Communication radar integration optical fiber remote system and phase locking method

Abstract

The present disclosure provides a communication radar integrated optical fiber remote system and a phase locking method. A remote antenna unit is configured to receive a reflected microwave signal, and modulate the amplitude of the microwave signal to obtain an initial optical carrier signal. A dispersion compensation unit is connected with the remote antenna unit and configured to perform dispersion compensation on the initial optical carrier signal to obtain an optical carrier signal. A central unit is connected with the dispersion compensation unit and configured to perform phase locking using the received optical carrier signal to obtain an output optical signal. The frequency of the output optical signal is the same as that of the optical carrier signal, and the phase of the output optical signal is the same as that of the optical carrier signal. A signal output unit is connected with the central unit and configured to output the output optical signal. The present disclosure realizes the consistency of the frequency and the phase synchronization of the output optical signal and the optical carrier signal, realizes low phase noise carrier recovery, and improves the communication and radar performance.

Description

Technical Field

[0001] This disclosure relates to the field of optical communication, and in particular to an integrated fiber optic remote extension system for communication and radar and a phase-locking method. Background Technology

[0002] With the advent of the 5G era, the number of wireless communication devices has increased dramatically. In order to achieve high-speed wireless communication and improve the distance resolution of integrated signals, the millimeter wave band has been introduced. However, since the transmission loss of radio frequency signals in the millimeter wave band is very large, it is necessary to use lossy optical fibers to deploy millimeter wave signals in order to provide effective geographical coverage.

[0003] Since optical equipment is relatively expensive compared to electronic equipment, the antenna end is simplified to only a photodetector and antenna that convert optical signals into electrical signals. The optical fiber is extended and connected to the central processing unit via optical fiber. However, the integrated communication radar signal is relatively sensitive to phase. Although the optical fiber extension solution saves costs compared to the traditional solution, it increases the transmission distance of the signal in the optical fiber to a certain extent, resulting in increased phase noise of the optical signal.

[0004] Therefore, how to reduce the phase noise of optical signals in the fiber optic cable extension of the integrated sensing and communication system in order to improve communication and radar performance has become an important research problem. Summary of the Invention

[0005] In view of this, the purpose of this disclosure is to propose an integrated fiber optic remote extension system for communication and radar and a phase-locking method to solve or partially solve the above problems.

[0006] To achieve the above objectives, the first aspect of this disclosure provides an integrated fiber optic remote communication and radar system, comprising:

[0007] The far-end antenna unit is configured to receive reflected microwave signals and perform amplitude modulation on the microwave signals to obtain an initial optical carrier signal;

[0008] A dispersion compensation unit, connected to the far-end antenna unit, is configured to receive the initial optical carrier signal transmitted by the far-end antenna unit, perform dispersion compensation on the initial optical carrier signal, and obtain an optical carrier signal.

[0009] The central unit, connected to the dispersion compensation unit, is configured to receive the optical carrier signal sent by the dispersion compensation unit, perform phase locking using the received optical carrier signal, and obtain an output optical signal, wherein the frequency of the output optical signal is the same as the frequency of the optical carrier signal, and the phase of the output optical signal is the same as the phase of the optical carrier signal.

[0010] The signal output unit, connected to the central unit, is configured to receive the output optical signal sent by the central unit and output the output optical signal.

[0011] Based on the same inventive concept, a second aspect of this disclosure proposes a phase-locking method applied to the aforementioned integrated communication and radar fiber optic remote extension system, comprising:

[0012] The microwave signal is received by the remote antenna unit, the microwave signal is amplitude modulated to obtain an initial optical carrier signal, and the initial optical carrier signal is sent to the dispersion compensation unit.

[0013] The initial optical carrier signal is subjected to dispersion compensation processing to obtain the optical carrier signal;

[0014] The optical carrier signal is sent to the central unit, which then performs phase locking on the received optical carrier signal to obtain the output optical signal.

[0015] The output optical signal is output using a signal output unit.

[0016] Based on the same inventive concept, a third aspect of this disclosure provides a non-transitory computer-readable storage medium that stores computer instructions for causing a computer to perform the methods described above.

[0017] As can be seen from the above, this disclosure proposes an integrated communication and radar fiber optic remote extension system and a phase-locking method. The dispersion compensation unit is connected to the remote antenna unit, alleviating the problem of limited spectrum resources in free space and solving the problem of short transmission distance for millimeter waves. The central unit performs phase locking on the optical carrier signal after passing through the dispersion compensation unit to obtain the output optical signal. This achieves frequency consistency and phase synchronization between the output optical signal and the optical carrier signal, realizing low-phase-noise carrier recovery, reducing phase noise of the optical signal in the fiber optic remote extension of the integrated communication and radar system, and improving communication and radar performance. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this disclosure or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of an integrated communication and radar fiber optic remote extension system according to an embodiment of the present disclosure;

[0020] Figure 2This is a flowchart of a phase-locking method according to an embodiment of the present disclosure.

[0021] Explanation of reference numerals in the attached figures:

[0022] 100-type integrated fiber optic remote communication and radar system;

[0023] The remote antenna unit 101, duplexer 1011, first frequency converter 1012, amplitude modulator 1013, polarization beam splitter 1014, band-stop filter 1015, third photodetector 1016, second electrical amplifier 1017, and second frequency converter 1018.

[0024] Dispersion compensation unit 102, second circulator 1021, transmission fiber 1022, third circulator 1023, second optical amplifier 1024, fourth circulator 1025, dispersion compensation fiber 1026, fifth circulator 1027.

[0025] The first port of the second circulator is 10211, the second port of the second circulator is 10212, and the third port of the second circulator is 10213.

[0026] The first port of the third circulator is 10231, the second port of the third circulator is 10232, and the third port of the third circulator is 10233;

[0027] The first port of the fourth circulator is 10251, the second port of the fourth circulator is 10252, and the third port of the fourth circulator is 10253.

