A method for acquisition, tracking and pointing in space laser communication

Abstract

The present invention relates to the field of space optical communication technology, and particularly to a method for acquisition, tracking and aiming in space laser communication. Terminal A sends a third optical signal to terminal B; the optical transceiver module of terminal B performs wavelength compensation on the wavelength included in the third optical signal, calculates the true scanning step sequence of terminal A at the current moment and the scanning space position vector of terminal A according to the compensated wavelength; calculates a deviation vector according to the own position vector of terminal B, the true scanning step sequence of terminal A at the current moment and the scanning space position vector of terminal A, corrects the return beam vector according to the deviation vector, and sends a return beam to terminal A according to the return beam vector; terminal A corrects the pointing of the tracking beam to be sent to terminal B next time according to the return beam. By applying emission light of a certain wavelength combination and improving the modulation method of the emission light, the present invention improves the transmission quality of the signal light and the anti-interference ability of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of space optical communication, and particularly to a method for acquisition, tracking and pointing of space laser communication. Background Art

[0002] In space laser communication, the interconnection of two terminals first requires ensuring the accurate acquisition, continuous tracking and precise pointing of the laser beam. These functions can be achieved by transmitting beacon light or signal light, and these beams pass through a complex cross-media channel composed of multiple media and finally reach the other terminal to achieve communication. The cross-media channel may include free space, atmosphere, thin clouds, fog or water vapor interface, etc.

[0003] However, the complexity of the cross-media channel brings challenges. Factors such as the random movement of the medium, absorption and scattering of the optical signal will cause unpredictable swings of the beam, resulting in phenomena such as amplitude attenuation and phase distortion of the optical signal, thus seriously affecting the acquisition and tracking performance of the beam. For example, turbulence and bad weather conditions in the atmospheric channel, as well as vibrations and disturbances on the space platform, may cause random changes in the beam position, thus exacerbating the difficulty of acquisition and tracking.

[0004] Traditional laser terminal acquisition, tracking and pointing systems usually rely on beacon light or signal light of a single wavelength, which has limited effect in countering the random changes in the spatial position of the beam in the cross-media channel, thus significantly reducing the acquisition and tracking performance, and there is no information modulation method for signal light of a certain combined wavelength in the prior art.

[0005] Therefore, there is an urgent need for a method for acquisition, tracking and pointing of space laser communication, which can effectively overcome the influence of large random changes in the spatial position of the beam in the cross-media channel on beam acquisition and tracking when laser communication is carried out between space laser terminals, and improve the beam acquisition and tracking performance of the cross-media channel. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a method for acquisition, tracking and pointing of space laser communication, which can effectively overcome the influence of large random changes in the spatial position of the beam in the cross-media channel on beam acquisition and tracking when laser communication is carried out between space laser terminals, and improve the beam acquisition and tracking performance of the cross-media channel.

[0007] The present invention provides a method for acquisition, tracking and pointing of space laser communication, which is implemented based on a space laser communication acquisition, tracking and pointing system, and the system includes: an optical transceiver module, a wavelength combination acquisition and tracking module;

[0008] An optical transceiver module, including a transmitting branch and a receiving branch, is used for splitting, filtering, modulating and combining optical signals to generate a broadband laser signal. The transmitting branch sends the broadband laser signal to a space channel, and the receiving branch is used to receive the broadband laser signal sent by a terminal and perform dispersion and optoelectronic processing;

[0009] A wavelength combination acquisition and tracking module, connected to the optical transceiver module, is used to send control instructions to the transmitting branch and the receiving branch of the optical transceiver module based on a space wavelength combination acquisition strategy and a tracking strategy, and at the same time demodulate the received broadband laser signal to obtain the information contained in the broadband laser signal;

[0010] The method includes the following steps:

[0011] S1. Terminal A enters the acquisition stage, starts a stepped spiral scan, initializes the transmission intelligent control module, and controls the optical transceiver module to modulate a first optical signal and a second optical signal , and combines the first optical signal and the second optical signal into a third optical signal , and sends the third optical signal to terminal B ;

[0012] S2. When terminal B receives the third optical signal from terminal A , the optical transceiver module of terminal B separates the wavelength combinations included in the third optical signal spatially from each other and outputs them to the receiving intelligent control module. The receiving intelligent control module first performs wavelength compensation on the wavelengths included in the third optical signal , and then calculates the true scanning step sequence of terminal A at the current moment based on the compensated wavelengths;

[0013] S3. The receiving intelligent control module of terminal B calculates the scanning space position vector of terminal A based on the true scanning step sequence of terminal A at the current moment, the scanning initial position, the terminal real-time position, the scanning parameters, and the speed information of terminal A;

[0014] S4. The receiving intelligent control module of terminal B calculates a deviation vector based on the own position vector of terminal B, the true scanning step sequence of terminal A at the current moment, and the scanning space position vector of terminal A, corrects the return beam vector according to the deviation vector, and sends a return beam to terminal A according to the return beam vector;

[0015] S5. Terminal A corrects the pointing of the tracking beam to be sent to terminal B next time according to the return beam feedback from terminal B, the acquisition stage is completed, and terminal A and terminal B enter the tracking stage.

