Radio frequency signal optical fiber synchronous conversion system

Abstract

The invention provides a radio frequency signal optical fiber synchronous conversion system, and particularly relates to the technical field of signal conversion and transmission. According to the invention, the central station unit platform and the antenna unit platform are interconnected only by adopting one single-core phase-stabilized optical cable, passive optical fiber devices such as an optical wavelength division multiplexer, an optical add drop multiplexer and an optical circulator are fully utilized, an optical path structure is redesigned based on an optical multiplexing technology, and single-core optical fiber two-way transmission of multiple paths of radio frequency signals is realized. And a reliable phase discrimination control module is matched to monitor the link phase drift in real time and feed back and control the delay amount of an optical path to carry out phase tracking compensation of the signal, so that stable-phase optical transmission of the radio-frequency signal is realized. Furthermore, the optical link composition structure under the condition of complex signal transmission is greatly simplified, the problem of inconsistent phase drift of the multi-core optical cable caused by external and self factors is physically avoided through the single-core optical cable interconnection mode, the signal phase is clamped in real time by combining phase monitoring and control, and the signal transmission efficiency is improved. And the signal phase of the radio frequency optical transmission link is ensured to be stable.

Description

Technical Field

[0001] This invention belongs to the field of signal transmission technology, and specifically relates to a radio frequency signal fiber optic synchronous conversion system. Background Technology

[0002] Optical transmission components using optical fiber as the transmission medium are widely used in distributed radar systems. Compared to traditional coaxial cables, they offer advantages such as longer transmission distance, higher operating frequency, larger communication capacity, resistance to electromagnetic interference, and lighter weight, leading to their widespread application. Most existing optical transmission components are based on digital optical communication technology, requiring complex clock recovery and decision circuits for reception, increasing power consumption and design complexity at the antenna platform. Radio frequency (RF) optical transmission, a branch of optical communication technology, essentially belongs to the analog communication field. It achieves distortion-free linear transmission of RF signals and offers significant advantages in size and power consumption compared to digital optical transmission.

[0003] While existing RF optical transmission component link structure design methods make good use of technologies such as optical multiplexing and phase control, they are mostly multi-path point-to-point unidirectional direct connections. At the receiving end, phase consistency of the signal is indirectly achieved by using phase detection between adjacent links and independent electronically controlled optical delay. This method is not suitable for applications requiring stable phase bidirectional transmission over a single fiber, which also needs to handle both transmission and reception, and cannot meet the application requirements of precise RF calibration, such as target ranging. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a radio frequency signal fiber optic synchronous conversion system to achieve bidirectional and phase-stable transmission of multiple radio frequency signals through a single-core fiber.

[0005] The first aspect discloses a radio frequency signal fiber optic synchronous conversion system, the system comprising: an uplink transmission transmitting module, an uplink transmission receiving module, a downlink transmission transmitting module, a downlink transmission receiving module, a central station optical path branching module, an antenna unit optical path branching module, and a single-core stable phase optical cable;

[0006] The uplink transmission transmitting module is used for optical modulation of the uplink input electrical signal to obtain a modulated uplink optical signal, and performs phase adjustment on the uplink optical signal according to the coupling signal and the coupling feedback signal output by the uplink transmission receiving module; the uplink transmission receiving module is used to receive the uplink optical signal, and perform photoelectric conversion to obtain a demodulated uplink output electrical signal, and obtain a coupling feedback signal according to the uplink output electrical signal; the downlink transmission transmitting module is used for optical modulation of the downlink echo electrical signal to obtain a modulated downlink optical signal, wherein the downlink echo electrical signal includes the coupling feedback signal; the downlink transmission receiving module is used to receive the downlink optical signal, and perform photoelectric conversion to obtain a demodulated downlink output electrical signal; the central station optical path branching module is used to realize uplink and downlink optical signal branching, multiplexing and demultiplexing at the central station platform; the antenna unit optical path branching module is used to realize uplink and downlink optical signal branching, add / drop and reconstruction, multiplexing and demultiplexing at the antenna unit platform; the single-core stable phase optical cable interconnects the two ends of the antenna unit platform and the central station platform, providing a stable phase bidirectional transmission medium for optical signals.

[0007] In one possible implementation, the uplink transmission module includes: a low-frequency input signal electro-optic conversion channel; the low-frequency input signal electro-optic conversion channel includes a low-frequency directional coupler, a directly modulated laser ITU-C26, and a low-frequency phase detection control module; the low-frequency directional coupler is used to couple and distribute the low-frequency input signal, with the larger output power portion serving as the main output of the through-hole, and the smaller output power portion serving as the low-frequency coupled signal input to the low-frequency phase detection control module; the directly modulated laser ITU-C26 is used to realize optical modulation of the low-frequency input signal to obtain a low-frequency uplink optical signal; the low-frequency phase detection control module is used to perform phase adjustment on the low-frequency uplink optical signal based on the acquired low-frequency coupled signal and the low-frequency coupled feedback signal.

[0008] As one possible implementation, the low-frequency phase detection control module includes: a first IQ demodulator, a first delay control circuit, and a first optical delay unit; the first IQ demodulator is used to acquire the phase difference between the low-frequency coupled signal and the low-frequency coupled feedback signal; the first delay control circuit calculates the corresponding delay amount based on the phase difference and feeds the delay amount back to the first optical delay unit to perform phase adjustment on the low-frequency uplink optical signal.

