electro-optical conversion unit connected to the N antennas, a reference signal generating unit and an optoelectronic synthesis conversion unit connected to the multi-channel electro-optical conversion unit, and a signal processing unit connected to the optoelectronic synthesis conversion unit. The present invention can achieve high-probability interception and accurate direction-finding of radio frequency signals in a large instantaneous frequency range, and has obvious advantages in terms of performance level and implementation architecture.

Description

Technical Field

[0001] The present invention belongs to the technical field of radio frequency signal processing, and in particular relates to a single-channel direction-finding system based on optical single-sideband modulation and an implementation method thereof. Background Art

[0002] Electronic reconnaissance equipment must analyze and identify the characteristics of radiation sources by receiving and processing radio frequency signals from space, thereby obtaining an accurate picture of the electromagnetic spectrum. Since radiation sources such as radar and communications are non-cooperative, signal parameters such as frequency, amplitude, phase, pulse width, and repetition period have the ability to change more flexibly within a wide instantaneous frequency range, posing a significant challenge to signal processing in electronic reconnaissance equipment. In complex electromagnetic environments, in addition to the basic signal parameters mentioned above, signal direction is a key parameter for effectively sorting and identifying radiation sources. Traditional direction-finding systems use multi-channel receivers to compare and calculate the amplitude or phase of radiation source signals received by multiple antennas to determine the signal direction.

[0003] Multi-antenna single-channel direction finding technology has been proposed and applied in the field of radio monitoring. High-speed RF switches with a response time of tens of nanoseconds are used to switch multiple antennas at different time points according to a certain periodic timing sequence, generating a single RF pulse signal that is serially output in the time domain. Each RF pulse signal is processed through a single receiving channel to determine the signal direction. Alternatively, single-channel direction finding can be achieved using optoelectronic hybrid processing technology. The RF signals received simultaneously by multiple antennas are modulated onto lasers of different wavelengths. The resulting modulated optical signal is chopped using a high-speed optical switch to generate modulated optical pulses of a fixed duration. By delaying and performing optoelectronic conversion on the modulated optical pulses of different wavelengths in the time domain, a train of completely staggered RF pulses is generated. Finally, each RF pulse signal is processed to achieve single-channel direction finding (see patent CN 116381597B, "A Broadband Single-Channel Direction Finding System and Implementation Method"). The essence of both of these methods is to achieve direction finding through time switching and time-sharing processing of multi-channel RF signals.

[0004] Current single-channel direction-finding systems require switching a set of fixed-duration pulses from the RF signals received by multiple antennas. When the signal frequency is fixed and the duration is long (hundreds to several milliseconds), polling and switching across multiple antennas does not cause signal loss. However, when the received RF signal exhibits frequency hopping, short duration, or uncertain arrival and end times, existing single-channel direction-finding technology cannot achieve broadband, high-probability, and real-time direction finding in electronic reconnaissance equipment, severely impacting accurate target acquisition and reconnaissance.

[0005] Therefore, the present invention provides a single-channel direction finding system based on optical single-sideband modulation and an implementation method thereof, so as to at least solve some of the above technical problems. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a single-channel direction finding system based on optical single-sideband modulation and an implementation method thereof, so as to at least solve some of the above technical problems.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A single-channel direction-finding system based on optical single-sideband modulation includes N antennas respectively used for receiving N radio frequency signals, a multi-channel electro-optical conversion unit connected to the N antennas, a reference signal generating unit and a photoelectric synthesis conversion unit connected to the multi-channel electro-optical conversion unit, and a signal processing unit connected to the photoelectric synthesis conversion unit.

[0009] Furthermore, the multi-channel electro-optical conversion unit includes a main single-sideband electro-optical conversion module, N-1 slave single-sideband electro-optical conversion modules connected to the main single-sideband electro-optical conversion module, and 1 N optical couplers; the reference signal generating unit is connected to N-1 slave single sideband electro-optical conversion modules respectively; the master single sideband electro-optical conversion module is connected to an antenna, and N-1 slave single sideband electro-optical conversion modules are connected to N-1 antennas respectively; the photoelectric synthesis conversion unit is connected to the master single sideband electro-optical conversion module and 1 N optocoupler connection.

[0010] Furthermore, the main single-sideband electro-optical conversion module includes a laser 1, a 1 connected to the laser 1 (N+1) optocoupler, and 1 (N+1) optical couplers connected to the dual parallel optical modulator 1, the orthogonal coupler 1 connected to the dual parallel optical modulator 1, the orthogonal coupler 1 is connected to an antenna, the dual parallel optical modulator 1 is connected to 1 N optocoupler connection, 1 The (N+1) optical couplers are respectively connected to the N-1 slave single-sideband electro-optical conversion modules and the photoelectric synthesis conversion units.

[0011] Furthermore, a single single sideband electro-optical conversion module includes lasers n+1, 1 2 Optocoupler A n 、1 2 Optocoupler B n , dual parallel optical modulator n+1, orthogonal coupler n+1, photodetector n, frequency divider n, phase detector n and low-pass filter n, where n is any number from 1, 2, 3, ..., N-1; laser n+1 connected to 1 2 Optocoupler A n , 1 2 Optocoupler A n Connect 1 in sequence 2 Optocoupler B n , photodetector n, frequency divider n, phase detector n, low-pass filter n and laser n+1,1 2 Optocoupler B n Connection 1 (N+1) optocoupler, 1 2 Optocoupler A n Connect the dual parallel optical modulator n+1, the orthogonal coupler n+1 connects the dual parallel optical modulator n+1, the orthogonal coupler n+1 is connected to 1 antenna, the dual parallel optical modulator n+1 is connected to 1 N optocoupler connection.

[0012] Furthermore, the reference signal generating unit includes a frequency source, a 1 connected to the frequency source (N-1) RF power splitter, 1 The (N-1) radio frequency power divider is connected to the phase detector n.

[0013] Furthermore, the photoelectric synthesis conversion unit includes 1 2 Optocoupler C, and 1 2 Optocoupler C connected to photodetector N, 1 2 optocouplers C and 1 (N+1) optocouplers and 1 N optical couplers are connected, and the photodetector N is connected to the signal processing unit.

[0014] Furthermore, the signal processing unit includes an analog-to-digital converter and a digital signal processor connected to the analog-to-digital converter, and the analog-to-digital converter is connected to the photodetector N.

