Decentralized four-dimensional space-time reference unification method and time keeping device

Abstract

The invention relates to a decentralized four-dimensional space-time reference unification method and timekeeping devices. The method comprises the following steps: setting at least three timekeeping devices at different positions in a coordinate system; carrying out local measurement of original time through a time keeping device, and converting the original time into origin coordinates; a plurality of clock error data tables are generated by performing pairwise comparison on origin coordinates at regular intervals; checking the conversion coefficient and adjusting the calendar of the conversion coefficient according to the clock difference data table; according to the newest clock error data table, deviation checking and deviation calendar adjustment are carried out, and four-dimensional space-time reference unification is achieved on the basis of the four-dimensional space-time synchronism condition; and according to the calendar for completing the four-dimensional space-time reference unification and the original time of local measurement, converting the original time into broadcast coordinate time, and performing time service on other time users by using a broadcast timestamp. According to the invention, a time unification method which is stable for a long time and can be traced to SI second definition in a single centroid coordinate system is established.

Description

Technical Field

[0001] The present invention relates to the technical field of time measurement, and particularly to a method for unifying a four-dimensional space-time reference in a decentralized manner and a timekeeping device. Background Art

[0002] For future lunar bases, Martian bases, Jupiter's satellites, Saturn's satellites, asteroids, etc., as well as deep-space spaceflight missions, unified time is the common language of all mankind and is even the cornerstone of science, technology, and engineering. The relativistic effects of "moving clocks run slow, clocks in weak gravitational potentials run fast" on atomic clocks cannot be ignored. The "timekeeping - time dissemination" time rule based on the standard time on Earth is not applicable to a wide area far from the Earth. The problem of how to unify time remains a common problem in the fields of astronomy, metrology, space science, and technology.

[0003] Currently, common research such as "Lunar time in general relativity" proposed by American scholars Kopeikin and Kaplan, Phy Rev, 110(8):084047, Oct. 2024, and "A relativistic framework to estimate clock rates on the Moon" proposed by American scholars Ashby and Patla, The Astronomical Journal, 168:112(14pp), 2024 September, only focuses on the differences between the Earth and the Moon and does not give a solution to the problem of how to unify time among multiple timekeeping devices located at different positions.

[0004] Others such as the method for unifying time in a wide - area space and the space timekeeping system provided by Chinese Patent ZL2020106073336 and the method for unifying time and the time user system based on the pulsar serial number rule provided by Chinese Patent ZL202210482311.0, for the problem of time unification among multiple local areas spanning different coordinate systems, do not give a solution to the problem of how to unify time among timekeeping devices in a single barycentric coordinate system.

[0005] The timekeeping system on Earth has the characteristic of centralization. It takes the Time - Frequency Metrology Laboratory of the Bureau International des Poids et Mesures (BIPM) as the center, calculates TAI and publishes UTC. However, the timekeeping system on Earth is restricted to the geoid and can only measure proper time according to the SI second definition on the geoid. Other time users outside the geoid do not measure proper time according to the SI second definition.

[0006] Therefore, how to achieve the unified four-dimensional space-time reference in a decentralized manner and establish a long-term stable time-unification method in a separate centroid coordinate system that can be traced back to the SI second definition has become an urgent problem to be solved. Summary of the Invention

[0007] To solve the above technical problems existing in the prior art, the object of the present invention is to provide a decentralized four-dimensional space-time reference unification method and a timekeeping device, which operate a decentralized feedback mechanism to achieve time unification among multiple timekeeping devices.

[0008] To achieve the above object of the invention, the present invention proposes a decentralized four-dimensional space-time reference unification method, including the following steps:

[0009] Step S1: Set at least three timekeeping devices at different positions in the coordinate system;

[0010] Step S2: Locally measure the proper time through the timekeeping device, and convert the locally measured proper time into the origin coordinate time according to the ephemeris of the timekeeping device;

[0011] Step S3: Regularly compare the origin coordinate times of the timekeeping devices pairwise to generate multiple clock difference data tables;

[0012] Step S4: Check the conversion coefficient through the timekeeping device according to the multiple clock difference data tables, and adjust the ephemeris of the conversion coefficient according to the inspection result;

[0013] Step S5: Check the deviation amount through the timekeeping device according to the latest clock difference data table, and adjust the ephemeris of the deviation amount according to the inspection result to complete the unification of the four-dimensional space-time reference;

[0014] Step S6: Convert the proper time into the broadcast coordinate time through the timekeeping device according to the ephemeris of the completed four-dimensional space-time reference unification and the locally measured proper time, and use the broadcast coordinate time to time other time users.

