Satellite-borne laser communication terminal and signal processing method thereof

Abstract

The application discloses a spaceborne laser communication terminal and a signal processing method thereof, which are used for improving the receiving sensitivity of the system in a low-speed mode, greatly reducing the corresponding transmitting end power, and further meeting the low-power consumption requirement of the system. The terminal comprises a signal processing device, a transmitting module, a receiving module and a transceiving light path. The signal processing device is used for generating baseband signals of different transmitting rates and sending the baseband signals to the transmitting module. The transmitting module is used for modulating the baseband signals into first optical signals of corresponding wavelengths according to the transmitting rates and sending the first optical signals to the transceiving light path. The transceiving light path is used for converting the first optical signals sent by the transmitting module into spatial light signals for transmission and converting the received spatial light signals into second optical signals for transmission to the receiving module when receiving the spatial light signals sent by the opposite end communication terminal. The receiving module is specifically used for converting the second optical signals into baseband signals for transmission to the signal processing device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser communication application, and in particular to a spaceborne laser communication terminal and a signal processing method thereof. BACKGROUND

[0002] Space laser communication is a communication mode that uses laser beams as carriers to transmit image, voice, signal and other data information in free space. It has the advantages of fast transmission rate, large communication capacity, strong anti-electromagnetic interference performance, high security, small communication terminal volume, low power consumption and good practicability. Inter-satellite laser communication is the core of the transmission layer of constellation system, and the transmission rate is generally between 100 Mbps and 10 Gbps. In order to reduce the average power consumption of the spaceborne laser communication terminal, the laser communication terminal of the multi-type system requires high speed and low speed two types of adjustable rates. The receiving sensitivity of the terminal receiving system is different in high speed and low speed states, so the transmission power required to achieve the same link budget is different. When the system data volume is high, the high-speed communication mode is adopted, and when the data volume is low, the low-speed mode is adopted to reduce the transmission end power. The low-speed mode can significantly reduce the system power consumption compared with the high-speed mode.

[0003] However, in actual engineering implementation, the power consumption benefit of the above method is limited. In the current design, the same APD is used for receiving different rates. The APD is generally designed for specific rate requirements, and the receiving photosensitive surface and the matching circuit of the back end are physically fixed at the time of design. The difference between high speed and low speed modes is not large, and it is difficult to achieve the theoretical value. Taking a domestic APD as an example, the receiving sensitivities of 1 Gbps and 10 Gbps are-31 dBm and-29 dBm respectively, and the sensitivity difference is only 2 dB. The difference between the sensitivity and the 10 dB theoretical value is large, and the system power consumption benefit in the low-speed mode is not significant. Therefore, how to greatly reduce the system power consumption in the low-speed mode has become one of the problems to be solved. SUMMARY

[0004] The present application provides a spaceborne laser communication terminal and a signal processing method thereof, which can improve the receiving sensitivity of the system in the low-speed mode, greatly reduce the corresponding transmission power, and meet the low-power consumption requirement of the system.

[0005] In a first aspect, a spaceborne laser communication terminal is provided, comprising: a signal processing device 1, a transmission module 2, a receiving module 3 and a transceiver optical path 4, wherein:

[0006] The signal processing device 1 is configured to generate baseband signals of different transmission rates and send them to the transmission module 2.

[0007] The transmission module 2 is configured to modulate the baseband signals into first optical signals of corresponding wavelengths according to the transmission rates and send them to the transceiver optical path 4.

[0008] The transceiving light path 4 is configured to convert the first optical signal sent by the transmitting module into spatial light for emission, and convert the received spatial light signal into a second optical signal for the receiving module 3 when receiving the spatial light signal sent by the communication terminal at the other end;

[0009] The receiving module 3 is configured to convert the second optical signal into a baseband signal for the signal processing device 1.

[0010] In an embodiment, the transmitting module 2 comprises several rate-adjustable lasers matching different receiving rates, a transmitting WDM, and a fiber amplifier; and

[0011] The signal processing device 1 is configured to send the baseband signal to the first rate-adjustable laser when determining that the baseband signal is a low-speed signal according to the transmitting rate, and send the baseband signal to the second rate-adjustable laser when determining that the baseband signal is a high-speed signal according to the transmitting rate.