[0015] A method for implementing a single-channel direction-finding system based on optical single-sideband modulation, characterized by comprising the following steps:

[0016] Step S1, N frequencies are all f RF The RF signal is received one-to-one by N antennas;

[0017] Step S2: The N radio frequency signals received by the N antennas are input into the multi-channel electro-optical conversion unit; the frequency source outputs a fixed frequency f REF RF signal, fixed frequency f REF The RF signal passes through 1 (N-1) RF power divider, N-1 frequencies are obtained, all of which are f REF Reference signal; N-1 reference signals are input into the multi-channel electro-optical conversion unit;

[0018] Step S3, N frequencies are all f RFThe RF signal and N-1 frequencies are all f REF The reference signal is processed by a multi-channel electro-optical conversion unit to obtain the local oscillator light 1 and the synthetic modulated optical signal;

[0019] Step S4: The local oscillator light 1 and the synthesized modulated optical signal are input into the optoelectronic synthesis conversion unit to obtain a frequency-shifted radio frequency signal sequence, where the frequency-shifted radio frequency signal sequence includes N frequency-shifted radio frequency signals.

[0020] Step S5: N frequency-shifted radio frequency signals are simultaneously input into a signal processing unit to obtain the direction of the incident signal.

[0021] Furthermore, step S3 includes:

[0022] Step S31: The laser input 1 emitted by the laser 1 The (N+1) optical coupler generates one local oscillator light 1, N-1 local oscillator lights n, and direct current light 1. RF signal 1 passes through quadrature coupler 1 to output in-phase RF signal 1 and quadrature RF signal 1. The in-phase RF signal 1 and the quadrature RF signal 1 are input into dual parallel optical modulator 1 from two RF input terminals, and the direct current light 1 is input into dual parallel optical modulator 1 to generate a single-sideband modulated optical signal 1 with suppressed carrier.

[0023] Step S32: For the nth single-sideband electro-optical conversion module, the laser input 1 emitted by the laser n+1 2 Optocoupler A n , output 1 branch light n+1 and 1 DC light n+1, branch light n+1 input 1 2 Optocoupler B n , DC light n+1 inputs dual parallel optical modulator n+1;

[0024] Step S33: The RF signal n+1 is output through the orthogonal coupler n+1 as an in-phase RF signal n+1 and an orthogonal RF signal n+1; the in-phase RF signal n+1 and the orthogonal RF signal n+1 are input from two RF input terminals to the dual parallel optical modulator n+1; the DC light n+1 is input into the dual parallel optical modulator n+1 to obtain a carrier-suppressed single-sideband modulated optical signal n+1; the branched light n+1 and the local oscillator light n+1 are input into 1 2 Optocoupler B n , the output combined light n enters the photodetector n, and the photodetector n outputs the beat signal n, where the frequency of the beat signal n is f b_n ;

[0025] Step S34: The beat signal n passes through the frequency divider n to obtain the frequency f b_n / m frequency division signal n, where m is the division ratio, where m=1, 2, 3, ..., N-1; the frequency division signal n and the reference signal n are input to phase detector n to obtain error signal n, which is then passed through low-pass filter n to obtain feedback signal n; the feedback signal n is input to laser n+1, and the wavelength of laser n+1 is adjusted to make the frequency of frequency division signal n equal to the frequency of the reference signal;

[0026] Step S35: Input 1 channel single sideband modulated optical signal 1 and N-1 channel single sideband modulated optical signal n+1 to 1 channel. N optical couplers are used to obtain a synthetic modulated optical signal.

[0027] Furthermore, in the dual parallel optical modulator, the DC bias points of the two intensity optical modulators are controlled at the minimum power point, and the phase offset of the phase optical modulator is 90 degrees; the output laser frequency of laser 1 is f0, and the output laser frequency of laser n+1 is f0+n f REF .

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] This invention proposes a single-channel direction-finding system and implementation method based on optical single-sideband modulation. This system single-sideband modulates radio frequency signals received by multiple antennas onto a wavelength-locked multi-channel laser. Optical technology is then used to process these multiple single-sideband modulated optical signals. Photoelectric detection then simultaneously generates multiple frequency-shifted radio frequency signals. Finally, real-time, high-precision detection and processing of these multiple frequency-shifted radio frequency signals completes direction-finding of the incident signal. This method, which offers significant advantages in performance and implementation architecture, is capable of high-probability interception and precise direction-finding of radio frequency signals over a wide instantaneous frequency range. It possesses significant application value for high-precision directional measurement of broadband signals in electronic reconnaissance equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a system structure diagram of the present invention.

[0031] Figure 2 This is a structural block diagram of the multi-channel electro-optical conversion unit of the present invention.

[0032] Figure 3 This is a structural block diagram of the main single-sideband electro-optical conversion module of the present invention.

[0033] Figure 4 This is a structural block diagram of the single-sideband electro-optical conversion module of the present invention.

[0034] Figure 5 This is a structural block diagram of the reference signal generating unit of the present invention.

[0035] Figure 6Schematic diagram of the frequency distribution of the synthetic modulated optical signal of the present invention.

[0036] Figure 7 This is a structural block diagram of the photoelectric synthesis conversion unit of the present invention.

[0037] Figure 8 Schematic diagram of the frequency distribution of the frequency-shifted radio frequency signal of the present invention.

[0038] Figure 9 This is a structural block diagram of the signal processing unit of the present invention. DETAILED DESCRIPTION

[0039] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] In the description of the present invention, it should be noted that the terms “first” and “second” are only used for descriptive purposes and should not be understood as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; of course, they may also refer to mechanical connections or electrical connections; in addition, they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0042] Example 1, as Figure 1 As shown, a single-channel direction-finding system based on optical single-sideband modulation includes N antennas for receiving N radio frequency signals, a multi-channel electro-optical conversion unit connected to the N antennas, a reference signal generating unit and an optoelectronic synthesis conversion unit connected to the multi-channel electro-optical conversion unit, and a signal processing unit connected to the optoelectronic synthesis conversion unit.

[0043] The N RF signals received by the N antennas are input into the multi-channel electro-optical conversion unit for processing. The multi-channel electro-optical conversion unit outputs one local oscillator light 1 and one composite modulated optical signal. After passing through the optoelectronic synthesis conversion unit, the local oscillator light 1 and the composite modulated optical signal are converted into a frequency-shifted RF signal sequence. The signal processing unit processes this frequency-shifted RF signal sequence and simultaneously obtains the frequencies and phases of the N frequency-shifted RF signals, thereby calculating the direction of the incident signal.

[0044] Embodiment 2, a single-channel direction-finding system based on optical single-sideband modulation, includes N antennas for receiving N radio frequency signals respectively, a multi-channel electro-optical conversion unit connected to the N antennas, a reference signal generating unit and an optoelectronic synthesis conversion unit connected to the multi-channel electro-optical conversion unit, and a signal processing unit connected to the optoelectronic synthesis conversion unit.