[0028] The first port of the fifth circulator is 10271, the second port of the fifth circulator is 10272, and the third port of the fifth circulator is 10273;

[0029] Central unit 103, first optical amplifier 1031, optical injection internal control unit 1032;

[0030] Power divider 10321, first circulator 10322, first laser 10323;

[0031] The first port of the first circulator is 103221, the second port of the first circulator is 103222, and the third port of the first circulator is 103223;

[0032] Signal output unit 104, first photodetector 1041, second photodetector 1042;

[0033] Signal modulation unit 105, baseband signal processing component 1051, analog-to-digital converter 1052, filter 1053, local oscillator 1054, signal processing component 1055, first electrical amplifier 1056;

[0034] Second laser 106;

[0035] Phase modulator 107;

[0036] Third optical amplifier 108. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0038] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this disclosure should have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar terms used in the embodiments of this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0039] The following are definitions of terms used in this disclosure:

[0040] OA: Optical Amplifier (OA) is a subsystem product that amplifies optical signals.

[0041] ADC: Analog to Digital Converter (ADC) is a front-end device that converts analog signals into digital signals for processing by subsequent digital devices.

[0042] LO tx The local oscillator generates a high-frequency, constant-amplitude sine wave signal that is one intermediate frequency higher than the received signal (37MHz in my country). This oscillation signal is then injected into the mixer and mixed with the high-frequency television signal to obtain the intermediate-frequency television signal.

[0043] PM: Phase modulation (PM) is a modulation method in which the deviation of the carrier phase from its reference phase changes proportionally to the instantaneous value of the modulating signal.

[0044] PD: Photoelectric Detector (PD) converts light signals into electrical signals.

[0045] IM: Intensity Modulation (IM).

[0046] PBS: Polarization beam splitter (PBS) is an optical device that can split a beam of light into two or more beams.

[0047] Based on the above description, this embodiment proposes an integrated fiber optic remote communication and radar system, such as... Figure 1 As shown, it includes:

[0048] The remote antenna unit 101 is configured to receive the reflected microwave signal and perform amplitude modulation on the microwave signal to obtain an initial optical carrier signal;

[0049] The dispersion compensation unit 102 is connected to the remote antenna unit 101 and is configured to receive the initial optical carrier signal sent by the remote antenna unit 101, perform dispersion compensation on the initial optical carrier signal, and obtain an optical carrier signal.

[0050] The central unit 103, connected to the dispersion compensation unit 102, is configured to receive the optical carrier signal sent by the dispersion compensation unit 102, perform phase locking using the received optical carrier signal, and obtain an output optical signal, wherein the frequency of the output optical signal is the same as the frequency of the optical carrier signal, and the phase of the output optical signal is the same as the phase of the optical carrier signal.

[0051] The signal output unit 104 is connected to the central unit 103 and is configured to receive the output optical signal sent by the central unit 103 and output the output optical signal.

[0052] In practice, the reflected microwave signal is received by the remote antenna unit 101, and the microwave signal is amplitude modulated to obtain an initial optical carrier signal, which is then sent to the dispersion compensation unit 102. The remote antenna unit 101 and the dispersion compensation unit 102 are connected by optical fiber, which alleviates the problem of limited spectrum resources in free space and solves the problem of short transmission distance of millimeter waves.

[0053] The dispersion compensation unit 102 receives the initial optical carrier signal and performs dispersion compensation processing on the initial optical carrier signal to obtain an optical carrier signal, thereby eliminating the dispersion generated when passing through other devices and avoiding distortion of the initial optical carrier signal.

[0054] The central unit 103 receives the optical carrier signal sent by the dispersion compensation unit 102 and uses the optical carrier signal to perform phase locking, so that the frequency of the output optical signal output by the central unit 103 is consistent with the frequency of the optical carrier signal, and the phase of the output optical signal is synchronized with the phase of the optical carrier signal, thereby reducing phase noise and improving radar resolution and communication demodulation accuracy.

[0055] The signal output unit 104 outputs the output optical signal to simplify the digital signal processing flow by using zero-difference detection, thereby improving the signal demodulation rate.

[0056] In some embodiments, the central unit 103 specifically includes:

[0057] The first optical amplifier 1031 is connected to the dispersion compensation unit 102 and is configured to receive the optical carrier signal sent by the dispersion compensation unit 102, amplify the frequency of the optical carrier signal, and obtain the first optical carrier signal.

[0058] The optical injection internal control unit 1032 is connected to the first optical amplifier 1031 and is configured to receive the first optical carrier signal sent by the first optical amplifier 1031, and use the first optical carrier signal to perform phase locking to obtain the output optical signal.

[0059] In specific implementation, the type of the first optical amplifier 1031 includes at least one of the following: an optical fiber amplifier or a semiconductor optical amplifier. The optical fiber amplifier includes at least one of the following: an erbium-doped optical fiber amplifier, a conventional optical fiber amplifier, or a Raman optical amplifier. In this embodiment, an erbium-doped optical fiber amplifier is preferred.

[0060] The first optical amplifier 1031 receives the optical carrier signal sent by the dispersion compensation unit 102, amplifies the frequency of the optical carrier signal using the first optical amplifier 1031 to increase the frequency of the optical carrier signal, obtains a first optical carrier signal, and sends it to the optical injection internal control unit 1032. The optical injection internal control unit performs phase locking on the first optical carrier signal to obtain an output optical signal.

[0061] In some embodiments, the light injection internal modulation unit 1032 specifically includes:

[0062] The power divider 10321 is connected to the first optical amplifier 1031 and is configured to divide the first optical carrier signal to obtain a first sub-optical carrier signal and a second sub-optical carrier signal.

[0063] A first circulator 10322 includes a first port 103221, a second port 103222, and a third port 103223. The first port 103221 of the first circulator 10322 is connected to the power divider 10321 and is configured to receive the first sub-optical carrier signal and control the unidirectional operation of the signal passing through the first circulator, wherein the direction of the unidirectional operation is from the first port of the first circulator to the second port of the first circulator to the third port of the first circulator.

