Optical communication device and doppler shift compensation method for inter-satellite optical communication

Abstract

To provide an optical communication device that can achieve efficient Doppler shift compensation through cooperation between the transmitting side and the receiving side.SOLUTION: An optical communication device (10A) is mounted on a first satellite (A) and performs optical communication with a second satellite (B), and includes an optical transmitter / receiver (103A-109A) that transmits and receives signal light with the second satellite, and a processor (101A) that performs Doppler shift compensation with the second satellite by transmitting and receiving the signal light by the optical transmitter / receiver, and after establishing optical acquisition and tracking of the second satellite, the processor determines a Doppler shift compensation method with the second satellite and shares compensation for the Doppler shift frequency with the second satellite in accordance with the Doppler shift compensation method.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inter-satellite optical communication system, and more particularly to a technique for compensating for Doppler shift between satellites. [Background technology]

[0002] When communicating between satellites using radio waves or light, the relative movement of the satellites causes Doppler shift. Many technologies have been proposed to compensate for this Doppler shift. Generally, the Doppler shift is calculated based on the satellite's orbital information, and the optical transmitter controls the frequency (wavelength) of the transmitted laser light so that the Doppler frequency is offset (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. WO2020-110956 Brochure Summary of the Invention [Problem to be solved by the invention]

[0004] However, there are various cases where Doppler shift compensation can be considered. For example, in non-coherent optical communications, a wavelength filter is required in the low-noise amplifier on the receiving side, making it difficult to shift the receiving frequency on the receiving side. In contrast, in coherent communications, compensation can be achieved by shifting the frequency of the local light source on the receiving side. However, there is a limit to the frequency range that can be accommodated by the local light source, and if the Doppler shift is large, it may be difficult to compensate on the receiver side alone.

[0005] In this way, although there are limitations to Doppler shift compensation on the receiving side, it is possible in some cases. In the background art described above, even if it is possible to compensate for the Doppler shift on the receiving side, Doppler shift compensation is always performed only on the transmitting side.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an optical communication device, a Doppler shift compensation method, and an optical communication system that can achieve efficient Doppler shift compensation through cooperation between the transmitting and receiving sides. [Means for solving the problem]

[0007] The optical communication device disclosed herein is an optical communication device that is mounted on a first satellite and performs optical communication with a second satellite, and includes an optical transceiver that transmits and receives signal light with the second satellite, and a processing unit that performs Doppler shift compensation with the second satellite by transmitting and receiving signal light by the optical transceiver, wherein after establishing optical acquisition and tracking of the second satellite, the processing unit determines a Doppler shift compensation method with the second satellite and shares compensation of the Doppler shift frequency with the second satellite in accordance with the Doppler shift compensation method. The Doppler shift compensation method disclosed herein is a Doppler shift compensation method in an optical communication device that is mounted on a first satellite and performs optical communication with a second satellite, wherein the optical communication device comprises an optical transceiver unit that transmits and receives signal light with the second satellite, and a processing unit that performs Doppler shift compensation with the second satellite by transmitting and receiving signal light by the optical transceiver unit, and is characterized in that after establishing optical acquisition and tracking of the second satellite, the processing unit determines a Doppler shift compensation method with the second satellite and shares compensation of the Doppler shift frequency with the second satellite in accordance with the Doppler shift compensation method. The optical communication system disclosed herein is an optical communication system that performs optical communication between a first satellite and a second satellite traveling at a relative speed, wherein the first satellite is capable of changing the frequency of transmitted light within a first frequency range, and the second satellite is capable of changing the frequency of received light within a second frequency range, and after optical acquisition and tracking is established between the first satellite and the second satellite, a Doppler shift compensation method is determined between the first satellite and the second satellite, and the first satellite and the second satellite share the compensation of the Doppler shift frequency in accordance with the Doppler shift compensation method. The program disclosed herein is a program that causes a computer to function as an optical communication device that is mounted on a first satellite and performs optical communication with a second satellite, wherein the optical communication device has an optical transceiver that transmits and receives signal light with the second satellite, and after establishing optical capture and tracking of the second satellite, the computer is provided with the functions of determining a Doppler shift compensation method with the second satellite and sharing compensation of Doppler shift frequency with the second satellite in accordance with the Doppler shift compensation method. [Effects of the Invention]