[0009] In one possible implementation, the uplink transmission module includes: a high-frequency input signal electro-optic conversion channel; the high-frequency input signal electro-optic conversion channel includes a high-frequency directional coupler, a directly modulated laser ITU-C30, and a high-frequency phase detection control module; the high-frequency directional coupler is used to couple and distribute the high-frequency input signal, with the portion with higher output power serving as the main output of the through-hole, and the portion with lower output power serving as the high-frequency coupled signal input to the high-frequency phase detection control module; the directly modulated laser ITU-C30 is used to achieve optical modulation of the high-frequency input signal to obtain a high-frequency uplink optical signal; the high-frequency phase detection control module is used to perform phase adjustment on the high-frequency uplink optical signal based on the acquired high-frequency coupled signal and the high-frequency coupled feedback signal.

[0010] In one possible implementation, the high-frequency phase detection control module includes: a second IQ demodulator, a second delay control circuit, and a second optical delay unit; the second IQ demodulator is used to acquire the phase difference between the high-frequency coupled signal and the high-frequency coupled feedback signal; the second delay control circuit calculates the corresponding delay amount based on the phase difference and feeds the delay amount back to the second optical delay unit to perform phase adjustment on the high-frequency uplink optical signal.

[0011] In one possible implementation, the uplink transmission receiving module includes: a low-frequency output signal photoelectric conversion channel and a high-frequency output signal photoelectric conversion channel; the low-frequency output signal photoelectric conversion channel includes a low-frequency directional coupler, which is used to perform power distribution on the photoelectric converted uplink optical signal, with the portion with higher output power serving as the main output at the through end and the portion with lower output power serving as the secondary output at the coupling end, and the secondary output portion serving as the low-frequency coupling feedback signal for link backhaul; the high-frequency output signal photoelectric conversion channel includes a high-frequency directional coupler, which is used to perform power distribution on the photoelectric converted uplink optical signal, with the portion with higher output power serving as the main output at the through end and the portion with lower output power serving as the secondary output at the coupling end, and the secondary output portion serving as the high-frequency coupling feedback signal for link backhaul.

[0012] As one possible implementation, the downlink transmission transmitting module includes: a low-frequency coupling feedback signal electro-optic conversion channel, used to perform electro-optic conversion on the low-frequency coupling feedback signal output by the uplink transmission receiving module, and transmit the downlink optical signal containing the low-frequency coupling feedback signal to the antenna unit optical path branch module; and a high-frequency coupling feedback signal electro-optic conversion channel, used to perform electro-optic conversion on the high-frequency coupling feedback signal output by the uplink transmission receiving module, and transmit the downlink optical signal containing the high-frequency coupling feedback signal to the antenna unit optical path branch module.

[0013] As one possible implementation, the central station optical path branching module includes: a first dense wavelength division multiplexer (DWDM), a second DWDM, and a first fiber optic circulator; the first DWDM receives uplink optical signals and performs optical path multiplexing and wavelength division, transmitting them to the first fiber optic circulator; the second DWDM receives downlink optical signals and performs optical path demultiplexing; the first fiber optic circulator completes the uplink and downlink branching of bidirectional optical signals.

[0014] As one possible implementation, the antenna unit optical path branching module includes: a third dense wavelength division multiplexer (DWDM), an optical add-drop multiplexer (OPD), and a second fiber optic circulator. The third DWDM receives downlink optical signals and outputs them to the loading port of the OPD after completing optical path multiplexing and wavelength division. The OPD is used to download the C26 and C30 channels from the uplink optical path and load the downlink optical path output by the third DWDM, thereby achieving optical path reconstruction without changing the wavelength channels. The second fiber optic circulator completes the uplink and downlink branching of bidirectional optical signals.

[0015] As one possible implementation, the temperature drift coefficient of the single-core stable phase optical cable is ≤15ps / km / ℃, and the optical connectors at both ends are of type FC / APC.

[0016] The beneficial effects of this invention are as follows: It interconnects the central station unit platform and antenna unit platform using only a single-core stable phase optical cable, fully utilizing passive fiber optic devices such as optical wavelength division multiplexers, optical add-drop multiplexers, and optical circulators. Based on optical multiplexing technology, the optical path structure is redesigned, achieving bidirectional transmission of multiple RF signals over a single-core fiber. Furthermore, a reliable phase detection control module monitors link phase drift in real time and provides feedback control to adjust optical path delay for signal phase tracking compensation, thus achieving stable phase transmission of RF signals. This invention greatly simplifies the optical link structure under complex signal transmission conditions. The single-core optical cable interconnection method physically avoids the phase drift inconsistency problem caused by external and internal factors in multi-core optical cables. Combined with phase monitoring and control, it clamps the signal phase in real time, ensuring the stability of the RF optical transmission link signal phase. Attached Figure Description

[0017] Figure 1 This is a structural diagram of a radio frequency signal fiber optic synchronous conversion component according to the present invention.

[0018] Figure 2 This is a structural diagram of the uplink transmission module for the component.

[0019] Figure 3 The diagram shows the structure of the low-frequency phase detection control module and the high-frequency phase detection control module.

