Inter-satellite high-precision distance measurement method and system based on optical frequency comb

Abstract

The invention provides an inter-satellite high-precision distance measurement method based on an optical frequency comb, which is applied to distance measurement between a first satellite and a second satellite, and modulates emission time information by controlling the generation time and the initial phase of an optical frequency comb pulse signal on the first satellite and the second satellite respectively. And furthermore, on the basis of time delay information analyzed and processed by the optical frequency comb signals received by the first satellite and the second satellite, noise of a transmission channel is suppressed in a bidirectional comparison mode, and finally, an accurate inter-satellite distance is calculated. The invention also provides an inter-satellite high-precision distance measurement system based on the optical frequency comb. Therefore, the problem that the space application scene is limited is solved, the problem of distance ambiguity caused by the pulse repetition period of the optical frequency comb is eliminated, and meanwhile, the problem of high transmitting power of the required optical frequency comb caused by the long distance between satellites is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of inter-satellite distance measurement, and in particular to an inter-satellite high-precision distance measurement method and system based on an optical frequency comb. Background Art

[0002] Realizing high-precision absolute distance measurement between satellites is of great significance to improving the efficiency of space applications such as satellite navigation, electronic reconnaissance, remote sensing imaging, satellite formation flying, and scientific exploration.

[0003] At present, the more mature intersatellite distance measurement technologies are mainly divided into two major technical routes: microwave-based and laser-based. Microwave distance measurement technology was developed the earliest and is the most mature, but the ranging accuracy is limited by the microwave wavelength. With the development and improvement of laser technology, laser-based intersatellite distance measurement technology has gradually become a research hotspot. It has high accuracy but there is a distance ambiguity problem, and is mainly suitable for relative distance measurement.

[0004] The optical frequency comb is an important invention of the 21st century. The optical frequency comb signal has excellent time-frequency domain characteristics such as narrow pulse width, wide spectral range, resolvable longitudinal mode, and high repetition frequency stability, which has greatly promoted the development of precision measurement. There are many existing optical frequency comb ranging methods, but there are four basic ranging methods, including time-of-flight method, multi-wavelength interferometry, dual-comb interferometry, and dispersion interferometry.

[0005] However, in actual distance measurement applications, especially large-scale long-distance measurements between satellites, traditional optical frequency comb measurement technology has problems such as limited effective range and distance ambiguity, which greatly restricts its application prospects in absolute distance measurement between satellites.

[0006] Therefore, in order to meet the actual needs of the development of future space engineering applications for high-precision ranging technology, there is an urgent need to explore an optical frequency comb intersatellite high-precision absolute distance measurement method and system with a longer range and no distance ambiguity. Summary of the invention

[0007] The purpose of the present invention is to provide a high-precision inter-satellite distance measurement method based on an optical frequency comb, which is used to solve the problem of limited space application scenarios, eliminate the distance ambiguity problem caused by the repetition period of the optical frequency comb pulse, and avoid the problem of high optical frequency comb transmission power required due to the long inter-satellite distance.

[0008] In order to achieve the above object, on the one hand, the present invention provides a high-precision inter-satellite distance measurement method based on an optical frequency comb, the method being applied to the distance measurement between a first satellite and a second satellite, comprising the steps of:

[0009] The first satellite receives the first optical frequency comb signal transmitted by the second satellite at its first receiving clock time, obtains the first transmitting clock time of the second satellite by tracking the phase of the received first optical frequency comb signal, and calculates the first time delay of the first satellite based on the first receiving clock time and the first transmitting clock time;

[0010] The second satellite receives the second optical frequency comb signal transmitted by the first satellite at its second receiving clock time, obtains the second transmitting clock time of the first satellite by tracking the phase of the received second optical frequency comb signal, and calculates the second time delay of the second satellite based on the second receiving clock time and the second transmitting clock time;

[0011] Returning the first time delay and the second time delay to an intermediate epoch to obtain a first target time delay and a second target time delay at the same time;

[0012] A path propagation delay between the first satellite and the second satellite is calculated according to the first target delay and the second target delay, and an inter-satellite distance between the first satellite and the second satellite is calculated based on the path propagation delay.

[0013] Furthermore, the path propagation delay is calculated based on the following formula:

[0014] ΔT AB =(ΔT A +ΔT B ) / 2;

[0015] Where, ΔT AB is the propagation delay of the path, ΔT A is the first target delay, ΔT B is the second target delay.

[0016] Furthermore, the inter-satellite distance between the first satellite and the second satellite is calculated based on the following formula:

[0017] L AB =(ΔT A +ΔT B ) / 2*c;

[0018] Among them, L AB is the inter-star distance, and c is the speed of light.