[0045] like Figure 2 As shown, the multi-channel electro-optical conversion unit includes a main single-sideband electro-optical conversion module, N-1 slave single-sideband electro-optical conversion modules connected to the main single-sideband electro-optical conversion module, and 1 N optical couplers; the reference signal generating unit is connected to N-1 slave single sideband electro-optical conversion modules respectively; the master single sideband electro-optical conversion module is connected to an antenna, and N-1 slave single sideband electro-optical conversion modules are connected to N-1 antennas respectively; the photoelectric synthesis conversion unit is connected to the master single sideband electro-optical conversion module and 1 N optocoupler connection.

[0046] N RF signals are respectively input into the main single-sideband electro-optical conversion module and N-1 slave single-sideband electro-optical conversion modules. The main single-sideband electro-optical conversion module outputs N local oscillator lights and 1 single-sideband modulated optical signal 1; 1 local oscillator light 1 is directly output, and N-1 local oscillator lights are respectively input into N-1 slave single-sideband electro-optical conversion modules; the reference signal generating unit generates N-1 reference signals, and the N-1 reference signals are respectively input into N-1 slave single-sideband electro-optical conversion modules for processing. The N-1 slave single-sideband electro-optical conversion modules output N-1 single-sideband modulated optical signals; the N single-sideband modulated optical signals enter 1 N optical couplers are used to obtain one channel of synthesized modulated optical signal.

[0047] Example 3, a single-channel direction-finding system based on optical single-sideband modulation, including N antennas for receiving N radio frequency signals respectively, a multi-channel electro-optical conversion unit connected to the N antennas, a reference signal generating unit and an optoelectronic synthesis conversion unit connected to the multi-channel electro-optical conversion unit, and a signal processing unit connected to the optoelectronic synthesis conversion unit.

[0048] The multi-channel electro-optical conversion unit includes a main single-sideband electro-optical conversion module, N-1 slave single-sideband electro-optical conversion modules connected to the main single-sideband electro-optical conversion module, and 1 N optical couplers; the reference signal generating unit is connected to N-1 slave single sideband electro-optical conversion modules respectively; the master single sideband electro-optical conversion module is connected to an antenna, and N-1 slave single sideband electro-optical conversion modules are connected to N-1 antennas respectively; the photoelectric synthesis conversion unit is connected to the master single sideband electro-optical conversion module and 1 N optocoupler connection.

[0049] like Figure 3 As shown, the main single-sideband electro-optical conversion module includes a laser 1, a 1 connected to the laser 1 (N+1) optocoupler, and 1 (N+1) optical couplers connected to the dual parallel optical modulator 1, the orthogonal coupler 1 connected to the dual parallel optical modulator 1, the orthogonal coupler 1 is connected to an antenna, the dual parallel optical modulator 1 is connected to 1 N optocoupler connection, 1 The (N+1) optical couplers are respectively connected to the N-1 slave single-sideband electro-optical conversion modules and the photoelectric synthesis conversion units.

[0050] Laser input 1 emitted by laser 1 (N+1) optocoupler, 1 The (N+1) optical coupler outputs N local oscillator lights and one direct current light 1, where the N local oscillator lights include one local oscillator light 1 and N-1 local oscillator lights n. An RF signal 1 received by an antenna passes through the orthogonal coupler 1, which outputs an in-phase RF signal 1 and a quadrature RF signal 1. The in-phase RF signal 1 and the quadrature RF signal 1 are input into a dual parallel optical modulator 1 from two RF input terminals, and the direct current light 1 is input into the dual parallel optical modulator 1 to obtain a single-sideband modulated optical signal 1 with a suppressed carrier.

[0051] Example 4, a single-channel direction-finding system based on optical single-sideband modulation, including N antennas for receiving N radio frequency signals respectively, a multi-channel electro-optical conversion unit connected to the N antennas, a reference signal generating unit and an optoelectronic synthesis conversion unit connected to the multi-channel electro-optical conversion unit, and a signal processing unit connected to the optoelectronic synthesis conversion unit.

[0052] The multi-channel electro-optical conversion unit includes a main single-sideband electro-optical conversion module, N-1 slave single-sideband electro-optical conversion modules connected to the main single-sideband electro-optical conversion module, and 1 N optical couplers; the reference signal generating unit is connected to N-1 slave single sideband electro-optical conversion modules respectively; the master single sideband electro-optical conversion module is connected to an antenna, and N-1 slave single sideband electro-optical conversion modules are connected to N-1 antennas respectively; the photoelectric synthesis conversion unit is connected to the master single sideband electro-optical conversion module and 1 N optocoupler connection.

[0053] The main single-sideband electro-optical conversion module includes a laser 1, a (N+1) optocoupler, and 1 (N+1) optical couplers connected to the dual parallel optical modulator 1, the orthogonal coupler 1 connected to the dual parallel optical modulator 1, the orthogonal coupler 1 is connected to an antenna, the dual parallel optical modulator 1 is connected to 1 N optocoupler connection, 1 The (N+1) optical couplers are respectively connected to the N-1 slave single-sideband electro-optical conversion modules and the photoelectric synthesis conversion units.

[0054] like Figure 4 As shown, a single SSB electro-optical conversion module includes lasers n+1, 1 2 Optocoupler A n 、1 2 Optocoupler B n , dual parallel optical modulator n+1, orthogonal coupler n+1, photodetector n, frequency divider n, phase detector n and low-pass filter n, where n is any number from 1, 2, 3, ..., N-1; laser n+1 connected to 1 2 Optocoupler A n , 1 2 Optocoupler A n Connect 1 in sequence 2 Optocoupler B n , photodetector n, frequency divider n, phase detector n, low-pass filter n and laser n+1,1 2 Optocoupler B n Connection 1 (N+1) optocoupler, 1 2 Optocoupler A n Connect the dual parallel optical modulator n+1, the orthogonal coupler n+1 connects the dual parallel optical modulator n+1, the orthogonal coupler n+1 is connected to 1 antenna, the dual parallel optical modulator n+1 is connected to 1 N optocoupler connection.