[0008] According to the present invention, efficient Doppler shift compensation can be achieved through cooperation between the transmitting and receiving sides. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram illustrating a schematic configuration of an optical communication device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a sequence diagram showing a first example of a method for compensating for Doppler shift between satellites equipped with optical communication devices according to the present disclosure. [Figure 3] FIG. 3 is a sequence diagram showing a second example of a method for compensating for Doppler shift between satellites equipped with optical communication devices according to the present disclosure. [Figure 4] FIG. 4 is a schematic diagram showing an example of a Doppler shift compensation range on the transmitting side and the receiving side in the optical communication device according to the present disclosure. [Figure 5] FIG. 5 is a block diagram illustrating a schematic configuration of an optical communication device according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Outline of the embodiment> According to one embodiment of the present disclosure, after optical acquisition and tracking between satellites is established, a Doppler shift compensation method is determined, and compensation of the Doppler shift frequency is shared among the satellites according to the Doppler shift compensation method. The Doppler shift compensation methods include: 1) a method in which, if the receiving satellite can compensate for the Doppler shift frequency, the receiving satellite is responsible for Doppler shift compensation; if not, the local satellite is responsible for Doppler shift compensation within a first frequency range in which the frequency of the transmitted light can be changed; and 2) a method in which the share of Doppler shift compensation between satellites is determined depending on the magnitude of the Doppler shift frequency. In other words, the receiving satellite, or both the transmitting and receiving satellites, are responsible for Doppler shift frequency compensation. This enables efficient Doppler shift compensation.

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the components described in the following embodiments are merely examples and are not intended to limit the technical scope of the present invention.

[0012] 1. One embodiment The following describes the configuration and operation of satellites A and B traveling in space on their respective orbits and transmitting signal light to each other's optical sections to perform Doppler shift compensation.

[0013] 1.1) System configuration 1, an optical communication device 10A according to this embodiment is mounted on a satellite A, and an optical communication device 10B having a similar configuration is mounted on a satellite B. The internal configuration of the optical communication device 10B is not shown because it is basically the same as that of the optical communication device 10A.

[0014] The optical communication device 10A has a processing unit 101A consisting of a computer or a processor, etc., and implements a Doppler shift compensation function (described later) by executing a program stored in a program memory 102A. The optical communication device 10A further has an optical transmitting and receiving unit, and its transmitting system includes a transmitting unit 103A, a transmitting light source 104A, a high-power optical amplifier (HPA) 105A, and an optical unit 106A, and its receiving system includes the optical unit 106A, a low-noise amplifier (LNA) 107A, a light-receiving unit 108A, and a receiving unit 109A.

[0015] The transmission light source 104A is a laser light source capable of controlling the wavelength (frequency) of the transmission light within a predetermined range (first frequency range) using a drive current. The transmission light is modulated by the transmission unit 103A according to transmission data under the control of the processing unit 101A. In this embodiment, the transmission light output from the transmission light source 104A includes laser light for optical acquisition and tracking, signal light (intensity-modulated light) with varied optical intensity used in the Doppler shift compensation process after acquisition and tracking is established, and a predetermined digitally modulated optical signal after communication is established. The transmission light is amplified by the HPA 105A and irradiated to the target satellite B by the optical unit 106A.

[0016] When the optical unit 106A receives laser light from the other satellite B, the received light is amplified by the LNA 107A and converted into an electrical signal by the light receiving unit 108A. If the light receiving unit 108A is a coherent system, it has an interference optical system with the local light, and can change the receiving frequency within a predetermined range by changing the wavelength of the local light. If the light receiving unit 108A is a non-coherent system, a wavelength filter is provided in the LNA 107A, and the changeable range of the receiving frequency depends on the frequency characteristics of the wavelength filter. The optical communication device 10A may also be provided with a sensor for optical acquisition and tracking.

