Satellite-borne laser communication and ranging integrated system and method with zero-value calibration

Abstract

The application provides a kind of zero value calibration's star-borne laser communication ranging integrated system and method, for solving the technical problem that the existing satellite internet inter-satellite communication system and ranging system are discrete, so that resource utilization is lower, and the initial system error exists in the inter-satellite laser distance measured by the existing laser ranging system.The zero value calibration's star-borne laser communication ranging integrated system provided by the application realizes the transmission of data by the mode of inter-satellite laser, simultaneously realizes the functions of communication and ranging, has the advantages of low power consumption, large data rate and the like.In addition, the application is provided with an external corner pyramid outside the signal transmitting end of the star-borne laser communication load optical head, and the zero value calibration function can be realized by the external corner pyramid.Compared with the existing laser ranging system, the initial system error of the application is greatly reduced, and the ranging precision is improved.

Description

TECHNICAL FIELD

[0001] The application relates to a spaceborne laser communication ranging method, in particular to a spaceborne laser communication ranging integrated system and method with zero value calibration. BACKGROUND

[0002] Satellite laser communication is like a "highway", has the advantages of wide frequency band, small antenna size, small volume, light weight, low power consumption, good secrecy, strong anti-interference ability, no frequency regulation restriction, etc., and can meet the needs of future space-earth integration information transmission system for high speed, large capacity, multi-service information transmission and interactive processing, and has become the primary choice for satellite communication development. It is urgent to establish a bidirectional laser inter-satellite link between satellites on the same orbit plane or adjacent orbit planes in a low earth orbit constellation, complete high-speed data transmission between satellite internet nodes, high-precision measurement of satellite distance, realize high-speed information interconnection and high-precision ranging of the whole network, and provide high-speed access services for low-orbit application satellites. However, the existing inter-satellite laser communication system and laser ranging system in the satellite internet are separate, the inter-satellite laser communication system only performs communication and cannot realize ranging function, so that the resource utilization rate of the system is low. In addition, the existing laser ranging system does not calibrate the system inherent time delay and zero distance, resulting in initial system error in the measured inter-satellite laser distance. SUMMARY

[0003] The application aims to solve the technical problems that the inter-satellite communication system and ranging system in the existing satellite internet are separate, the resource utilization rate is low, and the initial system error exists in the inter-satellite laser distance measured by the existing laser ranging system, and provides a spaceborne laser communication ranging integrated system and method with zero value calibration.

[0004] In order to achieve the above-mentioned purpose, the technical scheme provided by the application is as follows:

[0005] A spaceborne laser communication ranging integrated system with zero value calibration, which is characterized in that it comprises two identical ranging units;

[0006] The ranging unit comprises a spaceborne laser communication payload processor, an optical amplifier, a spaceborne laser communication payload optical head and an external corner cube (10); the spaceborne laser communication payload processor, the optical amplifier and the spaceborne laser communication payload optical head in each ranging unit are in bidirectional communication with each other;

[0007] The spaceborne laser communication payload processor is used for receiving the management and control instructions of the satellite platform to configure the working state of itself, and sending control signals to the optical amplifier and the spaceborne laser communication payload optical head according to the management and control instructions to configure the working states of the optical amplifier and the spaceborne laser communication payload optical head, respectively;

[0008] The star-borne laser communication load processor is used for controlling the internal laser to emit continuous laser, loading and modulating the electric data information generated by itself to be transmitted to the optical amplifier as the transmitting optical signal, receiving the optical fiber signal after low noise optical amplification of the optical amplifier, processing the optical fiber signal to realize the measurement of the communication error rate in the digital domain and the calculation of the distance between the star and the opposite end;

[0009] The optical amplifier is used for optically amplifying the received transmitting optical signal, outputting the high-power transmitting optical fiber signal formed after the optical amplification to the star-borne laser communication load optical head, receiving the optical fiber signal after coupling of the star-borne laser communication load optical head, and outputting the optical fiber signal after low noise optical amplification to the star-borne laser communication load processor;

[0010] The optical fiber connection between the star-borne laser communication load optical head and the optical amplifier is used for converting the received high-power transmitting optical fiber signal into high-power space signal light to be transmitted to the opposite end, receiving the space signal light transmitted by the ranging unit of the opposite end, coupling the space signal light to be output to the optical amplifier;

[0011] The external corner pyramid is used for reflecting the space signal light emitted by the star-borne laser communication load optical head when the transmitting optical axis of the star-borne laser communication load optical head points to the reflecting surface of the external corner pyramid, so that the backward reflected light is reversely incident to the inside of the star-borne laser communication load optical head to perform zero value calibration.