[0064] The first laser 10323 is configured to be connected to the second port 103222 of the first circulator 10322, and is configured to receive the first sub-optical carrier signal transmitted by the first circulator 10322, and generate an output optical signal based on the first sub-optical carrier signal.

[0065] In a specific implementation, the first optical carrier signal is divided by the power divider 10321 to obtain a first sub-optical carrier signal and a second sub-optical carrier signal. The first sub-optical carrier signal is then transmitted to the first laser 10323 via the first circulator 10322.

[0066] After receiving the first sub-optical carrier signal, the first laser 10323 generates an output optical signal that is in phase and frequency with the first sub-optical carrier signal. Specifically, this includes:

[0067] After receiving the first sub-optical carrier signal, the first laser 10323 coherently combines with the first laser 10323, causing a change in the internal field of the first laser 10323, thus causing the first laser 10323 to deviate from its free-running value. Once the first laser 10323 stabilizes internally, its wavelength is locked to the wavelength of the first sub-optical carrier signal, the frequency of the laser emitted by the first laser 10323 is consistent with the frequency of the first sub-optical carrier signal, and the phase of the laser emitted by the first laser 10323 is synchronized with the phase of the first sub-optical carrier signal.

[0068] In some embodiments, the signal output unit 104 specifically includes:

[0069] The first photodetector 1041 is connected to the third port 103223 of the first circulator 10322 and is configured to receive the output optical signal transmitted by the first circulator 10322, convert the output optical signal to obtain a first output signal, and output the first output signal via the analog-to-digital converter 1052.

[0070] The second photodetector 1042 is connected to the power divider 10321 and is configured to receive the second sub-optical carrier signal sent by the power divider 10321, perform conversion processing on the second sub-optical carrier signal to obtain a second output signal, and output the second output signal via the analog-to-digital converter 1052.

[0071] In a specific implementation, the first photodetector 1041 is connected to the third port 103223 of the first circulator 10322, receives the output optical signal transmitted by the first circulator 10322, and performs conversion processing on the output optical signal to obtain the first output signal;

[0072] The second photodetector 1042 is connected to the power divider 10321 and converts the second sub-optical carrier signal obtained by the power divider 10321 to obtain the second output signal.

[0073] The first output signal and the second output signal are input into the analog-to-digital converter 1052, and processed and output by the analog-to-digital converter 1052 and the baseband signal processing component 1051.

[0074] In some embodiments, the dispersion compensation unit 102 specifically includes:

[0075] The second circulator 1021 includes a first port 10211, a second port 10212, and a third port 10213. The third port 10213 of the second circulator 1021 is connected to the far-end antenna unit 101 and is configured to receive the initial optical carrier signal and control the unidirectional operation of the signal passing through the second circulator 1021. The direction of the unidirectional operation is from the first port 10211 of the second circulator 1021 to the second port 10212 to the third port 10213 of the second circulator 1021.

[0076] The transmission fiber 1022 is connected to the first port 10211 of the second circulator 1021 and is configured to receive the initial optical carrier signal transmitted by the second circulator 1021 and transmit the initial optical carrier signal.

[0077] The third circulator 1023 includes a first port 10231, a second port 10232, and a third port 10233. The second port 10232 of the third circulator 1023 is connected to the transmission optical fiber 1022 and is configured to receive the initial optical carrier signal and control the unidirectional operation of the signal passing through the third circulator 1023. The unidirectional operation direction is from the first port 10231 of the third circulator 1023 to the second port 10232 of the third circulator 1023 to the third port 10233 of the third circulator 1023.

[0078] The second optical amplifier 1024 is connected to the third port 10233 of the third circulator 1023 and is configured to receive the initial optical carrier signal transmitted by the third circulator 1023, and amplify the frequency of the initial optical carrier signal to obtain a first initial amplified optical carrier signal.

[0079] The fourth circulator 1025 includes a first port 10251, a second port 10252, and a third port 10253. The third port 10253 of the fourth circulator 1025 is connected to the second optical amplifier 1024 and is configured to receive the first initial amplified optical carrier signal and control the unidirectional operation of the signal passing through the fourth circulator 1025. The direction of the unidirectional operation is from the first port 10251 of the fourth circulator 1025 to the second port 10252 of the fourth circulator 1025 to the third port 10253 of the fourth circulator 1025.

[0080] Dispersion-compensating fiber 1026 is connected to the first port 10251 of the fourth circulator 1025 and is configured to receive the first initial amplified optical carrier signal transmitted by the fourth circulator 1025, perform dispersion compensation processing on the first amplified optical carrier signal, and obtain an optical carrier signal.

[0081] A fifth circulator 1027 includes a first port 10271, a second port 10272, and a third port 10273. The second port 10272 of the fifth circulator 1027 is connected to the dispersion compensation fiber 1026, and the third port 10273 of the fifth circulator 1027 is connected to the first optical amplifier 1031. It is configured to control the unidirectional operation of signals passing through the fifth circulator 1027, wherein the direction of unidirectional operation is from the first port 10271 of the fifth circulator 1027 to the second port 10272 of the fifth circulator 1027 to the third port 10273 of the fifth circulator 1027.

[0082] In specific implementation, the type of the second optical amplifier 1024 includes at least one of the following: an optical fiber amplifier or a semiconductor optical amplifier. The optical fiber amplifier includes at least one of the following: an erbium-doped optical fiber amplifier, a conventional optical fiber amplifier, or a Raman optical amplifier. In this embodiment, an erbium-doped optical fiber amplifier is preferred.

[0083] The third port 10213 of the second circulator 1021 is connected to the remote antenna unit 101 and receives the initial optical carrier signal transmitted by the remote antenna unit 101. This signal is then transmitted to the second optical amplifier 1024 via the transmission fiber 1022 and the third circulator 1023. The second optical amplifier 1024 amplifies the frequency of the initial optical carrier signal to obtain a first initially amplified optical carrier signal. This first initially amplified optical carrier signal is transmitted to the dispersion compensation fiber 1026 via the fourth circulator 1025. The dispersion compensation fiber 1026 performs dispersion compensation processing on the initial optical carrier signal to obtain an optical carrier signal, which is then transmitted to the first optical amplifier 1031 via the fifth circulator. The dispersion compensation fiber 1026 eliminates dispersion generated when passing through other devices, preventing distortion of the initial optical carrier signal.