[0016] Further, in S1, control the optical transceiver module to modulate the first optical signal and the second optical signal , and combine the first optical signal and the second optical signal into a third optical signal , and send the third optical signal to terminal B, including:

[0017] S11. Modulate the first optical signal . The transmission intelligent control module of terminal A controls the 0th branch of the optical transceiver module to output the first wavelength combination , and encodes the scanning initial position, real-time position, scanning parameters and terminal speed information of terminal A into a binary code stream and modulates it onto the first wavelength combination . The first optical signal contains the first wavelength combination . The first wavelength combination contains wavelengths ;

[0018] S12. Modulate the second optical signal . The transmission intelligent control module of terminal A controls the Q branches of the optical transceiver module except the 0th branch to output the second wavelength combination , encodes the scanning step sequence of terminal A into a binary code stream and modulates it onto the second wavelength combination . The second optical signal contains the second wavelength combination . The second wavelength combination contains at least one wavelength among wavelengths . With each scanning step, terminal A performs wavelength combination according to the preset step sequence table and changes the wavelength combination mode of the output second wavelength combination ; where Q represents the total number of wavelengths;

[0019] S13. Combine the third optical signal . The optical transceiver module combines the first optical signal and the second optical signal , that is , and terminal A emits the third optical signal in the spatial pointing direction of the current scanning position;

[0020] S14. In subsequent scanning steps, repeat steps S11, S12, and S13 until the predetermined number of scans is completed or the return beam from terminal B is received.

[0021] Further, in S12, modulating the second optical signal includes:

[0022] At the th scanning step, the transmission intelligent control module of terminal A controls the first branch of the optical transceiver module, so that the wavelength combination output through the first branch contains wavelength , and then modulates the code stream of the orthogonal code onto the wavelength combination . Then, the wavelength combination of the third optical signal output by terminal A is ;

[0023] At the th scanning step, the transmission intelligent control module of terminal A controls the th branch of the optical transceiver module, so that the wavelength combination output through the second branch contains wavelength , and then modulates the code stream of the orthogonal code onto the wavelength combination . Then, the wavelength combination of the third optical signal output by terminal A is ; and so on. At the th scanning step, the wavelength combination of the third optical signal output by terminal A is .

[0024] Furthermore, in S12, modulating the second optical signal includes:

[0025] At the th scanning step, the transmission intelligent control module of terminal A controls the first branch of the optical transceiver module, so that the wavelength combination output through the first branch contains wavelength and , and then modulates the code stream of the orthogonal code onto the wavelength combination . Then, the wavelength combination of the third optical signal output by terminal A is ;

[0026] At the th scanning step, the transmission intelligent control module of terminal A controls the th branch of the optical transceiver module, so that the wavelength combination output through the second branch contains wavelength , and then modulates the code stream of the orthogonal code onto the wavelength combination . Then, the wavelength combination of the third optical signal output by terminal A is ; and so on. At the th scanning step, the wavelength combination of the third optical signal output by terminal A is .

[0027] Further, in S12, modulate the second optical signal including:

[0028] At the th scanning step, the transmitting intelligent control module of terminal A controls the first branch of the optical transceiver module, so that the wavelength combination output through the first branch contains wavelength and any wavelength , and then modulates the code stream of the orthogonal code onto wavelengths and , then terminal A outputs a third optical signal whose wavelength combination is ; where n represents the nth wavelength;

[0029] At the th scanning step, the transmitting intelligent control module of terminal A controls the th branch of the optical transceiver module, so that the wavelength combination output through the second branch contains wavelength and any wavelength , and then modulates the code stream of the orthogonal code onto wavelength , then terminal A outputs a third optical signal whose wavelength combination is ; and so on. At the th scanning step, the wavelength combination of the third optical signal output by terminal A is .

[0030] Further, in S2, the receiving intelligent control module first performs wavelength compensation on the wavelengths included in the third optical signal . The wavelength compensation calculation formula is as follows:

[0031] When terminal B moves in the direction approaching terminal A, the wavelength compensation calculation formula is as follows:

[0032] ;

[0033] When terminal B moves in the direction away from terminal A, the wavelength compensation calculation formula is as follows:

[0034] ;

[0035] where is the wavelength of the third optical signal received by terminal B; is the original transmission wavelength emitted by terminal A in the medium; is the absolute value of the moving speed of terminal B relative to the medium; is the absolute value of the moving speed of terminal A relative to the medium; is the traveling speed of light in the medium.

