Multi-mode high-speed optical communication method, system and device based on underwater mobile platform

Abstract

The present invention belongs to the field of high-speed communication, and discloses a multi-mode high-speed optical communication method, system and device based on an underwater mobile platform. First, the FPGA control of the two communicating parties outputs ultra-short electrical pulses, and the laser is driven by the modulation circuit to emit high-energy pulsed lasers. The laser enters the water channel for raster scanning emission, and the camera spot coordinate position is calculated by MPPC or ARM, and the off-target amount is extracted, and the pan-tilt is controlled to align with the other party, and the pulse light is emitted while the maximum received signal is obtained to allow the other party to receive, and the rough alignment is completed; then the galvanometer is controlled to perform pointing fine alignment, while maintaining the fine tracking state, and the FPGA communication is started for processing, and finally the FPGA stops running after receiving the data stream or issuing a stop communication instruction, and the communication ends. The method disclosed in the present invention can realize that the AUV can communicate with the mother boat or (or fixed platform) in real time during movement, and establish an interactive system, which can be applied to the high-speed communication field between AUV and submersibles, between submersibles, etc., and between underwater mobile devices.

Description

Technical Field

[0001] The present invention belongs to the field of high-speed communications, and in particular relates to a multi-mode high-speed optical communication method, system and device based on an underwater mobile platform. Background Art

[0002] The ocean covers more than 70% of the world's area and contains rich resources. Ocean exploration has received increasing attention due to its scientific, strategic and economic importance, and one of the necessary conditions for ocean exploration and development is the ability to communicate underwater. Currently, the most widely used underwater communication method is still hydroacoustic communication. Although it can reach a transmission distance of several kilometers or even farther, the data rate is very low, usually tens of kilobits per second.

[0003] Seawater has a low absorption window of blue-green wavelengths, which provides feasibility for underwater optical wireless communication (UOWC). UWOC can be applied to underwater robots and frogman operations, AUV (Autonomous Underwater Vehicles) mobile observation, military submarine communications, shipwreck salvage and plane crash search, and underwater sensor networks, etc., to achieve dynamic communication between sensor nodes, UUVs, submarines, divers, etc. Therefore, the design and proposal of a small, low-cost, safe and reliable UWOC system is of great significance to the construction of wireless three-dimensional communication networks, marine national defense, etc., and also provides an important means for short-distance high-speed and large-capacity data transmission.

[0004] Currently, optical communication between underwater mobile platforms is greatly affected by beam alignment, water quality, communication rate, distance and field of view. Corresponding research is mostly carried out in laboratories or waters with good water quality, and the ability to adapt to the environment is weak, resulting in certain differences between theoretical simulations, laboratory tests and field dynamic tests. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a multi-mode high-speed optical communication method, system and device based on an underwater mobile platform, which has strong adaptability to complex water quality environments and moving platforms.

[0006] The present invention is implemented as follows: a multi-mode high-speed optical communication method based on an underwater mobile platform, the multi-mode high-speed optical communication method based on an underwater mobile platform comprising:

[0007] Step 1: Coarse target alignment;

[0008] Step 2: Target precise alignment;

[0009] Step 3, communication phase;

[0010] Step 4: Communication ends.

[0011] Further, the specific process of step one is:

[0012] The FPGA control output of the communicating parties is ultra-short electrical pulses, which are driven by the modulation circuit to emit high-energy pulsed lasers. The pulsed lasers are emitted through the scanning galvanometer and enter the water channel for raster scanning. The scanning angle of the galvanometer is + / -20 degrees, and the entire area can be scanned within 20 seconds.

[0013] If the silicon photomultiplier MPPC receives a weak single-photon signal, the optical line of sight deviation between the communicating parties is less than 20 degrees; if the received signal is strong enough, a high frame rate camera is used to capture the direction of the incident light beam, and the camera spot coordinate position is calculated by the MPPC or ARM to extract the off-target amount, which is used for feedback control of the gimbal to align the antenna with the other party to obtain the maximum received signal. At the same time, pulsed light is also emitted for the other party to receive, completing the rough alignment of the communicating parties.

