A method, system, equipment and medium for evaluating the performance of a high-precision space atomic clock.

Abstract

This invention discloses a method, system, device, and medium for evaluating the performance of a high-precision space atomic clock. The method includes the following steps: calculating the relative clock difference between space and ground based on a two-way time difference measurement method; wherein, a distance inconsistency delay error is introduced for correction during the calculation of the relative clock difference; calculating stability, sky stability, and space-to-ground alignment accuracy based on the calculated relative clock difference; and achieving performance evaluation of the high-precision space atomic clock based on the stability, sky stability, and space-to-ground alignment accuracy. In the technical solution provided by this invention, a space-to-ground time alignment network system based on a microwave ranging link is used, and the relative clock difference information between space and ground is calculated based on a two-way time difference measurement method. Finally, the performance of the high-precision space atomic clock can be evaluated using the relative clock difference information.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of space science and technology and time measurement methods, and relates to the field of high-precision atomic clock performance evaluation, and in particular to a method, system, device and medium for evaluating the performance of a space high-precision atomic clock. Background Technology

[0002] With the rapid development of space science and technology, its applications in verifying relativity, fundamental physics testing, geophysical measurement, deep space exploration, and satellite navigation are becoming increasingly widespread. However, the development and application of space science and technology in these fields cannot be separated from high-precision time and frequency. The measurement and performance evaluation of time and frequency provide an interconnected technical foundation for various applications of space science.

[0003] Currently, both internationally and domestically, there is a renewed understanding of low-Earth orbit (LEO) satellite resources. LEO satellites have demonstrated unique advantages and characteristics in various aspects such as navigation enhancement, information network communication, and manned spaceflight. Equipping a LEO space station with high-precision onboard atomic clocks can support various space science experiments. For the high-precision atomic clocks deployed on the space station, it is essential to first accurately evaluate their performance using appropriate methods. Only after the performance of the atomic clocks themselves is known and determined can various space science and technology research and experimental work be carried out smoothly.

[0004] The space station operates in a microgravity environment, and its atomic clocks are highly accurate (specifically, stability and uncertainty can even reach 10). -17 The performance of atomic clocks on low-Earth orbit (LEO) satellites is extremely limited, making accurate evaluation impossible using conventional methods. Furthermore, space stations, being low-Earth orbit satellites with high relative ground speeds, have very limited continuous visual contact with ground stations during each transit, hindering effective evaluation using standard data processing and evaluation algorithms. Therefore, a new performance evaluation method is urgently needed for high-performance atomic clocks mounted on LEO satellites such as space stations and other high-dynamic spacecraft. Summary of the Invention

[0005] The purpose of this invention is to provide a method, system, device, and medium for evaluating the performance of a high-precision space atomic clock, thereby solving one or more of the aforementioned technical problems. The technical solution provided by this invention utilizes a satellite-to-ground time comparison network system based on a microwave ranging link, and calculates the relative clock difference information between satellite and ground using a two-way time difference measurement method. Finally, the performance of a high-precision space atomic clock can be evaluated using this relative clock difference information.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a method for evaluating the performance of a high-precision space atomic clock, comprising the following steps:

[0008] Based on the two-way time difference measurement method, the relative clock difference between satellite and ground is calculated; wherein, in the process of calculating the relative clock difference between satellite and ground, a time delay error due to distance inconsistency is introduced for correction.

[0009] The stability, celestial stability, and satellite-to-ground alignment accuracy are calculated based on the relative clock difference between the satellite and the ground. The performance evaluation of a high-precision space atomic clock is then achieved based on these stability, celestial stability, and satellite-to-ground alignment accuracy.

[0010] A further improvement of the present invention is that, in the process of calculating the relative clock difference between satellite and ground based on the two-way time difference measurement method,

[0011] The expression for calculating the relative clock difference between the satellite and the ground is as follows:

[0012] Δt=(P1-P2) / 2+r / 2+& / 2;

[0013] In the formula, Δt is the relative clock difference between satellite and ground; P1 is the uplink pseudorange measurement; P2 is the downlink pseudorange measurement; r is the distance inconsistency delay error; (& 12 -& 21 ) = &, & 21 This represents the combined error of the propagation delays along the signal's uplink propagation path. 12 This represents the combined error of various propagation delays along the downlink propagation path of the signal;

[0014] r = R 12 -R 21 = [D_(SG')-D_(GS')] / c;

[0015] In the formula, R 21 R represents the uplink signal propagation geometric distance delay. 12 D_(SG') represents the downlink signal propagation geometric distance delay from S to G, and D_(GS') represents the uplink signal propagation geometric distance from G to S. S and G represent the low-orbit satellite and ground station equipped with high-precision atomic clocks, respectively. c represents the speed of light.