[0012] The first rate-adjustable laser is configured to modulate the baseband signal into a first optical signal of a first wavelength and send the first optical signal to the transmitting WDM.

[0013] The second rate-adjustable laser is configured to modulate the baseband signal into a first optical signal of a second wavelength and send the first optical signal to the transmitting WDM.

[0014] The transmitting WDM is configured to receive the first optical signal and send the first optical signal to the fiber amplifier.

[0015] The fiber amplifier is configured to amplify the first optical signal and send the amplified first optical signal to the transceiving light path 4.

[0016] In an embodiment, the receiving module 3 comprises several high-speed avalanche photodiodes (APDs) and several low-speed high-sensitivity APDs, a receiving WDM; and

[0017] The receiving WDM is configured to receive the second optical signal, and transmit the second optical signal to the low-speed high-sensitivity APD if the second optical signal is determined to be a low-speed signal according to the rate or wavelength of the second optical signal, and transmit the second optical signal to the high-speed APD if the second optical signal is determined to be a high-speed signal according to the rate or wavelength of the second optical signal.

[0018] The low-speed high-sensitivity APD or the high-speed APD is configured to convert the received second optical signal into a baseband signal and transmit the baseband signal to the signal processing device 1.

[0019] In an embodiment, the low-speed high-sensitivity APD corresponds to a processing rate of 100 Mbps-1 Gbps, and the wavelength of the low-speed signal includes C18-C61; the high-speed APD corresponds to a processing rate of 1 Gbps-10 Gbps, and the wavelength of the high-speed signal includes C18-C61.

[0020] In an embodiment, the low-speed high-sensitivity APD or the high-speed APD adopts InGaAs material as a photosensitive surface.

[0021] In an embodiment, the first rate-adjustable laser or the second rate-adjustable laser adopts an InP semiconductor laser.

[0022] In an embodiment, the transceiving optical path 4 and the fiber amplifier, the fiber amplifier and the transmitting WDM, the transmitting WDM and the first rate-adjustable laser and the second rate-adjustable laser are connected through a single-mode optical fiber; the single-mode optical fiber is a radiation-resistant single-mode optical fiber; and the transmitting WDM adopts a four-channel single-mode wavelength division multiplexer.

[0023] In an embodiment, the transceiving optical path 4 and the receiving WDM, the WDM and the low-speed high-sensitivity APD and the high-speed APD are connected through a multi-mode optical fiber; the multi-mode optical fiber is a radiation-resistant multi-mode optical fiber; and the receiving WDM adopts a two-channel multi-mode wavelength division multiplexer.

[0024] In an embodiment, the transceiving optical path 4 adopts a card-type coaxial transceiving optical path.

[0025] In a second aspect, a signal processing method of a spaceborne laser communication terminal is provided, which includes:

[0026] The signal processing device 1 generates baseband signals of different transmission rates and sends them to the transmitting module 2;

[0027] The transmitting module 2 modulates the baseband signals into first optical signals of corresponding wavelengths according to the transmission rates and sends them to the transceiving optical path 4;

[0028] The transceiving optical path 4 converts the first optical signals sent by the transmitting module 2 into spatial light emission; or when receiving spatial light signals sent by a peer communication terminal, converts the received spatial light signals into second optical signals and sends them to the receiving module 3;

[0029] The receiving module 3 converts the second optical signals into baseband signals and sends them to the signal processing device 1.

[0030] The satellite laser communication terminal and the signal processing method thereof provided by the embodiment of the application, the terminal comprises a signal processing device, a transmitting module, a receiving module and a transceiving light path, the transmitting module modulates the baseband signal generated by the signal processing device into an optical signal of a corresponding wavelength, and sends the optical signal to the transceiving light path, the transceiving light path converts the optical signal sent by the transmitting module into a spatial optical signal; when the transceiving light path receives the spatial optical signal sent by the opposite end communication terminal, the transceiving light path converts the received spatial optical signal into a fiber signal and sends the fiber signal to the receiving module, the receiving module converts the received fiber signal into a baseband signal and sends the baseband signal to the signal processing device, further, the signal processing device sends the baseband signal to a corresponding rate adjustable laser of the transmitting end according to the transmission rate of the baseband signal, and the optical signal obtained after the modulation is sent to the transmitting WDM, the transmitting WDM sends the received optical signal to the fiber amplifier, the optical signal is amplified by the fiber amplifier and then sent to the transceiving light path, further, the receiving WDM sends the received optical signal to an APD of a corresponding rate according to the rate or wavelength of the received optical signal, and the optical signal is converted into a baseband signal by the APD and then transmitted to the signal processing device.