[0017] The optical unit 106A has an optical antenna, and under the control of the processing unit 101A, it can mutually scan the laser light for acquisition and tracking with the other satellite B, and ultimately continue to track each other's laser light. An example of such optical acquisition and tracking technology is described in, for example, NEC Technical Report (Vol. 74 No. 1, pp. 143-145).

[0018] The optical communication device 10A may be provided with a function for acquiring position information and velocity information of satellite A (not shown). In this embodiment, the processing unit 101A calculates the position and velocity of each of satellites A and B based on the orbit calculation results. From these positions and velocities, the relative velocity between satellite A and satellite B is calculated, and the Doppler shift frequency, and therefore the Doppler shift compensation value, can be calculated.

[0019] Next, we will explain the operation until Doppler shift compensation is completed between satellite A and satellite B. However, since the optical communication device 10A and the optical communication device 10B have similar internal configurations, each block of the optical communication device 10B will be denoted by adding "B" to the reference number of the corresponding block of the optical communication device 10A.

[0020] 1.2) Example 1 2, first, satellite A and satellite B mutually scan their acquisition and tracking laser beams to establish acquisition and tracking between them (operations S201 and S202). The processing unit 101A of satellite A calculates a compensation value for the Doppler shift frequency based on the orbit determination value of satellite A and the orbit calculation result of satellite B (operation S203).

[0021] The processing unit 101A of satellite A transmits the Doppler shift compensation value as the satellite B's allocated value to satellite B as follows (operation S204). That is, under the control of the processing unit 101A, the transmitting unit 103A uses the Doppler shift compensation value as modulation data to drive the transmitting light source 104A and change the intensity of the transmitted light. As a result, the transmitting light source 104A emits intensity-modulated transmitted light, and this transmitted light is transmitted from the optical unit 106A to the optical unit 106B of satellite B via the HPA 105A. Because communication is not established when acquisition and tracking are established, information is transmitted by changing the intensity of the transmitted light and detecting the change in intensity with the light receiving sensor for acquisition and tracking.

[0022] The received light arriving at satellite B from satellite A passes through optical section 106B and LNA 107B, is converted into an electrical signal by light receiving section 108B, and is output by receiving section 109B to processing section 101B as received data, that is, a Doppler shift compensation value.

[0023] The processing unit 101B of satellite B determines whether the Doppler shift compensation value is compatible with the frequency changeable range of its own station (operation S205), and transmits the determination result to satellite A (operation S206). In the case of non-coherent optical communication, whether Doppler shift compensation is possible is determined based on whether the transmission wavelength (frequency) range of the wavelength filter provided in LNA 107B is wider than the frequency range for Doppler shift compensation. In the case of coherent optical communication, whether Doppler shift compensation is possible is determined based on whether the reception frequency range made possible by changing the wavelength of the local light of light receiving unit 108B is wider than the frequency range for Doppler shift compensation.

[0024] As described above, under the control of processing unit 101B, transmitting unit 103B uses the determination result as modulation data to drive transmitting light source 104B and change the intensity of the transmitting light. As a result, transmitting light source 104B emits intensity-modulated transmitting light, and this transmitting light is transmitted from optical unit 106B to optical unit 106A of satellite A via HPA 105B.

[0025] If the satellite B side cannot compensate for the Doppler shift (operation S207; "compensation not possible"), the processing unit 101A of the satellite A shifts the frequency of the light transmitted from the transmitting light source 104A to compensate for the Doppler shift (operation S208) and establishes communication with the satellite B (operation S209). If the satellite B side can compensate for the Doppler shift (operation S207; "compensation possible"), the processing unit 101A of the satellite A does not compensate for the Doppler shift and leaves it to the satellite B to establish communication (operation S209).

[0026] If Doppler shift compensation is possible (operation S208; YES), the processing unit 101B of satellite B performs Doppler shift compensation at its own station (operation S210) and establishes communication with satellite A (operation S211). If Doppler shift compensation is not possible (operation S208; NO), satellite B does not compensate and leaves it to satellite A to establish communication (operation S211).

