Integrated error compensation method for intersatellite laser communication ranging based on optical Doppler effect

Abstract

The present invention discloses an integrated error compensation method for intersatellite laser communication ranging based on the optical Doppler effect, belonging to the field of communication technology. The method is mainly implemented by utilizing a clock frequency measurement and speed calculation module based on optical Doppler frequency shift and a distance calculation module based on dynamic two-way one-way ranging. The present invention realizes real-time measurement of the relative speed between terminals by measuring the Doppler frequency shift of a receiving clock relative to a transmitting clock. The present invention can realize real-time high-precision speed measurement without adding additional hardware, and the measured speed is used to compensate for ranging errors under dynamic conditions, thereby greatly improving ranging accuracy under dynamic conditions.

Description

Technical Field

[0001] The present invention belongs to the field of laser communication, and in particular relates to an inter-satellite laser communication ranging integrated error compensation method based on the optical Doppler effect. Background Art

[0002] Laser communication and ranging integration, by inserting ranging information into the communication link, enables simultaneous distance measurement during communication. This is a key research area in intersatellite networking and satellite navigation. Current laser ranging schemes can be broadly categorized into one-way ranging (SOWR) and two-way ranging (DOWR). DOWR offers higher accuracy than SOWR due to the nearly symmetrical bidirectional transmission paths, allowing most transmission errors to cancel each other out. Currently, most research on laser communication and ranging integration uses the DOWR method.

[0003] There are many specific implementations of DOWR. Ranging methods based on clock counting and phase measurement have attracted widespread attention due to their simple implementation structure and high ranging accuracy. However, in actual use, the high-speed relative motion between satellites can lead to significant deviations in ranging results. If the relative velocity between two satellites can be measured in real time and compensated for the ranging value, the deviation in ranging can be greatly reduced. Since satellite payload capacity is extremely valuable, the motivation for this research is to achieve inter-terminal velocity measurement without adding additional hardware equipment and to use the measured relative velocity to compensate for the ranging results. Summary of the Invention

[0004] The present invention aims to solve the problem of deterioration of ranging performance of integrated laser communication ranging under dynamic conditions. An integrated error compensation method for intersatellite laser communication ranging based on the optical Doppler effect is proposed. This method adds a real-time speed measurement function to the ranging method based on clock counting and phase measurement, and uses the distance solution formula of two-way one-way ranging under dynamic conditions to solve the distance, which can effectively improve the ranging accuracy under dynamic conditions.

[0005] The specific technical solutions adopted in the present invention are as follows:

[0006] In a first aspect, the present invention provides an integrated error compensation method for intersatellite laser communication ranging based on the optical Doppler effect, which is as follows:

[0007] Using the clock frequency measurement and speed calculation module based on optical Doppler frequency shift, by measuring the receiving clock clk rx Relative transmit clock clk tx The Doppler shift is used to estimate the relative speed between the two terminals;

[0008] The distance calculation module based on dynamic two-way one-way ranging is used to calculate the distance by combining the flight time of the ranging information obtained by the two terminals using the two-way one-way ranging method and the relative speed calculated by the clock frequency measurement and speed calculation module based on optical Doppler shift.

[0009] Preferably, the clock frequency measurement and speed calculation module based on optical Doppler shift needs to use clock data recovery technology to recover the receiving clock clk from the received data stream. rx , clk rx Frequency f rx and the terminal's local send clock clk tx Frequency f tx And the relationship between the relative speed v between terminals can be expressed as:

[0010]

[0011] Where c is the speed of light, f tx It is known that the calculation formula of v can be further obtained:

[0012]

[0013] The clock frequency measurement and speed calculation module based on optical Doppler frequency shift measures f rx The relative velocity v is estimated based on the frequency.