[0014] Further, the specific process of step 2 is:

[0015] MPPC or camera spot coordinates are used to control the galvanometer for precise pointing alignment while maintaining precise tracking to keep the laser link aligned and receive the maximum signal.

[0016] Further, the specific process of step three is:

[0017] Start FPGA communication, including receiving data from the detector, decoding, and error correction; encoding and outputting the transmitted data; and exchanging data with the host computer.

[0018] Further, the specific process of step 4 is:

[0019] After receiving the data stream or the host computer issues a stop communication instruction, the FPGA stops running and ends the communication.

[0020] Another object of the present invention is to provide a multi-mode high-speed optical communication system based on an underwater mobile platform for implementing the multi-mode high-speed optical communication method based on an underwater mobile platform, wherein the multi-mode high-speed optical communication system based on an underwater mobile platform comprises a mother station and an underwater mobile platform AUV;

[0021] The mother platform and the underwater mobile platform AUV are both equipped with a two-dimensional pan-tilt platform, a laser, a guiding light source, a wide-angle CMOS camera, a receiving lens, a detector and an FPGA information processing module;

[0022] After the underwater mobile platform AUV moves to the vicinity of the mother platform, the 100-degree high-power wide-angle guide light on the AUV device emits a light source with high optical power and large divergence angle to indicate the location of the communication system;

[0023] After the other party's wide-angle CMOS camera captures the guiding light, the FPGA information processing module calculates the azimuth and pitch position of the guiding light, which are used to control the pan / tilt and galvanometer to accurately point the emitted light beam in the direction of the guiding light. After the two parties are aligned, the communication link is started to complete the communication task.

[0024] Another object of the present invention is to provide a multi-mode high-speed optical communication device based on an underwater mobile platform for implementing a multi-mode high-speed optical communication system based on an underwater mobile platform, characterized in that the multi-mode high-speed optical communication device based on an underwater mobile platform includes a transmitting end and a receiving end, and is composed of an Ethernet module, an FPGA information processing module, a laser driving module, a high-speed laser, an optical system, a photoelectric conversion module, a signal amplification processing circuit and a terminal, and uses a blue-green laser as a communication carrier to realize high-speed underwater laser communication;

[0025] The terminal host computer receives the data packet sent through the Ethernet module to the FPGA information processing module, performs internal data caching, and uses 8B / 10B encoding to perform parallel-to-serial conversion and input it into the laser driving circuit module. The optical signal is emitted into the underwater channel through the collimating optical lens, wherein the laser driving circuit module is composed of a Bias-T bias and a constant current source circuit;

[0026] Then, the optical signal is received by a photomultiplier tube (PMT) photodetector and an optical system at a receiving end, wherein the optical system at the receiving end includes a filter and an aspherical receiving lens;

[0027] Finally, the received optical signal is converted into photoelectric signals and then input into the signal amplification processing circuit. The amplified signal is then demodulated and decoded by the FPGA information processing module to restore the information and sent to the host computer software through the Ethernet module. The terminal analyzes and processes the relevant information.

[0028] Further, the FPGA information processing module includes a DDR memory control unit, an Ethernet frame encapsulation and decapsulation unit, an OOK modulation and demodulation unit, a TSE data transmission unit, an optical power data receiving unit, and a T-type bias transmission circuit for laser driving and a receiving conditioning circuit of MPPC;

[0029] The Ethernet driver part uses the GMII interface to connect to the MAC. MDC is the MAC drive clock signal, and MDIO is the serial data bus. A pull-up resistor is connected to ensure a high level in the idle state to complete the configuration of the PHY. The working status of the PHY is detected by reading the PHY register data. If an abnormality is found, consider writing data. By reading bit 5 of the basic mode status register 0X01, if it is 1, it means that the automatic negotiation is completed. The second register is [15:14] and 13 in the PHY specific status register 0X11, which are the current rate and full / half-duplex communication mode respectively. If the automatic negotiation is detected to be completed and it works in full-duplex mode, it means that the work is correct.