[0020] Figure 4 This is a structural diagram of the uplink transmission and receiving module of the component.

[0021] Figure 5 This is a structural diagram of the downlink transmission transmission module of the component.

[0022] Figure 6 This is a structural diagram of the downlink transmission and receiving module of the component.

[0023] Figure 7 This is a structural diagram of the optical path branch module of the component center station.

[0024] Figure 8 This is a structural diagram of the optical path branch module for the component antenna unit. Detailed Implementation

[0025] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0027] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," "up," "down," and similar expressions used herein are for illustrative purposes only and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0028] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0029] To achieve the above objectives, the present invention provides a radio frequency signal fiber optic synchronous conversion system, which is mainly applied to phased array radar systems.

[0030] In one embodiment, such as Figure 1 As shown, the present invention provides a radio frequency signal fiber optic synchronous conversion system, comprising seven parts: an uplink transmission transmitting module, an uplink transmission receiving module, a downlink transmission transmitting module, a downlink transmission receiving module, a central station optical path branching module, an antenna unit optical path branching module, and a single-core stable phase optical cable.

[0031] The uplink transmission transmitter module is used for optical modulation of the uplink input electrical signal to obtain the modulated uplink optical signal, and performs phase adjustment on the uplink optical signal according to the coupling signal and the coupling feedback signal output by the uplink transmission receiver module; the uplink transmission receiver module is used to receive the uplink optical signal, and perform photoelectric conversion to obtain the demodulated uplink output electrical signal, and obtain the coupling feedback signal according to the uplink output electrical signal.

[0032] The downlink transmission transmitting module is used for optical modulation of the downlink echo electrical signal to obtain the modulated downlink optical signal, wherein the downlink echo electrical signal includes the coupling feedback signal; the downlink transmission receiving module is used to receive the downlink optical signal, and after photoelectric conversion, obtain the demodulated downlink output electrical signal.

[0033] The central station optical path branching module is used to realize uplink and downlink optical signal branching, multiplexing and demultiplexing at the central station platform; the antenna unit optical path branching module is used to realize uplink and downlink optical signal branching, insertion and reconfiguration, multiplexing and demultiplexing at the antenna unit platform; the single-core stable phase optical cable interconnects the antenna unit platform and the central station platform, providing a stable phase bidirectional transmission medium for optical signals.

[0034] It should be noted that the radio frequency signal to be transmitted, i.e., the uplink input electrical signal, includes high-frequency input signals and low-frequency input signals. The high and low frequency input signals are processed and transmitted through their respective channels, thus realizing the transmission of multiple radio frequency signals. Furthermore, by constructing low-frequency and high-frequency channels, the application requirements of phased array radar systems, such as actual target ranging, which require precise radio frequency calibration, can be met.

[0035] In one embodiment, the uplink transmission module includes a low-frequency input signal electro-optic conversion channel.

[0036] The low-frequency input signal electro-optic conversion channel includes a low-frequency directional coupler, a direct-modulated laser (ITU-C26), and a low-frequency phase detection control module.

[0037] Specifically, the low-frequency directional coupler is used to couple and distribute the low-frequency input signal. The portion with higher output power is used as the main output of the through-hole, and the portion with lower output power is used as the low-frequency coupled signal input to the low-frequency phase detection control module. The directly modulated laser ITU-C26 is used to realize the optical modulation of the low-frequency input signal to obtain the low-frequency uplink optical signal. The low-frequency phase detection control module is used to adjust the phase of the low-frequency uplink optical signal according to the acquired low-frequency coupled signal and the low-frequency coupled feedback signal.

[0038] Furthermore, the low-frequency phase detection control module includes: a first IQ demodulator, a first delay control circuit, and a first optical delay unit; wherein, the first IQ demodulator is used to acquire the phase difference between the low-frequency coupled signal and the low-frequency coupled feedback signal; the first delay control circuit calculates the corresponding delay amount based on the phase difference and feeds the delay amount back to the first optical delay unit to perform phase adjustment on the low-frequency uplink optical signal.

[0039] In one embodiment, the uplink transmission module includes: a high-frequency input signal electro-optic conversion channel. Wherein,

[0040] The high-frequency input signal electro-optic conversion channel includes a high-frequency directional coupler, a direct-modulated laser ITU-C30, and a high-frequency phase detection control module.

[0041] Specifically, the high-frequency directional coupler is used to couple and distribute the high-frequency input signal. The portion with higher output power is used as the main output of the through-hole, and the portion with lower output power is used as the high-frequency coupling signal input to the high-frequency phase detection control module. The direct-modulated laser ITU-C30 is used to realize the optical modulation of the high-frequency input signal to obtain the high-frequency uplink optical signal. The high-frequency phase detection control module is used to adjust the phase of the high-frequency uplink optical signal according to the acquired high-frequency coupling signal and the high-frequency coupling feedback signal.

[0042] Furthermore, the high-frequency phase detection control module includes: a second IQ demodulator, a second delay control circuit, and a second optical delay unit; wherein, the second IQ demodulator is used to obtain the phase difference between the high-frequency coupled signal and the high-frequency coupled feedback signal; the second delay control circuit calculates the corresponding delay amount based on the phase difference and feeds back the delay amount to the second optical delay unit to perform phase adjustment on the high-frequency uplink optical signal.