[0016] A further improvement of the present invention is that the steps for obtaining the uplink pseudorange measurement value P1 and the downlink pseudorange measurement value P2 include:

[0017] The low-orbit satellite equipped with a high-precision atomic clock sends continuous ranging signals to the ground station via a microwave link ranging device at a fixed frequency f1, and the ground station sends continuous ranging signals to the low-orbit satellite via a microwave link ranging device at a fixed frequency f2.

[0018] After receiving the signal transmitted by the low-orbit satellite, the microwave link ranging equipment at the ground station processes it to obtain the downlink pseudorange measurement value, and then sends the downlink pseudorange measurement value to the receiving and processing equipment at the ground processing center through the ground data transmission network.

[0019] After receiving the signal sent by the ground station, the microwave link ranging equipment of the low-orbit satellite processes it to obtain the uplink pseudorange measurement value, and then sends the uplink pseudorange measurement value to the receiving and processing equipment of the ground processing center through the data telemetry backhaul link.

[0020] A further improvement of the present invention lies in the fact that, in the process of calculating the stability, sky stability, and satellite-to-ground alignment accuracy based on the calculated relative clock difference between the satellite and the ground,

[0021] The steps to calculate and obtain stability include:

[0022] The smoothing time is determined based on the visible continuous arc length of each low-Earth orbit satellite's overpass over the ground station. The modified Allan variance, Modσ, representing the stability, is then calculated using the stability calculation expression. y (τ), the stability calculation expression is,

[0023]

[0024] In the formula, τ is the smoothing time, τ=mτ0; m is the smoothing factor; τ0 is the sampling interval; N is the total number of data points, x i The obtained relative clock difference between the satellite and the ground is Δt;

[0025] The steps for calculating the celestial stability include: obtaining relative clock difference data between the Earth and the planet for a preset number of days as sample data, and calculating the celestial stability using the stability calculation expression;

[0026] The steps for calculating the satellite-to-ground alignment accuracy include: selecting satellite-to-ground measurement data for a continuous arc segment obtained from a single transit measurement; calculating the relative clock difference data between satellite and ground at each moment of the arc segment using a two-way time difference measurement method, and removing outliers; performing high-order polynomial fitting on the clock difference data after removing outliers, and then subtracting it from the original satellite-to-ground clock difference data to obtain a residual sequence; and calculating the standard deviation of the residual sequence to obtain the satellite-to-ground alignment accuracy.

[0027] This invention provides a high-precision space atomic clock performance evaluation system, comprising:

[0028] The satellite-to-ground relative clock difference acquisition module is used to calculate the satellite-to-ground relative clock difference based on a two-way time difference measurement method; wherein, in the process of calculating the satellite-to-ground relative clock difference, a distance inconsistency time delay error is introduced for correction;

[0029] The performance evaluation module is used to calculate the stability, sky stability, and star-to-ground alignment accuracy based on the calculated relative clock difference between the satellite and the ground. Based on the stability, sky stability, and star-to-ground alignment accuracy, the performance evaluation of the space high-precision atomic clock is realized.

[0030] A further improvement of the present invention is that, in the process of calculating the relative clock difference between the satellite and the ground based on the two-way time difference measurement method, the satellite-to-ground relative clock difference acquisition module...

[0031] The expression for calculating the relative clock difference between the satellite and the ground is as follows:

[0032] Δt=(P1-P2) / 2+r / 2+& / 2;

[0033] In the formula, Δt is the relative clock difference between satellite and ground; P1 is the uplink pseudorange measurement; P2 is the downlink pseudorange measurement; r is the distance inconsistency delay error; (& 12 -& 21 ) = &, & 21 This represents the combined error of the propagation delays along the signal's uplink propagation path. 12 This represents the combined error of various propagation delays along the downlink propagation path of the signal;

[0034] r = R 12 -R 21 = [D_(SG')-D_(GS')] / c;

[0035] In the formula, R 21 R represents the uplink signal propagation geometric distance delay. 12 D_(SG') represents the downlink signal propagation geometric distance delay from S to G, and D_(GS') represents the uplink signal propagation geometric distance from G to S. S and G represent the low-orbit satellite and ground station equipped with high-precision atomic clocks, respectively. c represents the speed of light.