[0036] Further, in S2, the true scanning step sequence of terminal A at the current moment is calculated according to the compensated wavelength The calculation formula is as follows:

[0037] When terminal B moves in the direction approaching terminal A, the calculation formula for the true scanning step sequence of terminal A at the current moment is as follows:

[0038] ;

[0039] When terminal B moves in the direction away from terminal A, the calculation formula for the true scanning step sequence of terminal A at the current moment is as follows:

[0040] ;

[0041] Where: is the third optical signal received by terminal B wavelength; j is the true scanning step sequence of terminal A; is the absolute value of the moving speed of terminal B relative to the medium; is the absolute value of the moving speed of terminal A relative to the medium; is the traveling speed of light in the medium; k is an engineering coefficient, which is set according to the measured value of the difference between two fixed wavelengths during system calibration.

[0042] Further, in S2, calculating the true scanning step sequence of terminal A at the current moment according to the compensated wavelength includes:

[0043] Using the method of looking up the correspondence table between the preset wavelength combination and the step sequence of the system to determine the true scanning step sequence of terminal A at the current moment .

[0044] Further, in S3, the receiving intelligent control module of terminal B calculates the scanning space position vector of terminal A according to the true scanning step sequence of terminal A at the current moment, the scanning initial position, the terminal real-time position, the scanning parameters, and the speed information of terminal A. The calculation formula is as follows:

[0045] ;

[0046] Where, is the scanning space position vector of terminal A for the th step; is the spiral interval; j is the true scanning step sequence of terminal A at the current moment; is the step parameter.

[0047] Further, in S4, the receiving intelligent control module of terminal B calculates a deviation vector based on the own position vector of terminal B, the actual scanning step sequence of terminal A at the current moment, and the scanning space position vector of terminal A, and corrects the return beam vector according to the deviation vector. :

[0048] S41. Calculate the deviation vector, and the calculation formula is as follows:

[0049] ;

[0050] Wherein, is the deviation vector caused by the cross-media channel of the th scanning step; is the vector between the spatial position coordinates of terminal B and the scanning initial origin;

[0051] S42. Correct the return beam vector according to the deviation vector The calculation formula is as follows:

[0052] ;

[0053] Wherein, is the return beam vector; is the spot width of the beam at the receiving end; is the position vector of terminal A.

[0054] The embodiments of the present invention have the following technical effects:

[0055] 1. Improve the capture and tracking performance: Traditional laser terminal capture, tracking and aiming systems usually use beacon light or signal light of a single wavelength for capture and tracking, but this method performs poorly in the face of random changes in the spatial position of the beam in the cross-media channel. The present invention can better adapt to the change of the beam position by modulating the signal onto the signal light of a certain wavelength combination. By adjusting the wavelength combination and using the orthogonal code group for modulation, the scanning space position of the transmitting end and the terminal position can be accurately calculated, thereby improving the capture and tracking performance.

[0056] 2. Improve flexibility and reliability: The present invention modulates the signal onto the signal light of a specific wavelength combination, and increases the flexibility of the system by adjusting the wavelength combination and output of the optical transceiver module. This modulation method improves the transmission quality of the signal and enhances the resistance of the system to interference. At the same time, compared with the traditional system, the present invention reduces the need for additional equipment and complex adjustment, and improves the reliability of the system. This innovative method enables the optical communication system to have higher adaptability and robustness, and can operate stably in a complex communication environment. Description of the Drawings

[0057] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0058] Figure 1 It is a flowchart of a method for acquisition, tracking and pointing of space laser communication provided by an embodiment of the present invention;

[0059] Figure 2 It is a schematic diagram of acquisition scanning of a cross-media channel laser communication system provided by an embodiment of the present invention;

[0060] Figure 3 It is a schematic diagram of the spectral composition of the third optical signal emitted in the first step-by-step spiral scan provided by an embodiment of the present invention;

[0061] Figure 4 It is a schematic diagram of the spectral composition of the third optical signal emitted in the second step-by-step spiral scan provided by an embodiment of the present invention;

[0062] Figure 5 It is a schematic diagram of the spectral composition of the third optical signal emitted in the third step-by-step spiral scan provided by an embodiment of the present invention;

[0063] Figure 6 It is a schematic diagram of using a grating as a receiving dispersion component to spatially separate the wavelength combinations included in the third optical signal provided by an embodiment of the present invention;

[0064] Figure 7 It is a schematic diagram of the acquisition scanning vector of a cross-media channel provided by an embodiment of the present invention;

[0065] Figure 8 It is a schematic diagram of a certain overlap in space of the emitted light of different wavelengths in the fine tracking stage provided by an embodiment of the present invention. Specific Embodiments

[0066] To make the objectives, technical solutions and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0067] Figure 1 It is a flowchart of a method for acquisition, tracking and pointing of space laser communication provided by an embodiment of the present invention,Figure 2 This is a schematic diagram of the acquisition and scanning of a cross-media channel laser communication system provided by an embodiment of the present invention. Refer to Figure 1 and Figure 2 , the present invention provides a method for acquisition, tracking, and aiming of space laser communication, which is implemented based on a space laser communication acquisition, tracking, and aiming system. The system includes: an optical transceiver module and a wavelength combination acquisition and tracking module;

