Used for long-distance intersatellite laser communication payload terminal and satellite communication system

Abstract

The present invention provides a payload terminal and a satellite communication system for long-distance intersatellite laser communication, comprising an optical antenna, a fast-reflection mirror, a transmitting structure and an avalanche diode; the optical antenna, the fast-reflection mirror and the transmitting structure constitute a transmitting optical path, and the transmitting optical path is used to transmit an optical signal that meets the coherent or incoherent mode of a docking payload; the optical antenna, the fast-reflection mirror and the avalanche diode constitute a receiving optical path, and the receiving optical path is used to receive an optical signal that is not affected by the polarization state of the light emitted by the docking payload; the terminal composed of the transmitting optical path and the receiving optical path is used for different types of intersatellite and satellite-to-ground payload communications, and because the avalanche diode can realize long-distance communication, high-sensitivity communication is realized through a terminal with a small size and simple structure, and the communication distance under the same conditions is 5.6 times that of an optical fiber coupling method, which effectively improves the efficiency of satellite communication.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a payload terminal and a satellite communication system for long-distance inter-satellite laser communication. Background Art

[0002] Satellite laser communication is a communication method that uses laser beams as carrier waves to transmit information such as images, voices, and signals in space. It has the advantages of high transmission rate, strong anti-interference ability, small system terminal size, light weight, and low power consumption. It can not only transmit data between satellites and the ground, but also realize the transmission of laser payload data between satellites, thereby expanding the coverage area and realizing global measurement and control. At present, with the increase of medium and high orbit satellite laser communication services, laser long-distance communication has become an important demand for the development of global satellite communication systems.

[0003] However, long-distance satellite communications will increase the loss of light in space, and it is necessary to increase the transmit and receive gains to meet the margin of inter-satellite and satellite-to-ground communication links, thereby increasing the receiving aperture and transmit power, which directly affects the power consumption and envelope size of the payload, resulting in limited inter-satellite laser payload communication distance. Summary of the invention

[0004] The present invention provides a payload terminal and a satellite communication system for long-distance intersatellite laser communication, so as to solve the defects of the prior art that the intersatellite laser payload communication terminal has a large size and a limited distance.

[0005] In a first aspect, the present invention provides a payload terminal for long-distance intersatellite laser communication, comprising: an optical antenna, a fast reflection mirror, a transmitting structure and an avalanche diode;

[0006] The optical antenna, the fast reflection mirror and the transmitting structure constitute a transmitting optical path, and the transmitting optical path is used to transmit an optical signal that satisfies the coherent or incoherent mode of the docking payload;

[0007] The optical antenna, the fast reflection mirror and the avalanche diode constitute a receiving optical path, and the receiving optical path is used to receive an optical signal that is not affected by the polarization state of the light emitted by the docking payload;

[0008] The terminal formed by the transmitting optical path and the receiving optical path is used for different types of inter-satellite and satellite-to-ground payload communications.

[0009] According to a payload terminal for long-distance intersatellite laser communication provided by the present invention, the transmitting optical path uses binary phase shift keying;

[0010] The receiving optical path uses on-off keying modulation.

[0011] According to a payload terminal for long-distance intersatellite laser communication provided by the present invention, the transmitting structure comprises: a transmitting collimator and a polarizer;

[0012] The emission collimator is used for emitting signals, and the polarizer is used for converting the linearly polarized light of the emission optical fiber into circularly polarized light.

[0013] According to a payload terminal for long-distance intersatellite laser communication provided by the present invention, the avalanche diode is used to convert the optical signal into an electrical signal in the optical head and input it into the processor for demodulation;

[0014] The sensitivity of the avalanche diode is -70dBm, and the target surface is larger than 0.5mm.

[0015] According to a payload terminal for long-distance intersatellite laser communication provided by the present invention, the avalanche diode comprises: a P+ layer, a depletion layer, a multiplication layer and an N+ layer;

[0016] The depletion layer is located on the upper surface of the P+ layer, the multiplication layer is located on the upper surface of the depletion layer, and the N+ layer is located on the upper surface of the multiplication layer.