[0036] A further improvement of the present invention is that the steps for obtaining the uplink pseudorange measurement value P1 and the downlink pseudorange measurement value P2 include:

[0037] The low-orbit satellite equipped with a high-precision atomic clock sends continuous ranging signals to the ground station via a microwave link ranging device at a fixed frequency f1, and the ground station sends continuous ranging signals to the low-orbit satellite via a microwave link ranging device at a fixed frequency f2.

[0038] After receiving the signal transmitted by the low-orbit satellite, the microwave link ranging equipment at the ground station processes it to obtain the downlink pseudorange measurement value, and then sends the downlink pseudorange measurement value to the receiving and processing equipment at the ground processing center through the ground data transmission network.

[0039] After receiving the signal sent by the ground station, the microwave link ranging equipment of the low-orbit satellite processes it to obtain the uplink pseudorange measurement value, and then sends the uplink pseudorange measurement value to the receiving and processing equipment of the ground processing center through the data telemetry backhaul link.

[0040] A further improvement of the present invention is that, in the process of calculating stability, sky stability, and satellite-to-ground alignment accuracy based on the calculated relative clock difference between satellite and ground, the performance evaluation module...

[0041] The steps to calculate and obtain stability include:

[0042] The smoothing time is determined based on the visible continuous arc length of each low-Earth orbit satellite's overpass over the ground station. The modified Allan variance, Modσ, representing the stability, is then calculated using the stability calculation expression. y (τ), the stability calculation expression is,

[0043]

[0044] In the formula, τ is the smoothing time, τ=mτ0; m is the smoothing factor; τ0 is the sampling interval; N is the total number of data points, x i The obtained relative clock difference between the satellite and the ground is Δt;

[0045] The steps for calculating the celestial stability include: obtaining relative clock difference data between the Earth and the planet for a preset number of days as sample data, and calculating the celestial stability using the stability calculation expression;

[0046] The steps for calculating the satellite-to-ground alignment accuracy include: selecting satellite-to-ground measurement data for a continuous arc segment obtained from a single transit measurement; calculating the relative clock difference data between satellite and ground at each moment of the arc segment using a two-way time difference measurement method, and removing outliers; performing high-order polynomial fitting on the clock difference data after removing outliers, and then subtracting it from the original satellite-to-ground clock difference data to obtain a residual sequence; and calculating the standard deviation of the residual sequence to obtain the satellite-to-ground alignment accuracy.

[0047] The present invention provides an electronic device comprising:

[0048] At least one processor; and,

[0049] A memory communicatively connected to the at least one processor; wherein,

[0050] The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the space high-precision atomic clock performance evaluation method as described in any one of the present invention.

[0051] The present invention provides a computer-readable storage medium storing a computer program, characterized in that, when the computer program is executed by a processor, it implements any of the above-described methods for evaluating the performance of a high-precision atomic clock in space.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] The space high-precision atomic clock performance evaluation method provided by this invention addresses the technical challenges of high precision and short transit time of space station atomic clocks. It employs a satellite-to-ground time comparison network system based on a microwave ranging link and calculates the relative clock difference between satellite and ground using a two-way time difference measurement method. Finally, it utilizes the relative clock difference information and employs strategies such as non-uniform data stitching and reasonable sampling interval configuration to evaluate the performance of the space high-precision atomic clock. The method provided by this invention can achieve picosecond-level satellite-to-ground time comparison accuracy, which is two orders of magnitude higher than the accuracy of currently mature time synchronization methods in the industry. It can also effectively evaluate 10... -17 The performance of this space atomic clock is groundbreaking in China. The method provided by this invention can be used to evaluate the performance of high-precision atomic clocks carried by high-speed low-Earth orbit satellites, such as those operating from space stations, by establishing a time synchronization network system. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0055] Figure 1 This is a flowchart illustrating a high-precision atomic clock performance evaluation method according to an embodiment of the present invention.

[0056] Figure 2 This is a schematic diagram of a bidirectional time comparison network system in an embodiment of the present invention;

[0057] Figure 3 This is a schematic diagram of distance inconsistency error correction in an embodiment of the present invention;

[0058] Figure 4 This is a schematic diagram illustrating the satellite-to-ground alignment accuracy evaluation in an embodiment of the present invention;

[0059] Figure 5 This is a schematic diagram of a high-precision atomic clock performance evaluation system according to an embodiment of the present invention. Detailed Implementation

[0060] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0061] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0062] The present invention will now be described in further detail with reference to the accompanying drawings:

[0063] Please see Figure 1 The present invention provides a method for evaluating the performance of a high-precision atomic clock in space, which is applicable to the performance evaluation of high-precision atomic clocks carried on low-Earth orbit satellites such as space stations. The method specifically includes the following steps:

[0064] Step 1: Establish a two-way time comparison network system based on the microwave ranging link.