[0014] Furthermore, the specific implementation method of the clock frequency measurement and speed calculation module based on optical Doppler shift to estimate the relative speed v is as follows:

[0015] (1) Terminal at clk tx The clock count is performed, and the count start mark pulse start is given, and the count reaches N t Then stop and give the stop sign pulse stop;

[0016] (2) Terminal at clk rx Downsample the rising edge of the start pulse, and start clock counting after sampling the rising edge of the start pulse;

[0017] (3) Terminal at clk rx Downsample the rising edge of the stop pulse, stop counting after sampling the rising edge of the stop pulse, and obtain the count value N, then f rx It can be approximated as:

[0018]

[0019] (4) The f measured in step (3) rx The approximate frequency Substitute the calculation formula of v and calculate:

[0020]

[0021] in This is the estimated relative speed between terminals.

[0022] Preferably, the distance calculation formula used by the distance calculation module based on dynamic two-way one-way ranging is:

[0023]

[0024] Where R is the calculated distance between terminals, T1 and T2 are the flight times of the ranging information measured by the two terminals using the two-way one-way ranging method. It is the relative speed between terminals calculated by the clock frequency measurement and speed calculation module based on optical Doppler shift.

[0025] Furthermore, the calculation formula used by the distance calculation module based on dynamic two-way one-way ranging is derived from the dynamic two-way one-way ranging formula:

[0026]

[0027] where R dyna is the distance between terminals calculated using the dynamic two-way one-way ranging formula, v a and v b are the radial motion speeds of the two terminals, v a +v b is the relative radial motion speed of the two terminals (i.e. the relative speed between the terminals), that is, v a +v b =v; in the above formula The effect of the term on the overall ranging error is very small and can be ignored for ranging with centimeter-level accuracy. Therefore, R dyna The calculation can be approximated as:

[0028]

[0029] The above approximated dynamic two-way one-way ranging formula is the distance calculation formula used by the distance calculation module based on dynamic two-way one-way ranging.

[0030] In a second aspect, the present invention provides an integrated error compensation device for inter-satellite laser communication and ranging based on the optical Doppler effect, comprising a memory, a processor, and an integrated error compensation program for inter-satellite laser communication and ranging based on the optical Doppler effect, which is stored in the memory and can be run on the processor; the integrated error compensation program for inter-satellite laser communication and ranging based on the optical Doppler effect includes a clock frequency measurement and speed calculation module based on optical Doppler frequency shift and a distance calculation module based on dynamic two-way one-way ranging. When the program is executed by the processor, it can implement the steps of any method described in the first aspect.

[0031] In a third aspect, the present invention provides a computer-readable storage medium storing an integrated error compensation program for intersatellite laser communication and ranging based on the optical Doppler effect. The integrated error compensation program for intersatellite laser communication and ranging based on the optical Doppler effect includes a clock frequency measurement and velocity calculation module based on optical Doppler frequency shift and a distance calculation module based on dynamic two-way one-way ranging. When executed by a processor, the program can implement the steps of any of the methods described in the first aspect. Compared to the prior art, the present invention has the following advantages:

[0032] The clock frequency measurement and speed calculation module based on optical Doppler shift proposed in the present invention can accurately measure the real-time relative speed between satellites without adding additional hardware, which is conducive to the simplification of equipment and the miniaturization of satellites. Substituting the measured speed and time into the distance calculation formula used by the distance calculation module of dynamic two-way and one-way ranging can greatly improve the accuracy of dynamic ranging. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the relative motion of two satellites at a certain moment in the embodiment.

[0034] Figure 2 This is a simulation diagram of the distance measurement error changing with speed in a dynamic state without speed compensation in the embodiment.

[0035] Figure 3 Schematic diagram of the clock frequency measurement principle of the clock frequency measurement and speed calculation module based on optical Doppler frequency shift.

[0036] Figure 4 The speed measurement accuracy of the speed measurement method in the present invention is affected by clk tx The impact of frequency accuracy. DETAILED DESCRIPTION

[0037] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention may be combined accordingly, provided that there is no conflict between them.

[0038] Example 1

[0039] This invention is applicable to dynamic ranging error compensation for ranging methods based on clock counting and phase measurement. This embodiment provides an integrated error compensation method for intersatellite laser communication ranging based on the optical Doppler effect. Specifically, it utilizes a clock frequency measurement and velocity calculation module based on optical Doppler frequency shift, and a distance calculation module based on dynamic bidirectional, one-way ranging.