[0017] A payload terminal for long-distance intersatellite laser communication provided by the present invention also includes:

[0018] When the incident light meets the response condition, the electron-hole pairs generated by the N+ layer move under the action of the electric field and gain kinetic energy;

[0019] When the carriers with the kinetic energy enter the P+ layer, they collide with the crystal atoms to generate new first electron-hole pairs;

[0020] The new first electron-hole pairs, under the action of the electric field, gain energy and generate new second electron-hole pairs through collision, thereby ultimately amplifying the number of initial carriers and realizing optical signal detection.

[0021] A payload terminal for long-distance intersatellite laser communication provided by the present invention also includes:

[0022] Determine the exit pupil equivalent isotropic radiated power, equivalent loss caused by atmospheric turbulence, entrance pupil receiving sensitivity and receiving antenna aperture;

[0023] The exit pupil equivalent isotropic radiation power, equivalent loss caused by atmospheric turbulence, etc., entrance pupil receiving sensitivity and receiving antenna aperture are input into the communication distance model, and the communication distance of the avalanche diode is output.

[0024] According to a payload terminal for long-distance intersatellite laser communication provided by the present invention, the communication distance model is:

[0025]

[0026] in, is the exit pupil equivalent isotropic radiated power, is the equivalent loss caused by atmospheric turbulence, etc., is the entrance pupil reception sensitivity, is the receiving antenna aperture.

[0027] A payload terminal for long-distance intersatellite laser communication provided by the present invention also includes: a capture tracking detector;

[0028] The capture tracking detector is used to capture the optical signal between the receiving optical paths to achieve capture tracking.

[0029] In a second aspect, the present invention also protects a satellite communication system, comprising a payload terminal for long-distance inter-satellite laser communication as described in any one of the above items.

[0030] The present invention provides a payload terminal and a satellite communication system for long-distance intersatellite laser communication, comprising an optical antenna, a fast-reflection mirror, a transmitting structure and an avalanche diode; the optical antenna, the fast-reflection mirror and the transmitting structure constitute a transmitting optical path, and the transmitting optical path is used to transmit an optical signal that meets the coherent or incoherent mode of a docking payload; the optical antenna, the fast-reflection mirror and the avalanche diode constitute a receiving optical path, and the receiving optical path is used to receive an optical signal that is not affected by the polarization state of the light transmitted by the docking payload; the terminal composed of the transmitting optical path and the receiving optical path is used for different types of intersatellite and satellite-to-ground payload communications, and because the avalanche diode can realize long-distance communication, high-sensitivity communication is achieved through a terminal with a small size and simple structure, and the communication distance under the same conditions is 5.6 times that of a fiber coupling method, thereby improving the efficiency of satellite communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 is a schematic diagram of the principle of a payload terminal for long-distance intersatellite laser communication provided by this embodiment;

[0033] Figure 2 is a schematic diagram of the internal structure of the avalanche diode 6 provided in this embodiment;

[0034] Reference numerals:

[0035] 1. Optical antenna; 2. Fast reflector; 3. Emission collimator; 4. Polarizer; 5. Capture and tracking detector; 6. Avalanche diode. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Figure 1 It is a schematic diagram of the principle of a payload terminal for long-distance intersatellite laser communication provided in this embodiment.

[0038] like Figure 1 As shown, the present embodiment provides a payload terminal for long-distance intersatellite laser communication, comprising: an optical antenna 1, a fast reflection mirror 2, a transmitting structure and an avalanche diode 6; wherein the optical antenna 1, the fast reflection mirror 2 and the transmitting structure constitute a transmitting optical path, and the transmitting optical path is used to transmit an optical signal that satisfies the coherent or incoherent mode of the docking payload; the optical antenna 1, the fast reflection mirror 2 and the avalanche diode 6 constitute a receiving optical path, and the receiving optical path is used to receive an optical signal that is not affected by the polarization state of the light transmitted by the docking payload; the terminal composed of the transmitting optical path and the receiving optical path is used for different types of intersatellite and satellite-to-ground payload communications.

[0039] In a specific implementation process, the optical terminal for long-distance small-aperture intersatellite laser communication payload formed by the transmitting optical path and the receiving optical path can be used to communicate with different types of intersatellite and satellite-to-ground payloads, and is not limited to coherent or incoherent systems. The high sensitivity is suitable for long-distance communication conditions. The optical payload uses binary phase shift keying (BPSK) for transmission, which meets the coherent or incoherent mode of the docking payload; the reception uses on-off keying modulation (OOK), which is not affected by the polarization state of the docking payload transmission light, and can improve the receiving sensitivity, which is suitable for long-distance laser communication.