[0027] In the operation illustrated in FIG. 2, when a determination result indicating whether compensation is possible is received from the receiving satellite B in the above-mentioned operation S206, the processing unit 101A of the satellite A determines the Doppler shift compensation method 1 and can execute the Doppler shift compensation operation of operations S207 to S211 in FIG. 2.

[0028] 1.3) Example 2 3, compensation of the Doppler shift frequency is shared between satellite A and satellite B. In the following explanation, the explanation of operations similar to those in operation example 1 above will be simplified.

[0029] 3, first, satellite A and satellite B mutually scan their acquisition and tracking laser beams to establish acquisition and tracking between them (operations S201 and S202). A processing unit 101A of satellite A calculates a compensation value for the Doppler shift frequency based on the orbit determination value of satellite A and the orbit calculation result of satellite B (operation S203).

[0030] Next, the processing unit 101A of the satellite A transmits the Doppler shift compensation value to the satellite B as the allocated value of the satellite B (Operation S301). Upon receiving the allocated value, the processing unit 101B of the satellite B determines whether or not the received Doppler shift compensation is possible as described in Operation Example 1 (Operation S302), and transmits the determination result together with the compensation possible range of the own station to the satellite A (Operation S303).

[0031] When the processing unit 101A of satellite A receives the compensable range of satellite B, it refers to the transmission frequency changeable range of satellite A (first frequency range) and the compensable range of satellite B (second frequency range) to determine whether Doppler shift compensation can be shared (Operation S304). If sharing is possible (YES in Operation S304), the processing unit 101A determines a Doppler shift compensation share value between the own station and satellite B (Operation S305) and transmits satellite B's share value to satellite B (Operation S306). For example, satellite B's share value is set within the compensable range of satellite B (second frequency range), and the own station's share value is set to the remaining Doppler shift compensation value after subtracting satellite B's share value.

[0032] Satellite A performs Doppler shift compensation by shifting the frequency of the light transmitted from transmission light source 104A by the allotted amount (operation S307), and satellite B performs Doppler shift compensation by shifting the reception frequency by the allotted amount, for example, by changing the wavelength of the local light (operation S308). In this way, communication is established between satellite A and satellite B (operations S309 and S310).

[0033] Furthermore, when the processing unit 101A of satellite A determines that Doppler shift compensation is not possible by referring to the transmission frequency changeable range (first frequency range) of satellite A and the compensationable range (second frequency range) of satellite B (operation S304; NO), it terminates the processing without performing Doppler shift compensation and the communication establishment process.

[0034] In the operation illustrated in FIG. 3, when a determination result including a compensable range is received from the receiving satellite B in the above-mentioned operation S303, the processing unit 101A of the satellite A determines the Doppler shift compensation method 2 and can execute the Doppler shift compensation operation of operations S304 to S310 in FIG. 3.

[0035] 1.3) Example 3 4, a Doppler shift compensation range (first frequency range) 401A on the transmitting side and a Doppler shift compensation range (second frequency range) 401B on the receiving side are each defined based on the center frequency without Doppler shift. Once these ranges 401A and 401B are acquired, the allocation of Doppler shift compensation can be determined by setting multiple thresholds. The Doppler shift compensation range 401A on the transmitting side is the wavelength change range of the transmitting light source 104A, and is wider than the Doppler shift compensation range (second frequency range) 401B on the receiving side.

[0036] 4, if the Doppler shift is within the Doppler shift compensation range 401B on the receiving side, it can be handled on the receiving side. Therefore, by setting a threshold ±TH1 below the Doppler shift compensation range 401B, if the generated Doppler shift frequency is within the threshold ±TH1, it can be determined that it can be handled by the Doppler shift compensation on the receiving side alone.

[0037] If the Doppler shift is within Doppler shift compensation range 401A, the transmitting side alone can compensate for the Doppler shift frequency. Even in this case, according to this embodiment, the transmitting side and receiving side can share the Doppler shift compensation. First, a threshold ±TH2 corresponding to Doppler shift compensation range 401A on the transmitting side is set. If the generated Doppler shift frequency is outside threshold ±TH1 but within threshold ±TH2, the receiving side is assigned to compensate for the upper limit of Doppler shift compensation range 401B, and the transmitting side is assigned to compensate for the remaining Doppler shift. This makes it possible to avoid the Doppler shift compensation load being concentrated on either the transmitting side or the receiving side, and suppress the magnitude of the frequency change.