[0019] Furthermore, the first time delay is the difference between the first receiving clock time and the first transmitting clock time, and the second time delay is the difference between the second receiving clock time and the second transmitting clock time.

[0020] The optical frequency comb-based intersatellite high-precision distance measurement method provided by the present invention can solve the problem of limited space application scenarios and is compatible with existing microwave systems; it eliminates the distance ambiguity problem caused by the optical frequency comb pulse repetition period and avoids the problem of high optical frequency comb transmission power required due to the long intersatellite distance.

[0021] On the other hand, based on the same inventive structure, the present invention also provides a high-precision inter-satellite distance measurement system based on an optical frequency comb, wherein the system is configured in a first satellite and a second satellite for relative inter-satellite distance measurement, and comprises:

[0022] The onboard atomic clock module is used to generate a stable frequency source to provide a frequency reference for optical frequency comb locking;

[0023] An optical frequency comb module, used to generate an optical frequency comb signal with a specified initial phase at a specified time according to a control instruction, wherein the optical frequency comb signal includes a propagation optical frequency comb used as a measurement signal and a reference optical frequency comb used as a tracking signal;

[0024] An optical transmission system module is used to transmit the signal of the propagation optical frequency comb to a relative other satellite, receive the relative propagation optical frequency comb from the relative other satellite, and transmit the signals of the relative propagation optical frequency comb and the reference optical frequency comb to a linear optical sampling system module; wherein the relative other satellite is a satellite that performs intersatellite distance measurement with the current satellite;

[0025] The linear optical sampling system module is used to calculate the time delay information between the relatively propagating optical frequency comb and the reference optical frequency comb;

[0026] A microwave terminal module, used for exchanging the time delay information respectively measured between the current satellite and the relative other satellite;

[0027] An information processing module is used to convert the first time delay information of the current satellite and the second time delay information relative to the other satellite into an intermediate epoch to obtain a first target time delay and a second target time delay at the same time, and calculate the path propagation delay between the current satellite and the relative other satellite according to the first target time delay and the second target time delay, and calculate the inter-satellite distance between the current satellite and the relative other satellite based on the path propagation delay.

[0028] Furthermore, the optical transmission system module is specifically used for:

[0029] The signal generated by the propagating optical frequency comb is sent to the relative other star through a laser transceiver channel, and the relative propagating optical frequency comb sent from the relative other star is received through the laser transceiver channel, and the signals of the relative propagating optical frequency comb and the reference optical frequency comb are transmitted to the linear optical sampling system module.

[0030] Furthermore, the linear optical sampling system module is specifically used for:

[0031] interfering the relatively propagating optical frequency comb and the reference optical frequency comb in a 50% splitting ratio optical fiber splitter;

[0032] The interfered signal is input into a balanced detector to filter out the DC component in the signal and obtain an AC signal;

[0033] The AC signal is converted into a voltage signal and amplified before being input into a low-pass filter, and then quantized and collected by an analog-to-digital converter to obtain the time delay information between the relative propagation optical frequency comb and the reference optical frequency comb.

[0034] Furthermore, the information processing module is also used to estimate the first time delay information of the current satellite using a Kalman filter based on the time delay information received from the linear optical sampling system module.

[0035] Furthermore, the microwave terminal module is specifically used to send the first time delay information to the relative other satellite, and receive the second time delay information sent by the relative other satellite.

[0036] Furthermore, the path propagation delay is calculated based on the following formula:

[0037] ΔT AB =(ΔT A +ΔT B ) / 2;

[0038] Where, ΔT AB is the propagation delay of the path, ΔT A is the first target delay, ΔT B is the second target delay;

[0039] The inter-satellite distance between the current satellite and the relative other satellite is calculated based on the following formula:

[0040] L AB =(ΔT A +ΔT B ) / 2*c;

[0041] Among them, L AB is the inter-star distance, and c is the speed of light.