[0031] The terminal adopts a rate switchable working mode, and under different communication rates, the rate and wavelength are matched and processed by WDM based on a plurality of APDs matched with different receiving rates. In high-speed communication, the signal is transmitted by using a conventional optical power. In low-speed communication, the APD receiving sensitivity is improved, the optical transmission power of the transmitting end is reduced under the same link state, the system communication capacity and reliability are increased, and the whole machine power consumption is reduced.

[0032] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application. In the drawings:

[0034] Figure 1 FIG. 1 is a structural schematic diagram of a satellite laser communication terminal according to an embodiment of the application;

[0035] Figure 2 FIG. 2 is a structural schematic diagram of a satellite laser communication terminal according to another embodiment of the application;

[0036] Figure 3 FIG. 3 is a schematic diagram of the working principle of a satellite laser communication terminal according to another embodiment of the application. DETAILED DESCRIPTION

[0037] In order to improve the receiving sensitivity of the system in the low speed mode, the corresponding transmitting end power is greatly reduced, and then the low power consumption requirement of the system is met, and the embodiment of the application provides a satellite laser communication terminal and a signal processing method thereof.

[0038] It should be noted that the terms "first", "second", and the like in the specification and claims of the embodiments of the application and the above-described drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0039] The preferred embodiments of the application are described below in conjunction with the accompanying drawings of the specification, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the application, and are not used to limit the application, and the embodiments in the application and the features in the embodiments can be combined with each other without conflict.

[0040] Embodiment one

[0041] The embodiment of the application is based on the wavelength division multiplexing technology, and provides a satellite laser communication terminal, such as Figure 1 According to the structure diagram of the satellite laser communication terminal according to the embodiment of the application, it comprises a signal processing device 1, a transmitting module 2, a receiving module 3, and a transceiving light path 4, wherein:

[0042] The signal processing device 1 is used to generate baseband signals of different transmission rates and send them to the transmitting module 2;

[0043] The transmitting module 2 is used to modulate the baseband signals into first optical signals of corresponding wavelengths according to the transmission rates and send them to the transceiving light path 4;

[0044] The transceiving light path 4 is used to convert the first optical signals sent by the transmitting module into spatial light emission, and when receiving the spatial light signals sent by the opposite end communication terminal, it converts the received spatial light signals into second optical signals and sends them to the receiving module 3;

[0045] The receiving module 3 is specifically used to convert the second optical signals into baseband signals and send them to the signal processing device 1.

[0046] In the implementation, the signal processing device 1 can adopt the X7 series of Xilinx, and the logic unit is more than one million gates, which can perform double-path parallel baseband signal processing.

[0047] Preferably, the transceiving light path 4 is implemented by a cassette coaxial transceiving light path.

[0048] In an embodiment, the transmitting module 2 comprises several rate-tunable lasers matching different receiving rates, a transmitting WDM and an optical fiber amplifier; and

[0049] The signal processing device 1 is specifically configured to send the baseband signal to the first rate-tunable laser when the baseband signal is determined as a low-speed signal according to the transmitting rate; and send the baseband signal to the second rate-tunable laser when the baseband signal is determined as a high-speed signal according to the transmitting rate.

[0050] The first rate-tunable laser is configured to modulate the baseband signal into a first optical signal of a first wavelength and send the first optical signal to the transmitting WDM.

[0051] The second rate-tunable laser is configured to modulate the baseband signal into a first optical signal of a second wavelength and send the first optical signal to the transmitting WDM.

[0052] The transmitting WDM is configured to send the received first optical signal to the optical fiber amplifier.

[0053] The optical fiber amplifier is configured to amplify the first optical signal and send the amplified first optical signal to the transceiving optical path 4.