[0038] 2. Other Embodiments Hereinafter, an embodiment will be described in which multiple satellites (here, satellites A, B, C, and D) are traveling in space on their respective orbits, and signal light is transmitted between satellite A and the other satellites to perform Doppler shift compensation. However, blocks having the same functions as those in FIG. 1 are given the same reference numerals, and their description will be omitted.

[0039] As shown in FIG. 5, the optical communication device 10A according to this embodiment is equipped with the same functions as those shown in FIG. 1, and furthermore, orbital information for other satellites B, C, and D is stored in a memory 110A. First, satellite A and each of the other satellites mutually scan their acquisition and tracking laser beams to establish acquisition and tracking between them. A processing unit 101A of satellite A calculates compensation values ​​for the Doppler shift frequencies of the other satellites B, C, and D based on the orbital information of the other satellites. Thereafter, Doppler shift compensation can be shared between satellite A and each of the other satellites by the same control as in the operational examples 1 to 3 described in the above embodiment. Details are as shown in FIGS. 2 to 4, and therefore will not be described here.

[0040] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0041] 3. Notes Some or all of the above-described embodiments and examples can be described as follows, but are not limited to these. (Appendix 1) An optical communication device mounted on a first satellite and performing optical communication with a second satellite, an optical transceiver for transmitting and receiving signal light to and from the second satellite; a processing unit that performs Doppler shift compensation between the optical transmitter and receiver and the second satellite by transmitting and receiving signal light by the optical transmitter and receiver; Equipped with The processing unit After establishing optical acquisition and tracking of the second satellite, determining a Doppler shift compensation method between the second satellite and the second satellite; sharing compensation for the Doppler shift frequency with the second satellite according to the Doppler shift compensation method; An optical communication device characterized by: (Appendix 2) The optical communication device described in Supplementary Note 1, characterized in that the Doppler shift compensation method is a method in which if the Doppler shift frequency can be compensated for by the second satellite, the second satellite is responsible for the Doppler shift compensation, and if the second satellite cannot compensate for the Doppler shift, the optical transceiver is responsible for the Doppler shift compensation within a first frequency range in which the frequency of the transmitted light can be changed. (Appendix 3) The optical communication device described in Appendix 1, characterized in that the Doppler shift compensation method is a method that determines the share of Doppler shift compensation between the first satellite and the second satellite depending on the magnitude of the Doppler shift frequency. (Appendix 4) the optical transceiver is capable of changing the frequency of the transmitted light within a first frequency range; the second satellite is capable of receiving received light within a second frequency range; The processing unit notifying the second satellite of the Doppler shift frequency; When receiving the allocation information including the second frequency range from the second satellite, calculating a first compensation allocation value of the first satellite and a second compensation allocation value of the second satellite based on the first frequency range and the second frequency range; transmitting the second compensation contribution to the second satellite; performing Doppler shift compensation according to the first compensation contribution value; 4. The optical communication device according to claim 3, (Appendix 5) the processing unit prepares a first threshold value indicating a frequency range equal to or lower than the second frequency range and a second threshold value indicating the first frequency range; If the Doppler shift frequency is smaller than the first threshold, the Doppler shift compensation is not performed and the Doppler shift compensation of the second satellite is left to be performed; If the Doppler shift frequency is equal to or greater than the first threshold and equal to or less than the second threshold, transmitting the second compensation share value to the second satellite and performing the Doppler shift compensation share according to the first compensation share value. 5. The optical communication device according to claim 4, (Appendix 6) The optical communication device according to any one of claims 1 to 5, characterized in that after optical acquisition and tracking of the second satellite is established but before the Doppler shift compensation is completed, communication by the optical transceiver unit is performed by intensity modulation of the signal light. (Appendix 7) A Doppler shift compensation method for an optical communication device mounted on a first satellite and performing optical communication with a second satellite, the optical communication device comprising: an optical transceiver unit that transmits and receives signal light to and from the second satellite; and a processing unit that performs Doppler shift compensation with the second satellite by transmitting and receiving the signal light by the optical transceiver unit; The processing unit After establishing optical acquisition and tracking of the second satellite, determining a Doppler shift compensation method between the second satellite and the second satellite; sharing compensation for the Doppler shift frequency with the second satellite according to the Doppler shift compensation method; A method for compensating for Doppler shift. (Appendix 8) The Doppler shift compensation method according to claim 7, characterized in that if the Doppler shift frequency can be compensated for by the second satellite, the second satellite is responsible for the Doppler shift compensation, and if the second satellite cannot compensate for the Doppler shift, the optical transceiver is responsible for the Doppler shift compensation within a first frequency range in which the frequency of the transmitted light can be changed. (Appendix 9) The Doppler shift compensation method described in Appendix 7, characterized in that the Doppler shift compensation method is a method of determining the share of Doppler shift compensation between the first satellite and the second satellite depending on the magnitude of the Doppler shift frequency. (Appendix 10) the optical transceiver is capable of changing the frequency of the transmitted light within a first frequency range; the second satellite is capable of receiving received light within a second frequency range; The processing unit notifying the second satellite of the Doppler shift frequency; When receiving the allocation information including the second frequency range from the second satellite, calculating a first compensation allocation value of the first satellite and a second compensation allocation value of the second satellite based on the first frequency range and the second frequency range; transmitting the second compensation contribution to the second satellite; performing Doppler shift compensation according to the first compensation contribution value; 10. The Doppler shift compensation method according to claim 9, (Appendix 11) the processing unit prepares a first threshold value indicating a frequency range equal to or lower than the second frequency range and a second threshold value indicating the first frequency range; If the Doppler shift frequency is smaller than the first threshold, the Doppler shift compensation is not performed and the Doppler shift compensation of the second satellite is left to be performed; If the Doppler shift frequency is equal to or greater than the first threshold and equal to or less than the second threshold, transmitting the second compensation share value to the second satellite and performing the Doppler shift compensation share according to the first compensation share value. 