[0043] In one specific embodiment, such as Figure 2As shown, the uplink transmission module includes four electro-optic conversion channels: a low-frequency input signal electro-optic conversion channel, a high-frequency input signal electro-optic conversion channel, a low-frequency standard transmission signal electro-optic conversion channel, and a high-frequency standard transmission signal electro-optic conversion channel.

[0044] It should be noted that low-frequency and high-frequency calibration signals are mainly used to calibrate parameters such as azimuth, range, and angle of the phased array radar system. These signals allow for the determination of signal deviations caused by the actual fiber optic link, providing a reliable calibration reference for actual low-frequency and high-frequency transmissions, thus fulfilling the closed-loop calibration function of the phased array radar system.

[0045] The low-frequency input signal electro-optic conversion channel includes: a low-frequency directional coupler, a low-frequency low-noise amplifier, a directly modulated laser (ITU-C26), and a low-frequency phase detection control module. The low-frequency directional coupler couples and distributes the low-frequency input signal, with the higher-power portion serving as the main output at the through-pass end and the lower-power portion as the secondary output at the coupling end. The secondary output serves as the input reference source for the low-frequency phase detection control module. The low-frequency low-noise amplifier receives the through-pass output from the directional coupler and performs pre-stage low-noise amplification to reduce the overall noise figure of the channel link and improve the system signal-to-noise ratio. The directly modulated laser (ITU-C26) performs optical modulation of the transmitted RF signal, completes the RF loading of the optical carrier, and outputs the modulated optical signal to the optical input port of the low-frequency phase detection control module. The low-frequency phase detection control module acquires the low-frequency coupled input signal and the low-frequency coupled feedback signal. The phase difference between the two signals is obtained through the IQ demodulation circuit within the module. The corresponding delay is calculated based on the obtained phase difference. The delay control circuit, with the microcontroller MCU as its core, feeds back the delay to the optical delay unit in real time, thereby achieving precise adjustment of the phase of the low-frequency input signal.

[0046] The low-frequency standard transmission signal electro-optical conversion channel includes a low-frequency low-noise amplifier and a directly modulated laser (ITU-C28). The low-frequency low-noise amplifier receives the low-frequency standard transmission input signal and performs pre-stage low-noise power amplification to reduce the overall noise figure of the channel link. The directly modulated laser (ITU-C28) performs optical modulation on the standard transmission signal before outputting it.

[0047] The high-frequency input signal electro-optic conversion channel includes a high-frequency directional coupler, a high-frequency low-noise amplifier, a directly modulated laser (ITU-C30), and a high-frequency phase detection control module. These devices have the same functions as their counterparts in the low-frequency input signal electro-optic conversion channel, but their specifications differ slightly. Details regarding the parameter configurations of specific devices are provided below and will not be elaborated upon here.

[0048] The high-frequency standard signal electro-optic conversion channel includes a high-frequency low-noise amplifier and a directly modulated laser (ITU-C32). These devices have the same function as their counterparts in the low-frequency standard signal electro-optic conversion channel, but their specifications differ slightly. Details regarding the parameter configurations of specific devices are provided below and will not be elaborated upon here.

[0049] In addition, such as Figure 3 As shown, specifically, the low-frequency coupled input signal and the low-frequency coupled feedback signal are mixed with the local low-phase-noise low-frequency signal source by a low-frequency mixer to complete the low-frequency signal down-conversion. Then, they are input to the IQ demodulator and decomposed into two orthogonal signal outputs containing phase information. The real-time phase difference of the low-frequency signal round-trip loop is obtained by the arctangent or anticotangent program of the microcontroller of the delay control circuit. Using the mathematical relationship between phase and time, the delay of the motorized optical delay line is controlled in real time to achieve accurate compensation of the link phase.

[0050] The high-frequency phase detection control module and the low-frequency phase detection control module have the same functions, but their specifications are slightly different. For details, please refer to the parameter configuration of the specific components below.

[0051] Furthermore, the specific configurations of each submodule in the uplink transmission module are as follows: Low-frequency directional coupler coupling: 6dB, insertion loss: ≤3dB; Low-frequency low-noise amplifier operating frequency: 8GHz-12GHz, noise figure: ≤2.5dB, gain: ≥10dB, output P-1: ≥15dB; High-frequency directional coupler coupling: 6dB, insertion loss: ≤3dB; High-frequency low-noise amplifier operating frequency: 12GHz-18GHz, noise figure: ≤2.5dB, gain: ≥10dB, output P-1: ≥15dB; Direct-tuned laser ITC-C26 center wavelength: 1556.55nm, Direct-tuned laser ITU-... C28 center wavelength: 1554.94nm; ITC-C30 direct-modulated laser center wavelength: 1553.33nm; ITU-C32 direct-modulated laser center wavelength: 1551.72nm; modulation bandwidth of the above direct-modulated lasers: 2GHz-18GHz; output optical power: ≥10dBm; low phase noise low-frequency signal source operating frequency: 8GHz; phase noise: ≤-95dBc / Hz@100KHz; low phase noise high-frequency signal source operating frequency: 15GHz; phase noise: ≤-92dBc / Hz@100KHz; IQ demodulator operating frequency: 400MHz-6GHz; intermediate frequency bandwidth: DC-390 MHz; amplitude balance: 0.07dB; phase accuracy: 0.2°; optical delayer operating wavelength: ITU-C; maximum delay time: 2ns; step accuracy: ≥1ps; return loss: ≥55dB.