[0040] This embodiment assumes that the communication rate is 1 Gbps, that is, f tx and f rx The reference frequency is 1GHz; the principle of the ranging method based on clock counting and phase measurement is that terminals A and B respectively tx The sending and receiving time of the ranging information is measured to obtain two time measurement values ​​T1 and T2, and then the distance is calculated using the two-way one-way ranging formula under static conditions. The formula is as follows:

[0041]

[0042] However, since satellites are usually in relatively high-speed motion, the distance calculated using the static two-way one-way ranging formula will have a very large ranging error. Figure 1 This is a schematic diagram of the relative motion of two satellites at a certain moment. It can be assumed that the radial velocity of the two satellites in a certain short period of time remains unchanged. If the relativistic effect is considered, then Figure 1 The dynamic two-way one-way ranging formula should be:

[0043]

[0044] where v a and v b are the radial motion speeds of the two terminals, v a +v b is the relative radial motion speed of the two terminals, that is, v a +v b =v, in the above formula The effect of the term on the overall ranging error is very small and can be ignored for ranging with centimeter-level accuracy. Therefore, R dyna The calculation can be approximated as:

[0045]

[0046] The present invention is to measure the relative speed between two satellites and then use R dyna The distance is calculated using the approximate calculation formula.

[0047] Figure 2A simulation diagram shows how the ranging error changes with speed in a dynamic state without speed compensation. The speed of satellite A is fixed at 3 km / s, and the speed of satellite B is adjusted for simulation. It can be seen that when the satellites approach each other at a speed of 3 km / s, that is, the relative motion speed is 6 km / s, the ranging error reaches 30m, seriously affecting the accuracy.

[0048] Figure 3 This is the clock frequency measurement principle of the clock frequency measurement and speed calculation module based on optical Doppler frequency shift. As can be seen from the figure, the clock frequency measurement first requires the terminal to be in clk tx The clock count is performed, and the count start mark pulse start is given, and the count reaches N t After stopping, a stop sign pulse stop is given; then at the same time at clk rx Downsample the rising edges of the start and stop pulses, start clock counting after sampling the rising edge of the start pulse, and stop counting after sampling the rising edge of the stop pulse to obtain the count value N.

[0049] The specific implementation method of the clock frequency measurement based on optical Doppler frequency shift and the speed calculation module for speed estimation in the present invention is as follows:

[0050] (1) Terminal at clk tx The clock count is performed, and the count start mark pulse start is given, and the count reaches N t Then stop and give the stop sign pulse stop;

[0051] (2) Terminal at clk rx Downsample the rising edge of the start pulse, and start clock counting after sampling the rising edge of the start pulse;

[0052] (3) Terminal at clk rx Downsample the rising edge of the stop pulse, stop counting after sampling the rising edge of the stop pulse, and obtain the count value N, then f rx It can be approximated as:

[0053]

[0054] (4) The f measured in (3) rx The approximate frequency Substitute the calculation formula of v and calculate:

[0055]

[0056] This is the calculated relative speed between terminals.

[0057] It should be noted that the speed measurement accuracy of this method is affected by clktx Frequency accuracy impact, such as Figure 4 As shown, for a clock source with a frequency deviation lower than 1e-8, the velocity measurement error using this method is lower than 5m / s, and a clock with a frequency accuracy of 1e-8 can be provided by a satellite-borne rubidium atomic clock.

[0058] The calculation formula of the distance calculation module based on dynamic two-way one-way ranging is:

[0059]

[0060] in It is the relative speed between terminals calculated by the clock frequency measurement and speed calculation module based on optical Doppler shift.

[0061] When using a clock source with a frequency deviation lower than 1e-8, The estimated error is less than 5m / s. When the satellite spacing is 3000km, T1 is about 10ms, and the residual ranging error is It can be seen that the present invention is very helpful in improving the ranging accuracy under dynamic conditions.

[0062] The embodiment described above is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Persons skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent substitution or equivalent transformation falls within the scope of protection of the present invention.