[0012] Further, the star-borne laser communication load optical head comprises a first lens, a leading fast mirror, a polarization beam splitter, a tracking fast mirror, an energy beam splitter, a tracking detector, a second lens, a reflecting mirror and a collimation and beam expansion system;

[0013] The first lens is used for coupling the high-power transmitting optical fiber signal transmitted by the optical amplifier into local space signal light;

[0014] The leading fast mirror, the polarization beam splitter, the tracking fast mirror, the reflecting mirror and the collimation and beam expansion system are sequentially located on the transmitting light path of the local space signal light, and are used for forming a signal transmitting branch and transmitting the local space signal light after collimation; the tracking fast mirror is located on the light path of the local space signal light after reflection of the polarization beam splitter, and the external corner pyramid is located outside the collimation and beam expansion system;

[0015] The collimation and beam expansion system, the reflecting mirror, the tracking fast mirror and the polarization beam splitter are sequentially located on the light path of the space signal light transmitted by the opposite end, and are used for capturing the space signal light transmitted by the opposite end or the backward reflected light of the external corner pyramid;

[0016] The energy beam splitter is located on the light path of the space signal light transmitted by the opposite end after transmission of the polarization beam splitter, and is used for splitting the space signal light of the opposite end or the backward reflected light of the external corner pyramid to form a transmitted light and a reflected light.

[0017] The second lens is located on the light path of the transmitted light, and is used for converging the captured opposite end space signal light or the back reflection light of the external corner cube to the optical fiber, and then coupling the optical fiber signal to the optical amplifier for output;

[0018] The tracking detector is located on the light path of the reflected light, and is used for detecting the opposite end reflected light or the back reflection light of the external corner cube, and realizing the feedback control of the tracking fast mirror by calculating the light signal energy and position of the target surface.

[0019] Further, a two-dimensional turntable is further included;

[0020] The spaceborne laser communication load optical head is arranged on the two-dimensional turntable, and the adjustment of the elevation angle and the azimuth angle of the spaceborne laser communication load optical head is realized by the rotation of the two-dimensional turntable.

[0021] The external corner cube is arranged on the base of the two-dimensional turntable.

[0022] In addition, the application further provides a spaceborne laser communication ranging method with zero value calibration, and the speciality thereof lies in comprising the following steps:

[0023] Step 1, the spaceborne laser communication ranging integrated system with zero value calibration is built, and two ranging units are respectively installed on the ground station or the target satellite of the opposite end.

[0024] Step 2, the satellite platform is used for respectively performing the telemetry and remote control configuration, the coaxial degree self-calibration, the optical axis pointing calibration and the state self-checking on the two ranging units;

[0025] Step 3, when the satellite platform control instruction is received by the spaceborne laser communication load processor of the spaceborne laser communication load, the internally generated transmission light signal is used as the space signal light and is transmitted outward through the corresponding spaceborne laser communication load optical head; the transmission optical axis of the spaceborne laser communication load optical head is adjusted so as to point to the reflection surface of the external corner cube, the back reflection light reflected by the external corner cube is reversely incident to the inside of the spaceborne laser communication load optical head, is coupled into the optical fiber signal, and then is output to the spaceborne laser communication load processor through the optical amplifier; the spaceborne laser communication load processor performs the autocorrelation operation according to the data information locally emitted and the data information reflected by the external corner cube at the same sampling moment, and obtains the time information corresponding to the local zero value distance under the triggering of the high-precision second pulse signal and the clock signal of the spaceborne laser communication load; correspondingly, the ranging unit of the opposite end has the same working process as the ranging unit of the spaceborne laser communication load, and obtains the time information corresponding to the zero value distance of the opposite end.

[0026] Step 4, the capture, tracking and link establishment of the space signal light;

[0027] Step 4.1: The optical heads of the spaceborne laser communication payloads of the two ranging units calculate the tracking and pointing guidance data respectively to achieve open-loop pointing tracking of the other end;

[0028] Step 4.2: Correct the two ranging units. After the correction is completed, start scanning each other between the local satellite and the other end. When the optical head of the onboard laser communication payload of the local satellite detects the space signal light emitted by the other end, stop scanning and adjust the line of sight to point to the other end.

[0029] Step 4.3: Use a tracking strategy to track the space signal light emitted by the other end to the center of the field of view until the optical heads of both spaceborne laser communication payloads continuously detect the space signal light emitted by the other.

[0030] Step 4.4: Based on the intensity and position information of the light signal output by the tracking detector in the optical head of the satellite laser communication payload at the other end, and the intensity of the light signal received by the corresponding optical amplifier, adjust the tracking point until the light spot detected by the tracking detectors of both sides is located at the center of its target surface, and the satellite laser communication payload processors of both sides continuously detect the space light signal.