11. The Doppler shift compensation method according to claim 10, (Appendix 12) The Doppler shift compensation method according to any one of appendices 7 to 11, characterized in that after optical acquisition and tracking of the second satellite is established but before the Doppler shift compensation is completed, communication by the optical transceiver is performed by intensity modulation of the signal light. (Appendix 13) An optical communication system for performing optical communication between a first satellite and a second satellite traveling at a relative speed, the first satellite is capable of varying the frequency of the transmitted light within a first frequency range, and the second satellite is capable of varying the frequency of the received light within a second frequency range; After optical acquisition and tracking is established between the first satellite and the second satellite, a Doppler shift compensation method is determined between the first satellite and the second satellite; Sharing compensation for Doppler shift frequency between the first satellite and the second satellite according to the Doppler shift compensation method; An optical communication system comprising: (Appendix 14) The optical communication system described in Supplementary Note 13, characterized in that the Doppler shift compensation method is a method in which, if the Doppler shift frequency can be compensated for by the second satellite, the second satellite is responsible for the Doppler shift compensation, and, if the Doppler shift frequency cannot be compensated for by the second satellite, the first satellite is responsible for the Doppler shift compensation within the first frequency range. (Appendix 15) The optical communication system described in Appendix 14, characterized in that the Doppler shift compensation method is a method of determining the share of Doppler shift compensation between the first satellite and the second satellite depending on the magnitude of the Doppler shift frequency. (Appendix 16) When the first satellite notifies the second satellite of the Doppler shift frequency and receives from the second satellite a sharing possibility including the second frequency range, a first compensation sharing value of the first satellite and a second compensation sharing value of the second satellite are calculated based on the first frequency range and the second frequency range; transmitting the second compensation contribution to the second satellite; the first satellite performs Doppler shift compensation according to the first compensation contribution value; the second satellite performs Doppler shift compensation according to the second compensation contribution value; 15. The optical communication system according to claim 14, (Appendix 17) The first satellite providing a first threshold value representing a frequency range equal to or lower than the second frequency range and a second threshold value representing the first frequency range; If the Doppler shift frequency is smaller than the first threshold, the Doppler shift compensation is not performed and the Doppler shift compensation of the second satellite is left to be performed; If the Doppler shift frequency is equal to or greater than the first threshold and equal to or less than the second threshold, transmitting the second compensation share to the second satellite; performing the Doppler shift compensation contribution according to the first compensation contribution value; the second satellite performs the Doppler shift compensation share according to the second compensation share value; 17. The optical communication system according to claim 16, (Appendix 18) The optical communication system described in any one of appendices 13-17, characterized in that after the first satellite and the second satellite have established optical acquisition and tracking of each other but before the Doppler shift compensation is completed, optical communication between the first satellite and the second satellite is performed by intensity modulation of signal light. (Appendix 19) A program that causes a computer to function as an optical communication device that is mounted on a first satellite and performs optical communication with a second satellite, the optical communication device comprising an optical transceiver that transmits and receives signal light to and from the second satellite, a function of determining a Doppler shift compensation method between the second satellite and the second satellite after establishing optical acquisition and tracking of the second satellite; a function of sharing compensation for Doppler shift frequency between the first satellite and the second satellite in accordance with the Doppler shift compensation method; A program for realizing the above on the computer. (Appendix 20) The program described in Appendix 19, characterized in that the Doppler shift compensation method is a method in which if the Doppler shift frequency can be compensated for by the second satellite, the second satellite is responsible for the Doppler shift compensation, and if the second satellite cannot compensate, the optical transceiver is responsible for the Doppler shift compensation within a first frequency range in which the frequency of the transmitted light can be changed. (Appendix 21) The program described in Appendix 19, characterized in that the Doppler shift compensation method is a method of determining the share of Doppler shift compensation between the first satellite and the second satellite depending on the magnitude of the Doppler shift frequency. (Appendix 22) the optical transceiver is capable of changing the frequency of the transmitted light within a first frequency range, and the second satellite is capable of receiving the received light within a second frequency range; notifying the second satellite of the Doppler shift frequency; When receiving the allocation information including the second frequency range from the second satellite, calculating a first compensation allocation value of the first satellite and a second compensation allocation value of the second satellite based on the first frequency range and the second frequency range; transmitting the second compensation contribution to the second satellite; performing Doppler shift compensation according to the first compensation contribution value; 22. The program according to claim 21, wherein the program is implemented in the computer. (Appendix 23) providing a first threshold value representing a frequency range equal to or lower than the second frequency range and a second threshold value representing the first frequency range; If the Doppler shift frequency is smaller than the first threshold, the Doppler shift compensation is not performed and the Doppler shift compensation of the second satellite is left to be performed; If the Doppler shift frequency is equal to or greater than the first threshold and equal to or less than the second threshold, transmitting the second compensation share value to the second satellite and performing the Doppler shift compensation share according to the first compensation share value. 23. The program according to claim 22, wherein the program is configured to cause the computer to implement the functions. (Appendix 24) A program described in any one of Appendices 19-23, wherein after optical capture and tracking of the second satellite is established but before the Doppler shift compensation is completed, communication by the optical transceiver is performed by intensity modulation of the signal light. [Industrial Applicability]