[0015] According to a technical solution of the present invention, the calculation formula for converting the proper time into the origin coordinate time is:

[0016] t i = t 0i + t di +(1 + k i )τ i

[0017] where, t i is the origin coordinate time converted by the timekeeping device i;

[0018] t 0i is the initial time of the timekeeping device i, which is a fixed quantity after initialization;

[0019] t di is the coordinate origin delay time of the timekeeping device i, obtained from the ephemeris of the timekeeping device, t di = d i / c, where c is the speed of light in vacuum in m / s, and d i is the distance from the broadcast antenna position of the timekeeping device i to the origin of the coordinate system, with the unit of m;

[0020] k i is the conversion coefficient, obtained from the ephemeris of the timekeeping device, with the unit of relative value (dimensionless);

[0021] τ i is the local measured value of the proper time on the timekeeping device i, with the unit of SI second;

[0022] The calculation formula for converting the proper time to the broadcast coordinates is:

[0023] t xi = t i - t di = t 0i +(1 + k i )τ i

[0024] In the formula, t xi is the broadcast coordinate time of the timekeeping device i;

[0025] For d i and k i in the above two formulas, they can be found by indexing with the local measured value τ i of the proper time in the ephemeris of the timekeeping device i, or can be calculated using the ephemeris formula with the independent variable τ i .

[0026] According to a technical solution of the present invention, in the step S3, the pairwise comparison of the origin coordinate times includes:

[0027] The timekeeping device traverses other timekeeping devices in the coordinate system twice, obtains the origin coordinate times of other timekeeping devices, and calculates the difference between the origin coordinate times of the timekeeping device and other timekeeping devices in the coordinate system, abbreviated as "clock difference", to form a clock difference data table; the calculation formula for the difference between the origin coordinate times of the timekeeping device and other timekeeping devices in the coordinate system is:

[0028] Δt ij = t i - t j i,j = 1,2,3…i≠j

[0029] In the formula: Δt ij is the difference between the origin coordinate times of the timekeeping devices i and j in the coordinate system; t i and t jwhen they are the origin coordinates of the timekeeping devices i and j respectively.

[0030] According to a technical solution of the present invention, in the step S3, the setting principle of the frequency of pairwise comparison is as follows:

[0031] The frequency of pairwise comparison satisfies that within the shortest ephemeris period, the timekeeping devices within the coordinates are traversed at least 2 times; the number of clock difference data tables retained by the timekeeping devices at least satisfies spanning one longest ephemeris period.

[0032] According to a technical solution of the present invention, in the step S4, it specifically includes:

[0033] Step S41: Perform conversion coefficient check: The timekeeping device calculates the clock difference change rate between it and other timekeeping devices in the coordinate system according to multiple clock difference data tables, and generates a clock difference change rate table;

[0034] The calculation formula of the clock difference change rate is:

[0035] D ij (m) =Δt ij (m) -Δt ij (m-1) i,j = 1,2,3…i≠j

[0036] In the formula: D ij (m) is the clock difference change rate between the timekeeping devices i and j; Δt ij (m) is the difference between the origin coordinates of the timekeeping devices i and j in the clock difference data table formed by the mth pairwise comparison; Δt ij (m-1) is the difference between the origin coordinates of the timekeeping devices i and j in the clock difference data table formed by the (m - 1)th pairwise comparison;

[0037] Step S42: The timekeeping device calculates and determines whether the average value of the clock difference change exceeds the clock difference change rate limit value according to the clock difference change rate table;

[0038] Step S43: If so, execute step S44; otherwise, execute step S5;

[0039] Step S44: The timekeeping device performs conversion coefficient ephemeris adjustment, and performs conversion coefficient check on the timekeeping device that has completed the conversion coefficient ephemeris adjustment, and assigns an initial time to the timekeeping device that meets the conversion coefficient check limit condition after adjustment.

[0040] According to a technical solution of the present invention, in the step S44, it specifically includes:

[0041] Adjust the conversion coefficient ephemeris of the timekeeping device multiple times repeatedly, and check the conversion coefficient of the adjusted timekeeping device, so that the clock error change rate of the adjusted timekeeping device is less than the clock error change rate limit value until it converges and stabilizes, and make the timekeeping device that has completed the adjustment of the conversion coefficient ephemeris reach the condition of the adjustment conversion coefficient check limit value;

[0042] The conversion coefficient check limit value condition is:

[0043]

[0044] In the formula: is the average value of the clock error change rate of the timekeeping device i after the mth pairwise comparison; D lim is the clock error change rate limit value;

[0045] For the timekeeping device that reaches the conversion coefficient check limit condition after adjustment, correct the initial clock error according to the following formula:

[0046]

[0047] In the formula: i is the serial number of the timekeeping device, is the average value of the origin coordinates of other timekeeping devices except the timekeeping device i in the coordinate system.