[0054] In implementation, in the low-speed communication mode, the signal processing device 1 sends the generated low-speed baseband signal to the corresponding rate-tunable laser, modulates the low-speed baseband signal into an optical signal of a first wavelength through the rate-tunable laser, inputs the optical signal into the transmitting WDM, and then inputs the optical signal into the optical fiber amplifier for signal amplification, and converts the optical signal into spatial light emission through the transceiving optical path 4; in the high-speed communication mode, the signal processing device 1 sends the generated high-speed baseband signal to the corresponding rate-tunable laser, modulates the high-speed baseband signal into an optical signal of a second wavelength through the rate-tunable laser, inputs the optical signal into the transmitting WDM, and then inputs the optical signal into the optical fiber amplifier for signal amplification, and converts the optical signal into spatial light emission through the transceiving optical path 4. The first wavelength and the second wavelength are matched by the receiving rate, and the receiving end matches and processes the rate and the wavelength through the receiving WDM.

[0055] Further, the several rate-tunable lasers matching different receiving rates are backed up to each other, which can effectively improve the on-orbit life and reliability of the system.

[0056] In an embodiment, the first rate-tunable laser or the second rate-tunable laser adopts an InP semiconductor laser.

[0057] In an embodiment, the transceiving optical path 4 and the fiber amplifier, the fiber amplifier and the transmitting WDM, the transmitting WDM and the first and second rate-tunable lasers are connected by single-mode optical fibers; the single-mode optical fibers are radiation-resistant single-mode optical fibers; and the transmitting WDM is a four-channel single-mode wavelength division multiplexer.

[0058] Preferably, the fiber amplifier is a two-stage erbium-doped fiber amplifier for high-power amplification.

[0059] In an embodiment, the receiving module 3 comprises a plurality of high-speed avalanche photodiodes (APDs) and a plurality of low-speed high-sensitivity APDs, and a receiving WDM.

[0060] The receiving WDM is configured to receive the second optical signal, and if the second optical signal is determined to be a low-speed signal according to the rate or wavelength of the second optical signal, transmit the second optical signal to the low-speed high-sensitivity APD, and if the second optical signal is determined to be a high-speed signal according to the rate or wavelength of the second optical signal, transmit the second optical signal to the high-speed APD.

[0061] The low-speed high-sensitivity APD or the high-speed APD is configured to convert the received second optical signal into a baseband signal and transmit the baseband signal to the signal processing device 1.

[0062] In a specific implementation, in a low-speed communication mode, when a spatial optical signal transmitted by a communication terminal at the other end is received, the spatial optical signal is converted into a fiber signal by the transceiving optical path 4 and input to the input end of the receiving WDM, the receiving WDM matches the low-speed signal of the first wavelength to the low-speed high-sensitivity APD to realize photoelectric conversion, and the low-speed high-sensitivity APD transmits the signal to the signal processing device 1 for data processing; in a high-speed communication mode, when a spatial optical signal transmitted by a communication terminal at the other end is received, the spatial optical signal is converted into a fiber signal by the transceiving optical path 4 and input to the input end of the receiving WDM, the receiving WDM matches the low-speed signal of the second wavelength to the high-speed APD to realize photoelectric conversion, and the high-speed APD transmits the signal to the signal processing device 1 for data processing.

[0063] Further, each APD is optimized in process and circuit design for its matching receiving rate, for example, different light-sensitive surface sizes and back-end matching circuit device parameters are selected, and at different communication rates, the system can achieve the best sensitivity designed, compared with the scheme of receiving by a single APD in a traditional mode, the sensitivity is effectively improved in low-speed communication, thereby realizing effective reduction of long-term power consumption of the laser communication terminal in orbit.

[0064] Further, the high-speed APD and the low-speed high-sensitivity APD back up each other, and the high-speed APD can process signals downwardly compatible, thereby improving the in-orbit life and reliability of the system.

[0065] The terminal adopts multi-rate switchable working mode: in high-speed communication, the conventional optical power is used for signal transmission. In low-speed communication, the APD receiving sensitivity is improved, the optical transmission power of the transmitting end is reduced under the same link state, and the whole machine power consumption is reduced. On this basis, the low-speed mode and the high-speed mode can work at the same time, and the receiving gating or transmission combining is realized through the wavelength division multiplexer, and the communication capacity of the system is further improved.