[0042] The present invention is applicable to optical communication devices and optical communication systems mounted on satellites. [Explanation of symbols]

[0043] 10A Optical communication equipment 101A Processing section 102A program memory 103A Transmitter 104A Transmitting Light Source 105A High Power Amplifier (HPA) 106A Optics Department 107A Low Noise Amplifier (LNA) 108A light receiving section 109A Receiver

Claims

1. An optical communication device mounted on a first satellite and performing optical communication with a second satellite, an optical transceiver for transmitting and receiving signal light to and from the second satellite; a processing unit that performs Doppler shift compensation between the optical transmitter and receiver and the second satellite by transmitting and receiving signal light by the optical transmitter and receiver; Equipped with The processing unit After establishing optical acquisition and tracking of the second satellite, determining a Doppler shift compensation method between the second satellite and the second satellite; sharing compensation for the Doppler shift frequency with the second satellite according to the Doppler shift compensation method; An optical communication device characterized by:

2. 2. The optical communication device according to claim 1, wherein the Doppler shift compensation method is such that if the Doppler shift frequency can be compensated for by the second satellite, the second satellite is responsible for the Doppler shift compensation, and if the second satellite cannot compensate for the Doppler shift, the optical transceiver is responsible for the Doppler shift compensation within a first frequency range in which the frequency of the transmitted light can be changed.