[0031] Step 4.5: After receiving the fiber optic signal amplified by the corresponding optical amplifier with low noise, the onboard laser communication payload processors of both parties compensate for the optical carrier Doppler and code Doppler, complete frame synchronization and bit synchronization, achieve correct demodulation, and complete link establishment.

[0032] Step 5: The onboard laser communication payload processors of both parties perform autocorrelation calculations based on the data information transmitted locally and the data information transmitted from the other party within the same sampling time. Under the triggering of high-precision second pulse signal and clock signal, they obtain the time information corresponding to the local pseudorange and the time information corresponding to the pseudorange of the other party, respectively.

[0033] Step 6: Calculate the distance between the local satellite and the remote satellite based on the time information corresponding to the zero-value distance and pseudorange of the remote satellite, as well as the time information corresponding to the zero-value distance and pseudorange of the local satellite. The distance measurement is then complete.

[0034] Furthermore, in step 3, the pointing accuracy of the emission optical axis of the spaceborne laser communication payload optical head is ≤5μrad.

[0035] Furthermore, in step 3, adjusting the emission optical axis of the spaceborne laser communication payload optical head to point towards the reflecting surface of the external pyramid specifically involves:

[0036] The pitch and azimuth angles of the optical head of the spaceborne laser communication payload are adjusted by using a two-dimensional turntable, and the reflection angle of the forward fast-reflecting mirror inside the optical head is also adjusted, thereby achieving the pointing of the emission optical axis of the spaceborne laser communication payload optical head.

[0037] Further, in step 4.4, the adjustment of the tracking point is specifically:

[0038] The adjustment of the tracking point is achieved by adjusting the reflection angle of the tracking fast mirror.

[0039] Further, in step 6, the distance L between the satellite and the ground station or the target satellite is calculated by the following formula:

[0040] L = (T1 + T3 - T0 - T2) / 2 * c

[0041] Wherein, T0 is the time information corresponding to the zero value distance of the local, T1 is the time information corresponding to the pseudo range sent by the opposite end, T2 is the time information corresponding to the zero value distance sent by the opposite end, T3 is the time information corresponding to the pseudo range of the local, and c is the speed of light.

[0042] The beneficial effects of the present application compared with the prior art are as follows:

[0043] 1. The satellite-borne laser communication ranging integrated system with zero value calibration provided by the present application realizes data transmission through inter-satellite laser, and simultaneously realizes communication and ranging functions, and has the advantages of low power consumption, large data rate, etc. In addition, the present application is provided with an external corner pyramid outside the signal transmitting end of the satellite-borne laser communication load optical head, and the zero value calibration function can be realized through the external corner pyramid. Compared with the existing laser ranging system, the present application greatly reduces the initial system error and improves the ranging precision.

[0044] 2. The present application integrates digital signal processing and control in the satellite-borne laser communication load processor, so that the control box of the traditional communication ranging system can be omitted, and the communication ranging integration can be realized only through the satellite-borne laser communication load optical head, the optical amplifier and the satellite-borne laser communication load processor three single machines, and the entire system is lighter in weight and smaller in size, greatly saving the on-board resources.

[0045] 3. The satellite-borne laser communication ranging integrated system with zero value calibration provided by the present application has high integration, strong compatibility and high utilization rate, and has great research significance and practical value for the new generation satellite internet transmission networking system.

[0046] 4. The satellite-borne laser communication ranging method with zero value calibration provided by the present application adopts the laser communication ranging integration method in a single inter-satellite laser link environment, combines communication and ranging, realizes communication modulation and demodulation and distance calculation in the digital domain through high-speed digital sampling, and has higher sensitivity and distance calculation precision compared with the analog demodulation scheme.

[0047] 5. The present application realizes the measurement of the system inherent time delay based on the high-precision second pulse signal, performs zero value calibration to calculate the absolute distance, and greatly reduces the initial system error in the measurement value. Attached Figure Description

[0048] Figure 1 This is a block diagram illustrating the communication principle of a single ranging unit in an embodiment of a spaceborne laser communication and ranging integrated system with zero-value calibration according to the present invention.

[0049] Figure 2 This is a schematic diagram of the core components of the optical head of the spaceborne laser communication payload in an embodiment of the spaceborne laser communication ranging integrated system with zero-value calibration according to the present invention.