[0042] Thus, the optical frequency comb-based high-precision intersatellite distance measurement method and system described in the present invention adopts an optical frequency comb signal with controllable time and initial phase as a measurement signal, thereby avoiding the distance ambiguity problem of traditional optical frequency comb signal measurement technology, and enabling it to realize long-distance distance measurement between satellites; at the same time, by controlling the time and phase of the reference optical frequency comb signal, the linear optical sampling technology is used to obtain the time delay between the optical frequency comb signal transmitted from another satellite and the reference optical frequency comb signal, and the transmission power requirement of the optical frequency comb signal transmitted from another satellite is lowered, thereby improving the sensitivity of the local satellite to the optical frequency comb signal processing and extending the effective range of the optical frequency comb ranging. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A flowchart of the steps of the high-precision inter-satellite distance measurement method based on optical frequency comb provided in one embodiment of the present invention;

[0044] Figure 2 A system block diagram of the inter-satellite high-precision distance measurement system based on optical frequency comb provided by an embodiment of the present invention;

[0045] Figure 3 A schematic diagram of the principle of the high-precision inter-satellite distance measurement method based on an optical frequency comb provided by an embodiment of the present invention;

[0046] Figure 4 A schematic diagram of the specific structure of the high-precision inter-satellite distance measurement system based on optical frequency comb provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0048] It should be noted that references to "one embodiment", "embodiment", "example embodiment", etc. in this specification refer to the embodiment described, which may include specific features, structures or characteristics, but not every embodiment must include these specific features, structures or characteristics. In addition, such expressions do not refer to the same embodiment. Furthermore, when describing specific features, structures or characteristics in conjunction with an embodiment, whether or not there is an explicit description, it has been shown that it is within the knowledge of those skilled in the art to combine such features, structures or characteristics into other embodiments.

[0049] In addition, certain words are used in the specification and subsequent claims to refer to specific components or parts. Those with ordinary knowledge in the relevant field should understand that manufacturers can use different nouns or terms to refer to the same component or part. This specification and subsequent claims do not use differences in names as a way to distinguish components or parts, but use differences in the functions of components or parts as the criteria for distinction. "Including" and "including" mentioned throughout the specification and subsequent claims are open-ended terms and should be interpreted as "including but not limited to". In addition, the word "connected" here includes any direct and indirect electrical connection means. Indirect electrical connection means include connection through other devices.

[0050] Embodiment 1

[0051] Figure 1 A high-precision inter-satellite distance measurement method based on an optical frequency comb provided by an embodiment of the present invention is shown. The method is applied to the distance measurement between a first satellite and a second satellite. Any two satellites whose inter-satellite distance is to be measured can be used as the first satellite and the second satellite, and there is no distinction between the first satellite and the second satellite. The method of this embodiment includes the following steps:

[0052] S101: A first satellite receives a first optical frequency comb signal transmitted by a second satellite at its first receiving clock time, obtains a first transmitting clock time of the second satellite by tracking the phase of the received first optical frequency comb signal, and calculates a first time delay of the first satellite based on the first receiving clock time and the first transmitting clock time.

[0053] This embodiment will be described by taking the first satellite as satellite A and the second satellite as satellite B as an example. In step S101, satellite A receives the clock face time t 2 The first optical frequency comb signal transmitted by satellite B is received, and then the transmitting clock time of satellite B is obtained by tracking the phase of the received optical frequency comb signal. 1 , that is, the first emission clock time is t 1 , the first receiving clock time is t 2 , t 2 Lag behind t 1 ; Then according to t 1 and t 2 A first time delay of the first satellite is calculated and obtained, where the first time delay includes a change in a path propagation delay of satellite B in the link system and a change in a clock difference between satellite A and satellite B itself.

[0054] The first time delay is the difference between the first receiving clock time and the first transmitting clock time. In combination with the above example, the first time delay ΔT A '=t 2 -t 1 .

[0055] In a specific implementation, the first satellite and the second satellite are both equipped with an intersatellite high-precision distance measurement system based on an optical frequency comb. The second satellite generates a first optical frequency comb signal with a specified initial phase at a specified time by its system according to a control instruction. The first optical frequency comb signal includes a propagation optical frequency comb used as a measurement signal and a reference optical frequency comb used as a tracking signal. After receiving the optical frequency comb signal transmitted from the second satellite to the propagation optical frequency comb, the system on the first satellite calculates the first delay of the first satellite based on the phase of the optical frequency comb signal of the transmission optical frequency comb to the second satellite combined with the reference optical frequency comb generated by itself.

[0056] Furthermore, the propagation optical frequency comb from the second satellite side and the reference optical frequency comb of the first satellite can be interfered in a 50% splitting ratio optical fiber splitter, and the interfered signal is input into a balanced detector to filter out the DC component in the signal to obtain an AC signal; the AC signal is then converted into a voltage signal and amplified and input into a low-pass filter, and finally quantized and collected through an analog-to-digital converter to obtain the first time delay.

[0057] S102: The second satellite receives the second optical frequency comb signal transmitted by the first satellite at its second receiving clock time, obtains the second transmitting clock time of the first satellite by tracking the phase of the received second optical frequency comb signal, and calculates the second delay of the second satellite based on the second receiving clock time and the second transmitting clock time. There is no logical order between step S101 and step S102 of this embodiment, and step S101 can be executed first, or step S102 can be executed first, or even step S101 and step S102 can be executed synchronously.