[0068] The optical transceiver module includes a transmitting branch and a receiving branch, and is used for splitting, filtering, modulating, and combining optical signals to generate a broadband laser signal. The transmitting branch sends the broadband laser signal to the space channel, and the receiving branch is used to receive the broadband laser signal sent by the terminal and perform dispersion and optoelectronic processing;

[0069] The wavelength combination acquisition and tracking module is connected to the optical transceiver module, and is used to send control instructions to the transmitting branch and the receiving branch of the optical transceiver module based on the space wavelength combination acquisition strategy and tracking strategy, and at the same time demodulate the received broadband laser signal to obtain the information contained in the broadband laser signal.

[0070] The method includes the following steps:

[0071] S1. Terminal A enters the acquisition stage, starts the stepped spiral scan, initializes the transmitting intelligent control module, and controls the optical transceiver module to modulate the first optical signal and the second optical signal , and combines the first optical signal and the second optical signal into a third optical signal , and sends the third optical signal to terminal B .

[0072] Specifically, controlling the optical transceiver module to modulate the first optical signal and the second optical signal , and combining the first optical signal and the second optical signal into a third optical signal , and sending the third optical signal to terminal B includes:

[0073] S11. Modulate the first optical signal , the transmitting intelligent control module of terminal A controls the 0th branch of the optical transceiver module to output the first wavelength combination , and encodes the scanning initial position, real-time position, scanning parameters, and terminal speed information of terminal A into a binary code stream and modulates it onto the first wavelength combination , and the first optical signal contains the first wavelength combination , the first wavelength combination includes wavelengths .

[0074] S12. Modulate the second optical signal , the transmission intelligent control module of terminal A controls the Q branches of the optical transceiver module except the 0th branch to output the second wavelength combination , encodes the scanning step sequence of terminal A into a binary code stream and modulates it onto the second wavelength combination . The second optical signal includes the second wavelength combination The second wavelength combination includes wavelengths in it. With each scanning step, terminal A performs wavelength combination according to the preset step sequence correspondence table and changes the wavelength combination mode of the output second wavelength combination ; where Q represents the total number of wavelengths.

[0075] Specifically, the preset step sequence correspondence table is preset for the entire system before terminal A and terminal B start capture, tracking, aiming, and communication, and the preset step sequence correspondence table is stored in terminal A and terminal B respectively. Terminal A performs wavelength combination according to the preset step sequence correspondence table, and terminal B also decodes the wavelength combination according to the preset step sequence correspondence table.

[0076] Figure 3 is the schematic diagram of the spectral composition of the third optical signal transmitted in the first step-by-step spiral scan provided by the embodiment of the present invention. Refer to Figure 3 , modulating the second optical signal includes:

[0077] At the th scanning step, the transmission intelligent control module of terminal A controls the first branch of the optical transceiver module, so that the wavelength combination output through the first branch includes wavelengths , and then modulates the code stream of the orthogonal code onto the wavelength combination . Then the wavelength combination of the third optical signal output by terminal A is ;

[0078] At the th scanning step, the transmission intelligent control module of terminal A controls the th branch of the optical transceiver module, so that the wavelength combination output through the second branch includes wavelengths , and then modulates the code stream of the orthogonal code onto the wavelength combination . Then the wavelength combination of the third optical signal output by terminal A is ; And so on, at the th scan step, the terminal A outputs a third optical signal with a wavelength combination of .

[0079] Figure 4 is a schematic diagram of the spectral composition of the third optical signal emitted in the second step-by-step spiral scan provided by the embodiment of the present invention. Refer to Figure 4 , modulating the second optical signal includes:

[0080] At the th scan step, the emission intelligent control module of the terminal A controls the first branch of the optical transceiver module, so that the wavelength combination output through the first branch contains wavelengths and . Then, the code stream of the orthogonal code is modulated onto the wavelength combination , and the terminal A outputs a third optical signal with a wavelength combination of ;

[0081] At the th scan step, the emission intelligent control module of the terminal A controls the th branch of the optical transceiver module, so that the wavelength combination output through the second branch contains wavelength . Then, the code stream of the orthogonal code is modulated onto the wavelength combination , and the terminal A outputs a third optical signal with a wavelength combination of ; And so on, at the th scan step, the terminal A outputs a third optical signal with a wavelength combination of .