[0065] In order to evaluate the performance of the high-precision onboard clock carried by a low-orbit satellite in this embodiment of the invention, it is first necessary to establish a time synchronization network system based on a microwave ranging link. On this basis, the relative clock difference information between the satellite atomic clock and the ground atomic clock is obtained, and the performance of the satellite atomic clock is further evaluated.

[0066] The specific method provided by the exemplary embodiments of the present invention includes: a satellite transmitting continuous ranging signals to the ground via a microwave link ranging device at a fixed frequency f1, while a ground station simultaneously transmits continuous ranging signals to the satellite via a microwave link ranging device at a fixed frequency f2; after receiving the signals transmitted by the satellite, the ground microwave link ranging device processes the signals to obtain downlink pseudorange measurements and transmits the downlink pseudorange measurements to the receiving and processing equipment at the ground processing center via a ground data transmission network; after receiving the signals transmitted by the ground, the satellite microwave link ranging device processes the signals to obtain uplink pseudorange measurements and transmits the uplink pseudorange measurements to the receiving and processing equipment at the ground processing center via a data telemetry backhaul link; a closed-loop time synchronization network system is thus formed between the ground processing center, the satellite, and the ground station, and a two-way time comparison network system is also provided. Figure 2 As shown.

[0067] Step 2: After the ground processing center collects the uplink and downlink pseudorange measurements from the satellite and the ground, it calculates the relative clock difference between the satellite and the ground based on the two-way time difference measurement method to support the realization of high-precision time synchronization.

[0068] In this embodiment of the invention, the bidirectional time difference measurement method is explained as follows: Bidirectional time difference measurement refers to the use of the fact that the paths of signal propagation at the same time are basically the same, and by subtracting the bidirectional ranging values, most of the common errors in the link can be canceled, thereby obtaining a high-precision satellite-to-ground clock difference.

[0069] The ground processing center collects uplink pseudorange measurements from the satellite (value P1) and ground-received pseudorange measurements from the ground (value P2). P1 and P2 are represented as follows:

[0070] P1 = R 21 +Δt+& 21 (1)

[0071] P2 = R 12 -Δt+& 12 (2)

[0072] Among them, R 21 R represents the uplink signal propagation geometric distance delay from ground transmission to satellite reception. 12 This represents the downlink signal propagation geometric distance delay from satellite transmission to ground reception; 21 This represents the combined error of the propagation delays along the signal's uplink propagation path. 12 The sum of propagation delays along the downlink propagation path represents the combined error of the propagation time delays, where Δt is the relative clock difference between the low-Earth orbit satellite and the ground.

[0073] Using the principle of two-way time difference measurement, subtracting formulas (1) and (2) yields the relative clock difference Δt between the satellite and the ground. The calculation expression is as follows:

[0074] Δt=(P1-P2) / 2+(R 12 -R 21 ) / 2+(& 12 -& 21 ) / twenty three)

[0075] In equation (3), the combined propagation delay error of each item in the uplink and downlink propagation paths is & 12 and& 21 It can be modified by appropriate methods, which is outside the scope of this invention. It is assumed that it is known (& 12 -& 21 ) = &.

[0076] For the signal propagation geometric distance time delay R 12 and R 21 Assuming the satellite and the ground are relatively stationary, the uplink and downlink signal propagation geometric paths can be considered to be inverses of each other, R. 21 and R 12 If they are completely equal, then subtracting equations (1) and (2) will result in (R) 12 -R 21 When ) = 0, formula (3) becomes:

[0077] Δt=(P1-P2) / 2+& / 2 (4)

[0078] Then, based on the pseudorange measurements P1 and P2 obtained from the ground processing center, as well as the known Δt value, the clock error Δt can be calculated.

[0079] However, in practical applications, the high-speed motion of low-orbit satellites relative to the ground causes a geometric distance delay R during uplink and downlink signal propagation in two-way measurement. 21 and R 12 They are not equal. The result obtained by directly using equation (4) will have a certain error. This error is the distance inconsistency delay error r. This error must be corrected accordingly. At this time, the relative clock difference between the satellite and the ground is expressed as: Δt=(P1-P2) / 2+r / 2+& / 2 (5).