[0052] In one embodiment, such as Figure 4 As shown, the uplink transmission and receiving module includes two electro-optical conversion channels: a low-frequency output signal photoelectric conversion channel and a high-frequency output signal photoelectric conversion channel.

[0053] The low-frequency output signal photoelectric conversion channel includes a low-frequency directional coupler. The low-frequency directional coupler is used to distribute the power of the uplink optical signal after photoelectric conversion. The part with larger output power is used as the main output of the through end, and the part with smaller output power is used as the secondary output of the coupling end. The secondary output part is used as the low-frequency coupling feedback signal for link backhaul.

[0054] The high-frequency output signal photoelectric conversion channel includes a high-frequency directional coupler. The high-frequency directional coupler is used to distribute the power of the uplink optical signal after photoelectric conversion. The part with larger output power is used as the main output of the through end, and the part with smaller output power is used as the secondary output of the coupling end. The secondary output part is used as the high-frequency coupling feedback signal for link backhaul.

[0055] Specifically, the low-frequency output signal photoelectric conversion channel includes a photodetector, a low-frequency controllable gain amplifier, a low-frequency directional coupler, and a 90° bridge-L. The photodetector receives the uplink optical signal, performs photoelectric conversion, and outputs it to the low-frequency controllable gain amplifier. After amplitude controllable adjustment, the output is sent to the low-frequency directional coupler. The low-frequency directional coupler performs power distribution on the amplified signal, with the larger output power serving as the main output at the through end and the smaller output power serving as the secondary output at the coupling end. The secondary output is used as the coupling feedback signal for the link return. The 90° bridge-L receives the main output of the low-frequency directional coupler and, after phase adjustment, outputs equal-amplitude, orthogonal low-frequency left-hand and right-hand rotary radio frequency signals as the antenna transmission signal source.

[0056] The high-frequency output signal photoelectric conversion channel includes a photodetector, a high-frequency controllable gain amplifier, a high-frequency directional coupler, and a 90° bridge-H. These devices have the same function as the corresponding devices in the low-frequency output signal photoelectric conversion channel, but their specifications are slightly different. For details, please refer to the parameter configuration of the specific devices below.

[0057] Furthermore, the specific configurations of each submodule in the uplink transmission and reception module are as follows: photodetector frequency bandwidth: DC-18GHz, wavelength range: 800nm-1650nm, responsivity: ≥0.85mA / mW; low-frequency controllable gain amplifier operating frequency: 8GHz-12GHz, gain range: 15dB-25dB; high-frequency controllable gain amplifier operating frequency: 12GHz-18GHz, gain range: 15dB-25dB; low-frequency directional coupler coupling, high-frequency directional coupler coupling degree: 10dB, insertion loss: ≤3dB; 90° bridge-L operating frequency: 8GHz-12GHz, amplitude balance: ≤1.0dB, phase balance: ≤6°; 90° bridge-H operating frequency: 12GHz-18GHz, amplitude balance: ≤1.0dB, phase balance: ≤6°.

[0058] In one embodiment, the downlink transmission transmission module includes: a low-frequency coupled feedback signal electro-optic conversion channel and a high-frequency coupled feedback signal electro-optic conversion channel.

[0059] Specifically, the low-frequency coupling feedback signal electro-optic conversion channel is used to electro-optically convert the low-frequency coupling feedback signal output by the uplink transmission receiving module, and send the downlink optical signal containing the low-frequency coupling feedback signal to the antenna unit optical path branch module.

[0060] The high-frequency coupled feedback signal electro-optic conversion channel is used to convert the high-frequency coupled feedback signal output by the uplink transmission receiving module into an electro-optic signal and send the downlink optical signal containing the high-frequency coupled feedback signal to the antenna unit optical path branch module.

[0061] In one specific embodiment, such as Figure 5 As shown, the downlink transmission module includes six electro-optic conversion channels: a low-frequency left-handed echo signal electro-optic conversion channel, a low-frequency right-handed echo signal electro-optic conversion channel, a high-frequency left-handed echo signal electro-optic conversion channel, a high-frequency right-handed echo signal electro-optic conversion channel, a low-frequency coupled feedback signal electro-optic conversion channel, and a high-frequency coupled feedback signal electro-optic conversion channel.

[0062] Specifically, the low-frequency left-handed echo signal electro-optic conversion channel includes a low-frequency low-noise amplifier and a directly modulated laser (ITU-C26). The low-frequency low-noise amplifier receives the left-handed echo input signal and performs pre-stage low-noise power amplification to reduce the overall noise figure of the link; the directly modulated laser completes the optical modulation of the echo signal to be transmitted.

[0063] The low-frequency right-handed echo signal electro-optic conversion channel includes a low-frequency low-noise amplifier and a direct-modulated laser ITU-C30. These devices have the same function as the corresponding devices in the low-frequency left-handed echo signal electro-optic conversion channel, but their specifications are slightly different. For details, please refer to the parameter configuration of the specific devices below, which will not be elaborated here.