[0082] Figure 5 is a schematic diagram of the spectral composition of the third optical signal emitted in the third step-by-step spiral scan provided by the embodiment of the present invention. Refer to Figure 5 , modulating the second optical signal includes:

[0083] At the th scan step, the emission intelligent control module of the terminal A controls the first branch of the optical transceiver module, so that the wavelength combination output through the first branch contains wavelengths and any wavelength . Then, the code stream of the orthogonal code is modulated onto wavelengths and , and the terminal A outputs a third optical signal with a wavelength combination of ; where n represents the nth wavelength;

[0084] At the th scanning step, the transmission intelligent control module of terminal A controls the th branch of the optical transceiver module, so that the wavelength combination output through the 2nd branch includes the wavelength and any wavelength . Then, the code stream of the orthogonal code is modulated onto the wavelength , and then terminal A outputs the third optical signal whose wavelength combination is ; and so on. At the th scanning step, the wavelength combination of the third optical signal output by terminal A is .

[0085] S13. Synthesize the third optical signal . The optical transceiver module synthesizes the first optical signal and the second optical signal , that is , and terminal A emits the third optical signal in the spatial pointing direction at the current scanning position.

[0086] Specifically, the transmission intelligent control module controls the optical combiner to combine the first optical signal and the second optical signal into the synthesized third optical signal , and emits it into the space channel in the spatial pointing direction at the current scanning position.

[0087] S14. In the subsequent scanning steps, repeat steps S11, S12, and S13 until the predetermined number of scans is completed or the return beam from terminal B is received.

[0088] Specifically, at the th scanning step in the subsequent steps, where , the transmission intelligent control module controls the optical combiner and the optical splitter to sequentially select the corresponding th branch, so that the wavelength combination of the optical signal output by the th branch is , and generates the corresponding second optical signal whose wavelength combination is , then synthesizes the optical signal . And emits the light beam to sequentially scan the spatial positions .

[0089] At the From the wavelengths, multiple wavelengths are selected to form a certain wavelength combination, and this combination is combined with each step scanning position of the step-by-step spiral scanning. For each step of the step-by-step spiral scanning, the wavelength combination of the th step is , where . In the first method, according to the step number , in sequence are . In the second method, according to the step number , in sequence are . The emission intelligent control module controls the optical splitter, optical combiner, optical filters and modulators of each branch of the optical transceiver unit, so that the th step sequence corresponds to the wavelengths selected from the broadband light source kinds of wavelength combinations , that is, the wavelength combination of the th step is . The interval between every two different step wavelength combinations can be equal or not equal.

[0090] Terminal A repeats the above operations in sequence, and completes the jth step scanning one by one until it receives the return beam sent by terminal B, or until the step number of a scan reaches the preset maximum value. If after a scan is completed, the return beam sent by the remote terminal B is still not received, then terminal A starts the second scan until it receives the return beam sent by terminal B, or until the scan number reaches the preset maximum value.

[0091] S2. When terminal B receives the third optical signal from terminal A, the optical transceiver module of terminal B separates the wavelength combinations included in the third optical signal from each other in space and outputs them to the receiving intelligent control module. The receiving intelligent control module first performs wavelength compensation on the wavelengths included in the third optical signal , and then calculates the actual scanning step sequence of terminal A at the current moment according to the compensated wavelengths.

[0092] Specifically, Figure 6 is a schematic diagram provided by an embodiment of the present invention of using a grating as a receiving dispersion component to separate the wavelength combinations included in the third optical signal from each other in space. Refer to Figure 6 , the receiving intelligent control module of terminal B controls the telescope and pointing module to receive the third optical signal and sends it to the receiving dispersion component; among them, the receiving dispersion component can be implemented by a grating. The receiving dispersion component separates the th step The first wavelength combination included and the second wavelength combination are spatially separated from each other and output to the focal plane and the signal processing module.

[0093] In the telescope and pointing module of the remote terminal B, the focal plane array detector uses pixels at different spatial positions to respectively detect optical signals of different wavelength combinations and , and according to its output electrical signal, respectively record the spatial position information of the optical signal , , and output to the receiving intelligent control module.

[0094] According to the velocity information of terminal A transmitted by the scanning beam , combined with the self-velocity information measured by terminal B, calculate the relative lateral velocity of the two terminals A and B , and then according to the Doppler frequency shift formula, calculate the wavelength Doppler wavelength shift of and the Doppler wavelength shift of wavelength The difference, that is , and then perform corresponding wavelength compensation on the central wavelength of the tunable narrowband optical filter and the spatial position on the focal plane array detector . The wavelength compensation calculation formula is as follows: When terminal B moves in the direction approaching terminal A, the wavelength compensation calculation formula is as follows:

[0095] When terminal B moves in the direction away from terminal A, the wavelength compensation calculation formula is as follows:

[0096] ;

[0097] When terminal B moves in the direction away from terminal A, the wavelength compensation calculation formula is as follows:

[0098] ;

[0099] Among them, is the third optical signal received by terminal B Wavelength; is the original emission wavelength emitted by terminal A in the medium; is the absolute value of the moving speed of terminal B relative to the medium; is the absolute value of the moving speed of terminal A relative to the medium; is the traveling speed of light in the medium.