[0084] In some embodiments, the remote antenna unit 101 specifically includes:

[0085] The duplexer 1011 is configured to receive the reflected initial microwave signal;

[0086] A first frequency converter 1012 is connected to the duplexer 1011 and is configured to receive an initial microwave signal sent by the duplexer 1011, perform frequency conversion processing on the initial microwave signal to obtain a first microwave signal, wherein the frequency of the first microwave signal is less than the frequency of the initial microwave signal.

[0087] Amplitude modulator 1013 is connected at one end to the first frequency converter 1012 and at the other end to the third port 10213 of the second circulator 1021. It is configured to receive a first microwave signal sent by the first frequency converter, perform amplitude modulation on the first microwave signal to obtain an initial optical carrier signal, and send the initial optical carrier signal to the second circulator 1021.

[0088] In specific implementation, duplexer 1011 receives the reflected initial microwave signal and sends it to first frequency converter 1012. The first frequency converter 1012 adjusts the frequency of the initial microwave signal to obtain a first microwave signal, wherein the frequency of the first microwave signal is less than that of the initial microwave signal; that is, the first frequency converter 1012 is a down-conversion frequency converter. Amplitude modulator 1013 receives the first microwave signal and adjusts its amplitude to obtain an initial optical carrier signal. The initial optical carrier signal is transmitted to second circulator 1021, which then sends it to the central unit 103 to achieve phase locking.

[0089] In some embodiments, the integrated communication and radar fiber optic remote extension system 100 further includes:

[0090] The signal modulation unit 105 is configured to receive an initial input signal and modulate the initial input signal to obtain a first input signal.

[0091] The second laser 106 is configured to generate the first optical signal;

[0092] Phase modulator 107 is connected to the first port 10271 of the signal modulation unit 105, the second laser 106 and the fifth circulator 1027 respectively, and is configured to receive a first input signal sent by the signal modulation unit 105 and a first optical signal sent by the second laser 106, and generate a second optical signal based on the first input signal and the first optical signal.

[0093] The third optical amplifier 108 is connected at one end to the second port 10252 of the fourth circulator 1025 and at the other end to the first port 10231 of the third circulator 1023. It is configured to receive the second optical signal transmitted via the fifth circulator 1027, the dispersion compensation fiber 1026 and the fourth circulator 1025, and amplify the frequency of the second optical signal to obtain the third optical signal.

[0094] In specific implementation, the type of the third optical amplifier 108 includes at least one of the following: an optical fiber amplifier or a semiconductor optical amplifier. The optical fiber amplifier includes at least one of the following: an erbium-doped optical fiber amplifier, a conventional optical fiber amplifier, or a Raman optical amplifier. In this embodiment, an erbium-doped optical fiber amplifier is preferred.

[0095] The received initial input signal is modulated by the signal modulation unit 105 to modulate its frequency to an intermediate frequency, thus obtaining a first input signal. The second laser 106 generates and emits a first optical signal. Based on the first optical signal, the phase modulator 107 transfers the first input signal onto a light wave, resulting in a second optical signal. After light compensation by the dispersion compensation fiber 1026, the frequency of the second optical signal is amplified by the third optical amplifier 108, resulting in a third optical signal.

[0096] In some embodiments, the signal modulation unit 105 includes:

[0097] The baseband signal processing component 1051 is configured to receive transmitted data and perform baseband signal processing on the transmitted data to obtain a first initial input signal.

[0098] An analog-to-digital converter 1052, connected to the baseband signal processing component 1051, is configured to receive the first initial input signal and convert the type of the first initial input signal;

[0099] Filter 1053, connected to analog-to-digital converter 1052, is configured to receive a first initial input signal sent by analog-to-digital converter, filter the first initial input signal, and obtain a filtered first initial input signal.

[0100] The local oscillator 1054 is configured to generate a second initial input signal;

[0101] Signal processing component 1055 is connected to filter 1053 and local oscillator 1054 respectively, and is configured to receive a filtered first initial input signal sent by filter 1053 and a second initial input signal sent by local oscillator, and combine the filtered first initial input signal and the second initial input signal to obtain a third initial input signal.

[0102] The first amplifier 1056 is connected at one end to the signal processing component 1055 and at the other end to the phase modulator 107. It is configured to receive a third initial input signal sent by the signal processing component, amplify the frequency of the third initial input signal, and obtain a first input signal.

[0103] In specific implementation, the baseband signal processing component 1051 receives transmitted data and performs baseband signal processing on the transmitted data to obtain a first initial input signal. The analog-to-digital converter 1052 samples the first initial input signal, converting it from an analog signal to a digital signal. A filter 1053 filters the first initial input signal to obtain a filtered first initial input signal. The signal processing component 1055 combines the filtered first initial input signal with a second initial input signal generated by the local oscillator 1054 to obtain a third initial input signal, wherein the combination involves multiplying the filtered first initial input signal with the second initial input signal. A first amplifier 1056 amplifies the frequency of the third initial input signal to obtain a first input signal, which is then sent to the phase modulator 107.

[0104] In some embodiments, the remote antenna unit 101 further includes:

[0105] The polarization beam splitter 1014 is connected to the second port 10212 of the second circulator 1021 and the other end is connected to the amplitude modulator 1013. It is configured to receive the third optical signal transmitted by the second circulator 1021, split the third optical signal to obtain an initial first sub-optical signal and an initial second sub-optical signal, and send the initial second sub-optical signal to the amplitude modulator for modulation based on the initial second sub-optical signal.

[0106] A band-stop filter 1015, connected to the polarization beamsplitter 1014, is configured to receive the initial first sub-optical signal sent by the polarization beamsplitter 1014, and filter the initial first sub-optical signal to obtain the first sub-optical signal.