[0055] For the nth single-sideband electro-optical conversion module, the laser input 1 emitted by laser n+1 (n is any number from 1, 2, 3, ..., N-1) 2 Optocoupler A n , 1 2 Optocoupler A n Output 1 split light n+1 and 1 DC light n+1; split light n+1 input 1 2 Optocoupler B n, DC light n+1 is input into the dual parallel optical modulator n+1; the RF signal n+1 received by the antenna is output through the orthogonal coupler n+1 as the in-phase RF signal n+1 and the orthogonal RF signal n+1; the in-phase RF signal n+1 and the orthogonal RF signal n+1 are input into the dual parallel optical modulator n+1 from the two RF input terminals and the DC light n+1 is input into the dual parallel optical modulator n+1 to obtain the single-sideband modulated optical signal n+1 with suppressed carrier; in the dual parallel optical modulator n+1, the DC bias points of the two intensity optical modulators are controlled at the minimum power point, and the phase offset of the phase optical modulator is 90 degrees; the split light n+1 and the local oscillator light n+1 are input into 1 2 Optocoupler B n , 1 2 Optocoupler B n The output combined light n enters the photodetector n, and the photodetector n outputs the beat signal n; the frequency of the beat signal n is f b_n , the beat signal n passes through the frequency divider n and obtains the frequency f b_n A frequency-divided signal n is generated by combining the frequency-divided signal n with the reference signal n, where m is the frequency-dividing ratio (m = 1, 2, 3, …, M). The frequency-divided signal n and the reference signal n are input into phase detector n to generate error signal n. This error signal n is then passed through low-pass filter n to generate feedback signal n. Feedback signal n is then input into laser n+1, which adjusts the wavelength of laser n+1 to equalize the frequency of frequency-divided signal n with that of the reference signal.

[0056] Example 5, a single-channel direction-finding system based on optical single-sideband modulation, including N antennas for receiving N radio frequency signals respectively, a multi-channel electro-optical conversion unit connected to the N antennas, a reference signal generating unit and an optoelectronic synthesis conversion unit connected to the multi-channel electro-optical conversion unit, and a signal processing unit connected to the optoelectronic synthesis conversion unit.

[0057] The multi-channel electro-optical conversion unit includes a main single-sideband electro-optical conversion module, N-1 slave single-sideband electro-optical conversion modules connected to the main single-sideband electro-optical conversion module, and 1 N optical couplers; the reference signal generating unit is connected to N-1 slave single sideband electro-optical conversion modules respectively; the master single sideband electro-optical conversion module is connected to an antenna, and N-1 slave single sideband electro-optical conversion modules are connected to N-1 antennas respectively; the photoelectric synthesis conversion unit is connected to the master single sideband electro-optical conversion module and 1 N optocoupler connection.

[0058] The main single-sideband electro-optical conversion module includes a laser 1, a (N+1) optocoupler, and 1 (N+1) optical couplers connected to the dual parallel optical modulator 1, the orthogonal coupler 1 connected to the dual parallel optical modulator 1, the orthogonal coupler 1 is connected to an antenna, the dual parallel optical modulator 1 is connected to 1 N optocoupler connection, 1 The (N+1) optical couplers are respectively connected to the N-1 slave single-sideband electro-optical conversion modules and the photoelectric synthesis conversion units.

[0059] A single SSB electro-optical conversion module includes laser n+1, 1 2 Optocoupler A n 、1 2 Optocoupler B n , dual parallel optical modulator n+1, orthogonal coupler n+1, photodetector n, frequency divider n, phase detector n and low-pass filter n, where n is any number from 1, 2, 3, ..., N-1; laser n+1 connected to 1 2 Optocoupler A n , 1 2 Optocoupler A n Connect 1 in sequence 2 Optocoupler B n , photodetector n, frequency divider n, phase detector n, low-pass filter n and laser n+1,1 2 Optocoupler B n Connection 1 (N+1) optocoupler, 1 2 Optocoupler A n Connect the dual parallel optical modulator n+1, the orthogonal coupler n+1 connects the dual parallel optical modulator n+1, the orthogonal coupler n+1 is connected to 1 antenna, the dual parallel optical modulator n+1 is connected to 1 N optocoupler connection.

[0060] like Figure 5 As shown, the reference signal generating unit includes a frequency source, a 1 connected to the frequency source (N-1) RF power splitter, 1 The (N-1) radio frequency power divider is connected to the phase detector n.

[0061] The frequency source outputs a fixed frequency of f REF The RF signal, after 1 The (N-1) RF power splitter outputs N-1 reference signals, and the frequency of each reference signal is f REF .

[0062] Example 6, a single-channel direction-finding system based on optical single-sideband modulation, comprising N antennas for receiving N radio frequency signals respectively, a multi-channel electro-optical conversion unit connected to the N antennas, a reference signal generating unit and an optoelectronic synthesis conversion unit connected to the multi-channel electro-optical conversion unit, and a signal processing unit connected to the optoelectronic synthesis conversion unit.

[0063] The multi-channel electro-optical conversion unit includes a main single-sideband electro-optical conversion module, N-1 slave single-sideband electro-optical conversion modules connected to the main single-sideband electro-optical conversion module, and 1 N optical couplers; the reference signal generating unit is connected to N-1 slave single sideband electro-optical conversion modules respectively; the master single sideband electro-optical conversion module is connected to an antenna, and N-1 slave single sideband electro-optical conversion modules are connected to N-1 antennas respectively; the photoelectric synthesis conversion unit is connected to the master single sideband electro-optical conversion module and 1 N optocoupler connection.

[0064] The main single-sideband electro-optical conversion module includes a laser 1, a (N+1) optocoupler, and 1 (N+1) optical couplers connected to the dual parallel optical modulator 1, the orthogonal coupler 1 connected to the dual parallel optical modulator 1, the orthogonal coupler 1 is connected to an antenna, the dual parallel optical modulator 1 is connected to 1 N optocoupler connection, 1 The (N+1) optical couplers are respectively connected to the N-1 slave single-sideband electro-optical conversion modules and the photoelectric synthesis conversion units.

[0065] A single SSB electro-optical conversion module includes laser n+1, 1 2 Optocoupler A n 、1 2 Optocoupler B n , dual parallel optical modulator n+1, orthogonal coupler n+1, photodetector n, frequency divider n, phase detector n and low-pass filter n, where n is any number from 1, 2, 3, ..., N-1; laser n+1 connected to 1 2 Optocoupler A n , 1 2 Optocoupler A n Connect 1 in sequence 2 Optocoupler B n , photodetector n, frequency divider n, phase detector n, low-pass filter n and laser n+1,1 2 Optocoupler B n Connection 1 (N+1) optocoupler, 1 2 Optocoupler A nConnect the dual parallel optical modulator n+1, the orthogonal coupler n+1 connects the dual parallel optical modulator n+1, the orthogonal coupler n+1 is connected to 1 antenna, the dual parallel optical modulator n+1 is connected to 1 N optocoupler connection.

[0066] The reference signal generating unit includes a frequency source, a (N-1) RF power splitter, 1 The (N-1) radio frequency power divider is connected to the phase detector n.