[0050] The specific reference numerals in the attached figures are as follows:

[0051] 1-First lens; 2-Advanced fast-reflecting mirror; 3-Polarizing beam splitter; 4-Tracking fast-reflecting mirror; 5-Energy beam splitter; 6-Tracking detector; 7-Second lens; 8-Reflecting mirror; 9-Collimating and beam expanding system; 10-External corner cone. Detailed Implementation

[0052] To make the advantages and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] like Figure 1 As shown, a spaceborne laser communication ranging system with zero-value calibration includes two identical ranging units, one for the local satellite and one for the peer (ground station or target satellite). Each ranging unit includes a spaceborne laser communication payload processor, an optical amplifier, a spaceborne laser communication payload optical head, an external corner cone 10, and a two-dimensional turntable. In this embodiment, the peer is the target satellite, and the spaceborne laser communication payload processor, optical amplifier, and optical head within each ranging unit communicate bidirectionally with each other.

[0054] The spaceborne laser communication payload processor is used to receive and respond to the control commands from the satellite platform. It configures its own operating status by parsing the control commands from the satellite platform, and sends control signals to the optical amplifier and the optical head of the spaceborne laser communication payload to configure their operating status respectively.

[0055] The spaceborne laser communication payload processor is used to control its internal laser to emit continuous laser light at the transmitting end, so as to load and modulate the electrical data information generated by itself and send it as the transmitted optical signal to the local optical amplifier. At the receiving end, it receives the fiber optic signal after low-noise optical amplification by the local optical amplifier, processes it, and realizes the measurement of communication bit error rate in the digital domain, as well as the calculation of the distance between the satellite and the peer.

[0056] The optical amplifier is used to amplify the received transmitted optical signal to form a high-power transmitted fiber optic signal, which is then output to the optical head of the spaceborne laser communication payload. It also receives the fiber optic signal coupled from the optical head of the spaceborne laser communication payload, amplifies it with low noise, and then outputs it to the spaceborne laser communication payload processor.

[0057] The optical fiber connection between the optical head and the optical amplifier of the spaceborne laser communication payload is used to convert the received high-power transmission fiber signal into high-power space signal light and then transmit it to the other end. It also receives the space signal light transmitted after being stably tracked by the other end, couples it into an optical fiber signal, and then outputs it to the optical amplifier.

[0058] like Figure 2 As shown, the core components of the optical head of the spaceborne laser communication payload include a first lens 1, a pre-amplifier (PAA) 2, a polarization beam splitter 3, a tracking fast mirror (FSM) 4, an energy beam splitter 5, a tracking detector 6, a second lens 7, a reflector 8, and a collimation and beam expansion system 9. The first lens 1 couples the high-power transmitting fiber signal from the optical amplifier into space signal light. The pre-amplifier 2, polarization beam splitter 3, tracking fast mirror 4, reflector 8, and collimation and beam expansion system 9 are sequentially located on the optical path of the local space signal light, forming a signal transmission branch. After collimating the space signal light, it is emitted to the other end or to the reflecting surface of the external corner cone 10. The collimation and beam expansion system 9, reflector 8, tracking fast mirror 4, and polarization beam splitter 3 are sequentially located on the optical path of the space signal light emitted from the other end, capturing the space signal light emitted from the other end or the back-reflected light from the external corner cone 10.

[0059] The collimation and beam expanding system 9 serves as the transmitting end of the optical head of the spaceborne laser communication payload, emitting space signal light to the receiving end and simultaneously receiving space signal light emitted by the receiving end. The advanced fast-reflecting mirror 2 is used to adjust the pointing angle of the space signal light emitted by the optical head of the spaceborne laser communication payload. The tracking fast-reflecting mirror 4 is located on the optical path after the space signal light is reflected by the polarizing beam splitter, and is used to adjust the transmission angle of the space signal light received by the optical head of the spaceborne laser communication payload, ensuring that its light spot accurately enters the target field of view of the tracking detector 6. The energy beam splitter 5 is located on the optical path after the space signal light from the receiving end is transmitted through the polarizing beam splitter 3, and is used to split the space signal light emitted by the receiving end or the back-reflected light from the external corner cone 10, forming a transmitted beam and a reflected beam. In this embodiment, the splitting ratio of the energy beam splitter 5 is 9:1, where 90% of the transmitted light is used as the communication receiving signal and 10% of the reflected light is used as the fine tracking receiving signal. The polarizing beam splitter 3 is used to separate the emitted and received light through different polarization states.

[0060] The second lens 7 is located on the light path of the transmitted light, and forms a communication receiving branch with the collimating beam expander system 9, the reflecting mirror 8, the tracking fast mirror 4 and the polarization beamsplitter 3, and is used for converging the captured opposite end space signal light or the backward reflected light of the external corner cube 10 to the rear output of the optical fiber. The tracking detector 6 is located on the light path of the reflected light, and forms a fine tracking receiving branch with the collimating beam expander system 9, the reflecting mirror 8, the tracking fast mirror 4 and the polarization beamsplitter 3, and is used for detecting the opposite end reflected light or the backward reflected light of the external corner cube 10, and realizing the feedback control of the tracking fast mirror 4 by calculating the light signal energy and position (tracking off-target amount) of the target surface.