[0080] Please see Figure 3 In this embodiment of the invention, when calculating the relative clock difference between satellite and ground, it is necessary to correct for the time delay error r due to distance inconsistency. The specific calculation method for r includes the following steps:

[0081] Assume that S and G represent a low-Earth orbit satellite and a ground station, respectively. S and G transmit ranging signals to each other at time t0. When S receives the ranging signal sent by G at t0, it moves to the position of S', and the time is t1. When G receives the ranging signal sent by S at t0, it moves to the position of G', and the time is t2.

[0082] D_(SG) represents the instantaneous geometric distance between S and G at time t0, D_(SG') represents the downlink signal propagation geometric distance from the ranging signal transmitted by S to the signal received by G, and D_(GS') represents the uplink signal propagation geometric distance from the ranging signal transmitted by G to the signal received by S.

[0083] Based on the above description, the uplink and downlink distance inconsistency delay error r is:

[0084] r = R 12 -R 21 =[D_(SG')-D_(GS')] / c (6)

[0085] Where c is the speed of light.

[0086] Since the ground station coordinates and the precise ephemeris of the low-Earth orbit satellite are known, the spatial geometric distance D_(SG') can be obtained using the orbital position of the low-Earth orbit satellite at time t0 and the ground station position coordinates at time t2; similarly, D_(GS') can be obtained using the ground station position coordinates at time t0 and the low-Earth orbit satellite position at time t1. Finally, the distance inconsistency delay error r is calculated according to formula (6), and substituted into formula (5) to obtain the relative clock difference between the satellite and the ground.

[0087] Step 3: Utilize the relative clock difference information between the satellite and the ground to evaluate the performance of the spaceborne atomic clock.

[0088] In this embodiment of the invention, after obtaining the relative clock difference between the satellite and the ground as described above, the performance of the atomic clock of the low-orbit satellite is further evaluated based on the relative clock difference data between the satellite and the ground. The specific evaluation method is to calculate three indicators: 300-second stability, sky stability, and satellite-to-ground alignment accuracy, respectively, using a segment of satellite-to-ground clock difference data sequence.

[0089] In this embodiment of the invention, the stability assessment uses the modified Allen variance to characterize the frequency stability. Generally, calculating stability using Allen variance requires at least 15 consecutive sampling data points. However, during the operation of a low-Earth orbit (LEO) satellite, due to its high-speed dynamic operation, it passes over and is visible to ground stations several times a day, with each visible continuous duration lasting only tens to hundreds of seconds. The remaining time makes it impossible to obtain the satellite-to-ground clock difference through satellite-to-ground time comparison. Given the limited link establishment period and duration between the LEO satellite and the ground station, the usable data obtained is very limited, making it difficult to obtain uniform and continuous data samples. Therefore, the following strategy and data stitching method are used to assess the performance of LEO-borne atomic clocks.

[0090] In this embodiment of the invention, the stability is evaluated based on the arc length of a single entry as the smoothing time, including:

[0091] The smoothing time is first determined based on the visible continuous arc length of each low-orbit satellite passing over the ground station.

[0092] The stability Modσ, which is characterized by the modified Allan variance, is obtained using the following equation (7). y (τ).

[0093]

[0094] Where τ is the smoothing time, and τ=mτ0, m is the smoothing factor, τ0 is the sampling interval, N is the total number of data, and x i For the obtained relative clock error data Δt, when m=1, the Allan variance is corrected to degenerate into Allan variance.

[0095] For example, if the average duration of each transit arc of the space station is about 5 minutes, then the stability of the space station can be evaluated for 300 seconds. If there is 1 measurement data per second in the actual space-to-ground time comparison measurement link, there are 300 measurement data within 300 seconds of each transit arc. 10 high-quality measurement data are selected from each arc as sample data (10 consecutive data can be taken from the middle section of each arc). Sample data from at least 15 consecutive arcs are selected and spliced ​​together to obtain at least 15*10=150 sample data points. Using these 15*10 sample data, the stability for 300 seconds is calculated using formula (7). At this time, the smoothing time τ is 300, the smoothing factor m is 10, and the sampling interval τ0 is 30. More sample data can also be selected for each arc, that is, by increasing the smoothing factor m and adjusting the sampling interval τ0 accordingly, and then the stability for 300 seconds is calculated according to formula (7).

[0096] To be further specific, given that the results obtained by the above method are based on splicing non-uniform data, their stability performance will inevitably be worse than that obtained by actually using uniform and continuous measurement data. This result can be taken as the minimum requirement for 300-second stability.