[0067] like Figure 7 As shown, the photoelectric synthesis conversion unit includes 1 2 Optocoupler C, and 1 2 Optocoupler C connected to photodetector N, 1 2 optocouplers C and 1 (N+1) optocouplers and 1 N optical couplers are connected, and the photodetector N is connected to the signal processing unit.

[0068] Local oscillator light 1 and synthesized modulated optical signal input 1 2 Optical coupler C outputs a beat optical signal, which is input to photodetector N for processing to obtain a frequency-shifted RF signal sequence; the frequency-shifted RF signal sequence includes N frequency-shifted RF signals with different frequencies, and the N frequency-shifted RF signals overlap in the time domain. Figure 8 This is a diagram of the frequency distribution of the frequency-shifted RF signal sequence. The frequency interval between adjacent frequency-shifted RF signals is f REF The frequency of the pth frequency-shifted RF signal is f RF +(p-1) f REF (p=1,2,3,…,N). The instantaneous distribution bandwidth of N frequency-shifted RF signals is (N-1) f REF .

[0069] Example 7, as Figures 1-9 As shown, a single-channel direction-finding system based on optical single-sideband modulation includes N antennas for receiving N radio frequency signals, a multi-channel electro-optical conversion unit connected to the N antennas, a reference signal generating unit and an optoelectronic synthesis conversion unit connected to the multi-channel electro-optical conversion unit, and a signal processing unit connected to the optoelectronic synthesis conversion unit.

[0070] The multi-channel electro-optical conversion unit includes a main single-sideband electro-optical conversion module, N-1 slave single-sideband electro-optical conversion modules connected to the main single-sideband electro-optical conversion module, and 1 N optical couplers; the reference signal generating unit is connected to N-1 slave single sideband electro-optical conversion modules respectively; the master single sideband electro-optical conversion module is connected to an antenna, and N-1 slave single sideband electro-optical conversion modules are connected to N-1 antennas respectively; the photoelectric synthesis conversion unit is connected to the master single sideband electro-optical conversion module and 1 N optocoupler connection.

[0071] The main single-sideband electro-optical conversion module includes a laser 1, a (N+1) optocoupler, and 1 (N+1) optical couplers connected to the dual parallel optical modulator 1, the orthogonal coupler 1 connected to the dual parallel optical modulator 1, the orthogonal coupler 1 is connected to an antenna, the dual parallel optical modulator 1 is connected to 1 N optocoupler connection, 1 The (N+1) optical couplers are respectively connected to the N-1 slave single-sideband electro-optical conversion modules and the photoelectric synthesis conversion units.

[0072] A single SSB electro-optical conversion module includes laser n+1, 1 2 Optocoupler A n 、1 2 Optocoupler B n , dual parallel optical modulator n+1, orthogonal coupler n+1, photodetector n, frequency divider n, phase detector n and low-pass filter n, where n is any number from 1, 2, 3, ..., N-1; laser n+1 connected to 1 2 Optocoupler A n , 1 2 Optocoupler A n Connect 1 in sequence 2 Optocoupler B n , photodetector n, frequency divider n, phase detector n, low-pass filter n and laser n+1,1 2 Optocoupler B n Connection 1 (N+1) optocoupler, 1 2 Optocoupler A n Connect the dual parallel optical modulator n+1, the orthogonal coupler n+1 connects the dual parallel optical modulator n+1, the orthogonal coupler n+1 is connected to 1 antenna, the dual parallel optical modulator n+1 is connected to 1 N optocoupler connection.

[0073] The reference signal generating unit includes a frequency source, a (N-1) RF power splitter, 1 The (N-1) radio frequency power divider is connected to the phase detector n.

[0074] The photoelectric synthesis conversion unit includes 1 2 Optocoupler C, and 1 2 Optocoupler C connected to photodetector N, 1 2 optocouplers C and 1 (N+1) optocouplers and 1 N optical couplers are connected, and the photodetector N is connected to the signal processing unit.

[0075] like Figure 9 As shown, the signal processing unit includes an analog-to-digital converter and a digital signal processor connected to the analog-to-digital converter, and the analog-to-digital converter is connected to the photodetector N.

[0076] The optoelectronic synthesis conversion unit inputs the frequency-shifted RF signal sequence into an analog-to-digital converter, generating a high-precision digital signal. The digital signal then enters the digital signal processor, where the direction of the incident signal (measurement result) is determined through signal detection and parameter calculation. The distributed bandwidth of the frequency-shifted RF signal matches the instantaneous bandwidth of the signal processing unit, ensuring simultaneous processing of N frequency-shifted RF signals. Signal detection uses digital channelization or short-time fast Fourier transform to perform real-time spectrum analysis of the digital signal, simultaneously obtaining the frequency and phase parameters of the N frequency-shifted RF signals. Using the frequencies and phases of the N frequency-shifted RF signals, combined with the known distances between the N antennas, the direction of the incident signal can be calculated using the commonly used interferometer phase comparison method.

[0077] Example 8, as Figure 1-9 As shown, a method for implementing a single-channel direction finding system based on optical single-sideband modulation includes the following steps:

[0078] Step S1, N frequencies are all f RF The RF signal is received one-to-one by N antennas;

[0079] Step S2: The N radio frequency signals received by the N antennas are input into the multi-channel electro-optical conversion unit; the frequency source outputs a fixed frequency f REF RF signal, fixed frequency f REF The RF signal passes through 1 (N-1) RF power splitter processing, get N-1 frequencies are f REF Reference signal; N-1 reference signals are input into the multi-channel electro-optical conversion unit;

[0080] Step S3, N frequencies are all f RF The RF signal and N-1 frequencies are all f REF The reference signal is processed by a multi-channel electro-optical conversion unit to obtain the local oscillator light 1 and the synthetic modulated optical signal;

[0081] Step S4: local oscillator light 1 and synthesized modulated optical signal input 1 2 optical coupler C, obtains a beat optical signal; the beat optical signal is input into the photodetector N to obtain a frequency-shifted radio frequency signal sequence, the frequency-shifted radio frequency signal sequence includes N frequency-shifted radio frequency signals;

[0082] Step S5: N frequency-shifted RF signals are simultaneously input into an analog-to-digital converter for analog-to-digital conversion to obtain N digital signals; the N digital signals are simultaneously input into a digital signal processor for signal detection and parameter calculation to obtain the direction of the incident signal.