[0100] Furthermore, for the first step-by-step spiral scan and the equal interval between wavelengths way, calculate the true scanning step order of terminal A at the current moment according to the compensated wavelength The calculation formula is as follows:

[0101] When terminal B moves in the direction approaching terminal A, the calculation formula for the actual scanning step sequence of terminal A at the current moment is as follows:

[0102] ;

[0103] When terminal B moves in the direction away from terminal A, the calculation formula for the actual scanning step sequence of terminal A at the current moment is as follows:

[0104] ;

[0105] Where: is the third optical signal received by terminal B wavelength; j is the actual scanning step sequence of terminal A; is the absolute value of the moving speed of terminal B relative to the medium; is the absolute value of the moving speed of terminal A relative to the medium; is the traveling speed of light in the medium; k is an engineering coefficient, which is set according to the measured value of the difference between two fixed wavelengths during system calibration. Exemplarily, can be set to 1.

[0106] Furthermore, for the second and third step-by-step spiral scanning cases, and the wavelengths are equally spaced or unequally spaced, then first use the wavelength compensation calculation formula, and then use the method of looking up the corresponding table of the preset wavelength combination and step sequence of the system to determine the actual scanning step sequence of terminal A at the current moment .

[0107] S3. The receiving intelligent control module of terminal B calculates the scanning space position vector of terminal A according to the actual scanning step sequence of terminal A at the current moment, the scanning initial position, the terminal real-time position, the scanning parameters, and the speed information of terminal A.

[0108] Specifically, Figure 7 is a schematic diagram of the capture scanning vector of a cross-media channel provided by an embodiment of the present invention. Refer to Figure 7 , during the normal scanning process, the light beam starts from the normal scanning position of the th step , and steps to the normal scanning position of the th step , and the change in its position vector is . Due to the influence of the cross-media channel, the light beam undergoes random vibration or even swaying. The actual spatial position after the light beam deviates is , and the change in its position vector is . The terminal B adopts a capture intelligent processing algorithm to calculate the scanning space position vector of the terminal A. , . The calculation formula is:

[0109] ;

[0110] Among them, is the scanning space position vector of the terminal A at the th step; is the spiral interval; j is the actual scanning step order of the terminal A at the current moment; is the step parameter.

[0111] S4. The receiving intelligent control module of the terminal B calculates the deviation vector according to the own position vector of the terminal B, the actual scanning step order of the terminal A at the current moment, and the scanning space position vector of the terminal A, corrects the return beam vector according to the deviation vector, and sends the return beam to the terminal A according to the return beam vector.

[0112] S41. Calculate the deviation vector, and the calculation formula is as follows:

[0113] ;

[0114] Among them, is the deviation vector caused by the cross-media channel at the th scanning step; is the vector between the space position coordinate of the terminal B and the scanning initial origin, and the coordinate position of the terminal B is .

[0115] The terminal B corrects the return beam vector sent from the terminal B to the terminal A according to its own position vector , the real-time position vector of the terminal A, and the scanning space position vector . Among them, the position vector is calculated through the information carried in the beam sent by the terminal A, and the scanning space position vector is calculated using the formula.

[0116] S42. Correct the return beam vector according to the deviation vector . The calculation formula is as follows:

[0117] ;

[0118] Among them, is the return beam vector; is the spot width of the beam at the receiving end; is the position vector of the terminal A.

[0119] S5. The terminal A corrects the pointing of the tracking beam to be sent to the terminal B next time according to the return beam feedback by the terminal B. The capture phase is completed, and the terminal A and the terminal B enter the tracking phase.

[0120] Specifically, after the system completes the capture phase, it enters the tracking phase. After the two terminals achieve coarse tracking, they enter the phase of fine tracking and communication simultaneously. The two terminals control the beam to track the opposite terminal to keep the optical axes of the two terminals aligned, and complete data communication at the same time.

[0121] Further, in the fine tracking phase, the terminal A estimates the direction and amplitude of the total tracking vector of the current beam movement and vibration according to the deviation vector received in the capture and coarse tracking phases and the coordinates of the terminal B, and corrects the pointing of the transmitted beam.

[0122] Meanwhile, the terminal A selects a combination mode from the wavelength combinations and selects a certain beam overlap factor , and then controls the optical transceiver unit to overlap the beams of different wavelengths in a certain way in space and transmit them into the space channel.

[0123] Figure 8 FIG. is a schematic diagram of forming a certain overlap in space for the emitted light of different wavelengths in the fine tracking phase provided by the embodiment of the present invention. Refer to Figure 8 . In the fine tracking phase, the optical switch of the telescope and the pointing module is in the on state. The received optical signal passes through the transmitting dispersion component. According to the different wavelengths 、 、 、 、...... of the optical signal, it is spatially dispersion-separated. Among them ， at the same time, the lights of different wavelengths form a certain overlap mode in space, and then are emitted into the space channel through the internal optical path. The size of the overlapping part is determined by the overlap factor .