[0048] According to a technical solution of the present invention, in the step S5, it specifically includes:

[0049] Step S51: Calculate the deviation average value of the timekeeping device according to the latest clock error data table, and screen out the timekeeping device with the largest deviation average value and greater than the deviation limit value as the over-deviation device;

[0050] Step S52: The over-deviation device actively adjusts the distance from the position of the broadcast antenna in its ephemeris to the origin of the coordinate system until the deviation average value of the over-deviation device does not exceed the deviation limit value.

[0051] According to a technical solution of the present invention, in the step S6, use the broadcast coordinate time to time other time users, specifically including:

[0052] The timekeeping device forms a time stamp according to the broadcast coordinate time and the position coordinates of the broadcast antenna and broadcasts it through the broadcast antenna to provide time service for other time users.

[0053] According to an aspect of the present invention, a timekeeping device is provided for implementing the above-mentioned decentralized four-dimensional space-time reference unification method, including:

[0054] A primary clock for locally measuring the primary time of the timekeeping device;

[0055] A coordinate real-time clock, which is used to convert the real time measured by the original real-time clock into the origin coordinate time and the broadcast coordinate time;

[0056] A comparison antenna, which is used to communicate with other timekeeping devices to obtain origin coordinate time comparison information;

[0057] A time service unit, which is used to generate a time stamp according to the broadcast coordinate time and the broadcast antenna position coordinates of the timekeeping device;

[0058] A broadcast antenna, which is used to unidirectionally broadcast a time stamp to time users in its nearby area, and time other time users through the time stamp;

[0059] A clock difference comparison unit, which is used to generate a clock difference data table and a clock difference change rate table according to the origin coordinate time comparison information, and perform conversion coefficient check and deviation amount check;

[0060] An ephemeris unit, which is used to record the ephemeris of the timekeeping device, and adjust the ephemeris according to the check results of the conversion coefficient check and the deviation amount check.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] The present invention proposes a decentralized four-dimensional space-time reference unification method, and establishes a long-term stable time unification method that can be traced back to the SI second definition. When multiple timekeeping devices existing on the surface of a celestial body with a centroid and in its nearby space orbit operate independently, due to the relativistic effect, the clock speeds are inconsistent, or the hardware has drift instability and other situations resulting in inconsistent clock readings, the present invention provides a solution. It solves the problem that the timekeeping system on the earth is limited to the geoid, and it is difficult for other time users to measure the original time according to the definition of the SI second. It also solves the problem that different original times within the same coordinate system cannot be directly compared due to the influence of the relativistic effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0064] Figure 1 Schematically showing the flowchart of the decentralized four-dimensional space-time reference unification method provided in an embodiment of the present invention;

[0065] Figure 2 Schematically showing the distribution diagram of the timekeeping device in the four-dimensional space-time coordinate system according to an embodiment of the present invention;

[0066] Figure 3 Schematically shows the working principle diagram of the timekeeping device according to an embodiment of the present invention. Detailed implementation manners

[0067] The description of the implementation manners of this specification should be combined with the corresponding drawings, and the drawings should be regarded as a part of the complete specification. In the drawings, the shape or thickness of the embodiments may be enlarged, and simplified or convenient markings are used. Furthermore, the parts of each structure in the drawings will be described separately. It should be noted that the elements not shown in the drawings or not described in words are in the forms known to those of ordinary skill in the art.

[0068] Any reference to directions and orientations in the description of the embodiments herein is only for the convenience of description and should not be construed as any limitation to the protection scope of the present invention. The following description of the preferred embodiments involves combinations of features, which may exist independently or in combination. The present invention is not particularly limited to the preferred embodiments. The scope of the present invention is defined by the claims.

[0069] As Figure 1 shown, a decentralized four-dimensional space-time reference unification method provided by the present invention includes the following steps:

[0070] Step S1: Set at least three timekeeping devices at different positions in the coordinate system;

[0071] Step S2: Locally measure the proper time through the timekeeping device, and convert the locally measured proper time into the origin coordinate time according to the ephemeris of the timekeeping device;

[0072] Step S3: Regularly compare the origin coordinate times of the timekeeping devices pairwise to generate multiple clock difference data tables;

[0073] Step S4: Check the conversion coefficients through the timekeeping device according to the multiple clock difference data tables, and adjust the ephemeris of the conversion coefficients according to the inspection results;

[0074] Step S5: Check the deviation amount through the timekeeping device according to the latest clock difference data table, and adjust the ephemeris of the deviation amount according to the inspection results to complete the four-dimensional space-time reference unification;

[0075] Step S6: Convert the proper time into the broadcast coordinate time through the timekeeping device according to the ephemeris after completing the four-dimensional space-time reference unification and the locally measured proper time, and use the broadcast coordinate time to time other time users.

[0076] The method of the present invention for unifying the time of the space-time reference on the barycentric coordinate system outside the Earth (such as the barycentric coordinate systems of the Moon, Mars, Jupiter's satellites, Mars' satellites, etc.) solves the problem that different proper times within the same coordinate system cannot be directly compared due to the influence of relativistic effects.