[0107] The third photodetector 1016 is connected to the band-stop filter 1015 and is configured to receive the first sub-optical signal sent by the band-stop filter, convert the first sub-optical signal, and obtain the first output electrical signal.

[0108] The second electrical amplifier 1017 is connected to the third photodetector 1016 and is configured to receive the first output electrical signal sent by the third photodetector 1016 and amplify the frequency of the second output electrical signal to obtain the second output electrical signal.

[0109] The second frequency converter 1018 is connected at one end to the second electrical amplifier 1017 and at the other end to the duplexer 1011. It is configured to receive the second output electrical signal sent by the second electrical amplifier 1017, perform frequency conversion processing on the second output electrical signal to obtain a third output electrical signal, and emit the third output electrical signal through the duplexer 1011. The frequency of the third output electrical signal is greater than the frequency of the second output electrical signal. The third output signal is reflected to obtain the initial microwave signal.

[0110] In specific implementation, a polarization beamsplitter 1014 is used to split the received third optical signal transmitted by the second circulator 1021 to obtain an initial first sub-optical signal and an initial second sub-optical signal, wherein the initial first sub-optical signal has phase modulation. The initial second sub-optical signal is sent to the amplitude modulator 1013 for modulation based on the initial second sub-optical signal. Specifically, based on the initial second sub-optical signal, the amplitude modulator 1013 transfers the first microwave signal onto an optical wave to obtain an initial optical carrier optical signal.

[0111] The initial first sub-optical signal is filtered by a band-stop filter 1015 to obtain a first sub-optical signal. The first sub-optical signal is converted into a first output electrical signal by a third photodetector 1016, and the first output electrical signal is sent to a second amplifier 1017 to amplify the frequency of the second output electrical signal to obtain a second output electrical signal.

[0112] The second output electrical signal is frequency-converted by the second frequency converter 1018 to obtain a third output electrical signal, which is then transmitted via the duplexer 1011. The frequency of the third output electrical signal is greater than that of the second output electrical signal. After being transmitted via the duplexer 1011, the third output signal is reflected to obtain the initial microwave signal.

[0113] In some embodiments, the optical injection internal control unit includes an optical bandpass filter, one end of which is connected to the power divider 10321 and the other end of which is connected to the first circulator 10322. The optical bandpass filter is configured to filter the first sub-optical carrier signal to reduce the locking frequency of the first laser.

[0114] Based on the same inventive concept, corresponding to the above embodiments, this disclosure also provides a phase-locking method, applied to the communication-radar integrated fiber optic remote extension system described in the above embodiments, such as... Figure 2 As shown, the method includes:

[0115] Step 201: The remote antenna unit receives a microwave signal, modulates the amplitude of the microwave signal to obtain an initial optical carrier signal, and then transmits the initial optical carrier signal to the dispersion compensation unit. Specifically, the remote antenna unit and the dispersion compensation unit are connected via optical fiber. By using the remote antenna unit to receive the microwave signal, adjusting the amplitude of the microwave signal to obtain the initial optical carrier signal, and then transmitting the optical carrier signal to the dispersion compensation unit via optical fiber, the problem of limited spectrum resources in free space is alleviated, and the problem of short transmission distance for millimeter waves is solved.

[0116] Step 202: Perform dispersion compensation processing on the initial optical carrier signal to obtain the optical carrier signal.

[0117] In practice, the dispersion compensation unit is used to perform dispersion compensation processing on the initial optical carrier signal to obtain an optical carrier signal, thereby eliminating the dispersion generated when passing through other devices and avoiding distortion of the initial optical carrier signal.

[0118] Step 203: The optical carrier signal is sent to the central unit, and the central unit performs phase locking on the received optical carrier signal to obtain the output optical signal.

[0119] In practice, phase locking is performed using the optical carrier signal, so that the frequency of the output optical signal from the central unit is consistent with the frequency of the optical carrier signal, and the phase of the output optical signal is synchronized with the phase of the optical carrier signal, thereby reducing phase noise and improving radar resolution and communication demodulation accuracy.

[0120] Step 204: Output the output optical signal using the signal output unit.

[0121] In practice, the output optical signal is output to simplify the digital signal processing flow by using zero-difference detection, thereby solving for the speed and distance of the target that receives the reflected microwave signal, thus improving the signal demodulation rate.

[0122] In some embodiments, step 203 specifically includes:

[0123] Step 2031: The optical carrier signal is sent to the first optical amplifier using the fifth circulator to amplify the frequency of the optical carrier signal and obtain the first optical carrier signal.

[0124] Step 2032: Phase-lock the first optical carrier signal through the optical injection internal modulation unit to obtain the output optical signal.

[0125] In specific implementation, the fifth circulator receives the optical carrier signal and transmits it to the first optical amplifier to amplify the frequency of the optical carrier signal to obtain the first optical carrier signal for subsequent phase locking.

[0126] In some embodiments, step 2032 specifically includes:

[0127] Step 20321: The first optical carrier signal is divided using a power divider to obtain a first sub-optical carrier signal and a second sub-optical carrier signal.

[0128] Step 20322: The first sub-optical carrier signal is transmitted to the first laser via the first circulator, and an output optical signal is generated based on the first sub-optical carrier signal.

[0129] In specific implementation, after the first laser receives the first sub-optical carrier signal, the first sub-optical carrier signal coherently combines with the first laser, causing a change in the internal field of the first laser, causing the first laser to deviate from its free-running value. Once the first laser stabilizes internally, its wavelength is locked to the wavelength of the first sub-optical carrier signal. The frequency of the laser emitted by the first laser is consistent with the frequency of the first sub-optical carrier signal, and the phase of the laser emitted by the first laser is synchronized with the phase of the first sub-optical carrier signal. That is, the output optical signal has the same frequency and phase as the first sub-optical carrier signal.

[0130] In some embodiments, step 201 specifically includes:

[0131] Step 2011: Receive the reflected initial microwave signal using a duplexer and send the initial microwave signal to the first frequency converter.