[0061] The spaceborne laser communication load optical head is arranged on the two-dimensional turntable, and the adjustment of the elevation angle and the azimuth angle of the spaceborne laser communication load optical head is realized by the rotation of the two-dimensional turntable. The external corner cube 10 is used for the light self-emission and self-reception to realize the function of zero-value calibration, is arranged outside the collimating beam expander system 9, and is arranged on the fixed plane of the two-dimensional turntable at the same time, and is used for forming the backward reflected light on the reflecting surface of the external corner cube 10 when the emission axis of the spaceborne laser communication load optical head points to the reflecting surface of the external corner cube 10, so that the backward reflected light reversely enters the spaceborne laser communication load optical head. Specifically, the pointing angle of the emission axis of the spaceborne laser communication load optical head is coarsely adjusted by the two-dimensional turntable, and the fine adjustment is realized by adjusting the reflecting angle of the leading fast mirror 2.

[0062] Based on the above-mentioned spaceborne laser communication ranging system with zero-value calibration, the application further provides a spaceborne laser communication ranging method with zero-value calibration, and specifically includes the following steps:

[0063] Step 1, one of the ranging units in the above-mentioned spaceborne laser communication ranging system with zero-value calibration is installed on the present satellite, and the other ranging unit is installed on the target satellite at the opposite end.

[0064] Step 2, the two ranging units are respectively configured by the satellite platform for remote measurement and remote control, self-calibration of coaxiality, light axis pointing calibration and state self-checking.

[0065] Step 3, zero-value calibration.

[0066] The zero value calibration of the ranging unit on the satellite: the elevation angle and azimuth angle of the satellite-borne laser communication load optical head are adjusted by the two-dimensional turntable, and the reflection angle of the satellite-borne laser communication load optical head is adjusted, so that the emission optical axis of the satellite-borne laser communication load optical head is directed to the reflecting surface of the external corner cube 10; when the satellite platform control command is received by the satellite-borne laser communication load processor of the satellite, continuous laser is generated, the continuous laser loads and modulates the electrical data generated by itself, and then is transmitted to the optical amplifier of the satellite, and after optical amplification, the high-power space signal light is converted by the satellite-borne laser communication load optical head of the satellite and emitted, the outgoing space signal light is reflected to generate back reflection light by the external corner cube 10 of the satellite, the back reflection light is reversely incident into the satellite-borne laser communication load optical head of the satellite, and is coupled into an optical fiber signal and then output to the optical amplifier of the satellite, and after low-noise optical amplification, the output is output to the satellite-borne laser communication load processor of the satellite; the satellite-borne laser communication load processor of the satellite converts the low-noise optical amplified optical fiber signal into an electrical signal and performs digital signal processing, so that frame synchronization and bit synchronization are completed in the digital domain, and correct demodulation is realized; the satellite-borne laser communication load processor of the satellite obtains the number of integral code elements of the phase of the transmitted frame at the sampling time of the received frame of the satellite and the subdivision phase in the single code element of the phase of the transmitted frame at the sampling time of the received frame of the satellite through self-correlation operation under the triggering of the high-precision second pulse signal and the clock signal of the satellite, and then calculates the time information T0 corresponding to the local zero value distance.

[0067] The zero value calibration of the ranging unit on the satellite: the elevation angle and azimuth angle of the satellite-borne laser communication load optical head are adjusted by the two-dimensional turntable, and the reflection angle of the satellite-borne laser communication load optical head is adjusted, so that the emission optical axis of the satellite-borne laser communication load optical head is directed to the reflecting surface of the external corner cube 10; when the satellite platform control command is received by the satellite-borne laser communication load processor of the satellite, continuous laser is generated, the continuous laser loads and modulates the electrical data generated by itself, and then is transmitted to the optical amplifier of the satellite, and after optical amplification, the high-power space signal light is converted by the satellite-borne laser communication load optical head of the satellite and emitted, the outgoing space signal light is reflected to generate back reflection light by the external corner cube 10 of the satellite, the back reflection light is reversely incident into the satellite-borne laser communication load optical head of the satellite, and is coupled into an optical fiber signal and then output to the optical amplifier of the satellite, and after low-noise optical amplification, the output is output to the satellite-borne laser communication load processor of the satellite; the satellite-borne laser communication load processor of the satellite converts the low-noise optical amplified optical fiber signal into an electrical signal and performs digital signal processing, so that frame synchronization and bit synchronization are completed in the digital domain, and correct demodulation is realized; the satellite-borne laser communication load processor of the satellite obtains the number of integral code elements of the phase of the transmitted frame at the sampling time of the received frame of the satellite and the subdivision phase in the single code element of the phase of the transmitted frame at the sampling time of the received frame of the satellite through self-correlation operation under the triggering of the high-precision second pulse signal and the clock signal of the satellite, and then calculates the time information T0 corresponding to the local zero value distance.