[0058] In combination with the above example, in this embodiment, satellite B receives the clock face time t 4 The second optical frequency comb signal transmitted by satellite A is received, and the transmitting clock time of satellite A is obtained by tracking the phase of the received second optical frequency comb signal. 3 , that is, the second transmitting clock time is t 3 , the second receiving clock time is t 4 , t 4 Lag behind t 3 ; Then according to t 3 and t 4 A second delay of the second satellite is calculated and obtained, where the second delay includes a change in the path propagation delay of satellite A in the link system and a change in the clock difference between satellite A and satellite B itself.

[0059] The second time delay is the difference between the second receiving clock time and the second transmitting clock time. In combination with the above example, the second time delay ΔT B 'B=t 4 -t 3 .

[0060] In a specific implementation, the first satellite generates a second optical frequency comb signal with a specified initial phase at a specified time by its system according to a control instruction, and the second optical frequency comb signal includes a propagation optical frequency comb used as a measurement signal and a reference optical frequency comb used as a tracking signal. After receiving the optical frequency comb signal transmitted from the first satellite to the propagation optical frequency comb, the system on the second satellite calculates the second delay of the second satellite based on the phase of the optical frequency comb signal of the transmission optical frequency comb to the first satellite combined with the reference optical frequency comb generated by itself.

[0061] Furthermore, the propagation optical frequency comb from the first satellite side and the reference optical frequency comb of the second satellite can be interfered in a 50% splitting ratio optical fiber splitter, and the interfered signal is input into a balanced detector to filter out the DC component in the signal to obtain an AC signal; the AC signal is then converted into a voltage signal and amplified and input into a low-pass filter, and finally quantized and collected through an analog-to-digital converter to obtain a second time delay.

[0062] S103: The first time delay and the second time delay are converted to the intermediate epoch to obtain the first target time delay and the second target time delay at the same time. Step S103 may be performed in the first satellite or the second satellite, and the first satellite or the second satellite may receive the time delay information calculated by the other satellite end through a microwave communication link, such as the first satellite receiving the second time delay calculated by the second satellite through a microwave communication link, or the second satellite receiving the first time delay calculated by the first satellite through a microwave communication link.

[0063] Since the first receiving clock time t 2 and the second receiving clock time t 4 are different times, so this embodiment uses the reference satellite orbit and clock error to directly convert the first time delay ΔT' of the dual one-way observation value A and the second delay ΔT' B Calculate back to the middle epoch and get the first target delay ΔT at the same time A and the second target delay ΔT B In the specific implementation, after the satellite on either side (the first satellite or the second satellite) obtains the delay information calculated by the other satellite end, it then calculates the first delay ΔT' A and the second delay ΔT' B Calculate to the intermediate epoch to obtain the time delay ΔT from the same time to the first target A and the second target delay ΔT B , where the first target delay ΔT A It means that the first time delay ΔT A 'The delay information obtained by returning to the intermediate epoch, the second target delay ΔT B It means that the second delay ΔT B 'The delay information obtained by returning to the intermediate epoch, the first target delay ΔTA and the second target delay ΔT B It is the time delay information calculated on the first satellite and the second satellite at the same time.

[0064] S104: Calculate the path propagation delay between the first satellite and the second satellite according to the first target delay and the second target delay, and calculate the inter-satellite distance between the first satellite and the second satellite based on the path propagation delay. Step S104 of this embodiment can be performed on the first satellite side or on the second satellite side.

[0065] Assume that there is a clock error between the satellite A clock and the satellite B clock, and the local oscillator optical frequency combs at both ends are locked to their respective clocks, which results in a time difference in the generation of the optical frequency combs at both ends, denoted as T AB In combination with the above example, the time difference can be calculated in the processing system of satellite A according to the time and phase of the received optical frequency comb signal, and the time difference is the first target delay ΔT A , ΔT A Including the change of satellite B's path transmission delay in the link system ΔT path and the change in the two clock differences themselves, ΔT AB , then ΔT A =ΔT path +ΔT AB .

[0066] Since the link is bidirectional, the propagation delay of the signal from satellite A to satellite B is basically the same as the propagation delay from satellite A to satellite B and the propagation delay from satellite B to satellite A. Therefore, the time difference ΔT calculated by satellite B is similar. B =ΔT B =ΔT path -ΔT AB .