[0132] Step 2012: The initial microwave signal is frequency-converted by the first frequency converter to obtain a first microwave signal, wherein the frequency of the first microwave signal is less than the frequency of the initial microwave signal.

[0133] In specific implementation, the frequency of the initial microwave signal reflected by the duplexer is adjusted by the first frequency converter to obtain the first microwave signal. The first frequency converter is a down-conversion frequency converter, and the frequency of the first microwave signal is less than the frequency of the initial microwave signal.

[0134] Step 2013: Receive the first microwave signal sent by the first frequency converter, and perform amplitude modulation on the first microwave signal to obtain an initial optical carrier signal.

[0135] In some embodiments, step 202 specifically includes:

[0136] Step 2021: The second circulator receives the initial optical carrier signal and transmits the initial optical carrier signal to the transmission optical fiber.

[0137] Step 2022: The initial optical carrier signal is transmitted to the second optical amplifier via the third circulator using the transmission optical fiber. The frequency of the initial optical carrier signal is adjusted by the second amplifier to obtain the first initial amplified optical carrier signal.

[0138] Step 2023: The first initial amplified optical carrier signal is sent to the dispersion compensation fiber via the fourth circulator, and dispersion compensation processing is performed on the first amplified optical carrier signal to obtain the optical carrier signal.

[0139] In specific implementation, the frequency of the initial optical carrier signal is amplified using the second optical amplifier to obtain a first initial amplified optical carrier signal. This first initial amplified optical carrier signal is then transmitted to a dispersion-compensating optical fiber via the fourth circulator. The dispersion-compensating optical fiber is used to perform dispersion compensation processing on the initial optical carrier signal to obtain an optical carrier signal. Passing through the dispersion-compensating optical fiber eliminates dispersion generated when passing through other devices, thus preventing distortion of the initial optical carrier signal.

[0140] In some embodiments, step 204 specifically includes:

[0141] Step 2041: Receive the output optical signal transmitted by the first circulator through the first photodetector, perform conversion processing on the output optical signal to obtain a first output signal, and output the first output signal via an analog-to-digital converter.

[0142] Step 2042: Receive the second sub-optical carrier signal sent by the power divider through the second photodetector, perform conversion processing on the second sub-optical carrier signal to obtain the second output signal, and output the second output signal through the analog-to-digital converter.

[0143] In practice, the output optical signal is converted by a first photodetector to obtain a first output signal, and the second sub-optical carrier signal is converted by a second photodetector to obtain a second output signal. The first and second output signals are then processed by an analog-to-digital converter and a baseband signal processing component for subsequent coherent detection of the first output signal, thereby determining the speed and distance of the target from which the reflected microwave signal is obtained.

[0144] In some embodiments, the method further includes the following step prior to step 201:

[0145] Step 20A: Receive the initial input signal through the signal modulation unit, and modulate the initial input signal to obtain the first input signal.

[0146] Step 20B: Generate a first optical signal using the second laser, receive the first input signal sent by the signal modulation unit and the first optical signal sent by the second laser through the phase modulator, and generate a second optical signal based on the first input signal and the first optical signal.

[0147] In practice, a signal modulation unit modulates the received initial input signal to an intermediate frequency, obtaining a first input signal. A second laser generates and emits a first optical signal. Based on the first optical signal, a phase modulator transfers the first input signal onto an optical wave to obtain a second optical signal.

[0148] Step 20C: The second optical signal is transmitted to the third optical amplifier via the fifth circulator, the dispersion compensation fiber and the fourth circulator to amplify the frequency of the second optical signal to obtain the third optical signal.

[0149] Step 20D: The third optical signal is split by a polarization beam splitter to obtain an initial first sub-optical signal and an initial second sub-optical signal. The initial second sub-optical signal is then sent to the amplitude modulator for modulation based on the initial second sub-optical signal.

[0150] In specific implementation, the initial second sub-optical signal is sent to the amplitude modulator so that the amplitude modulator can modulate based on the initial second sub-optical signal. Specifically, based on the initial second sub-optical signal, the amplitude modulator transfers the first microwave signal onto an optical wave to obtain an initial optical carrier signal.

[0151] Step 20E: The initial first sub-optical signal is filtered using a band-stop filter to obtain the first sub-optical signal.

[0152] Step 20F: The first sub-optical signal is converted by the third photodetector to obtain the first output electrical signal.

[0153] Step 20G: Receive the first output electrical signal sent by the third photodetector, amplify the frequency of the second output electrical signal, and obtain the second output electrical signal.

[0154] Step 20H: The second output electrical signal is frequency-converted using the second frequency converter to obtain a third output electrical signal. The third output electrical signal is then emitted via the duplexer, wherein the frequency of the third output electrical signal is greater than the frequency of the second output electrical signal. The third output signal is reflected to obtain the initial microwave signal.

[0155] In specific implementation, the second frequency converter is an up-conversion frequency converter. Therefore, the second frequency converter is used to perform frequency conversion processing on the second output electrical signal to obtain a third output electrical signal. The frequency of the third output electrical signal is greater than the frequency of the second output electrical signal. The third output electrical signal is transmitted through a duplexer, and after being reflected by the target, the initial microwave signal is obtained.

[0156] In some embodiments, step 20A specifically includes:

[0157] Step 20A1: Receive the transmitted data through the baseband signal processing component, perform baseband signal processing on the transmitted data, and obtain the first initial input signal.

[0158] Step 20A2: Use an analog-to-digital converter to convert the type of the first initial input signal.

[0159] In specific implementation, the first initial input signal is sampled by the analog-to-digital converter, and the type of the first initial input signal is converted from an analog signal to a digital signal.

[0160] Step 20A3: Filter the first initial input signal using a filter to obtain the filtered first initial input signal.

[0161] Step 20A4: Receive the filtered first initial input signal and the second initial input signal generated by the local oscillator, and combine the filtered first initial input signal and the second initial input signal through the signal processing component to obtain the third initial input signal.