[0083] Example 9, as Figure 1-9 As shown, a method for implementing a single-channel direction finding system based on optical single-sideband modulation includes the following steps:

[0084] Step S1, N frequencies are all f RF The RF signal is received one-to-one by N antennas;

[0085] Step S2: The N radio frequency signals received by the N antennas are input into the multi-channel electro-optical conversion unit; the frequency source outputs a fixed frequency f REF RF signal, fixed frequency f REF The RF signal passes through 1 (N-1) RF power splitter processing, get N-1 frequencies are f REF Reference signal; N-1 reference signals are input into the multi-channel electro-optical conversion unit;

[0086] Step S3, N frequencies are all f RF The RF signal and N-1 frequencies are all f REF The reference signal is processed by a multi-channel electro-optical conversion unit to obtain the local oscillator light 1 and the synthetic modulated optical signal;

[0087] Step S4: local oscillator light 1 and synthesized modulated optical signal input 1 2 optical coupler C, obtains a beat optical signal; the beat optical signal is input into the photodetector N to obtain a frequency-shifted radio frequency signal sequence, the frequency-shifted radio frequency signal sequence includes N frequency-shifted radio frequency signals;

[0088] Step S5: N frequency-shifted RF signals are simultaneously input into an analog-to-digital converter for analog-to-digital conversion to obtain N digital signals; the N digital signals are simultaneously input into a digital signal processor for signal detection and parameter calculation to obtain the direction of the incident signal.

[0089] Step S3 includes:

[0090] Step S31: The laser input 1 emitted by the laser 1 The (N+1) optical coupler obtains 1 local oscillator light 1, N-1 local oscillator lights, and direct current light 1; the radio frequency signal 1 passes through the orthogonal coupler 1 to output an in-phase radio frequency signal 1 and an orthogonal radio frequency signal 1; the in-phase radio frequency signal 1 and the orthogonal radio frequency signal 1 are input into the dual parallel optical modulator 1 from two radio frequency input terminals, and the direct current light 1 is input into the dual parallel optical modulator 1 to obtain a single-sideband modulated optical signal 1 with a suppressed carrier;

[0091] Step S32: For the nth single-sideband electro-optical conversion module, the laser input 1 emitted by the laser n+1 2 Optocoupler A n , output 1 branch light n+1 and 1 DC light n+1, branch light n+1 input 1 2 Optocoupler B n , DC light n+1 inputs dual parallel optical modulator n+1;

[0092] Step S33: The RF signal n+1 is output through the orthogonal coupler n+1 as an in-phase RF signal n+1 and an orthogonal RF signal n+1; the in-phase RF signal n+1 and the orthogonal RF signal n+1 are input from two RF input terminals to the dual parallel optical modulator n+1; the DC light n+1 is input into the dual parallel optical modulator n+1 to obtain a carrier-suppressed single-sideband modulated optical signal n+1; the branched light n+1 and the local oscillator light n+1 are input into 1 2 Optocoupler B n , the output combined light n enters the photodetector n, and the photodetector n outputs the beat signal n, where the frequency of the beat signal n is f b_n ;

[0093] Step S34: The beat signal n passes through the frequency divider n to obtain the frequency f b_n / m frequency-divided signal n, where m is the frequency-dividing ratio (m=1, 2, 3, ..., M); frequency-divided signal n and reference signal n are input into phase detector n to obtain error signal n, which is then passed through low-pass filter n to obtain feedback signal n; feedback signal n is input into laser n+1 to adjust the wavelength of laser n+1 so that the frequency of frequency-divided signal n is equal to that of the reference signal;

[0094] Step S35: Input 1 channel single sideband modulated optical signal 1 and N-1 channel single sideband modulated optical signal n+1 to 1 channel. N optical couplers are used to obtain a synthetic modulated optical signal.

[0095] Example 10, as Figure 1-9 As shown, a method for implementing a single-channel direction finding system based on optical single-sideband modulation includes the following steps:

[0096] Step S1, N frequencies are all f RF The RF signal is received one-to-one by N antennas;

[0097] Step S2: The N radio frequency signals received by the N antennas are input into the multi-channel electro-optical conversion unit; the frequency source outputs a fixed frequency f REF RF signal, fixed frequency f REF The RF signal passes through 1 (N-1) RF power splitter processing, get N-1 frequencies are f REF Reference signal; N-1 reference signals are input into the multi-channel electro-optical conversion unit;

[0098] Step S3, N frequencies are all f RF The RF signal and N-1 frequencies are all f REF The reference signal is processed by a multi-channel electro-optical conversion unit to obtain the local oscillator light 1 and the synthetic modulated optical signal;

[0099] Step S4: local oscillator light 1 and synthesized modulated optical signal input 1 2 optical coupler C, obtains a beat optical signal; the beat optical signal is input into the photodetector N to obtain a frequency-shifted radio frequency signal sequence, the frequency-shifted radio frequency signal sequence includes N frequency-shifted radio frequency signals;

[0100] Step S5: N frequency-shifted RF signals are simultaneously input into an analog-to-digital converter for analog-to-digital conversion to obtain N digital signals; the N digital signals are simultaneously input into a digital signal processor for signal detection and parameter calculation to obtain the direction of the incident signal.

[0101] Step S3 includes:

[0102] Step S31: The laser input 1 emitted by the laser 1 The (N+1) optical coupler obtains 1 local oscillator light 1, N-1 local oscillator lights, and direct current light 1; the radio frequency signal 1 passes through the orthogonal coupler 1 to output an in-phase radio frequency signal 1 and an orthogonal radio frequency signal 1; the in-phase radio frequency signal 1 and the orthogonal radio frequency signal 1 are input into the dual parallel optical modulator 1 from two radio frequency input terminals, and the direct current light 1 is input into the dual parallel optical modulator 1 to obtain a single-sideband modulated optical signal 1 with a suppressed carrier;

[0103] Step S32: for the nth SSB electro-optical conversion module, the laser input 1 emitted by the laser n+1 2 Optocoupler A n , output 1 branch light n+1 and 1 DC light n+1, branch light n+1 input 1 2 Optocoupler B n , DC light n+1 inputs dual parallel optical modulator n+1;

[0104] Step S33: The RF signal n+1 is output through the orthogonal coupler n+1 as an in-phase RF signal n+1 and an orthogonal RF signal n+1; the in-phase RF signal n+1 and the orthogonal RF signal n+1 are input from two RF input terminals to the dual parallel optical modulator n+1; the DC light n+1 is input into the dual parallel optical modulator n+1 to obtain a carrier-suppressed single-sideband modulated optical signal n+1; the branched light n+1 and the local oscillator light n+1 are input into 1 2 Optocoupler B n , the output combined light n enters the photodetector n, and the photodetector n outputs the beat signal n, where the frequency of the beat signal n is f b_n ;

[0105] Step S34: The beat signal n passes through the frequency divider n to obtain the frequency f b_n / m frequency-divided signal n, where m is the frequency-dividing ratio (m=1, 2, 3, ..., M); frequency-divided signal n and reference signal n are input into phase detector n to obtain error signal n, which is then passed through low-pass filter n to obtain feedback signal n; feedback signal n is input into laser n+1 to adjust the wavelength of laser n+1 so that the frequency of frequency-divided signal n is equal to that of the reference signal;

[0106] Step S35: Input 1 channel single sideband modulated optical signal 1 and N-1 channel single sideband modulated optical signal n+1 to 1 channel. N optical couplers are used to obtain a synthetic modulated optical signal.