[0030] Furthermore, the processing flow of the FPGA information processing module is as follows:

[0031] The FPGA information processing module at the transmitting end receives the data stream sent by the host computer through the network communication mode, and performs RS encoding, 8B / 10B encoding, parallel-to-serial conversion on the data, and then transmits the signal to the LD driving circuit at the LVTTL level;

[0032] The FPGA information processing module at the receiving end performs serial-to-parallel conversion, 8B / 10B decoding, and RS decoding on the received LVTTL level, and then returns the information to the host computer at the receiving end through network communication.

[0033] Furthermore, the FPGA information processing module is also provided with a communication clock that generates bit synchronization according to the data, so as to enable the receiving end to receive and collect the data from the transmitting end.

[0034] Furthermore, a background light irradiance measuring device is installed at the communication receiving end to obtain the upward and downward background irradiance data simultaneously during the communication process, providing a basis for the subsequent analysis of the detection sensitivity and signal-to-noise ratio; at the same time, an automatic gain control module is designed at the receiving and processing end, which can perform automatic gain reception according to the background light intensity; two receiving optical paths are added to the receiving terminal, which can realize multi-aperture receiving signal synthesis and improve the receiving sensitivity; a window sediment flushing device is added to the underwater terminal to prevent siltation in the window during the test, which will affect communication.

[0035] Another object of the present invention is to provide a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the multi-mode high-speed optical communication method based on an underwater mobile platform.

[0036] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to execute the steps of the multi-mode high-speed optical communication method based on an underwater mobile platform.

[0037] Another object of the present invention is to provide an information data processing terminal, which is used to implement the multi-mode high-speed optical communication system based on the underwater mobile platform.

[0038] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0039] First, in view of the technical problems existing in the above-mentioned prior art and the difficulty of solving the problems, the technical solutions to be protected by the present invention and the results and data during the research and development process are closely combined to analyze in detail and deeply how the technical solutions of the present invention solve the technical problems, and some creative technical effects brought about after solving the problems. The specific description is as follows:

[0040] Aiming at high-speed data optical transmission between underwater mobile platforms and fixed platforms, the present invention has developed a high-speed, large dynamic range, adaptive gain optical signal modulation, reception, and demodulation method, and realized an underwater high-speed dual-wavelength light source (LED / LD) optical communication system by optimizing OOK high-power LED / LD modulation / demodulation, APD / PMT dual receiving modules, and ns-level laser pulse high-speed APD / PMT receiving signal gain adjustment modules.

[0041] Aiming at the problem of efficient alignment and docking of underwater moving platform optical communication system, a wide-angle laser capture and tracking system is designed, which can realize fast alignment based on optical communication between underwater unmanned platform and fixed station. Underwater optical communication host computer software is compiled to realize functions such as mode selection, bit error rate monitoring, communication rate control, and file transfer.

[0042] Second, considering the technical solution as a whole or from the perspective of the product, the technical effects and advantages of the technical solution to be protected by the present invention are described in detail as follows:

[0043] The present invention proposes a high-speed optical communication method between an AUV and a mothership (or a fixed platform) based on a multi-mode optical communication mode, which can enable the AUV to communicate with the mothership or (or a fixed platform) in real time while moving, and establish an interactive system. The invention can also be applied to the field of high-speed communication between AUV and submersibles, between submersibles, and between underwater mobile devices.

[0044] In order to solve the problems of high-speed, large dynamic range, adaptive gain optical signal modulation, reception and demodulation, the OOK high-power LED / LD modulation / demodulation technology was optimized, and the APD / PMT dual receiving module and the high-speed APD / PMT receiving signal gain adjustment module of ns-level laser pulse were used to realize the design and trial production of the underwater high-speed dual-wavelength light source (LED / LD) optical communication system prototype.

[0045] Aiming at the problem of efficient alignment and docking of the optical communication system of underwater moving platform, a wide-angle laser capture and tracking system was designed, which can realize rapid alignment based on optical communication between underwater unmanned platform and fixed station.