[0064] The high-frequency left-handed echo signal electro-optic conversion channel includes a high-frequency low-noise amplifier and a directly modulated laser (ITU-C34). The high-frequency low-noise amplifier receives the left-handed echo input signal and performs pre-stage low-noise power amplification to reduce the overall noise figure of the link; the directly modulated laser completes the optical modulation of the echo signal to be transmitted.

[0065] The high-frequency right-handed echo signal electro-optic conversion channel includes a high-frequency low-noise amplifier and a direct-modulated laser ITU-C36. These devices have the same function as the corresponding devices in the high-frequency left-handed echo signal electro-optic conversion channel, but their specifications are slightly different. For details, please refer to the parameter configuration of the specific devices below.

[0066] Furthermore, the specific configurations of each submodule in the downlink transmission module are as follows: Low-frequency low-noise amplifier operating frequency: 8GHz-12GHz, noise figure: ≤2.5dB, gain: ≥10dB, output P-1: ≥15dB; High-frequency low-noise amplifier operating frequency: 12GHz-18GHz, noise figure: ≤2.5dB, gain: ≥10dB, output P-1: ≥15dB; Direct-tuned laser ITU-C26 center wavelength: 1556.55nm, direct... The center wavelengths of the directly modulated lasers are as follows: ITU-C30: 1553.33nm; ITC-C34: 1550.12nm; ITU-C36: 1548.51nm; ITU-C38: 1546.92nm; and ITU-C40: 1545.32nm. The modulation bandwidth of the above directly modulated lasers is 2GHz-18GHz, and the output optical power is ≥10dBm.

[0067] In one specific embodiment, such as Figure 6 As shown, the downlink transmission receiving module includes eight optoelectronic conversion channels: low-frequency left-handed echo signal optoelectronic conversion channel, low-frequency right-handed echo signal optoelectronic conversion channel, high-frequency left-handed echo signal optoelectronic conversion channel, high-frequency right-handed echo signal optoelectronic conversion channel, low-frequency coupled feedback signal optoelectronic conversion channel, high-frequency coupled feedback signal optoelectronic conversion channel, low-frequency standard transmission signal electro-optical conversion channel, and high-frequency standard transmission signal electro-optical conversion channel.

[0068] Specifically, the low-frequency left-handed rotary echo signal photoelectric conversion channel includes a photodetector and a low-frequency controllable gain amplifier. The photodetector receives the downlink optical signal, performs photoelectric conversion, and outputs it to the low-frequency controllable gain amplifier, where it is output after amplitude controllable adjustment.

[0069] The high-frequency left-handed rotary echo signal photoelectric conversion channel includes a photodetector and a high-frequency controllable gain amplifier. The photodetector receives the downlink optical signal, performs photoelectric conversion, and outputs it to the high-frequency controllable gain amplifier, where it is output after amplitude controllable adjustment.

[0070] The photoelectric conversion channels for low-frequency right-handed echo signals and low-frequency coupled feedback signals have the same device functions and types as the corresponding devices for low-frequency left-handed echo signals, but their specifications are slightly different. For details, please refer to the parameter configuration of the specific devices below, which will not be elaborated here.

[0071] The high-frequency right-handed echo signal photoelectric conversion channel, the high-frequency coupled feedback signal photoelectric conversion channel, and the high-frequency standard emission signal electro-optical conversion channel have the same internal device functions and types as the corresponding devices in the low-frequency left-handed echo signal photoelectric conversion channel, but their specifications are slightly different. For details, please refer to the parameter configuration of the specific devices below.

[0072] Furthermore, the specific configurations of each submodule in the downlink transmission and reception module are as follows: photodetector frequency bandwidth: DC-18GHz, wavelength range: 800nm-1650nm, responsivity: ≥0.85mA / mW; low-frequency controllable gain amplifier operating frequency: 8GHz-12GHz, gain range: 15dB-25dB; high-frequency controllable gain amplifier operating frequency: 12GHz-18GHz, gain range: 15dB-25dB;

[0073] In one embodiment, such as Figure 7 As shown, the central station optical path branching module includes a first dense wavelength division multiplexer (DWDM), a second DWDM, and a first fiber optic circulator. The first DWDM receives the uplink optical signal, performs optical path multiplexing and wavelength division, and then transmits it to the first fiber optic circulator. The second DWDM receives the downlink optical signal and performs optical path demultiplexing. The first fiber optic circulator completes the uplink and downlink branching of the bidirectional optical signal.

[0074] Furthermore, the specific configurations of each device in the central station optical path branch module are as follows: Number of channels in the first dense wavelength division multiplexer: 4 (ITU-26 / 28 / 30 / 32), channel spacing: 200GHz, isolation: ≥30dB; Number of channels in the second dense wavelength division multiplexer: 8 (ITU-C26 / 28 / 30 / 32 / 34 / 36 / 38 / 40), spacing: 200GHz, isolation: ≥30dB; Number of ports in the first fiber optic circulator: 3, center wavelength: ITU-C, isolation: ≥40dB.

[0075] In one embodiment, such as Figure 8 As shown, the antenna unit optical path branching module includes a third dense wavelength division multiplexer, an optical add-drop multiplexer, and a second fiber optic circulator.