[0107] In the dual parallel optical modulator, the DC bias points of the two intensity optical modulators are controlled at the minimum power point, and the phase offset of the phase optical modulator is 90 degrees; the output laser frequency of laser 1 is f0, and the output laser frequency of laser n+1 is f0+n f REF .

[0108] Figure 6 The composite modulated optical signal frequency distribution diagram of the present invention. The composite modulated optical signal includes N single-sideband modulated optical signals, and the frequency interval between adjacent optical signals is f REF The frequency of the pth single-sideband modulated optical signal is f0+f RF +(p-1) f REF (p=1,2,3,…,N).

[0109] Figure 8 The frequency distribution diagram of the frequency-shifted radio frequency signal sequence of the present invention is shown in FIG. The frequency-shifted radio frequency signal sequence includes N frequency-shifted radio frequency signals, and the frequency interval between adjacent frequency-shifted radio frequency signals is f REF The frequency of the pth frequency-shifted RF signal is f RF +(p-1) f REF(p=1,2,3,…,N). The instantaneous distribution bandwidth of N frequency-shifted RF signals is (N-1) f REF .

[0110] This invention single-sideband modulates the radio frequency signals received by multiple antennas onto a wavelength-locked multi-channel laser. It then uses optical technology to process these single-sideband modulated optical signals. Photoelectric detection then simultaneously generates multiple frequency-shifted radio frequency signals. Finally, the method performs real-time, high-precision detection and processing of these frequency-shifted radio frequency signals to achieve direction finding of the incident signal. The proposed method achieves high-probability interception and precise direction finding of radio frequency signals across a large instantaneous frequency range, offering significant advantages in performance and implementation architecture. It has significant application value for high-precision directional measurement of broadband signals in electronic reconnaissance equipment.

[0111] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention and are intended to illustrate the technical solutions of the present invention, rather than limiting them, and certainly not limiting the patent scope of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features therein may be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention. In other words, any changes or refinements made to the main design concept and spirit of the present invention that have no substantive significance, provided that the technical problems they solve are still consistent with those of the present invention, should be included in the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields should also be included in the patent protection scope of the present invention.

Claims

1. A single-channel direction finding system based on optical single-sideband modulation, characterized in that: The device comprises N antennas for receiving N radio frequency signals respectively, a multi-channel electro-optical conversion unit connected to the N antennas, a reference signal generating unit and a photoelectric synthesis conversion unit connected to the multi-channel electro-optical conversion unit, and a signal processing unit connected to the photoelectric synthesis conversion unit; The multi-channel electro-optical conversion unit includes a main single-sideband electro-optical conversion module, N-1 slave single-sideband electro-optical conversion modules connected to the main single-sideband electro-optical conversion module, and 1 N optical couplers; the reference signal generating unit is connected to N-1 slave single sideband electro-optical conversion modules respectively; the master single sideband electro-optical conversion module is connected to an antenna, and N-1 slave single sideband electro-optical conversion modules are connected to N-1 antennas respectively; the photoelectric synthesis conversion unit is connected to the master single sideband electro-optical conversion module and 1 N optocoupler connection; The main single-sideband electro-optical conversion module includes a laser 1, a (N+1) optocoupler, and 1 (N+1) optical couplers connected to the dual parallel optical modulator 1, the orthogonal coupler 1 connected to the dual parallel optical modulator 1, the orthogonal coupler 1 is connected to an antenna, the dual parallel optical modulator 1 is connected to 1 N optocoupler connection, 1 (N+1) optical couplers are respectively connected to N-1 slave single-sideband electro-optical conversion modules and photoelectric synthesis conversion units; A single SSB electro-optical conversion module includes laser n+1, 1 2 Optocoupler A n 、1 2 Optocoupler B n , dual parallel optical modulator n+1, orthogonal coupler n+1, photodetector n, frequency divider n, phase detector n and low-pass filter n, where n is any number from 1, 2, 3, ..., N-1; laser n+1 connected to 1 2 Optocoupler A n , 1 2 Optocoupler A n Connect 1 in sequence 2 Optocoupler B n , photodetector n, frequency divider n, phase detector n, low-pass filter n and laser n+1,1 2 Optocoupler B n Connection 1 (N+1) optocoupler, 1 2 Optocoupler A n Connect the dual parallel optical modulator n+1, the orthogonal coupler n+1 connects the dual parallel optical modulator n+1, the orthogonal coupler n+1 is connected to 1 antenna, the dual parallel optical modulator n+1 is connected to 1 N optocoupler connection; N RF signals are respectively input into the main single-sideband electro-optical conversion module and N-1 slave single-sideband electro-optical conversion modules. The main single-sideband electro-optical conversion module outputs N local oscillator lights and 1 single-sideband modulated optical signal 1; 1 local oscillator light 1 is directly output, and N-1 local oscillator lights are respectively input into N-1 slave single-sideband electro-optical conversion modules; the reference signal generating unit generates N-1 reference signals, and the N-1 reference signals are respectively input into N-1 slave single-sideband electro-optical conversion modules for processing. The N-1 slave single-sideband electro-optical conversion modules output N-1 single-sideband modulated optical signals; the N single-sideband modulated optical signals enter 1 N optical couplers are used to obtain one channel of synthesized modulated optical signal; Laser input 1 emitted by laser 1 (N+1) optocoupler, 1 The (N+1) optical coupler outputs N local oscillator (LO) lights and one DC light (1), where the N LO lights include LO light 1 and N-1 LO light n. An RF signal 1 received by an antenna passes through a quadrature coupler 1, which outputs an in-phase RF signal 1 and a quadrature RF signal 1. The in-phase RF signal 1 and the quadrature RF signal 1 are input into a dual parallel optical modulator 1 from two RF input terminals, and the DC light 1 is input into the dual parallel optical modulator 1 to generate a carrier-suppressed single-sideband modulated optical signal 1. For the nth SSB electro-optical conversion module, the laser input 1 emitted by laser n+1 2 Optocoupler A n , 1 2 Optocoupler A n Output 1 split light n+1 and 1 DC light n+1; split light n+1 input 1 2 Optocoupler B n , DC light n+1 is input into the dual parallel optical modulator n+1; the RF signal n+1 received by the antenna is output through the orthogonal coupler n+1 as the in-phase RF signal n+1 and the orthogonal RF signal n+1; the in-phase RF signal n+1 and the orthogonal RF signal n+1 are input into the dual parallel optical modulator n+1 from the two RF input terminals and the DC light n+1 is input into the dual parallel optical modulator n+1 to obtain the single-sideband modulated optical signal n+1 with suppressed carrier; in the dual parallel optical modulator n+1, the DC bias points of the two intensity optical modulators are controlled at the minimum power point, and the phase offset of the phase optical modulator is 90 degrees; the split light n+1 and the local oscillator light n+1 are input into 1 2 Optocoupler B n , 1 2 Optocoupler B n The output combined light n enters the photodetector n, and the photodetector n outputs the beat signal n; the frequency of the beat signal n is f b_n , the beat signal n passes through the frequency divider n and obtains the frequency f b_n / m frequency-divided signal n, where m is the frequency-dividing ratio; frequency-divided signal n and reference signal n are input into phase detector n to obtain error signal n, which is then passed through low-pass filter n to obtain feedback signal n; feedback signal n is input into laser n+1 to adjust the wavelength of laser n+1 so that the frequency of frequency-divided signal n is equal to that of the reference signal; The photoelectric synthesis conversion unit includes 1 2 Optocoupler C, and 1 2 Optocoupler C connected to photodetector N, 1 2 optocouplers C and 1 (N+1) optocouplers and 1 N optical couplers are connected, and the photodetector N is connected to the signal processing unit; Local oscillator light 1 and synthesized modulated optical signal input 1 2. Optical coupler C outputs a beat optical signal, which is input to photodetector N for processing to obtain a frequency-shifted radio frequency signal sequence; the frequency-shifted radio frequency signal sequence includes N frequency-shifted radio frequency signals with different frequencies, and the N frequency-shifted radio frequency signals overlap in the time domain; The signal processing unit processes the frequency-shifted radio frequency signal sequence and simultaneously obtains the frequencies and phases of the N frequency-shifted radio frequency signals, thereby calculating the direction of the incident signal.