[0097] In this embodiment of the invention, the day stability evaluation strategy includes:

[0098] Select at least 15 consecutive days of relative clock difference data between the Earth and the satellite. Take only one high-quality measurement data point per day as the sample data. This will result in at least 15 consecutive sample data points. Use these 15 sample data points to correct the Allan variance using formula (7) to calculate the daily stability. The smoothing time τ is 86400, the smoothing factor m is 1, and the sampling interval τ0 is 86400. Alternatively, more measurement data can be selected as sample data each day by increasing the smoothing factor m and adjusting the sampling interval τ0 accordingly. Then, the daily stability can be calculated using formula (7).

[0099] In this embodiment of the invention, the air-to-ground time comparison accuracy evaluation strategy includes:

[0100] By selecting satellite-to-ground measurement data for a continuous arc segment obtained from a single transit measurement, the relative clock difference between satellite and ground at each moment within this arc segment is calculated using a two-way time difference measurement method. Outliers are then removed, and a high-order polynomial fit is applied to the clock difference data after outlier removal. This fit is then subtracted from the original satellite-to-ground clock difference data to obtain a residual sequence. Finally, the standard deviation of this residual sequence is calculated to determine the satellite-to-ground alignment accuracy. This value can assess the satellite-to-ground time alignment accuracy over a period of time, reflecting the performance of the atomic clock from another perspective.

[0101] This invention provides a method for evaluating the performance of a high-precision atomic clock in space. Assuming a low-Earth orbit satellite A, a ground station B, and a ground processing center C, A, B, and C form a satellite-to-ground time synchronization network system based on a microwave ranging link. Satellite A transmits continuous ranging signals to the ground via a microwave ranging device at a fixed frequency f1. Simultaneously, ground station B transmits continuous ranging signals to the satellite via a microwave ranging device at a fixed frequency f2 (for example, one measurement data point is transmitted per second). After receiving the signals from the satellite, the ground microwave ranging device processes them to obtain downlink pseudorange measurements and transmits these measurements to the receiving and processing equipment at the ground processing center via a ground data transmission network. Similarly, after receiving the signals from the ground, the satellite microwave ranging device processes them to obtain uplink pseudorange measurements and transmits these measurements to the receiving and processing equipment at the ground processing center via a data telemetry backhaul link. This bidirectional measurement process between satellite and ground lasts for at least 15 days, during which the ground processing center collects the bidirectional pseudorange measurements for 15 days.

[0102] The ground processing center uses the known satellite orbit and ground station coordinates to calculate the distance inconsistency delay error r at the corresponding time according to formula (6); the ground processing center uses the two-way time synchronization principle and formula (5) to calculate the relative clock difference between the satellite and the ground at the corresponding time within 15 days.

[0103] The relative clock difference data between the satellite and the ground were selected from 15 consecutive transit arcs. Only 10 measurement data points were selected from each arc as sample data. The sample data from the 15 consecutive arcs were spliced ​​together to obtain 15*10=150 sample data points. Using these 15*10 sample data points, the smoothing time τ was set to 300, the smoothing factor m was set to 10, and the sampling interval τ0 was set to 30. The stability for 300 seconds was calculated according to formula (7). The relative clock difference data between the satellite and the ground was used for 15 consecutive days, and one data point was taken each day. The measured data are used as sample data, resulting in 15 consecutive sample data points. Using these 15 sample data, the smoothing time τ is set to 86400, the smoothing factor m is set to 1, and the sampling interval τ0 is set to 86400. The stability of the sky is calculated according to formula (7). A relative clock difference between the satellite and the ground is selected with a transit arc duration of approximately 300s. The satellite and ground clock difference data is fitted with a high-order polynomial and subtracted from the original satellite and ground clock difference data to obtain a residual sequence. Finally, the standard deviation of the residual sequence is calculated (refer to the standard deviation calculation). Figure 4 The method is to obtain the accuracy of the satellite-to-ground time comparison.

[0104] The following are embodiments of the apparatus of the present invention, which can be used to execute embodiments of the method of the present invention. For details not omitted in the apparatus embodiments, please refer to the embodiments of the method of the present invention.

[0105] Please see Figure 5 In another embodiment of the present invention, a high-precision space atomic clock performance evaluation system is provided, comprising:

[0106] The satellite-to-ground relative clock difference acquisition module is used to calculate the satellite-to-ground relative clock difference based on a two-way time difference measurement method; wherein, in the process of calculating the satellite-to-ground relative clock difference, a distance inconsistency time delay error is introduced for correction;

[0107] The performance evaluation module is used to calculate the stability, sky stability, and star-to-ground alignment accuracy based on the calculated relative clock difference between the satellite and the ground. Based on the stability, sky stability, and star-to-ground alignment accuracy, the performance evaluation of the space high-precision atomic clock is realized.