[0066] In an embodiment, the low-speed high-sensitivity APD corresponds to a communication rate of 100Mbps-1Gbps, and the matching wavelength includes C18-C61. The high-speed APD corresponds to a communication rate of 1Gbps-10Gbps, and the matching wavelength includes C18-C61.

[0067] In an embodiment, the low-speed high-sensitivity APD or the high-speed APD uses InGaAs material as the light-sensitive surface to realize high-sensitivity detection.

[0068] In an embodiment, the transceiving optical path 4, the receiving WDM, the WDM, the low-speed high-sensitivity APD and the high-speed APD are connected through a multimode optical fiber; the multimode optical fiber is a radiation-resistant multimode optical fiber; and the receiving WDM uses a dual-channel multimode optical fiber wavelength division multiplexer.

[0069] Preferably, the low-speed high-sensitivity APD, the high-speed APD, the first rate-adjustable laser and the second rate-adjustable laser are mounted on an optical transceiver module substrate, and the optical transceiver module substrate can be an FR4 substrate. The signal processing device 1 is connected to each APD and each rate-adjustable laser through a connection line, and the connection line can be in the form of a high-speed signal line on a PCB (printed circuit board).

[0070] The terminal can select multiple groups of APDs and rate-adjustable lasers according to system requirements, match different receiving rates respectively, and match different wavelengths for each receiving rate to realize switching of multiple rates and corresponding multiple system transmission powers.

[0071] In order to meet the requirement of reducing the power consumption of the non-coherent laser terminal in low-speed mode, the embodiment one provides a satellite laser communication terminal. The terminal is composed of APD matching different receiving rates, receiving WDM, transmitting WDM and signal processing device, etc. The independent APD matches different receiving rates and transmitting wavelengths, and the corresponding communication rate is designed, and the transmitting and receiving light signals are received and selected or transmitted and combined by the WDM. The different communication rates and wavelengths correspond to each other, and the WDM selects or combines the signals to the corresponding transmitting and receiving ports to realize the receiving processing or transmitting amplification function in the working mode. Thus, the receiving sensitivity of the terminal is effectively improved, the low power consumption requirement of the system is met, the long-term power consumption of the terminal is significantly reduced, the communication capacity and reliability of the system are increased, and the effective technical means for the engineering application of the laser communication terminal in orbit is provided.

[0072] Embodiment two

[0073] On the basis of the embodiment one, in order to make the skilled in the art better understand, the embodiment two is provided, and the embodiment is introduced in detail as follows.

[0074] In order to meet the requirement of reducing the power consumption of the non-coherent laser terminal in low-speed mode, the embodiment one provides a satellite laser communication terminal. The terminal is composed of APD matching different receiving rates, receiving WDM, transmitting WDM and signal processing device, etc. The independent APD matches different receiving rates and transmitting wavelengths, and the corresponding communication rate is designed, and the transmitting and receiving light signals are received and selected or transmitted and combined by the WDM. The different communication rates and wavelengths correspond to each other, and the WDM selects or combines the signals to the corresponding transmitting and receiving ports to realize the receiving processing or transmitting amplification function in the working mode. Thus, the receiving sensitivity of the terminal is effectively improved, the low power consumption requirement of the system is met, the long-term power consumption of the terminal is significantly reduced, the communication capacity and reliability of the system are increased, and the effective technical means for the engineering application of the laser communication terminal in orbit is provided.

[0075] In order to reduce the average power consumption of the laser communication terminal in orbit, the satellite laser communication terminal provided by the embodiment adopts a double-rate switchable working mode. In the high-speed communication, the conventional optical power is used for signal transmission. In the low-speed communication, the APD receiving sensitivity is improved, the optical transmission power of the transmitting end is reduced under the same link state, and the power consumption of the terminal is reduced.