[0046] Third, as auxiliary evidence of the inventiveness of the claims of the present invention, it is also reflected in the following important aspects:

[0047] The expected benefits and commercial value of the technical solution of the present invention after transformation are:

[0048] After the technical solution of the present invention is transformed, it can be applied to fields such as short-distance high-speed communication between frogman formations, networking information exchange between underwater vehicles, high-speed docking communication between underwater fixed stations and mobile platforms, and cross-media communication between aerial platforms and underwater application platforms. It can significantly improve the communication efficiency of the marine information network and has important application prospects and commercial value in military and civilian fields.

[0049] (2) The technical solution of the present invention fills the technical gap in the industry at home and abroad:

[0050] The technical solution of the present invention aims at the problems of short distance and high bit error rate caused by seawater absorption and scattering, underwater turbulence, etc., and establishes an underwater optical communication system and channel simulation model under complex hydrological conditions, which can support the engineering application of multi-mode optical communication technology in different scenarios. The technical solution optimizes the OOK high-power LED / LD modulation / demodulation technology, adopts APD / PMT dual receiving channels, high-speed APD / PMT receiving signal gain adjustment of ns-level laser pulses, RS encoding and decoding and other technologies, which can solve the problems of high-speed, large dynamic range, adaptive gain optical signal encoding, modulation, reception, demodulation and decoding of optical communication systems under complex hydrological conditions. The designed wide-angle laser capture and tracking system can solve the problems of rapid capture, alignment and tracking of optical communications between underwater unmanned platforms and fixed stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a diagram showing the working principle of a system provided by an embodiment of the present invention;

[0052] Figure 2 It is a schematic diagram of the composition of an underwater multi-mode high-speed optical communication device provided by an embodiment of the present invention;

[0053] Figure 3 It is a framework diagram of an FPGA logic unit provided by an embodiment of the present invention;

[0054] Figure 4 It is a flow chart of FPGA information processing provided by an embodiment of the present invention.

[0055] Figure 5 (a) and (b) are respectively the prototype and trial status diagrams of the multi-mode high-speed optical communication prototype provided by the embodiment of the present invention.

[0056] Figure 6 (a) and (b) are respectively a test curve diagram and a test site diagram of a multi-mode high-speed optical communication test provided by an embodiment of the present invention.

[0057] Figure 7 As shown, underwater optical communication equipment can be used to realize information exchange between underwater UUV platforms, thereby realizing coordinated reconnaissance, coordinated strike and other actions between UUVs. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0059] In order to enable those skilled in the art to fully understand how to implement the present invention in detail, this section is an explanatory embodiment that expands and describes the technical solution of the claims.

[0060] The embodiment of the present invention provides a multi-mode high-speed optical communication method based on an underwater mobile platform, and the specific process is as follows:

[0061] Step 1: Coarse target alignment;

[0062] Step 2: Target precise alignment;

[0063] Step 3, communication phase;

[0064] Step 4: Communication ends.

[0065] Further, the specific process of step one is:

[0066] The FPGA control of the communicating parties outputs ultra-short electrical pulses, which are driven by the modulation circuit to emit high-energy pulsed lasers. The pulsed lasers pass through the scanning galvanometer and enter the water channel for raster scanning. The scanning angle of the galvanometer is + / -20 degrees, and the entire area is scanned within 20 seconds. If the silicon photomultiplier MPPC receives a weak single-photon signal, it means that the optical axis deviation of both parties is less than 20 degrees. If the received signal is strong enough, the high frame rate camera can see the direction of the incident light beam, and the MPPC or ARM calculates the camera spot coordinate position and extracts the off-target amount, which is used to feedback control the gimbal to align its antenna with the other party to obtain the maximum received signal. At the same time, pulsed light is also emitted for the other party to receive, thus completing the rough alignment of the two parties.

[0067] Further, the specific process of step 2 is:

[0068] Because the laser divergence angle is very small, both parties need to be finely aligned after rough alignment. Use MPPC or camera spot coordinates to control the galvanometer to make precise pointing adjustments while maintaining precise tracking status to keep the laser link aligned and receive the maximum signal.