[0068] The standard for correct demodulation in the embodiment is that the error code is less than 10 -7 , and the pointing accuracy of the emission optical axis of the satellite-borne laser communication load optical head is ≤5μrad.

[0069] Step 4, capture, tracking and link establishment of space signal light.

[0070] Step 4.1, open loop pointing: the satellite-borne laser communication load optical head of the satellite calculates the tracking pointing guide data according to the target satellite ephemeris, the local satellite ephemeris and the platform attitude information of the satellite, so as to control the optical antenna boresight to realize open loop pointing tracking of the opposite end in a digital guide tracking mode. Specifically, after the ranging units of the two satellites complete the open loop pointing to the predetermined position, the next process can be started according to the readings of the optical encoder in the satellite-borne laser communication load optical head (angle information of the elevation axis and azimuth axis of the satellite-borne laser communication load optical head).

[0071] Step 4.2, capture start: two ranging units are corrected by open-loop pointing and fast feedback mirror, and after correction, the target satellite of the home satellite and the target satellite of the opposite end start to scan each other, and when the space signal light emitted by the opposite end is detected by the capture detector 6 in the optical head of the onboard laser communication payload of the home satellite, the scanning is stopped, and the optical axis is adjusted to point to the target satellite.

[0072] Step 4.3, when the space signal light of the opposite end is detected by the capture detector 6, the tracking strategy is adopted to track the space signal light emitted by the opposite end to the center of the field of view of the capture detector 6 until the space signal light of the opposite end is continuously detected by both onboard laser communication payload optical heads;

[0073] Step 4.4, according to the light signal intensity and position information output by the capture detector 6 of both sides, and the light signal intensity received by the corresponding optical amplifier, the reflection angle of the tracking fast feedback mirror 4 is adjusted to realize the adjustment of the tracking point until the light spot detected by the capture detector 6 of both sides is located at the center position of the target surface, and the communication detector in the onboard laser communication payload processor continuously detects the space light signal emitted by the opposite end.

[0074] Step 4.5, the onboard laser communication payload processor of both sides respectively receives the optical fiber signal (modulated signal light) after low-noise optical amplification of the corresponding optical amplifier, compensates the optical carrier Doppler and code Doppler, completes frame synchronization, bit synchronization, realizes correct demodulation, and completes chain building.

[0075] Step 5, the onboard laser communication payload processor of the home satellite performs autocorrelation operation on the data information locally emitted and the data information emitted by the opposite end at the same sampling time, obtains the number of phase integral code elements of the transmitted frame at the sampling time of the received frame of the home satellite and the subdivision phase in a single code element of the phase of the transmitted frame at the sampling time of the received frame of the home satellite under the trigger of the high-precision second pulse signal and the clock signal of the home satellite, and further calculates to obtain the time information T3 corresponding to the local pseudo-range. Correspondingly, the onboard laser communication payload processor of the target satellite of the opposite end calculates to obtain the time information T1 corresponding to the pseudo-range of the opposite end.

[0076] Step 6, after the home satellite and the opposite end complete the chain building, the time information corresponding to the zero distance and the time information corresponding to the pseudo-range of the opposite end can be transmitted to the onboard laser communication payload processor of the home satellite through the space light signal, and the time information corresponding to the zero distance and the time information corresponding to the pseudo-range of the local can also be transmitted to the onboard laser communication payload processor of the opposite end through the space light signal. The distance between the home satellite and the opposite end is calculated by the time information corresponding to the zero distance and the time information corresponding to the pseudo-range of the opposite end and the time information corresponding to the zero distance and the time information corresponding to the pseudo-range of the local in any one of the two onboard laser communication payload processors. Preferably, the data in the onboard laser communication payload processor of the home satellite is usually used for correlation operation, and the specific operation formula is as follows:

[0077] L = (T1 + T3 - T0 - T2) / 2 * c

[0078] Wherein, L is the distance between the star and the opposite end, c is the speed of light.

[0079] The above is only used to illustrate the technical solutions of the present application, but not to limit it. For ordinary skilled in the art, the specific technical solutions recorded in the above examples can be modified, or some technical features can be replaced equivalently, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions protected by the present application.