[0076] The terminal is composed of APD matching different receiving rates, receiving WDM, transmitting WDM and signal processing device, etc. The independent APD matches different receiving rates and transmitting wavelengths, and the corresponding communication rate is designed, and the transmitting and receiving light signals are received and selected or transmitted and combined by the WDM. The different communication rates and wavelengths correspond to each other, and the WDM selects or combines the signals to the corresponding transmitting and receiving ports to realize the receiving processing or transmitting amplification function in the working mode. Thus, the receiving sensitivity of the terminal is effectively improved, the low power consumption requirement of the system is met, the long-term power consumption of the terminal is significantly reduced, the communication capacity and reliability of the system are increased, and the effective technical means for the engineering application of the laser communication terminal in orbit is provided. Figure 2 According to the structure diagram of the satellite laser communication terminal of another embodiment of the application, it comprises:

[0077] Signal processing device, low-speed high-sensitivity APD, high-speed APD, rate-adjustable laser 1, rate-adjustable laser 2, receiving WDM, transmitting WDM, fiber amplifier, transceiving optical path, connection line 1-connection line 4, multi-mode optical fiber 1-multi-mode optical fiber 2, multi-mode optical fiber 3, single-mode optical fiber 3-single-mode optical fiber 4, optical transceiver module substrate, and the above components collectively constitute a satellite-borne laser communication terminal transceiving system. The low-speed high-sensitivity APD, the high-speed APD, the rate-adjustable laser 1, and the rate-adjustable laser 2 are all mounted on the optical transceiver module substrate. The signal processing device is connected with the low-speed high-sensitivity APD, the high-speed APD, the rate-adjustable laser 1, and the rate-adjustable laser 2 through the connection line 1-connection line 4, and the connection line can be realized in the form of a PCB printed circuit or a high-speed communication cable. The low-speed high-sensitivity APD and the high-speed APD are connected with the receiving WDM through the multi-mode optical fiber 1-multi-mode optical fiber 2, and the rate-adjustable laser 1 and the rate-adjustable laser 2 are connected with the transmitting WDM through the single-mode optical fiber 1-single-mode optical fiber 2, and the receiving WDM is connected with the transceiving optical path through the multi-mode optical fiber 3. The transmitting WDM is connected with the fiber amplifier through the single-mode optical fiber 3, and the fiber amplifier is connected with the transceiving optical path through the single-mode optical fiber 4.

[0078] As Figure 3 According to another embodiment of the present application, a working principle schematic diagram of a satellite-borne laser communication terminal is shown. In order to ensure the transceiving isolation, the wavelength is distinguished according to the AB machine, the A machine receives the wavelength 1 (corresponding to the low-speed mode) and the wavelength 2 (corresponding to the high-speed mode), and transmits the wavelength 3 (corresponding to the low-speed mode) and the wavelength 4 (corresponding to the high-speed mode), and the B machine is opposite.

[0079] In the low-speed communication mode: the wavelength 1 and the wavelength 3 are used in pairs: the signal processing device of the A machine generates a low-speed baseband signal, modulates the low-speed baseband signal to the optical signal of the wavelength 3 through the rate-adjustable laser 1, inputs the optical signal to the transmitting WDM, and inputs the optical signal to the fiber amplifier for signal amplification, and converts the optical signal to the spatial light through the transceiving optical path; the B machine receives the signal, converts the signal to the fiber signal through the transceiving optical path, and inputs the fiber signal to the input end of the receiving WDM, the receiving WDM matches the signal of the wavelength 3 to the low-speed high-sensitivity APD to realize the photoelectric conversion, and inputs the signal to the signal processing device of the B machine for data processing. When the B machine transmits, the low-speed signal is modulated to the wavelength 1 for transmission, and the A machine receives the signal through the receiving WDM to realize the matching and processing of the rate and the wavelength.

[0080] In high-speed communication mode: wavelength 2 and wavelength 4 are used in pairs. The signal processing device of the A machine generates a high-speed baseband signal, which is modulated into an optical signal of wavelength 4 by the rate-adjustable laser 2, input into the transmitting WDM, and then input into the optical fiber amplifier for signal amplification, and then converted into spatial light through the transmitting and receiving light path; the B machine receives the signal, converts it into an optical fiber signal through the transmitting and receiving light path, and inputs it into the receiving WDM input end. The receiving WDM matches the wavelength 4 signal to the public APD to realize photoelectric conversion, and then inputs it into the B machine signal processing device for data processing. When the B machine transmits, the high-speed signal is modulated into wavelength 2 and transmitted, and the A machine receives the signal through the receiving WDM to realize rate and wavelength matching and processing.