[0069] Further, the specific process of step three is:

[0070] After the precise tracking is completed, the FPGA starts the communication process. The functions of the FPGA processing board are: (a) receiving the received data from the detector, decoding, and error correction processing; (b) encoding and outputting the transmitted data; (c) exchanging data with the host computer.

[0071] Further, the specific process of step 4 is:

[0072] When the FPGA receives the data stream or the host computer issues a stop communication command, it stops running and ends the communication.

[0073] like Figure 1 As shown, an embodiment of the present invention provides a multi-mode high-speed optical communication system based on an underwater mobile platform, including a mother station and an underwater mobile platform AUV; the mother station and the underwater mobile platform AUV are both equipped with a two-dimensional pan-tilt platform, a laser, a guide light source, a wide-angle CMOS camera, a receiving lens, a detector and an FPGA information processing module;

[0074] After the underwater mobile platform AUV moves to the vicinity of the mother platform, the high-power wide-angle (100-degree) guide light on the AUV device emits a light source with high optical power and large divergence angle, similar to the role of a lighthouse guiding ships, marking the location of the communication system;

[0075] After the other party's wide-angle CMOS camera captures the guiding light, the azimuth and pitch position of the guiding light are calculated by FPGA, and the parameters are used to control the pan-tilt and galvanometer to accurately point the transmitted light beam in the direction of the guiding light. After the two parties are aligned, the communication link is started to complete the communication task.

[0076] Furthermore, in terms of system design, a background light irradiance measuring device is installed at the communication receiving end. During the communication process, the upward and downward background irradiance data are obtained simultaneously, providing a basis for the later analysis of detection sensitivity and signal-to-noise ratio; at the receiving and processing end, an automatic gain control module is designed, which can automatically gain reception according to the background light intensity; two receiving optical paths are added to the receiving terminal, which can realize multi-aperture receiving signal synthesis and improve receiving sensitivity; a window sediment flushing device is added to the underwater terminal to prevent siltation in the window during the test, which affects communication. Blue-green LED and LD dual light sources are used as communication carriers to realize optical communication docking of underwater unmanned platforms with tracking and aiming functions.

[0077] like Figure 2As shown, the present invention also provides a multi-mode high-speed optical communication device based on an underwater mobile platform, the multi-mode high-speed optical communication device based on an underwater mobile platform includes a transmitting end and a receiving end, and is composed of an Ethernet module, an FPGA information processing module, a laser driving module, a high-speed laser, an optical system, a photoelectric conversion module, a signal amplification processing circuit and a terminal;

[0078] The terminal host computer receives the data packet sent through the Ethernet module to the FPGA information processing module, performs internal data caching, and uses 8B / 10B encoding to perform parallel-to-serial conversion and input it into the laser driving circuit module, wherein the laser driving circuit module is composed of a Bias-T bias and a constant current source circuit; the optical signal is emitted into the underwater channel through a collimating optical lens;

[0079] The optical signal is received by a photomultiplier tube (PMT) photodetector and an optical system at the receiving end, wherein the optical system at the receiving end includes a filter and an aspherical receiving lens, and is used to achieve a large field of view and ultra-high sensitivity receiving function;

[0080] The received optical signal is converted into photoelectric signals and then input into the signal amplification processing circuit. The amplified signal is then demodulated and decoded by the FPGA information processing module to restore the information and sent to the host computer software through the Ethernet module. Finally, the terminal analyzes and processes the relevant information.

[0081] Furthermore, the FPGA information processing module, as a data processing core, can perform the following Figure 3 The unit division is shown in the figure. It mainly includes DDR memory control unit, Ethernet frame encapsulation and decapsulation unit, OOK modulation and demodulation unit, TSE data transmission unit, optical power data receiving unit, etc., as well as T-type bias transmission circuit for laser driving and MPPC receiving and conditioning circuit.

[0082] The Ethernet driver uses the GMII interface to connect to the MAC. MDC is the MAC drive clock signal, and MDIO is a serial data bus. A pull-up resistor needs to be connected to ensure a high level in the idle state, thereby configuring the PHY. The PHY register data is read to detect its working status. If an abnormality is found, consider writing data. By reading bit 5 of the basic mode status register 0X01, if it is 1, it means that the automatic negotiation is completed. The second register is [15:14] and 13 in the PHY specific status register 0X11, which are the current rate and full / half-duplex communication mode respectively. If the automatic negotiation is detected to be completed and it works in full-duplex mode, it means that the work is correct.