[0067] Based on this, the path propagation delay between satellite A and satellite B can be obtained: ΔT AB =(ΔT A +ΔT B ) / 2; where ΔT AB is the propagation delay of the path, ΔT A is the first target delay, ΔT B is the second target delay.

[0068] Furthermore, combined with the speed of light c, we can get the absolute distance between satellite A and satellite B: L AB =ΔT AB *c; that is, the inter-satellite distance between the first satellite and the second satellite is calculated based on the following formula:

[0069] L AB =(ΔT A+ΔT B ) / 2*c;

[0070] Among them, L AB is the inter-star distance, and c is the speed of light.

[0071] Since the fight can be carried out almost at the same time, the error caused by link jitter can be basically offset.

[0072] The method of this embodiment modulates the transmission time information by controlling the generation time and initial phase of the optical frequency comb pulse signal, suppresses the transmission channel noise by bidirectional comparison, and finally realizes accurate inter-satellite distance measurement.

[0073] Embodiment 2

[0074] See also Figure 2 Based on the same inventive structure, the present invention provides a high-precision intersatellite distance measurement system 100 based on an optical frequency comb in a second embodiment. The system 100 is configured in a first satellite and a second satellite that perform intersatellite distance measurement relatively. Specifically, the system 100 is configured in both the first satellite and the second satellite. The system 100 includes a satellite-borne atomic clock module 10, an optical frequency comb module 20, an optical transmission system module 30, a linear optical sampling system module 40, a microwave terminal module 50, and an information processing module 60, wherein:

[0075] The onboard atomic clock module 10 is used to generate a stable frequency source to provide a frequency reference for optical frequency comb locking; the optical frequency comb module 20 is used to generate an optical frequency comb signal with a specified initial phase at a specified time according to a control instruction, and the optical frequency comb signal includes a propagation optical frequency comb used as a measurement signal and a reference optical frequency comb used as a tracking signal; the optical transmission system module 30 is used to transmit the signal of the propagation optical frequency comb to a relative other satellite, and receive the relative propagation optical frequency comb from the relative other satellite, and transmit the signals of the relative propagation optical frequency comb and the reference optical frequency comb to the linear optical sampling system module; wherein, the relative other satellite is the intersatellite distance with the current satellite. The measured satellite; the linear optical sampling system module 40 is used to calculate the time delay information between the relative propagation optical frequency comb and the reference optical frequency comb; the microwave terminal module 50 is used to exchange the time delay information measured by the current satellite and the relative other satellite; the information processing module 60 is used to convert the first time delay information of the current satellite and the second time delay information relative to the other satellite into the intermediate epoch, obtain the first target delay and the second target delay at the same time, and calculate the path propagation delay between the current satellite and the relative other satellite according to the first target delay and the second target delay, and calculate the inter-satellite distance between the current satellite and the relative other satellite based on the path propagation delay.

[0076] This embodiment only takes the system 100 configured on the first satellite as an example for explanation, wherein the current satellite is the first satellite, and the relative other satellite is the second satellite opposite thereto; the system 100 configured on the second satellite can be specifically referred to the relevant description on the first satellite, and this embodiment will not go into details therein.

[0077] The satellite-borne atomic clock module 10 of this embodiment may be an optical clock or an ultra-stable laser.

[0078] The optical frequency comb signal generated by the propagating optical frequency comb is used to transmit to the other end as a measurement signal, and the reference optical frequency comb is used as a tracking signal to assist in processing the received relative propagation optical frequency comb.

[0079] Furthermore, the optical transmission system module 30 of the present embodiment is specifically used to: send the signal generated by the propagation optical frequency comb to a relative other satellite (i.e., the second satellite) via a laser transceiver channel, and receive the relative propagation optical frequency comb sent from the relative other satellite via the laser transceiver channel, and transmit the signals of the relative propagation optical frequency comb and the reference optical frequency comb to the linear optical sampling system module 40.

[0080] The linear optical sampling system module 40 is used to process the relative propagation optical frequency comb signal of the other star and the reference optical frequency comb signal of the local star and obtain the time delay between the two. In this module, there is a small difference in the repetition frequency of the two optical frequency comb signals. Assume that the repetition frequency of the local reference optical comb is f r , the repetition frequency of the other star transmission light comb is f r +Δf r , with a small repetition frequency difference Δf r It is the key to realize the linear optical sampling technology. In this regard, the linear optical sampling system module 40 of this embodiment is specifically used to: interfere the relative propagation optical frequency comb and the reference optical frequency comb in a 50% splitting ratio optical fiber splitter; input the interfered signal into a balanced detector to filter out the DC component in the signal to obtain an AC signal; convert the AC signal into a voltage signal and amplify it before inputting it into a low-pass filter, and then quantize and collect it through an analog-to-digital converter to obtain the time delay information between the relative propagation optical frequency comb and the reference optical frequency comb.