[0081] In specific implementation, the signal processing device uses Xilinx X7 series, with more than one million logic units, which can process dual-channel parallel baseband signals. The low-speed high-sensitivity APD and the high-speed APD both use InGaAs material as the photosensitive surface to realize high-sensitivity detection. The rate-adjustable laser 1 and the rate-adjustable laser 2 use InP semiconductor lasers. The receiving WDM uses a dual-channel multimode fiber wavelength division multiplexer, and the transmitting WDM uses a four-channel single-mode wavelength division multiplexer. The optical fiber amplifier uses a two-stage erbium-doped optical fiber amplifier to realize high-power amplification. The transmitting and receiving light path uses a card-type coaxial transmitting and receiving light path, and the connection line 1-connection line 4 are high-speed signal lines on a PCB printed board. The multimode optical fiber 1, the multimode optical fiber 2, and the multimode optical fiber 3 are anti-radiation multimode optical fibers, and the single-mode optical fiber 1-single-mode optical fiber 4 are anti-radiation single-mode optical fibers. The optical transceiver module substrate uses an FR4 substrate. The low-speed communication mode has a rate of 100Mbps-1Gbps, and the matched wavelength is C18-C61. The high-speed communication mode has a rate of 1Gbps-10Gbps, and the matched wavelength is C18-C61. When the terminal is working, the low-speed high-sensitivity APD in the low-speed communication mode has a receiving sensitivity of-39dBm at 1Gbps and a 10e-3 error rate, and the corresponding transmitting power of the transmitting end is 0.5W (optical fiber amplifier transmitting power 5W). The high-speed APD in the high-speed communication mode has a receiving sensitivity of-29dBm at 10Gbps and a 10e-3 error rate, and the corresponding transmitting power of the transmitting end is 4W (optical fiber amplifier transmitting power 40W). The power consumption of the low-speed communication mode is 35W lower than that of the high-speed mode. When working in dual-channel parallel mode, the maximum rate can reach 20Gbps, and the service life is improved by more than 3 years compared with the traditional design.

[0082] The same APD is used for receiving in different working modes of the current incoherent optical communication system. Limited by the photosensitive surface, processing technology and the matching of the back end, the sensitivity of the low-speed working mode is limited compared with the high-speed working mode, which is far lower than the theoretical value. The terminal provided in the embodiment effectively improves the receiving sensitivity of the system in the low-speed mode by using two independent APDs to match two different receiving rates and transmitting and receiving wavelengths, greatly reduces the corresponding transmitting end power, and thus meets the low-power requirement of the system, solving the problem that the power reduction benefit brought by the switchable working rate of the laser communication terminal in the prior art is limited.

[0083] Embodiment three

[0084] Based on the same technical concept, the embodiment of the present application also provides a signal processing method of a spaceborne laser communication terminal. Since the principle of the above-mentioned device for solving the problem is similar to a spaceborne laser communication terminal, the implementation of the above-mentioned method can be referred to the implementation of the terminal, and the repeated parts will not be described again.

[0085] The signal processing method of the spaceborne laser communication terminal provided in the embodiment of the present application comprises:

[0086] Step one, the signal processing device 1 generates a baseband signal of different transmitting rates and sends it to the transmitting module 2;

[0087] Step two, the transmitting module 2 modulates the baseband signal into a first optical signal of a corresponding wavelength according to the transmitting rate and sends it to the transmitting and receiving optical path 4;

[0088] Step three, the transmitting and receiving optical path 4 converts the first optical signal sent by the transmitting module 2 into a spatial light emission; or when receiving the spatial light signal sent by the opposite communication terminal, converts the received spatial light signal into a second optical signal and sends it to the receiving module 3;

[0089] Step four, the receiving module 3 converts the second optical signal into a baseband signal and sends it to the signal processing device 1.

[0090] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including all changes and modifications falling within the scope of the present application.

[0091] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations.