[0108] In another embodiment of the present invention, a computer device is provided, comprising a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions from the computer storage medium to achieve a corresponding method flow or corresponding function. The processor described in this embodiment of the present invention can be used for the operation of a space high-precision atomic clock performance evaluation method.

[0109] In another embodiment of the present invention, a storage medium is provided, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, the storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the space high-precision atomic clock performance evaluation method in the above embodiments.

[0110] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0111] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0112] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0113] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for evaluating the performance of a space high-precision atomic clock, characterized in that, The method comprises the following steps: The star-ground relative clock difference is calculated based on a two-way time difference measurement method, wherein a distance inconsistency time delay error is introduced in the calculation of the star-ground relative clock difference for correction; The stability, the sky stability, and the star-ground comparison accuracy are calculated based on the calculated star-ground relative clock difference, and the space high-precision atomic clock performance evaluation is realized based on the stability, the sky stability, and the star-ground comparison accuracy. In the process of obtaining stability based on the calculated satellite-ground relative clock difference, high-quality short samples are respectively intercepted from multiple transit arcs based on the calculated satellite-ground relative clock difference, the intercepted high-quality short samples are spliced into a virtual long continuous sequence, and the modified Allan variance table is calculated based on the virtual long continuous sequence to represent the stability , the calculation expression is ； In the formula, The smoothing time is determined according to the visible continuous arc length of the ground station by each transit of the low-orbit satellite; The smoothing factor is The sampling interval is ; The total number of data is The obtained satellite-ground relative clock difference is .

2. The method for evaluating the performance of a space high-precision atomic clock according to claim 1, characterized in that, In the calculation of the star-ground relative clock difference based on the two-way time difference measurement method, The calculation expression of the star-ground relative clock difference is = (P1-P2) / 2 + r / 2 + & / 2; In the formula, is the relative clock error between the satellite and the ground; P1 is the uplink pseudorange measurement value; P2 is the downlink pseudorange measurement value; r is the distance inconsistency delay error; and 12 21 21 represents the comprehensive error of the propagation delay of the uplink signal propagation path, 12 represents the comprehensive error of the propagation delay of the downlink signal propagation path.​​ r = R 12 - R 21 = [D_(SG') - D_(GS')] / c; In the formula, R 21 represents the uplink signal propagation geometry distance delay, R 12 represents the downlink signal propagation geometry distance delay; D_(SG') represents the downlink signal propagation geometry distance of the S-to-G ranging signal, D_(GS') represents the uplink signal propagation geometry distance of the G-to-S ranging signal; S and G represent a low earth orbit satellite carrying a high-precision atomic clock and a ground station, respectively; and c represents the speed of light.

3. The method for evaluating the performance of a space high-precision atomic clock according to claim 2, characterized in that, The uplink pseudo-range measurement value P1 and the downlink pseudo-range measurement value P2 are obtained by: The low-orbit satellite carrying the high-precision atomic clock sends continuous ranging signals downward to the ground station through the microwave link ranging device of the fixed frequency f1, and the ground station sends continuous ranging signals upward to the low-orbit satellite through the microwave link ranging device of the fixed frequency f2; After receiving the signal sent by the low-orbit satellite, the microwave link ranging device of the ground station processes to obtain the downlink pseudo-range measurement value, and sends the downlink pseudo-range measurement value to the receiving and processing device of the ground processing center through the ground data transmission network; After receiving the signal sent by the ground station, the microwave link ranging device of the low-orbit satellite processes to obtain the uplink pseudo-range measurement value, and sends the uplink pseudo-range measurement value to the receiving and processing device of the ground processing center through the data telemetry return link.

4. The method for evaluating the performance of a space high-precision atomic clock according to claim 2, characterized in that, In the calculation of the stability, the sky stability, and the star-ground comparison accuracy based on the calculated star-ground relative clock difference, The step of calculating the sky stability comprises: obtaining star-ground relative clock difference data of a preset number of days as sample data, and calculating the sky stability by using the stability calculation expression; The step of calculating the star-ground comparison accuracy comprises: selecting star-ground measurement data of a continuous arc segment obtained by one-time transit measurement, calculating the star-ground relative clock difference data of each time of the arc segment by using the two-way time difference measurement method, and eliminating outliers; performing high-order polynomial fitting on the clock difference data after eliminating outliers, and then subtracting the original star-ground clock difference data to obtain a residual sequence; and obtaining the star-ground comparison accuracy by calculating the standard deviation of the residual sequence.