[0162] In a specific implementation, the filtered first initial input signal and the second initial input signal generated by the local oscillator are combined by the signal processing component to obtain the third initial input signal, wherein the combination method is to multiply the filtered first initial input signal and the second initial input signal.

[0163] Step 20A5: The frequency of the third initial input signal is amplified by the first electrical amplifier to obtain the first input signal.

[0164] In some embodiments, when multiple wavelengths of optical carrier signals need to be transmitted, a wavelength division multiplexing (WDM) multiplexer can be used to combine the multiple wavelengths of optical carrier signals together and couple them into the same optical fiber for transmission. After transmission, a demultiplexer is used to separate the multiple wavelengths of optical carrier signals transmitted through the optical fiber. By extending the optical fiber, multiple antennas can share the same processing unit and optical devices, reducing system costs and improving geographical coverage.

[0165] It should be noted that the method of this disclosure embodiment can be executed by a single device, such as a computer or server. The method of this embodiment can also be applied to a distributed scenario, where multiple devices cooperate to complete the task. In such a distributed scenario, one of these devices may execute only one or more steps of the method of this disclosure embodiment, and the multiple devices will interact with each other to complete the method described.

[0166] It should be noted that the above description describes some embodiments of this disclosure. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in a different order than that shown in the above embodiments and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0167] Based on the same inventive concept, corresponding to the methods of any of the above embodiments, this disclosure also provides a non-transitory computer-readable storage medium storing computer instructions for causing the computer to execute the phase-locking method as described in any of the above embodiments.

[0168] The computer-readable medium of this embodiment includes permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transfer medium that can be used to store information accessible by a computing device.

[0169] The computer instructions stored in the storage medium of the above embodiments are used to cause the computer to execute the phase locking method as described in any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0170] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this disclosure (including the claims) is limited to these examples; within the framework of this disclosure, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of this disclosure as described above, which are not provided in detail for the sake of brevity.

[0171] Additionally, to simplify the description and discussion, and to avoid obscuring the embodiments of this disclosure, the provided drawings may or may not show well-known power / ground connections to integrated circuit (IC) chips and other components. Furthermore, the apparatus may be shown in block diagram form to avoid obscuring the embodiments of this disclosure, and this also takes into account the fact that the details of implementation of these block diagram apparatuses are highly dependent on the platform on which the embodiments of this disclosure will be implemented (i.e., these details should be fully understood by those skilled in the art). While specific details (e.g., circuitry) have been set forth to describe exemplary embodiments of this disclosure, it will be apparent to those skilled in the art that the embodiments of this disclosure may be implemented without these specific details or with variations thereof. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0172] Although this disclosure has been described in conjunction with specific embodiments thereof, many substitutions, modifications, and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may be used with the embodiments discussed.

[0173] This disclosure is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A fiber optic remote extension system integrating communication and radar, characterized in that, include: The far-end antenna unit is configured to receive reflected microwave signals and perform amplitude modulation on the microwave signals to obtain an initial optical carrier signal; A dispersion compensation unit, connected to the far-end antenna unit, is configured to receive the initial optical carrier signal transmitted by the far-end antenna unit, perform dispersion compensation on the initial optical carrier signal, and obtain an optical carrier signal. The central unit, connected to the dispersion compensation unit, is configured to receive the optical carrier signal sent by the dispersion compensation unit, perform phase locking using the received optical carrier signal, and obtain an output optical signal, wherein the frequency of the output optical signal is the same as the frequency of the optical carrier signal, and the phase of the output optical signal is the same as the phase of the optical carrier signal. A signal output unit, connected to the central unit, is configured to receive the output optical signal sent by the central unit and output the output optical signal. The dispersion compensation unit includes: The second circulator includes a first port, a second port, and a third port. The third port of the second circulator is connected to the far-end antenna unit and is configured to receive the initial optical carrier signal and control the unidirectional operation of the signal passing through the second circulator. The direction of the unidirectional operation is from the first port of the second circulator to the second port of the second circulator to the third port of the second circulator. The transmission optical fiber is connected to the first port of the second circulator and is configured to receive the initial optical carrier signal transmitted by the second circulator and transmit the initial optical carrier signal. The third circulator includes a first port, a second port, and a third port. The second port of the third circulator is connected to the transmission optical fiber and is configured to receive the initial optical carrier signal and control the unidirectional operation of the signal passing through the third circulator. The direction of the unidirectional operation is from the first port of the third circulator to the second port of the third circulator and then to the third port of the third circulator. The second optical amplifier, connected to the third port of the third circulator, is configured to receive the initial optical carrier signal transmitted by the third circulator, and amplify the frequency of the initial optical carrier signal to obtain a first initial amplified optical carrier signal. The fourth circulator includes a first port, a second port, and a third port. The third port of the fourth circulator is connected to the second optical amplifier and is configured to receive the first initial amplified optical carrier signal and control the unidirectional operation of the signal passing through the fourth circulator. The direction of the unidirectional operation is from the first port of the fourth circulator to the second port of the fourth circulator to the third port of the fourth circulator. A dispersion-compensating fiber is connected to the first port of the fourth circulator and is configured to receive the first initial amplified optical carrier signal transmitted by the fourth circulator, perform dispersion compensation processing on the first initial amplified optical carrier signal, and obtain an optical carrier signal. A fifth circulator, comprising a first port, a second port, and a third port, wherein the second port of the fifth circulator is connected to the dispersion compensation fiber, and the third port of the fifth circulator is connected to a first optical amplifier, and is configured to control the unidirectional operation of signals passing through the fifth circulator, wherein the direction of unidirectional operation is from the first port of the fifth circulator to the second port of the fifth circulator to the third port of the fifth circulator.

2. The integrated fiber optic remote communication and radar system according to claim 1, characterized in that, The central unit includes: A first optical amplifier is connected to the dispersion compensation unit and is configured to receive the optical carrier signal sent by the dispersion compensation unit, amplify the frequency of the optical carrier signal, and obtain a first optical carrier signal. The optical injection internal control unit is connected to the first optical amplifier and is configured to receive the first optical carrier signal sent by the first optical amplifier, and use the first optical carrier signal to perform phase locking to obtain the output optical signal.