Claims

1. A space-borne laser communication terminal, characterized by The terminal comprises a signal processing device (1), a transmitting module (2), a receiving module (3) and a transceiving optical path (4), wherein: The signal processing device (1) is configured to generate baseband signals of different transmission rates and send the baseband signals to the transmitting module (2); The transmitting module (2) is configured to modulate the baseband signals into first optical signals of corresponding wavelengths according to the transmission rates and send the first optical signals to the transceiving optical path (4); The transceiving optical path (4) is configured to convert the first optical signals sent by the transmitting module into spatial light emission, and convert received spatial light signals into second optical signals and send the second optical signals to the receiving module (3) when receiving the spatial light signals sent by a communication terminal at the other end; The receiving module (3) comprises a plurality of high-speed avalanche photodiodes (APDs) and a plurality of low-speed high-sensitivity APDs, and a receiving WDM; The receiving WDM is configured to receive the second optical signals, and if it is determined that the second optical signals are low-speed signals according to the rates of the second optical signals, then the second optical signals are transmitted to the low-speed high-sensitivity APDs, and if it is determined that the second optical signals are high-speed signals according to the rates of the second optical signals, then the second optical signals are transmitted to the high-speed APDs; The low-speed high-sensitivity APDs or the high-speed APDs are configured to convert the received second optical signals into baseband signals and transmit the baseband signals to the signal processing device (1); The low-speed high-sensitivity APDs correspond to a processing rate of 100 Mbps-1 Gbps, and the wavelengths of the low-speed signals include C18-C61; the high-speed APDs correspond to a processing rate of 1 Gbps-10 Gbps, and the wavelengths of the high-speed signals include C18-C61.

2. The terminal according to claim 1, characterized by The transmitting module (2) comprises a plurality of rate-adjustable lasers matched with different receiving rates, a transmitting WDM and a fiber amplifier; and The signal processing device (1) is specifically configured to send the baseband signals to a first rate-adjustable laser when it is determined that the baseband signals are low-speed signals according to the transmission rates, and send the baseband signals to a second rate-adjustable laser when it is determined that the baseband signals are high-speed signals according to the transmission rates; The first rate-adjustable laser is configured to modulate the baseband signals into first optical signals of a first wavelength and send the first optical signals to the transmitting WDM; The second rate-adjustable laser is configured to modulate the baseband signals into first optical signals of a second wavelength and send the first optical signals to the transmitting WDM; The transmitting WDM is configured to send the received first optical signals to the fiber amplifier; The fiber amplifier is configured to amplify the first optical signals and send the amplified first optical signals to the transceiving optical path (4).

3. The terminal according to claim 2, characterized by The low-speed high-sensitivity APDs or the high-speed APDs adopt InGaAs material as a light-sensitive surface.

4. The terminal according to claim 2, characterized by The first rate-adjustable laser or the second rate-adjustable laser adopts an InP semiconductor laser.

5. The terminal according to claim 2, wherein The transceiver optical path (4) and the fiber amplifier, the fiber amplifier and the transmitting WDM, the transmitting WDM and the first rate adjustable laser and the second rate adjustable laser are connected through a single-mode fiber; the single-mode fiber is an anti-radiation single-mode fiber; the transmitting WDM adopts a four-channel single-mode wavelength division multiplexer.

6. The terminal according to claim 3, wherein The transceiver optical path (4) and the receiving WDM, the WDM and the low-speed high-sensitivity APD and the high-speed APD are connected through a multi-mode fiber; the multi-mode fiber is an anti-radiation multi-mode fiber; the receiving WDM adopts a two-channel multi-mode fiber wavelength division multiplexer.

7. The terminal according to any one of claims 1 to 6, characterized by The transceiver optical path (4) adopts a card-type coaxial transceiver optical path.

8. A signal processing method for the space-borne laser communication terminal according to any one of claims 1 to 7, characterized by, Comprise: The signal processing device (1) generates baseband signals of different transmission rates and sends them to the transmitting module (2); The transmitting module (2) modulates the baseband signals into first optical signals of corresponding wavelengths according to the transmission rates and sends them to the transceiver optical path (4); The transceiver optical path (4) converts the first optical signals sent by the transmitting module (2) into spatial light emission; or when receiving the spatial light signals sent by the opposite communication terminal, converts the received spatial light signals into second optical signals and sends them to the receiving module (3); The receiving module (3) converts the second optical signals into baseband signals and sends them to the signal processing device (1).

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