[0040] like Figure 1 As shown, the light path indicated by the solid line is the emission light path, which is composed of an emission collimator 3, a polarizer 4, a fast mirror 2 and an optical antenna 1. The position relationship is as shown in FIG. Figure 1As shown, the transmitted light enters the fast mirror 2 through the polarizer 4 and then interacts with the satellite through the optical antenna 1. Among them, the transmitting collimator 3 is used to transmit the signal, and the polarizer 4 is used to convert the linear polarized light of the transmitting optical fiber into circular polarized light to meet the coherent physical requirements of the intersatellite docking payload. If the intersatellite docking payload is also in an incoherent mode, the polarizer 4 can be removed. The fast mirror 2 ensures the stability and reliability of the optical communication link by accurately controlling the direction of the light beam. The fast mirror 2 can correct the tilt error in the optical path and stabilize the direction of the light beam through its high-speed response and high-precision control capabilities. It also plays a role in the rapid tracking system, ensuring the reliability of the transmitted light and satellite communication.

[0041] like Figure 1 As shown, the light path indicated by the dotted line is the receiving light path. Since the receiving light path uses the OOK mode, only the intensity of the received light signal needs to be considered, and the phase of the light signal is not considered. The avalanche diode 6 is selected to replace the coupling optical fiber. The avalanche diode 6 is used to convert the light signal into an electrical signal in the optical head and input it into the processor for demodulation; the sensitivity of the avalanche diode 6 is -70dBm, and the target surface is larger than 0.5mm.

[0042] Figure 2 Schematic diagram of the internal structure of the avalanche diode provided in this embodiment. Figure 2 As shown, the avalanche diode 6 includes: a P+ layer, a depletion layer, a multiplication layer and an N+ layer; it usually works under a reverse bias voltage of up to hundreds of volts, the depletion layer is located on the upper surface of the P+ layer, the multiplication layer is located on the upper surface of the depletion layer, and the N+ layer is located on the upper surface of the multiplication layer. When the incident light meets the response conditions, the electron-hole pairs generated by the N+ layer move under the action of a strong electric field and obtain very high kinetic energy. When the carriers with kinetic energy enter the P+ layer, they collide with the crystal atoms to generate new first electron-hole pairs. Under the action of the strong electric field, the new first electron-hole pairs gain energy and generate new second electron-hole pairs through collision, which ultimately amplifies the initial number of carriers by hundreds of times, thereby achieving high-sensitivity optical signal detection.

[0043] The field of view of the avalanche diode 6 is relatively large, and can cover the small window field of view of the capture camera after precise tracking; and since the core diameter of the coupled optical fiber is 10um, the optical coupling efficiency after adjustment can generally only reach 0.5, so the communication sensitivity of the optical head can only reach about -55dBm, and it is necessary to add a fast mirror 2 to compensate for the received light with different incident angles in real time. When calculating the link, the use of the coupled optical fiber method requires increasing the receiving aperture and increasing the receiving gain to meet the sensitivity requirements. The use of an avalanche diode 6 can reduce the receiving aperture and a fast mirror 2 to a certain extent, making the overall optical head miniaturized, lightweight, and low-cost. According to the comparison of receiving sensitivity, the avalanche diode 6 can increase the sensitivity of the coupled optical fiber method by 15dBm. According to the maximum communication distance, the maximum communication distance of the avalanche diode 6 mode is 5.6 times that of the coupled optical fiber method.

[0044] The method for calculating the farthest distance of the avalanche diode 6 is to determine the equivalent isotropic radiated power of the exit pupil, the equivalent loss caused by atmospheric turbulence, etc., the entrance pupil receiving sensitivity and the receiving antenna aperture; input the equivalent isotropic radiated power of the exit pupil, the equivalent loss caused by atmospheric turbulence, etc., the entrance pupil receiving sensitivity and the receiving antenna aperture into the communication distance model, and output the communication distance of the avalanche diode.