[0076] The third dense wavelength division multiplexer (DWDM) utilizes only six channels (C26, C30, C34, C36, C38, and C40) to receive downlink optical signals, perform optical path multiplexing and wavelength division, and output the signals to the loading port of the optical add-drop multiplexer (OPD). The OPD loads two channels (C26 and C30) from the uplink optical path and loads the downlink optical path output from the third DWDM, achieving optical path reconstruction without changing the wavelength channel selection. The second fiber optic circulator completes the uplink and downlink branching of the bidirectional optical signals.

[0077] Furthermore, the specific configurations of each component in the antenna unit optical path branch module are as follows: Third DWDM channel count: 4 (ITU-26 / 28 / 30 / 32), channel spacing: 200GHz, isolation: ≥30dB; Third DWDM channel count: 8 (ITU-C26 / 28 / 30 / 32 / 34 / 36 / 38 / 40), spacing: 200GHz, isolation: ≥30dB; Optical add-drop multiplexer wavelength range: 1500nm-1620nm, channel count: 2, download channel: ITU-26 / 28, load channel: ITU-C26 / 28 / 30 / 32 / 34 / 36 / 38 / 40, spacing: 200GHz, isolation: ≥30dB; Second fiber optic circulator port count: 3, center wavelength: ITU-C, isolation: ≥40dB.

[0078] In one embodiment, the single-core stable phase optical cable is 1000 meters long, has a temperature drift coefficient of ≤15ps / km / ℃, and the optical connectors at both ends are of type FC / APC.

[0079] It should be noted that by using FC / APC optical connectors, the 8° angled connector ferrule end face can reduce optical path return loss and avoid the impact of multipath interference on component transmission performance. This embodiment, through the setting of the temperature drift coefficient and connector type of the single-core stable phase optical cable, enables the single-core stable phase optical cable to meet the reliability and transmission quality requirements of the transmission medium.

[0080] In summary, this invention uses only a single-core stable phase optical cable to interconnect the central station unit platform and the antenna unit platform. It fully utilizes passive fiber optic devices such as wavelength division multiplexers, optical add-drop multiplexers, and optical circulators, and redesigns the optical path structure based on optical multiplexing technology, achieving bidirectional transmission of multiple RF signals over a single core fiber. Furthermore, a reliable phase detection and control module monitors link phase drift in real time and provides feedback control to adjust optical path delay for signal phase tracking compensation, achieving stable phase transmission of RF signals. Moreover, this invention greatly simplifies the optical link structure under complex signal transmission conditions. The single-core optical cable interconnection method physically avoids the phase drift inconsistencies caused by external and internal factors in multi-core optical cables. Combined with phase monitoring and control, it clamps the signal phase in real time, ensuring the stability of the RF optical transmission link signal phase.

[0081] In addition, this invention has comprehensive business functions such as stable signal transmission, closed-loop calibration, and antenna status monitoring. Through a certain number of scientific spatial layouts of this system, it is suitable for long-distance stable phase synchronous transmission of radio frequency signals between the central station and antenna end of a distributed phased array radar system with multiple antennas, realizing multi-dimensional electromagnetic detection and having higher phase coherence efficiency.

[0082] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A radio frequency signal fiber optic synchronous conversion system, characterized in that, The system includes: an uplink transmission transmitting module, an uplink transmission receiving module, a downlink transmission transmitting module, a downlink transmission receiving module, a central station optical path branching module, an antenna unit optical path branching module, and a single-core stable phase optical cable; The uplink transmission transmitting module is used for optical modulation of the uplink input electrical signal to obtain a modulated uplink optical signal, and performs phase adjustment on the uplink optical signal according to the coupling signal and the coupling feedback signal output by the uplink transmission receiving module; the uplink transmission receiving module is used to receive the uplink optical signal, and perform photoelectric conversion to obtain a demodulated uplink output electrical signal, and obtain a coupling feedback signal according to the uplink output electrical signal. The downlink transmission transmitting module is used for optical modulation of the downlink echo electrical signal to obtain a modulated downlink optical signal, wherein the downlink echo electrical signal includes the coupling feedback signal; the downlink transmission receiving module is used to receive the downlink optical signal, and after photoelectric conversion, obtain a demodulated downlink output electrical signal. The central station optical path branching module is used to realize uplink and downlink optical signal branching, multiplexing and demultiplexing at the central station platform; the antenna unit optical path branching module is used to realize uplink and downlink optical signal branching, insertion and reconfiguration, multiplexing and demultiplexing at the antenna unit platform; the single-core stable phase optical cable interconnects the two ends of the antenna unit platform and the central station platform, providing a stable phase bidirectional transmission medium for optical signals.

2. The radio frequency signal fiber optic synchronous conversion system according to claim 1, characterized in that, The uplink transmission module includes: a low-frequency input signal electro-optic conversion channel; The low-frequency input signal electro-optic conversion channel includes a low-frequency directional coupler, a direct-modulated laser ITU-C26, and a low-frequency phase detection control module; The low-frequency directional coupler is used to couple and distribute the low-frequency input signal. The portion with higher output power is used as the main output of the through-hole, and the portion with lower output power is used as the low-frequency coupled signal input to the low-frequency phase detection control module. The direct-modulated laser ITU-C26 is used to realize optical modulation of the low-frequency input signal to obtain a low-frequency uplink optical signal. The low-frequency phase detection control module is used to adjust the phase of the low-frequency uplink optical signal according to the acquired low-frequency coupled signal and the low-frequency coupled feedback signal.