3. 2. The optical communication device according to claim 1, wherein the Doppler shift compensation method determines a share of Doppler shift compensation between the first satellite and the second satellite depending on the magnitude of the Doppler shift frequency.

4. the optical transceiver is capable of changing the frequency of the transmitted light within a first frequency range; the second satellite is capable of receiving received light within a second frequency range; The processing unit notifying the second satellite of the Doppler shift frequency; When receiving the allocation information including the second frequency range from the second satellite, calculating a first compensation allocation value of the first satellite and a second compensation allocation value of the second satellite based on the first frequency range and the second frequency range; transmitting the second compensation contribution to the second satellite; performing Doppler shift compensation according to the first compensation contribution value; 4. The optical communication device according to claim 3.

5. the processing unit prepares a first threshold value indicating a frequency range equal to or lower than the second frequency range and a second threshold value indicating the first frequency range; If the Doppler shift frequency is smaller than the first threshold, the Doppler shift compensation is not performed and the Doppler shift compensation of the second satellite is left to the second satellite; If the Doppler shift frequency is equal to or greater than the first threshold and equal to or less than the second threshold, transmitting the second compensation share value to the second satellite and performing the Doppler shift compensation share according to the first compensation share value.

5. The optical communication device according to claim 4.

6. The optical communication device according to any one of claims 1 to 5, characterized in that after optical acquisition and tracking of the second satellite is established and before the Doppler shift compensation is completed, communication by the optical transceiver unit is performed by intensity modulation of the signal light.

7. A Doppler shift compensation method for an optical communication device mounted on a first satellite and performing optical communication with a second satellite, the optical communication device comprising: an optical transceiver unit that transmits and receives signal light to and from the second satellite; and a processing unit that performs Doppler shift compensation with the second satellite by transmitting and receiving the signal light by the optical transceiver unit; The processing unit After establishing optical acquisition and tracking of the second satellite, determining a Doppler shift compensation method between the second satellite and the second satellite; sharing compensation for the Doppler shift frequency with the second satellite according to the Doppler shift compensation method; A Doppler shift compensation method comprising:

8. 8. The Doppler shift compensation method according to claim 7, wherein the Doppler shift compensation method is a method in which, if the Doppler shift frequency can be compensated for by the second satellite, the second satellite is responsible for the Doppler shift compensation, and, if the Doppler shift frequency cannot be compensated for by the second satellite, the optical transceiver is responsible for the Doppler shift compensation within a first frequency range in which the frequency of the transmitted light can be changed.

9. An optical communication system for performing optical communication between a first satellite and a second satellite traveling at a relative speed, the first satellite is capable of varying the frequency of the transmitted light within a first frequency range, and the second satellite is capable of varying the frequency of the received light within a second frequency range; After optical acquisition and tracking is established between the first satellite and the second satellite, a Doppler shift compensation method is determined between the first satellite and the second satellite; sharing compensation for Doppler shift frequency between the first satellite and the second satellite according to the Doppler shift compensation method; An optical communication system comprising:

10. A program that causes a computer to function as an optical communication device that is mounted on a first satellite and performs optical communication with a second satellite, the optical communication device comprising an optical transceiver that transmits and receives signal light to and from the second satellite, a function of determining a Doppler shift compensation method between the second satellite and the second satellite after establishing optical acquisition and tracking of the second satellite; a function of sharing compensation for Doppler shift frequency between the first satellite and the second satellite in accordance with the Doppler shift compensation method; A program for realizing the above on the computer.

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