[0045] Among them, the communication distance model is formula (1):

[0046] (1)

[0047] in, is the exit pupil equivalent isotropic radiated power, is the equivalent loss caused by atmospheric turbulence, etc., is the entrance pupil reception sensitivity, is the receiving antenna aperture.

[0048] The payload terminal for long-distance small-aperture intersatellite laser communication of the present invention has a simple structure, is easy to realize low power consumption, miniaturization and mass production integration, and effectively improves the communication distance. It is suitable for different types of intersatellite and satellite-to-ground payload communications and is not limited to coherent or incoherent systems. At the same time, it also improves the receiving gain.

[0049] Furthermore, if Figure 1 As shown, this embodiment also includes: a capture tracking detector 5; the capture tracking detector 5 is used to capture the optical signal between the receiving optical paths to achieve capture tracking. Specifically, the capture tracking detector 5 ensures the stability and reliability of the communication link. Through the capture, tracking and aiming technology, the detector can accurately locate the relative position between the satellites, thereby ensuring the smooth progress of laser communication.

[0050] Based on the same general inventive concept, the present invention also protects a satellite communication system, including a payload terminal for long-distance inter-satellite laser communication as in any of the above embodiments.

[0051] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0052] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A payload terminal for long-distance intersatellite laser communication, characterized in that: include: Optical antennas, fast mirrors, transmitting structures and avalanche diodes; The optical antenna, the fast reflection mirror and the transmitting structure constitute a transmitting optical path, and the transmitting optical path is used to transmit an optical signal that satisfies the coherent or incoherent mode of the docking payload; The optical antenna, the fast reflection mirror and the avalanche diode constitute a receiving optical path, and the receiving optical path is used to receive an optical signal that is not affected by the polarization state of the light emitted by the docking payload; The terminal formed by the transmitting optical path and the receiving optical path is used for different types of inter-satellite and satellite-to-ground payload communications; The transmitting optical path uses binary phase shift keying; The receiving optical path uses on-off keying modulation; the transmitting structure includes: a transmitting collimator and a polarizer; the transmitting collimator is used to transmit signals, and the polarizer is used to convert the linear polarized light of the transmitting optical fiber into circular polarized light; Determine the exit pupil equivalent isotropic radiation power, the equivalent loss caused by atmospheric turbulence, the entrance pupil receiving sensitivity and the receiving antenna aperture; input the exit pupil equivalent isotropic radiation power, the equivalent loss caused by atmospheric turbulence, the entrance pupil receiving sensitivity and the receiving antenna aperture into the communication distance model, and output the communication distance of the avalanche diode; The communication distance model is: ； in, is the exit pupil equivalent isotropic radiated power, is the equivalent loss caused by atmospheric turbulence, is the entrance pupil reception sensitivity, is the receiving antenna aperture.

2. The payload terminal for long-distance intersatellite laser communication according to claim 1, characterized in that: The avalanche diode is used to convert the optical signal into an electrical signal in the optical head and input it into the processor for demodulation; The sensitivity of the avalanche diode is -70dBm, and the target surface is larger than 0.5mm.

3. The payload terminal for long-distance intersatellite laser communication according to claim 1, characterized in that: The avalanche diode comprises: a P+ layer, a depletion layer, a multiplication layer and an N+ layer; The depletion layer is located on the upper surface of the P+ layer, the multiplication layer is located on the upper surface of the depletion layer, and the N+ layer is located on the upper surface of the multiplication layer.

4. The payload terminal for long-distance intersatellite laser communication according to claim 3 is characterized in that: Also includes: When the incident light meets the response condition, the electron-hole pairs generated by the N+ layer move under the action of the electric field and gain kinetic energy; When the carriers with the kinetic energy enter the P+ layer, they collide with the crystal atoms to generate new first electron-hole pairs; The new first electron-hole pairs, under the action of the electric field, gain energy and generate new second electron-hole pairs through collision, thereby ultimately amplifying the number of initial carriers and realizing optical signal detection.

5. The payload terminal for long-distance intersatellite laser communication according to any one of claims 1 to 4, characterized in that: Also includes: Capture tracking probe; The capture tracking detector is used to capture the optical signal between the receiving optical paths to achieve capture tracking.

6. A satellite communication system, characterized in that: It comprises a payload terminal for long-distance intersatellite laser communication as described in any one of claims 1 to 5.

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