[0081] The microwave terminal module 50 of this embodiment is used to exchange information with the microwave terminal module of the relative other satellite. Taking the first satellite as an example, the optical frequency comb module 20 of the first satellite obtains the delay information calculated by the satellite from the linear optical sampling system 40, and then sends it to the relative other satellite (i.e., the second satellite); and the microwave terminal module 50 is also used to receive the delay information calculated by it from the second satellite; in this embodiment, the delay information calculated by the first satellite is recorded as the first delay information, and the delay information calculated by the second satellite is recorded as the second delay information. The first delay information of this embodiment specifically corresponds to the first delay ΔT in the aforementioned embodiment 1. A', the second delay information specifically corresponds to the second delay ΔT in the aforementioned embodiment 1 B ' B .

[0082] Furthermore, the information processing module 60 is also used to estimate the first time delay information of the current satellite using a Kalman filter based on the time delay information received from the linear optical sampling system module 40. Specifically, the information processing module 60 uses a Kalman filter to further estimate the time deviation of the optical frequency comb light pulse propagating relative to the other satellite relative to the reference optical frequency comb light pulse of the local satellite based on the optical pulse delay obtained by the linear optical sampling system module 40, and returns the time delay information of the first satellite and the second satellite to the same time, and then calculates the distance between the two satellites. The microwave terminal module 50 is specifically used to send the first time delay information to the relative other satellite, and receive the second time delay information sent relative to the other satellite.

[0083] Furthermore, the path propagation delay is calculated based on the following formula:

[0084] ΔT AB =(ΔT A +ΔT B ) / 2;

[0085] Where, ΔT AB is the path propagation delay, ΔT A is the first target delay, ΔT B is the second target delay;

[0086] The intersatellite distance between the current satellite and the relative satellite is calculated based on the following formula:

[0087] L AB =(ΔT A +ΔT B ) / 2*c;

[0088] Among them, L AB is the inter-star distance, and c is the speed of light.

[0089] A specific application example of the inter-satellite high-precision distance measurement system 100 based on an optical frequency comb is described below.

[0090] See also Figures 3-4 In an application example, the first satellite is satellite A, the second satellite is satellite B, and both satellite A and satellite B are equipped with the inter-satellite high-precision distance measurement system 100 based on optical frequency comb of the above embodiment, then the distance measurement method between satellite A and satellite B is as follows:

[0091] 1. The onboard atomic clock modules of Satellite A and Satellite B generate a stable frequency source, providing an accurate frequency reference for optical frequency comb locking.

[0092] 2. Satellite B’s optical frequency comb module is locked to its onboard atomic clock module and is activated at t according to control commands. 1 The propagation optical frequency comb signal X with a phase of π / 6 is generated at all times B .

[0093] 3. The optical transmission system module of satellite B transmits the propagated optical frequency comb signal X B Launch out.

[0094] 4. Satellite A's optical frequency comb module is locked to its onboard atomic clock module and generates a reference optical frequency comb signal X according to the control command. AL .

[0095] 5. The linear optical sampling system module of satellite A is at its clock face time t 2 Receive the optical frequency comb signal X transmitted by satellite B B After that, the propagation optical frequency comb signal X of satellite B B The reference optical frequency comb signal X from satellite A AL Interference is performed in a 50:50 optical fiber splitter, and the interfered signal enters a balanced detector. The DC component of the signal is filtered out by the balanced detector, and the obtained AC signal is converted into a voltage and amplified before entering a low-pass filter. Finally, it is quantized and collected by an ADC (analog-to-digital converter) to calculate the broadcast frequency comb signal X of satellite B. B The reference optical frequency comb signal X from satellite A AL The delay between

[0096] 6. The delay of the optical pulse received by the information processing module of satellite A and its linear optical sampling system module The Kalman filter is used to further estimate the precise time deviation ΔT' A .

[0097] 7. The microwave terminal module of satellite A will 2 And the corresponding time deviation ΔT' A Transmitted to satellite B.

[0098] 8. Satellite A's optical frequency comb module is locked to its onboard atomic clock module and is activated at t according to control commands. 3 The propagation optical frequency comb signal X with a phase of π / 3 is generated at all times A .

[0099] 9. Satellite A's optical transmission system module will transmit the optical frequency comb signal X A Transmitted to satellite B.