[0124] Further, in the tracking phase, the terminal B receives the laser signal of a certain wavelength combination , and detects the wavelength combination information of the laser signal through the optical transceiver unit . The receiving intelligent control module calculates or looks up the table for the wavelength combination information of the received light. At the same time, according to the wavelength combination information of the received light, the wavelength space information, and the information carried by the received optical modulation code stream, it estimates the direction and amplitude of the total beam jitter vector .

[0125] The total jitter vector calculated by Terminal B based on the received light wavelength combination information and wavelength space information for its direction and amplitude, stores them locally, and sends them to the peer Terminal A via the return beam. Meanwhile, the total jitter vector is predicted using the extended Kalman filter method, and then the line-of-sight direction of Terminal B is adjusted. Terminal A receives the direction and amplitude of the total jitter vector , stores them locally, then predicts the total jitter vector using the extended Kalman filter method, and then adjusts the line-of-sight direction of Terminal A.

[0126] Exemplarily, Terminal A uses a broadband light source to output a broadband laser signal with a comb-like spectral characteristic having multiple wavelengths and equally spaced wavelengths, that is, the light signal whose wavelengths include . An optical comb is used to implement the broadband light source. Terminal A emits a beam with a wavelength combination , and turns on the optical switch of the telescope and pointing module to spatially disperse and separate the multi-wavelength optical signal, and at the same time form a certain overlapping pattern of different wavelengths in space. Then it is emitted into the space channel through the internal optical path. The size of the overlapping part is determined by the overlapping factor .

[0127] Terminal B uses the received intelligent control module to calculate or look up the received light wavelength combination information. Meanwhile, based on the received light wavelength combination information, wavelength space information, and the information carried by the received optical modulation code stream, it estimates the direction and amplitude of the total jitter vector of the beam.

[0128] The total jitter vector calculated by Terminal B based on the received light wavelength combination information and wavelength space information for its direction and amplitude, stores them locally, and sends them to the peer Terminal A via the return beam. Meanwhile, the total jitter vector is predicted using the extended Kalman filter method, and then the line-of-sight direction of Terminal B is adjusted. Terminal A receives the direction and amplitude of the total jitter vector , stores them locally, then predicts the total jitter vector using the extended Kalman filter method, and then adjusts the line-of-sight direction of Terminal A.

[0129] In the embodiment of the present invention, by modulating the signal onto the signal light of a certain wavelength combination, it can better adapt to the change of the beam position. By adjusting the wavelength combination and using the orthogonal code group for modulation, the scanning space position of the transmitting end and the terminal position can be accurately calculated, thus improving the capture and tracking performance.

[0130] The present invention modulates a signal onto an optical signal of a specific wavelength combination, and by adjusting the wavelength combination and output of the optical transceiver module, the flexibility of the system is increased. This modulation method improves the transmission quality of the signal and enhances the anti-interference ability of the system. At the same time, compared with the traditional system, the present invention reduces the need for additional equipment and complex adjustments, and improves the reliability of the system. This innovative method enables the optical communication system to have higher adaptability and robustness and can operate stably in a complex communication environment.

[0131] It should be noted that the terms used in the present invention are only for describing specific embodiments and do not limit the scope of the present application. As shown in the specification of the present invention, unless the context clearly indicates an exception, words such as "a", "an", "one" and / or "the" are not specifically singular and may also include the plural. The term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method or device including the said element.

[0132] It should also be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation of the present invention. Unless otherwise clearly defined and limited, terms such as "installed", "connected", "connected to" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific cases.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for acquisition, tracking, and pointing in space laser communication, characterized in that, This method is implemented based on a space laser communication acquisition, tracking and pointing system, which includes: an optical transceiver module, a wavelength combination acquisition and tracking module; the method specifically includes: S1. Send an optical signal to terminal B; S2. Terminal B separates the optical signal, calculates the true scanning step sequence of terminal A at the current moment after wavelength compensation; when terminal B moves in the direction approaching or moving away from terminal A, the true scanning step sequence j of terminal A is calculated by the following formula: ； Where: λ rx is the wavelength of the optical signal; λ1 is the wavelength of the optical signal output through the first branch; λ2 is the wavelength of the optical signal output through the second branch; is the engineering coefficient; S3. Terminal B calculates the scanning space position vector of terminal A according to the parameters of terminal A at the current moment, and the calculation formula is as follows: ； Among them, is the th scanning space position vector of the stepping terminal A; D s is the spiral interval; j is the actual scanning step sequence of the terminal A at the current moment; ξ is the step size parameter; S4. Terminal B calculates the return beam vector according to its own position vector, the true scanning step sequence of terminal A at the current moment, and the scanning space position vector of terminal A, and sends it to terminal A; the steps of calculating the return beam vector include: S41. Calculate the deviation vector :[[]] ； Among them, is the vector between the spatial position coordinates of terminal B and the scanning initial origin; S42. Calculate the return beam vector based on the deviation vector :[[]] ； Among them, is the spot width of the beam at the receiving end; is the position vector of terminal A; S5. Terminal A corrects the pointing of the tracking beam to be sent to terminal B next time according to the return beam feedback by terminal B, the acquisition stage is completed, and terminal A and terminal B enter the tracking stage.