[0083] Furthermore, the processing flow of the FPGA information processing module is as follows:

[0084] The FPGA information processing module of the transmitting end mainly receives the data stream sent by the host computer through the network communication mode, and performs RS encoding, 8B / 10B encoding, parallel-to-serial conversion and other processing on the data, and then transmits the signal to the LD driving circuit at the LVTTL level;

[0085] The FPGA information processing module at the receiving end performs serial-to-parallel conversion, 8B / 10B decoding, and RS decoding on the received LVTTL level, and returns the information to the host computer at the receiving end through network communication. The structural block diagram is shown in FIG. Figure 4 shown.

[0086] Furthermore, the FPGA information processing module is also provided with a communication clock that generates bit synchronization according to the data, so as to enable the receiving end to accurately receive and collect the data from the transmitting end.

[0087] In order to prove the creativity and technical value of the technical solution of the present invention, this section provides application examples of the claimed technical solution on specific products or related technologies.

[0088] The embodiments of the present invention can be applied in the following scenarios:

[0089] 1. Information exchange between underwater submersible groups;

[0090] 2. Information transmission between underwater submersibles and underwater fixed base stations;

[0091] 3. Short-distance high-speed communication between frogman formations;

[0092] 4. Cross-media communication between aerial platforms and underwater fixed or mobile platforms.

[0093] like Figure 7 As shown, underwater optical communication equipment can be used to realize information exchange between underwater UUV platforms, and then realize actions such as coordinated reconnaissance and coordinated strike between UUVs.

[0094] The embodiments of the present invention have achieved some positive effects during the development or use process, and indeed have great advantages over the prior art. The following content is described in conjunction with data, charts, etc. of the test process.

[0095] The embodiments of the present invention aim at the difficult problems of high-speed, large dynamic range, adaptive gain optical signal modulation, reception, and demodulation, optimize the OOK high-power LED / LD modulation / demodulation technology, and adopt the APD / PMT dual receiving module and the high-speed APD / PMT receiving signal gain adjustment module of ns-level laser pulses to realize the design and trial production of the underwater high-speed dual-wavelength light source (LED / LD) optical communication system prototype. In order to solve the problem of efficient alignment and docking of underwater moving platform optical communication systems, a wide-angle laser capture and tracking system is designed to realize rapid alignment of optical communications between underwater unmanned platforms and fixed stations. Underwater optical communication host computer software is compiled to realize functions such as mode selection, bit error rate monitoring, communication rate control, and file transfer.

[0096] The single-chip microcomputer is used to sample the current value of the modulation end in real time. The single-chip microcomputer determines the size of the output control voltage value according to the sampled current value, and finally forms the modulation current control to realize the modulation of the high-power LED / LD signal. The transmitting system uses two light sources: light-emitting diodes and laser light sources. The light-emitting diode uses two LEDs with different wavelengths for two-way communication. The laser uses a blue-green high-power semiconductor laser, which has the advantages of small size, light weight, low power consumption, etc., which is conducive to miniaturization. The design of dual light sources can realize short-distance high-speed communication and long-distance low-speed communication, and can also realize the simultaneous transmission of multiple beams. It has high illumination and relatively concentrated input energy, which can transmit over longer distances, and can also reduce the bit error rate of the communication system.

[0097] The present invention adopts a detection module combining PMT and APD. The PMT uses a Hamamatsu H14447 photodetector, which has a photosensitive diameter of 25 mm, a peak value of 450 nm, a response band of 300-650 nm, a photosensitive area of ​​156.25 mm2, and a sensitivity of 670 A / W. The sensitivity of the PMT is about -55.6 dBm when tested in combination with a designed signal processing circuit. The APD receiving system uses a Hamamatsu S8664-50K avalanche photodiode, which has a peak sensitivity wavelength of 600 nm, a spectral response range of 320-1000 nm, a cut-off frequency of 60 MHz, a photosensitive area of ​​19.6 mm2, and a sensitivity of 16 A / W. The sensitivity of the APD detector is about -31.3 dBm when tested in combination with a designed signal processing circuit.