[0100] 10. Satellite B's optical frequency comb module is locked to its onboard atomic clock module and generates a reference optical frequency comb signal X according to the control command.BL .

[0101] 11. The linear optical sampling system module of satellite B is at t on its clock face. 4 Receive the optical frequency comb signal X transmitted by satellite A A Then, satellite A transmits the optical frequency comb signal X A The reference optical frequency comb signal X from satellite B BL The interference is carried out in the 50:50 optical fiber splitter. The interfered signal enters the balanced detector. The DC component of the signal is filtered out by the balanced detector. The obtained AC signal is converted into voltage and amplified before entering the low-pass filter. Finally, it is quantized and collected by the ADC to calculate the optical frequency comb signal X from satellite A to the transmission. A The reference optical frequency comb signal X from satellite B BL The delay between

[0102] 12. The information processing module of satellite B receives the optical pulse delay obtained by the linear optical sampling system module The Kalman filter is used to further estimate the precise time deviation ΔT' B .

[0103] 13. The microwave terminal module of satellite B will 4 And the corresponding time deviation ΔT' B The time t at which the microwave terminal module of satellite A is transmitted and received 2 And the corresponding time deviation ΔT' A .

[0104] 14. The information processing module of satellite B converts the clock time of satellite B to 4 ΔT' B and the time on the satellite A clock 2 ΔT' A Calculate to the same time and get ΔT at the same time A and ΔT B ; Then according to the formula L AB =(ΔT A +ΔT B ) / 2*c to calculate the absolute distance between satellite A and satellite B.

[0105] 15. The time t when the microwave terminal module of satellite A receives the microwave terminal module of satellite B 4 And the corresponding time deviation ΔT' B .

[0106] 16. Satellite A’s information processing module converts the clock time of satellite A to t 2 With ΔT' A and satellite B clock time4 ΔT' B Calculate to the same time and get ΔT at the same time A and ΔT B ; Then according to the formula L AB =(ΔT A +ΔT B ) / 2*c to calculate the absolute distance between satellite A and satellite B.

[0107] In summary, the optical frequency comb-based high-precision intersatellite distance measurement method and system described in the present invention adopts an optical frequency comb signal with controllable time and initial phase as a measurement signal, avoiding the distance ambiguity problem of traditional optical frequency comb signal measurement technology, so that it can realize absolute distance measurement at long distances between satellites; at the same time, by controlling the time and phase of the reference optical frequency comb signal, the linear optical sampling technology is used to obtain the time delay between the optical frequency comb signal transmitted from another satellite and the reference optical frequency comb signal, and the transmission power requirement of the optical frequency comb signal transmitted from another satellite is lower, which improves the sensitivity of the local satellite to the optical frequency comb signal processing and expands the effective range of the optical frequency comb ranging.

[0108] It should be noted that the present application can be implemented in software and / or a combination of software and hardware, for example, can be implemented using an application specific integrated circuit (ASIC), a general purpose computer or any other similar hardware device. In one embodiment, the software program of the present application can be executed by a processor to implement the above steps or functions. Similarly, the software program of the present application (including relevant data structures) can be stored in a computer-readable recording medium, for example, a RAM memory, a magnetic or optical drive or a floppy disk and similar devices. In addition, some steps or functions of the present application can be implemented using hardware, for example, as a circuit that cooperates with a processor to perform each step or function.

[0109] The method according to the present invention can be implemented on a computer as a computer-implemented method, or implemented in dedicated hardware, or implemented in a combination of the two. The executable code or part thereof for the method according to the present invention can be stored on a computer program product. The example of a computer program product includes a memory device, an optical storage device, an integrated circuit, a server, online software, etc. Preferably, the computer program product includes a non-temporary program code component stored on a computer-readable medium so as to perform the method according to the present invention when the program product is executed on a computer.

[0110] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A high-precision intersatellite distance measurement method based on optical frequency comb, characterized in that: The method is applied to the distance measurement between a first satellite and a second satellite, comprising the steps of: The first satellite receives the first optical frequency comb signal transmitted by the second satellite at its first receiving clock time, obtains the first transmitting clock time of the second satellite by tracking the phase of the received first optical frequency comb signal, and calculates the first time delay of the first satellite based on the first receiving clock time and the first transmitting clock time; The second satellite receives the second optical frequency comb signal transmitted by the first satellite at its second receiving clock time, obtains the second transmitting clock time of the first satellite by tracking the phase of the received second optical frequency comb signal, and calculates the second time delay of the second satellite based on the second receiving clock time and the second transmitting clock time; Returning the first time delay and the second time delay to an intermediate epoch to obtain a first target time delay and a second target time delay at the same time; A path propagation delay between the first satellite and the second satellite is calculated according to the first target delay and the second target delay, and an inter-satellite distance between the first satellite and the second satellite is calculated based on the path propagation delay.