2. A method for acquisition, tracking and pointing of space laser communication according to claim 1, characterized in that, The specific content of S1 includes: S11. Modulate the first optical signal S0. Terminal A controls the 0th branch to output the first wavelength combination β0, and encodes the scanning initial position, terminal real-time position, scanning parameters and terminal speed information of terminal A into a binary bit stream and modulates it onto the first wavelength combination β0. The first optical signal S0 includes the first wavelength combination β0, and the first wavelength combination β0 includes the wavelength λ1; S12. Modulate the second optical signal S ji , Terminal A controls the Q branches of the optical transceiver module except the 0th branch to output the second wavelength combination β ji , encodes the scanning step sequence of Terminal A into a binary bit stream and modulates it onto the second wavelength combination β ji . The second optical signal S ji includes the second wavelength combination β ji . The second wavelength combination β ji includes at least one wavelength among wavelengths λ1, λ2, ……, λ Q . With each scanning step, Terminal A performs wavelength combination according to the preset step sequence table and changes the wavelength combination mode of the output second wavelength combination β ji ; where Q represents the total number of wavelengths. S13. Synthesize a third optical signal S ji based on the first optical signal S0 and the second optical signal S T , i.e., S T = S0 + S ji . The terminal A emits the third optical signal S T in the spatial pointing direction at the current scanning position; S14. In subsequent scanning steps, repeat steps S11, S12 and S13 until the predetermined number of scans is completed or the return beam from terminal B is received.

3. A method for acquisition, tracking and pointing of space laser communication according to claim 2, characterized in that, In S12, modulating the second optical signal S ji includes: At the j = 1st scanning step, terminal A controls the first branch to make the wavelength combination β output through the first branch 1i include wavelength λ1, and then modulate the code stream of the orthogonal code onto the wavelength combination β 1i Then, the wavelength combination of the third optical signal S output by terminal A T is (λ0, λ1); At the j = 2nd scanning step, the second branch of terminal A enables the wavelength combination β output through the second branch 2i to include the wavelength λ2, and then modulates the code stream of the orthogonal code onto the wavelength combination β 2i . Then, terminal A outputs the third optical signal S T with the wavelength combination of (λ0, λ2); and so on. At the j = Lth scanning step, terminal A outputs the third optical signal S T with the wavelength combination of (λ0, λ L ).

4. A method for acquisition, tracking and pointing of space laser communication according to claim 2, characterized in that, In S12, modulating the second optical signal S ji includes: At the j = 1st scanning step, terminal A controls the first branch to make the wavelength combination β output through the first branch 1i include wavelengths λ1 and λ2, and then modulate the code stream of the orthogonal code onto the wavelength combination β 1i Then, the wavelength combination of the third optical signal S output by terminal A T is (λ0, λ1, λ2); At the j = 2nd scanning step, terminal A controls the second branch to make the wavelength combination β output through the second branch 2i include wavelengths λ3 and λ4, and then modulate the code stream of the orthogonal code onto the wavelength combination β 2i . Then, the wavelength combination of the third optical signal S output by terminal A is (λ0, λ3, λ4); and so on. At the j = Lth scanning step, the wavelength combination of the third optical signal S output by terminal A is (λ0, λ T , λ T 2L-1 , λ 2L ).​ 5. A method for acquisition, tracking, and pointing of space laser communication according to claim 2, characterized in that, In S12, modulating the second optical signal S ji comprises: At the j = 1st scanning step, terminal A controls the first branch to make the wavelength combination β output through the first branch 1i include wavelength λ1 and any wavelength λ n , and then modulate the code stream of the orthogonal code onto wavelengths λ1 and λ n . Then, the wavelength combination of the third optical signal S output by terminal A is (λ0, λ1, λ T ); where n represents the nth wavelength; n ) At the j = 2nd scanning step, terminal A controls the second branch to make the wavelength combination β output through the second branch 2i include wavelength λ2 and any wavelength λ n , and then modulate the code stream of the orthogonal code onto wavelengths λ2 and λ n . Then, the wavelength combination of the third optical signal S output by terminal A is (λ0, λ2, λ T ); and so on. At the j = Lth scanning step, the wavelength combination of the third optical signal S output by terminal A is (λ0, λ n ), λ T ); (λ L , λ n ).

6. A method for acquisition, tracking and pointing in space laser communication according to any one of claims 4 or 5, characterized in that In S2, calculating the true scanning step sequence of terminal A at the current moment according to the compensated wavelength includes: Adopt the method of looking up the correspondence table between the preset wavelength combination and the step sequence of the system to judge the true scanning step sequence j of terminal A at the current moment.

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