Claims

1. A method for integrated error compensation of intersatellite laser communication ranging based on optical Doppler effect, characterized in that: The details are as follows: Using the clock frequency measurement and speed calculation module based on optical Doppler frequency shift, the received clock Relative send clock The Doppler shift is used to estimate the relative speed between the two terminals; Distance calculation is performed using a distance calculation module based on dynamic two-way one-way ranging, combining the flight time of the ranging information obtained by each of the two terminals using the two-way one-way ranging method and the relative speed calculated by the clock frequency measurement and speed calculation module based on optical Doppler shift; The calculation formula used by the distance calculation module based on dynamic two-way one-way ranging is derived from the dynamic two-way one-way ranging formula: ； in is the distance between terminals calculated using the dynamic two-way one-way ranging formula, and are the radial motion speeds of the two terminals, is the relative speed between the two terminals, that is In the above formula The effect of the term on the overall ranging error is very small and can be ignored for ranging with centimeter-level accuracy. The calculation can be approximated as: ； The above approximated dynamic two-way one-way ranging formula is the distance calculation formula used by the distance calculation module based on dynamic two-way one-way ranging.

2. The method for integrated error compensation for intersatellite laser communication and ranging based on the optical Doppler effect according to claim 1, characterized in that: The clock frequency measurement and speed calculation module based on optical Doppler frequency shift needs to use clock data recovery technology to recover the receiving clock from the received data stream. , Frequency and the terminal's locally generated transmit clock Frequency and the relative speed between terminals The relationship can be expressed as: ； where c is the speed of light, Known, further available The calculation formula is: ； The clock frequency measurement and speed calculation module based on optical Doppler frequency shift measures Frequency versus relative speed Make an estimate.

3. The integrated error compensation method for intersatellite laser communication and ranging based on the optical Doppler effect according to claim 2, characterized in that: The clock frequency measurement and speed calculation module based on optical Doppler frequency shift is used to calculate the relative speed. The specific implementation method of the estimation is as follows: (1) Terminal The clock count is performed under the clock, and the count start mark pulse start is given. Then stop and give the stop sign pulse stop; (2) Terminal Downsample the rising edge of the start pulse, and start clock counting after sampling the rising edge of the start pulse; (3) Terminal Downsample the rising edge of the stop pulse, stop counting after sampling the rising edge of the stop pulse, and obtain the count value N. It can be approximated as: ； (4) The measured value obtained in step (3) The approximate frequency Substitution The calculation formula is calculated as follows: ； in This is the estimated relative speed between terminals.

4. The integrated error compensation method for intersatellite laser communication and ranging based on the optical Doppler effect according to claim 1 is characterized in that: The distance calculation formula used by the distance calculation module based on dynamic two-way one-way ranging is: ； in is the calculated distance between terminals, and are the flight time of the ranging information obtained by the two terminals using the two-way one-way ranging method respectively, It is the relative speed between terminals calculated by the clock frequency measurement and speed calculation module based on optical Doppler shift.

5. An integrated error compensation device for intersatellite laser communication and ranging based on the optical Doppler effect, characterized in that: The invention comprises a memory, a processor, and an integrated error compensation program for inter-satellite laser communication and ranging based on the optical Doppler effect, which is stored in the memory and can be run on the processor; the integrated error compensation program for inter-satellite laser communication and ranging based on the optical Doppler effect comprises a clock frequency measurement and speed calculation module based on optical Doppler frequency shift and a distance calculation module based on dynamic two-way one-way ranging. When the program is executed by the processor, the steps of the method according to any one of claims 1 to 4 can be implemented.

6. A computer-readable storage medium, characterized in that The computer-readable storage medium stores an integrated error compensation program for inter-satellite laser communication and ranging based on the optical Doppler effect; the integrated error compensation program for inter-satellite laser communication and ranging based on the optical Doppler effect includes a clock frequency measurement and speed calculation module based on optical Doppler frequency shift and a distance calculation module based on dynamic two-way one-way ranging. When the program is executed by a processor, the steps of the method described in any one of claims 1 to 4 can be implemented.

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