2. The method for high-precision distance measurement between satellites based on optical frequency comb according to claim 1, characterized in that: The path propagation delay is calculated based on the following formula: ΔT AB =(ΔT A +ΔT B ) / 2; Where, ΔT AB is the propagation delay of the path, ΔT A is the first target delay, ΔT B is the second target delay.

3. The method for high-precision intersatellite distance measurement based on optical frequency comb according to claim 2, characterized in that: The inter-satellite distance between the first satellite and the second satellite is calculated based on the following formula: L AB =(ΔT A +ΔT B ) / 2*c; Among them, L AB is the inter-star distance, and c is the speed of light.

4. The method for high-precision intersatellite distance measurement based on optical frequency comb according to claim 1, characterized in that: The first time delay is the difference between the first receiving clock time and the first transmitting clock time, and the second time delay is the difference between the second receiving clock time and the second transmitting clock time.

5. A high-precision intersatellite distance measurement system based on optical frequency comb, characterized in that: The system is configured in a first satellite and a second satellite for relative inter-satellite distance measurement, and includes: The onboard atomic clock module is used to generate a stable frequency source to provide a frequency reference for optical frequency comb locking; An optical frequency comb module, used to generate an optical frequency comb signal with a specified initial phase at a specified time according to a control instruction, wherein the optical frequency comb signal includes a propagation optical frequency comb used as a measurement signal and a reference optical frequency comb used as a tracking signal; An optical transmission system module is used to transmit the signal of the propagation optical frequency comb to a relative other satellite, receive the relative propagation optical frequency comb from the relative other satellite, and transmit the signals of the relative propagation optical frequency comb and the reference optical frequency comb to a linear optical sampling system module; wherein the relative other satellite is a satellite that performs intersatellite distance measurement with the current satellite; The linear optical sampling system module is used to calculate the time delay information between the relatively propagating optical frequency comb and the reference optical frequency comb; A microwave terminal module, used for exchanging the time delay information respectively measured between the current satellite and the relative other satellite; An information processing module is used to convert the first time delay information of the current satellite and the second time delay information relative to the other satellite into an intermediate epoch to obtain a first target time delay and a second target time delay at the same time, and calculate the path propagation delay between the current satellite and the relative other satellite according to the first target time delay and the second target time delay, and calculate the inter-satellite distance between the current satellite and the relative other satellite based on the path propagation delay.

6. The high-precision intersatellite distance measurement system based on optical frequency comb according to claim 5, characterized in that: The optical transmission system module is specifically used for: The signal generated by the propagating optical frequency comb is sent to the relative other star through a laser transceiver channel, and the relative propagating optical frequency comb sent from the relative other star is received through the laser transceiver channel, and the signals of the relative propagating optical frequency comb and the reference optical frequency comb are transmitted to the linear optical sampling system module.

7. The high-precision intersatellite distance measurement system based on optical frequency comb according to claim 5, characterized in that: The linear optical sampling system module is specifically used for: interfering the relatively propagating optical frequency comb and the reference optical frequency comb in a 50% splitting ratio optical fiber splitter; The interfered signal is input into a balanced detector to filter out the DC component in the signal and obtain an AC signal; The AC signal is converted into a voltage signal and amplified before being input into a low-pass filter, and then quantized and collected by an analog-to-digital converter to obtain the time delay information between the relative propagation optical frequency comb and the reference optical frequency comb.

8. The high-precision intersatellite distance measurement system based on optical frequency comb according to claim 5, characterized in that: The information processing module is also used to estimate the first time delay information of the current satellite using a Kalman filter according to the time delay information received from the linear optical sampling system module.

9. The high-precision intersatellite distance measurement system based on optical frequency comb according to claim 5, characterized in that: The microwave terminal module is specifically used to send the first time delay information to the relative other satellite, and receive the second time delay information sent by the relative other satellite.

10. The high-precision intersatellite distance measurement system based on optical frequency comb according to any one of claims 5 to 9, characterized in that: The path propagation delay is calculated based on the following formula: ΔT AB =(ΔT A +ΔT B ) / 2; Where, ΔT AB is the propagation delay of the path, ΔT A is the first target delay, ΔT B is the second target delay; The inter-satellite distance between the current satellite and the relative other satellite is calculated based on the following formula: L AB =(ΔT A +ΔT B ) / 2*c; Among them, L AB is the inter-star distance, and c is the speed of light.

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