Claims

1. A satellite-borne laser communication ranging integrated system with zero-value calibration, comprising two identical ranging units, wherein each ranging unit comprises a satellite-borne laser communication payload processor, an optical amplifier, a satellite-borne laser communication payload optical head, and an external corner cube (10); the satellite-borne laser communication payload processor, the optical amplifier, and the satellite-borne laser communication payload optical head in each ranging unit are in bidirectional communication with each other; the satellite-borne laser communication payload processor is configured to receive control instructions from a satellite platform to configure its own working state, and to send control signals to the optical amplifier and the satellite-borne laser communication payload optical head according to the control instructions to configure the working states of the optical amplifier and the satellite-borne laser communication payload optical head, respectively; the satellite-borne laser communication payload processor is configured to control a laser inside to emit continuous laser light, to load and modulate electrical data information generated by itself as a transmission optical signal, to send the transmission optical signal to the optical amplifier, to receive a low-noise optical amplified optical fiber signal from the optical amplifier, to process the optical fiber signal to measure a communication bit error rate in a digital domain, and to calculate a distance between the satellite and a peer; the optical amplifier is configured to optically amplify the received transmission optical signal, to output a high-power transmission optical fiber signal to the satellite-borne laser communication payload optical head, and to receive an optical fiber signal coupled by the satellite-borne laser communication payload optical head and output a low-noise optical amplified optical fiber signal to the satellite-borne laser communication payload processor; the satellite-borne laser communication payload optical head is optically connected to the optical amplifier, configured to convert the received high-power transmission optical fiber signal into a high-power space signal light and emit the space signal light to the peer, and to receive a space signal light emitted by a ranging unit of the peer, to couple the space signal light into an optical fiber signal and output the optical fiber signal to the optical amplifier; and the external corner cube (10) is configured to reflect the space signal light emitted by the satellite-borne laser communication payload optical head when a transmission optical axis of the satellite-borne laser communication payload optical head points to a reflecting surface of the external corner cube (10), so that the back-reflected light is reversely incident into the satellite-borne laser communication payload optical head to perform zero-value calibration. 2.The satellite-borne laser communication ranging integrated system with zero-value calibration according to claim 1, wherein the satellite-borne laser communication payload optical head comprises a first lens (1), a pre-quick mirror (2), a polarization beam splitter (3), a tracking quick mirror (4), an energy beam splitter (5), a tracking detector (6), a second lens (7), a reflecting mirror (8), and a collimation and beam expansion system (9); the first lens (1) is configured to couple the high-power transmission optical fiber signal output by the optical amplifier into a local space signal light; the pre-quick mirror (2), the polarization beam splitter (3), the tracking quick mirror (4), the reflecting mirror (8), and the collimation and beam expansion system (9) are sequentially arranged in a transmission light path of the local space signal light, configured to form a signal transmission branch and to collimate and emit the local space signal light; the tracking quick mirror (4) is arranged in a light path of the local space signal light after being reflected by the polarization beam splitter (3); and the external corner cube (10) is arranged outside the collimation and beam expansion system (9). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The collimating and expanding system (9), the mirror (8), the tracking fast mirror (4) and the polarization beam splitter (3) are sequentially located on the light path of the spatial signal light emitted by the opposite end, and are used for capturing the spatial signal light emitted by the opposite end or the back-reflected light of the external corner cube (10); The energy beam splitter (5) is located on the light path of the spatial signal light transmitted by the polarization beam splitter (3), and is used for splitting the spatial signal light emitted by the opposite end or the back-reflected light of the external corner cube (10) to form a transmitted light and a reflected light; The second lens (7) is located on the light path of the transmitted light, and is used for converging the captured spatial signal light emitted by the opposite end or the back-reflected light of the external corner cube (10) to the optical fiber to be coupled into the optical fiber signal and then output to the optical amplifier; The tracking detector (6) is located on the light path of the reflected light, and is used for detecting the opposite reflected light or the back-reflected light of the external corner cube (10), and realizing the feedback control of the tracking fast mirror (4) by calculating the light signal energy and position of the target surface.

3. The spaceborne laser communication and ranging integrated system with zero-value calibration according to claim 1 or 2, characterized in that: a two-dimensional turntable is further included; the spaceborne laser communication load optical head is arranged on the two-dimensional turntable, and the adjustment of the elevation angle and the azimuth angle of the spaceborne laser communication load optical head is realized by the rotation of the two-dimensional turntable; the external corner cube (10) is arranged on the base of the two-dimensional turntable.