3. The radio frequency signal fiber optic synchronous conversion system according to claim 2, characterized in that, The low-frequency phase detection control module includes: a first IQ demodulator, a first delay control circuit, and a first optical delay unit; The first IQ demodulator is used to obtain the phase difference between the low-frequency coupled signal and the low-frequency coupled feedback signal; the first delay amount control circuit calculates the corresponding delay amount according to the phase difference and feeds back the delay amount to the first optical delay unit to perform phase adjustment on the low-frequency uplink optical signal.

4. The radio frequency signal fiber optic synchronous conversion system according to claim 1, characterized in that, The uplink transmission module includes: a high-frequency input signal electro-optic conversion channel; The high-frequency input signal electro-optic conversion channel includes a high-frequency directional coupler, a direct-modulated laser ITU-C30, and a high-frequency phase detection control module; The high-frequency directional coupler is used to couple and distribute the high-frequency input signal. The portion with higher output power is used as the main output of the through-hole, and the portion with lower output power is used as the high-frequency coupling signal input to the high-frequency phase detection control module. The direct-modulation laser ITU-C30 is used to realize optical modulation of the high-frequency input signal to obtain a high-frequency uplink optical signal. The high-frequency phase detection control module is used to adjust the phase of the high-frequency uplink optical signal according to the acquired high-frequency coupling signal and the high-frequency coupling feedback signal.

5. The radio frequency signal fiber optic synchronous conversion system according to claim 4, characterized in that, The high-frequency phase detection control module includes: a second IQ demodulator, a second delay control circuit, and a second optical delay unit; The second IQ demodulator is used to obtain the phase difference between the high-frequency coupled signal and the high-frequency coupled feedback signal; the second delay amount control circuit calculates the corresponding delay amount according to the phase difference and feeds back the delay amount to the second optical delay unit to perform phase adjustment on the high-frequency uplink optical signal.

6. The radio frequency signal fiber optic synchronous conversion system according to claim 1, characterized in that, The uplink transmission receiving module includes: a low-frequency output signal photoelectric conversion channel and a high-frequency output signal photoelectric conversion channel; The low-frequency output signal photoelectric conversion channel includes a low-frequency directional coupler. The low-frequency directional coupler is used to distribute the power of the uplink optical signal after photoelectric conversion. The part with larger output power is used as the main output of the through end, and the part with smaller output power is used as the secondary output of the coupling end. The secondary output part is used as the low-frequency coupling feedback signal for link backhaul. The high-frequency output signal photoelectric conversion channel includes a high-frequency directional coupler. The high-frequency directional coupler is used to distribute the power of the uplink optical signal after photoelectric conversion. The part with larger output power is used as the main output of the through end, and the part with smaller output power is used as the secondary output of the coupling end. The secondary output part is used as the high-frequency coupling feedback signal for link backhaul.

7. The radio frequency signal fiber optic synchronous conversion system according to claim 1, characterized in that, The downlink transmission module includes: The low-frequency coupled feedback signal electro-optic conversion channel is used to perform electro-optic conversion on the low-frequency coupled feedback signal output by the uplink transmission receiving module, and to send the downlink optical signal containing the low-frequency coupled feedback signal to the antenna unit optical path branch module. The high-frequency coupling feedback signal electro-optic conversion channel is used to perform electro-optic conversion on the high-frequency coupling feedback signal output by the uplink transmission receiving module, and to send the downlink optical signal containing the high-frequency coupling feedback signal to the antenna unit optical path branch module.

8. The radio frequency signal fiber optic synchronous conversion system according to claim 1, characterized in that, The central station optical path branching module includes: a first dense wavelength division multiplexer, a second dense wavelength division multiplexer, and a first fiber optic circulator; The first dense wavelength division multiplexer receives the uplink optical signal and completes optical path multiplexing and wavelength division, transmitting it to the first fiber optic circulator; the second dense wavelength division multiplexer receives the downlink optical signal and completes optical path demultiplexing; the first fiber optic circulator completes the uplink and downlink optical path branching of the bidirectional optical signal.

9. The radio frequency signal fiber optic synchronous conversion system according to claim 1, characterized in that, The antenna unit optical path branching module includes: a third dense wavelength division multiplexer, an optical add-drop multiplexer, and a second fiber optic circulator; The third dense wavelength division multiplexer is used to receive downlink optical signals and output them to the loading port of the optical add-drop multiplexer after completing optical path multiplexing and wavelength division. The optical add-drop multiplexer is used to download the C26 and C30 channels in the uplink optical path and load the downlink optical path output by the third dense wavelength division multiplexer to achieve optical path reconstruction without changing the wavelength channels. The second fiber optic circulator completes the uplink and downlink branching of bidirectional optical signals.

10. The radio frequency signal fiber optic synchronous conversion system according to claim 1, characterized in that, The temperature drift coefficient of the single-core stable phase optical cable is ≤15ps / km / ℃, and the optical connectors at both ends are of type FC / APC.

Images