[0098] In the design of the receiving optical system, the two ends of underwater optical communication use different wavelength signals for communication to avoid mutual interference between the same wavelengths. One end of the communication uses 470nm light, and the other end uses 530nm light. Two filters with different bands are used to filter the system, and the bands of the two filters do not overlap. Using filters with different wavelengths can reduce the interference of the signal light itself and reduce the influence of external ambient light.

[0099] In terms of signal reception and processing, the transimpedance amplifier in the system uses the OPA657 chip to convert the current signal generated by the PMT / APD into a voltage signal, and the voltage signal output by the transimpedance amplifier is output as an LVTTL level signal through a filtering circuit, a limiting amplifier circuit and a level conversion circuit.

[0100] According to the technical solution proposed by the present invention, a sample test machine has been manufactured in the embodiment of the present invention, and the underwater Indian platform multi-mode high-speed optical communication prototype equipment is as follows: Figure 5 As shown, the multi-mode high-speed optical communication test is as follows Figure 6 shown.

[0101] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A multi-mode high-speed optical communication method based on an underwater mobile platform, characterized in that: The multi-mode high-speed optical communication method based on an underwater mobile platform comprises: Step 1: Coarse target alignment; Step 2: Target precise alignment; Step 3, communication phase; Step 4: Communication ends; The specific process of step one is: The FPGA control of both communicating parties outputs ultra-short electrical pulses, which are driven by the modulation circuit to emit high-energy pulsed lasers. The pulsed lasers pass through the scanning galvanometer and enter the water channel for raster scanning. The scanning angle of the galvanometer is + / -20 degrees, and the entire area can be scanned within 20 seconds. If the silicon photomultiplier MPPC receives a weak single-photon signal, the optical line of sight deviation between the two communicating parties is less than 20 degrees. If the received signal is strong enough, a high frame rate camera is used to capture the direction of the incident light beam, and the camera spot coordinate position is calculated by the MPPC or ARM to extract the miss distance, which is used for feedback control of the gimbal to align the antenna with the other party to obtain the maximum received signal. At the same time, pulse light is also emitted for the other party to receive, completing the rough alignment of the two communicating parties. The specific process of step 2 is: MPPC or camera spot coordinates are used to control the galvanometer for precise pointing alignment while maintaining precise tracking to keep the laser link aligned and receive the maximum signal.

2. The multi-mode high-speed optical communication method based on an underwater mobile platform as claimed in claim 1, characterized in that: The specific process of step three is: Start FPGA communication, including receiving data from the detector, decoding, and error correction; encoding and outputting the transmitted data; and exchanging data with the host computer.

3. The multi-mode high-speed optical communication method based on an underwater mobile platform as claimed in claim 1, characterized in that: The specific process of step 4 is as follows: After receiving the data stream or the host computer issues a stop communication instruction, the FPGA stops running and ends the communication.

4. A multi-mode high-speed optical communication system based on an underwater mobile platform implementing the multi-mode high-speed optical communication method based on an underwater mobile platform as claimed in any one of claims 1 to 3, characterized in that: The multi-mode high-speed optical communication system based on an underwater mobile platform includes a mother station and an underwater mobile platform AUV; The mother platform and the underwater mobile platform AUV are both equipped with a two-dimensional pan-tilt platform, a laser, a guiding light source, a wide-angle CMOS camera, a receiving lens, a detector and an FPGA information processing module; After the underwater mobile platform AUV moves to the vicinity of the mother platform, the 100-degree high-power wide-angle guide light on the AUV device emits a light source with high optical power and large divergence angle to indicate the location of the communication system; After the other party's wide-angle CMOS camera captures the guiding light, the FPGA information processing module calculates the azimuth and pitch position of the guiding light, which are used to control the pan / tilt and galvanometer to accurately point the emitted light beam in the direction of the guiding light. After the two parties are aligned, the communication link is started to complete the communication task.