4. A space-borne laser communication ranging method with zero-value calibration, characterized in that, The method comprises the following steps: Step 1: a spaceborne laser communication and ranging integrated system with zero-value calibration according to any one of claims 1-3 is built, and two ranging units in the system are respectively installed on the ground station or the target satellite of the satellite and the opposite end; Step 2: the satellite platform performs remote measurement and remote control configuration, coaxiality self-calibration, optical axis pointing calibration and state self-checking on the two ranging units respectively; Step 3: when the satellite platform control instruction is received by the spaceborne laser communication load processor of the satellite, the internally generated transmission light signal is used as the spatial signal light and is transmitted outward through the corresponding spaceborne laser communication load optical head; the transmission optical axis of the spaceborne laser communication load optical head is adjusted to point to the reflecting surface of the external corner cube, the back-reflected light reflected by the external corner cube is reversely incident into the spaceborne laser communication load optical head, and then is coupled into the optical fiber signal and output to the spaceborne laser communication load processor through the optical amplifier; the spaceborne laser communication load processor performs autocorrelation operation on the local data information and the data information reflected by the external corner cube at the same sampling time, and obtains the time information corresponding to the local zero-value distance under the triggering of the high-precision second pulse signal and the clock signal of the satellite; correspondingly, the ranging unit of the opposite end has the same working process as the ranging unit of the satellite, and obtains the time information corresponding to the zero-value distance of the opposite end; Step 4: capture, tracking and link establishment of the spatial signal light; Step 4.1: the spaceborne laser communication load optical heads of the two ranging units calculate the tracking pointing guide data respectively, and realize the open-loop pointing tracking of the opposite end. Step 4.2, two ranging units are corrected, and after the correction, the home star and the opposite end start to scan each other, and when the space signal light emitted by the opposite end is detected by the optical head of the home star, the scanning is stopped, and the line-of-sight pointing direction is adjusted to the opposite end; Step 4.3, the space signal light emitted by the opposite end is tracked to the center of the field of view by using a tracking strategy until the space signal light emitted by the opposite end is continuously detected by the optical heads of the laser communication payloads on both sides; Step 4.4, the tracking point is adjusted according to the light signal intensity and position information output by the capture and tracking detector in the optical head of the laser communication payload on the opposite side and the light signal intensity received by the corresponding optical amplifier until the light spots detected by the capture and tracking detectors are located at the center of the target surface and the space light signal is continuously detected by the processing machines of the laser communication payloads on both sides; Step 4.5, the processing machines of the laser communication payloads on both sides receive the low-noise optical amplification of the optical fiber signals from the corresponding optical amplifiers, compensate for the optical carrier Doppler and code Doppler, complete frame synchronization and bit synchronization, correctly demodulate, and complete the link establishment; Step 5, the processing machines of the laser communication payloads on both sides perform autocorrelation operation on the data information emitted by the local side and the data information transmitted by the opposite side according to the same sampling time, and obtain the time information corresponding to the local pseudo-range and the time information corresponding to the pseudo-range of the opposite side under the triggering of high-precision second pulse signals and clock signals; Step 6, the distance between the home star and the opposite end is calculated according to the time information corresponding to the zero-value distance of the opposite end, the time information corresponding to the pseudo-range, the time information corresponding to the zero-value distance of the local side, and the time information corresponding to the pseudo-range, and the ranging is completed.

5. The star-borne laser communication ranging method with zero-value calibration according to claim 4, characterized in that: In step 3, the pointing accuracy of the emission optical axis of the optical head of the star-borne laser communication payload is ≤5μrad.

6. The star-borne laser communication ranging method with zero-value calibration according to claim 5, characterized in that: In step 3, the adjustment of the pointing direction of the emission optical axis of the optical head of the star-borne laser communication payload is specifically as follows: The pitch angle and azimuth angle of the optical head of the star-borne laser communication payload are adjusted by a two-dimensional turntable, and the reflection angle of the pre-quick mirror in the optical head of the star-borne laser communication payload is adjusted to realize the pointing adjustment of the emission optical axis of the optical head of the star-borne laser communication payload.

7. The star-borne laser communication ranging method with zero-value calibration according to claim 5, characterized in that: In step 4.4, the adjustment of the tracking point is specifically as follows: The reflection angle of the tracking quick mirror is adjusted to realize the adjustment of the tracking point.

8. The star-borne laser communication ranging method with zero-value calibration according to claim 4, characterized in that: In step 6, the distance L between the home star and the ground station or the target satellite is calculated by the following formula: L=(T1+T3-T0-T2) / 2*c Wherein, T0 is the time information corresponding to the zero-value distance of the local side, T1 is the time information corresponding to the pseudo-range transmitted by the opposite end, T2 is the time information corresponding to the zero-value distance transmitted by the opposite end, T3 is the time information corresponding to the pseudo-range of the local side, and c is the speed of light.

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