3. The integrated fiber optic remote communication and radar system according to claim 2, characterized in that, The optical injection internal modulation unit includes: A power divider, connected to the first optical amplifier, is configured to divide the first optical carrier signal to obtain a first sub-optical carrier signal and a second sub-optical carrier signal; A first circulator, comprising a first port, a second port and a third port, wherein the first port of the first circulator is connected to the power divider and is configured to receive the first sub-optical carrier signal and control the unidirectional operation of the signal passing through the first circulator, wherein the direction of the unidirectional operation is from the first port of the first circulator to the second port of the first circulator to the third port of the first circulator. A first laser is configured to be connected to a second port of the first circulator and to receive a first sub-optical carrier signal transmitted by the first circulator, and to generate an output optical signal based on the first sub-optical carrier signal.

4. The integrated fiber optic remote communication and radar system according to claim 3, characterized in that, The signal output unit includes: A first photodetector is connected to the third port of the first circulator and is configured to receive the output optical signal transmitted by the first circulator, convert the output optical signal to obtain a first output signal, and output the first output signal via an analog-to-digital converter. The second photodetector is connected to the power divider and is configured to receive the second sub-optical carrier signal sent by the power divider, perform conversion processing on the second sub-optical carrier signal to obtain a second output signal, and output the second output signal via an analog-to-digital converter.

5. The integrated fiber optic remote communication and radar system according to claim 1, characterized in that, The remote antenna element includes: A duplexer is configured to receive the reflected initial microwave signal; A first frequency converter, connected to the duplexer, is configured to receive an initial microwave signal sent by the duplexer, perform frequency conversion processing on the initial microwave signal to obtain a first microwave signal, wherein the frequency of the first microwave signal is less than the frequency of the initial microwave signal. An amplitude modulator, with one end connected to the first frequency converter and the other end connected to the third port of the second circulator, is configured to receive a first microwave signal sent by the first frequency converter, perform amplitude modulation on the first microwave signal to obtain an initial optical carrier signal, and send the initial optical carrier signal to the second circulator.

6. The integrated fiber optic remote communication and radar system according to claim 1, characterized in that, Also includes: A signal modulation unit is configured to receive an initial input signal and modulate the initial input signal to obtain a first input signal. A second laser is configured to generate the first optical signal; A phase modulator is connected to the first port of the signal modulation unit, the second laser, and the fifth circulator, respectively, and is configured to receive a first input signal sent by the signal modulation unit and a first optical signal sent by the second laser, and generate a second optical signal based on the first input signal and the first optical signal. The third optical amplifier, with one end connected to the second port of the fourth circulator and the other end connected to the first port of the third circulator, is configured to receive the second optical signal transmitted via the fifth circulator, the dispersion compensation fiber and the fourth circulator, and amplify the frequency of the second optical signal to obtain the third optical signal.

7. The integrated fiber optic remote communication and radar system according to claim 6, characterized in that, The signal modulation unit includes: A baseband signal processing component is configured to receive transmitted data and perform baseband signal processing on the transmitted data to obtain a first initial input signal; An analog-to-digital converter, connected to the baseband signal processing component, is configured to receive the first initial input signal and convert the type of the first initial input signal; A filter, connected to the analog-to-digital converter, is configured to receive a sampled first initial input signal sent by the analog-to-digital converter, and to filter the first initial input signal to obtain a filtered first initial input signal. The local oscillator is configured to generate a second initial input signal; A signal processing component, connected to the filter and the local oscillator respectively, is configured to receive a filtered first initial input signal sent by the filter and a second initial input signal sent by the local oscillator, and to combine the filtered first initial input signal and the second initial input signal to obtain a third initial input signal. A first electrical amplifier, with one end connected to the signal processing component and the other end connected to the phase modulator, is configured to receive a third initial input signal sent by the signal processing component, amplify the frequency of the third initial input signal, and obtain a first input signal.

8. The integrated fiber optic remote communication and radar system according to claim 5, characterized in that, The remote antenna unit further includes: A polarization beam splitter, with one end connected to the second port of the second circulator and the other end connected to an amplitude modulator, is configured to receive a third optical signal transmitted by the second circulator, split the third optical signal to obtain an initial first sub-optical signal and an initial second sub-optical signal, and send the initial second sub-optical signal to the amplitude modulator for modulation based on the initial second sub-optical signal. A band-stop filter, connected to the polarization beamsplitter, is configured to receive the initial first sub-optical signal sent by the polarization beamsplitter, and to filter the initial first sub-optical signal to obtain a first sub-optical signal. The third photodetector, connected to the band-stop filter, is configured to receive the first sub-optical signal sent by the band-stop filter, and convert the first sub-optical signal to obtain the first output electrical signal. The second electrical amplifier is connected to the third photodetector and is configured to receive the first output electrical signal sent by the third photodetector, amplify the frequency of the first output electrical signal, and obtain the second output electrical signal. The second frequency converter is connected at one end to the second electrical amplifier and at the other end to the duplexer. It is configured to receive the second output electrical signal sent by the second electrical amplifier, perform frequency conversion processing on the second output electrical signal to obtain a third output electrical signal, and emit the third output electrical signal through the duplexer. The frequency of the third output electrical signal is greater than the frequency of the second output electrical signal. The third output electrical signal is reflected to obtain the initial microwave signal.

9. A phase-locking method, characterized in that, The communication and radar integrated fiber optic remote extension system according to any one of claims 1-8 comprises: The microwave signal is received by the remote antenna unit, the microwave signal is amplitude modulated to obtain an initial optical carrier signal, and the initial optical carrier signal is sent to the dispersion compensation unit. The initial optical carrier signal is subjected to dispersion compensation processing to obtain the optical carrier signal; The optical carrier signal is sent to the central unit, which then performs phase locking on the received optical carrier signal to obtain the output optical signal. The output optical signal is output using a signal output unit.

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