5. A multi-mode high-speed optical communication device based on an underwater mobile platform for implementing the multi-mode high-speed optical communication system based on an underwater mobile platform as claimed in claim 4, characterized in that: The multi-mode high-speed optical communication device based on the underwater mobile platform includes a transmitting end and a receiving end, and is composed of an Ethernet module, an FPGA information processing module, a laser driving module, a high-speed laser, an optical system, a photoelectric conversion module, a signal amplification processing circuit and a terminal. The blue-green laser is used as a communication carrier to realize high-speed underwater laser communication. The host computer of the terminal receives the data packet sent through the Ethernet module to the FPGA information processing module, performs internal data caching, and uses 8B / 10B encoding to perform parallel-to-serial conversion and input it into the laser driving module. The optical signal is emitted into the underwater channel through the collimating optical lens, wherein the laser driving module is composed of a Bias-T bias and a constant current source circuit; Then, the optical signal is received by a photomultiplier tube (PMT) photodetector and an optical system at the receiving end, wherein the optical system at the receiving end includes a filter and an aspherical receiving lens, wherein the filter can filter out background interference light and improve the signal-to-noise ratio of signal reception detection, and the aspherical receiving lens can achieve convergence reception of the incident light beam and improve the signal light receiving gain; Finally, the received optical signal is converted into photoelectric signals and then input into the signal amplification processing circuit. The amplified signal is then demodulated and decoded by the FPGA information processing module to restore the information and sent to the host computer software through the Ethernet module. The terminal analyzes and processes the relevant information.

6. The multi-mode high-speed optical communication device based on an underwater mobile platform as claimed in claim 5, characterized in that: The FPGA information processing module includes a DDR memory control unit, an Ethernet frame encapsulation and decapsulation unit, an OOK modulation and demodulation unit, a TSE data transmission unit, an optical power data receiving unit, and a T-type bias transmission circuit for LD driving and a receiving conditioning circuit of MPPC; The Ethernet driver part uses the GMII interface to connect to the MAC. MDC is the MAC drive clock signal, and MDIO is the serial data bus. A pull-up resistor is connected to ensure a high level in the idle state to complete the configuration of the PHY. The working status of the PHY is detected by reading the PHY register data. If an abnormality is found, consider writing data. By reading bit 5 of the basic mode status register 0X01, if it is 1, it means that the automatic negotiation is completed. The second register is [15:14] and 13 in the PHY specific status register 0X11, which are the current rate and full / half-duplex communication mode respectively. If the automatic negotiation is detected to be completed and it works in full-duplex mode, it means that the work is correct.

7. The multi-mode high-speed optical communication device based on an underwater mobile platform as claimed in claim 5, characterized in that: The processing flow of the FPGA information processing module is as follows: The FPGA information processing module at the transmitting end receives the data stream sent by the host computer through the network communication mode, and performs RS encoding, 8B / 10B encoding, parallel-to-serial conversion on the data, and then transmits the signal to the LD driving circuit at the LVTTL level; The FPGA information processing module at the receiving end performs serial-to-parallel conversion, 8B / 10B decoding, and RS decoding on the received LVTTL level, and then returns the information to the host computer at the receiving end through network communication.

8. The multi-mode high-speed optical communication device based on an underwater mobile platform as claimed in claim 5, characterized in that: The FPGA information processing module is also provided with a communication clock that generates bit synchronization according to the data, so as to enable the receiving end to receive and collect the data of the transmitting end; A background light irradiance measuring device is installed at the communication receiving end. During the communication process, the upward and downward background irradiance data are obtained simultaneously, which provides a basis for the later analysis of detection sensitivity and signal-to-noise ratio. At the same time, an automatic gain control module is designed at the receiving processing end, which can automatically gain the reception according to the background light intensity. The receiving terminal adds two receiving optical paths to realize multi-aperture receiving signal synthesis and improve receiving sensitivity; The underwater terminal has added a window sediment flushing device to prevent the window from silting up during the test and affecting communications.

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