5. A space high-precision atomic clock performance evaluation system, characterized in that, The method comprises the following steps: The star-ground relative clock difference is calculated based on a two-way time difference measurement method, wherein a distance inconsistency time delay error is introduced in the calculation of the star-ground relative clock difference for correction; The stability, the sky stability, and the star-ground comparison accuracy are calculated based on the calculated star-ground relative clock difference, and the space high-precision atomic clock performance evaluation is realized based on the stability, the sky stability, and the star-ground comparison accuracy. In the process of obtaining stability based on the calculated satellite-ground relative clock difference, high-quality short samples are respectively intercepted from multiple transit arcs based on the calculated satellite-ground relative clock difference, the intercepted high-quality short samples are spliced into a virtual long continuous sequence, and the modified Allan variance table is calculated based on the virtual long continuous sequence to represent the stability , the calculation expression is ； wherein is the smoothing time, determined from the visible continuous arc length of the ground station for each pass of the low earth orbit satellite; is the smoothing factor, is the sampling interval ; is the total number of data; is the obtained satellite-ground relative clock error .

6. The system for evaluating performance of a space high-precision atomic clock according to claim 5, wherein, In the calculation of the star-ground relative clock difference based on the two-way time difference measurement method, The calculation expression of the star-ground relative clock difference is = (P1-P2) / 2 + r / 2 + & / 2; In the formula, is the relative clock error between the satellite and the ground; P1 is the uplink pseudorange measurement value; P2 is the downlink pseudorange measurement value; r is the distance inconsistency delay error; and 12 21 21 represents the comprehensive error of the propagation delay of the uplink signal propagation path, 12 represents the comprehensive error of the propagation delay of the downlink signal propagation path.​​ r = R 12 - R 21 = [D_(SG') - D_(GS')] / c; wherein R 21 represents the uplink signal propagation geometry distance delay, R 12 represents the downlink signal propagation geometry distance delay; D_(SG’) represents the downlink signal propagation geometry distance of the S transmitting ranging signal to the G receiving signal, D_(GS’) represents the uplink signal propagation geometry distance of the G transmitting ranging signal to the S receiving signal; S, G represent a low earth orbit satellite carrying a high-precision atomic clock and a ground station in turn respectively; c represents the speed of light.

7. The system for evaluating performance of a space high-precision atomic clock according to claim 6, wherein, The uplink pseudo-range measurement value P1 and the downlink pseudo-range measurement value P2 are obtained by: The low-orbit satellite carrying the high-precision atomic clock sends continuous ranging signals downward to the ground station through the microwave link ranging device of the fixed frequency f1, and the ground station sends continuous ranging signals upward to the low-orbit satellite through the microwave link ranging device of the fixed frequency f2; The microwave link ranging equipment of the ground station receives the signal transmitted by the low-orbit satellite, processes to obtain a downlink pseudo-range measurement value, and sends the downlink pseudo-range measurement value to the receiving and processing equipment of the ground processing center through a ground data transmission network; The microwave link ranging equipment of the low-orbit satellite receives the signal transmitted by the ground station, processes to obtain an uplink pseudo-range measurement value, and sends the uplink pseudo-range measurement value to the receiving and processing equipment of the ground processing center through a data telemetry return link.

8. The system for evaluating performance of a space high-precision atomic clock according to claim 6, wherein, The performance evaluation module implements a process of calculating stability, day stability and satellite-ground comparison accuracy based on the calculated satellite-ground relative clock difference, The step of calculating the day stability includes: obtaining satellite-ground relative clock difference data of a preset number of days as sample data, and calculating the day stability by using the stability calculation expression; The step of calculating the satellite-ground comparison accuracy includes: selecting satellite-ground measurement data of a continuous arc segment obtained by one-time transit measurement, calculating satellite-ground relative clock difference data of each time of the arc segment by using a two-way time difference measurement method, and eliminating outliers; performing high-order polynomial fitting on the clock difference data after eliminating outliers, and then subtracting the original satellite-ground clock difference data to obtain a residual sequence; and obtaining the satellite-ground comparison accuracy by calculating the standard deviation of the residual sequence.

9. An electronic device, comprising: Comprise: At least one processor; And The memory is in communication connection with the at least one processor; wherein The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the space high-precision atomic clock performance evaluation method according to any one of claims 1 to 4.

10. A computer readable storage medium storing a computer program, characterized in that, The computer program is executed by the processor to implement the space high-precision atomic clock performance evaluation method according to any one of claims 1 to 4.

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