2. The single-channel direction finding system based on optical single sideband modulation according to claim 1, characterized in that: The reference signal generating unit includes a frequency source, a (N-1) RF power splitter, 1 The (N-1) radio frequency power divider is connected to the phase detector n.

3. The single-channel direction finding system based on optical single sideband modulation according to claim 1, characterized in that: The signal processing unit includes an analog-to-digital converter and a digital signal processor connected to the analog-to-digital converter. The analog-to-digital converter is connected to the photodetector N.

4. A method for implementing a single-channel direction finding system based on optical single sideband modulation according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step S1, N frequencies are all f RF The RF signal is received one-to-one by N antennas; Step S2: N radio frequency signals received by the N antennas are input into a multi-channel electro-optical conversion unit; The frequency source outputs a fixed frequency f REF RF signal, fixed frequency f REF The RF signal passes through 1 (N-1) RF power divider, N-1 frequencies are obtained, all of which are f REF Reference signal; N-1 reference signals are input into the multi-channel electro-optical conversion unit; Step S3, N frequencies are all f RF The RF signal and N-1 frequencies are all f REF The reference signal is processed by a multi-channel electro-optical conversion unit to obtain the local oscillator light 1 and the synthetic modulated optical signal; Step S4: The local oscillator light 1 and the synthesized modulated optical signal are input into the optoelectronic synthesis conversion unit to obtain a frequency-shifted radio frequency signal sequence, where the frequency-shifted radio frequency signal sequence includes N frequency-shifted radio frequency signals. Step S5: N frequency-shifted radio frequency signals are simultaneously input into a signal processing unit to obtain the direction of the incident signal.

5. The method for implementing a single-channel direction finding system based on optical single sideband modulation according to claim 4, characterized in that: Step S3 includes: Step S31: The laser input 1 emitted by the laser 1 The (N+1) optical coupler generates one local oscillator light 1, N-1 local oscillator lights n, and direct current light 1. RF signal 1 passes through quadrature coupler 1 to output in-phase RF signal 1 and quadrature RF signal 1. The in-phase RF signal 1 and the quadrature RF signal 1 are input into dual parallel optical modulator 1 from two RF input terminals, and the direct current light 1 is input into dual parallel optical modulator 1 to generate a single-sideband modulated optical signal 1 with suppressed carrier. Step S32: For the nth single-sideband electro-optical conversion module, the laser input 1 emitted by the laser n+1 2 Optocoupler A n , output 1 branch light n+1 and 1 DC light n+1, branch light n+1 input 1 2 Optocoupler B n , DC light n+1 inputs dual parallel optical modulator n+1; Step S33: The RF signal n+1 is output through the orthogonal coupler n+1 as an in-phase RF signal n+1 and an orthogonal RF signal n+1; the in-phase RF signal n+1 and the orthogonal RF signal n+1 are input from two RF input terminals to the dual parallel optical modulator n+1; the DC light n+1 is input into the dual parallel optical modulator n+1 to obtain a carrier-suppressed single-sideband modulated optical signal n+1; the branched light n+1 and the local oscillator light n+1 are input into 1 2 Optocoupler B n , the output combined light n enters the photodetector n, and the photodetector n outputs the beat signal n, where the frequency of the beat signal n is f b_n ; Step S34: The beat signal n passes through the frequency divider n to obtain the frequency f b_n / m frequency division signal n, where m is the division ratio, where m=1, 2, 3, ..., N-1; the frequency division signal n and the reference signal n are input to phase detector n to obtain error signal n, which is then passed through low-pass filter n to obtain feedback signal n; the feedback signal n is input to laser n+1, and the wavelength of laser n+1 is adjusted to make the frequency of frequency division signal n equal to the frequency of the reference signal; Step S35: Input 1 channel single sideband modulated optical signal 1 and N-1 channel single sideband modulated optical signal n+1 to 1 channel. N optical couplers are used to obtain a synthetic modulated optical signal.

6. The method for implementing a single-channel direction finding system based on optical single sideband modulation according to claim 5, characterized in that: In the dual parallel optical modulator, the DC bias points of the two intensity optical modulators are controlled at the minimum power point, and the phase offset of the phase optical modulator is 90 degrees; the output laser frequency of laser 1 is f0, and the output laser frequency of laser n+1 is f0+n f REF .

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