[0077] The embodiments of the present invention will be described below with reference to the accompanying drawings of the specification.

[0078] The following are some noun terms whose meanings are reaffirmed in this embodiment:

[0079] Barycentric coordinate system: A coordinate system with the origin of coordinates at the center of mass of the system, and the origin of coordinates is unanimously recognized by all observers.

[0080] Timekeeping device: A device that independently measures proper time, participates in system feedback, and broadcasts coordinate time.

[0081] Proper time: According to the definition of the SI second, the time measured locally by a timekeeping device.

[0082] Coordinate time: The time measured by a clock at the origin of the barycentric coordinate system or at an infinite distance point according to the definition of the SI second. Coordinate time cannot physically exist. Only through calculation can the measured proper time be converted into coordinate time. When there is a simultaneity condition, the time scale (or called time unit, clock step, clock running speed, etc.) of the clock can be corrected, and the time can be directly measured according to the scale of the coordinate time. The reading of this clock can be used as the coordinate time.

[0083] Ephemeris: A list in which the space parameters change with time and the space parameter values are indexed by time, and it can also be represented by a time-varying function. The space parameters include, but are not limited to, space coordinate values, coordinate time conversion coefficients, etc.

[0084] Ephemeris period: The period during which the space parameters in the ephemeris change with time. When there are multiple periods superimposed, the period with the largest change in the amplitude of the space parameters is taken as the ephemeris period.

[0085] Time stamp: The four-dimensional coordinate values of the broadcast antenna, which provide the position and time information of the antenna to the covered area in the form of omnidirectional propagation of electromagnetic wave signals. The four-dimensional coordinate values include three space coordinate values and a time value.

[0086] In an embodiment of the present invention, a decentralized four-dimensional space-time reference unification method is provided, which includes six steps: measuring proper time, calculating coordinate time, comparing coordinate time, checking and adjusting the conversion coefficient, checking and adjusting the deviation amount, and broadcasting the time stamp. Specifically, it includes:

[0087] Step S1: Set at least three timekeeping devices at different positions in the coordinate system;

[0088] The positions of the timekeeping devices can be set to be fixed on the celestial body surface or to orbit the celestial body with the satellite.

[0089] Step S2: Perform local measurement of the proper time through a timekeeping device, and convert the locally measured proper time into the origin coordinate time according to the ephemeris of the timekeeping device;

[0090] The coordinate time is calculated by using a conversion formula to calculate the two types of coordinate times corresponding to the proper time, namely the origin coordinate time and the broadcast coordinate time.

[0091] The origin coordinate time is the coordinate time at the origin of the coordinate system, and the four-dimensional space-time simultaneity can be checked by comparing the clocks of the timekeeping devices pairwise. The origin coordinate time is denoted by the symbol t i and its calculation formula is as follows:

[0092] t i = t 0i + t di +(1 + k i )τ i (1)

[0093] In the formula: t i is the origin coordinate time converted by the timekeeping device i;

[0094] t 0i is the initial time of the timekeeping device i. After initialization, the initial time of the timekeeping device is a fixed quantity;

[0095] t di is the coordinate origin delay time of the timekeeping device i, t di = d i / c, where c is the speed of light in vacuum in m / s, and d i is the distance from the broadcast antenna position of the timekeeping device i to the origin of the coordinate system, with the unit of m. d i can be queried through the ephemeris;

[0096] k i is the conversion coefficient, with the unit of relative value (dimensionless). k i can be queried through the ephemeris;

[0097] τ i is the proper time measured by the timekeeping device i, that is, the reading of the proper time clock on the timekeeping device, with the unit of SI second.

[0098] The broadcast coordinate time is used to provide a time stamp for the time service unit for use by other time users. The broadcast coordinate time is denoted by the symbol t xi and its calculation formula is as follows:

[0099] t xi = t i - t di = t 0i +(1 + k i )τ i(2)

[0100] where t xi is the broadcast coordinate time converted by the timekeeping device i and is used to form a timestamp.

[0101] In formulas (1) and (2), the proper time τ i is a quantity that increases uniformly, indicating the uniform passage of local time. Among them, d i and k i can be found by indexing from the local measurement value τ of the proper time in the ephemeris of the timekeeping device i, or can be calculated using the ephemeris formula of the independent variable τ i i .

[0102] In formulas (1) and (2), the conversion coefficient k i is a quantity to be adjusted and is a relatively stable small quantity. If the timekeeping device i is fixed on the surface of the celestial body, the value of k i is related to the position altitude of the proper time clock of the timekeeping device i and the tidal gravitational potential of the celestial body where the timekeeping device i is located. At initialization, the k i ephemeris of the timekeeping device i is known. Using the proper time τ measured by the timekeeping device i as the time index, look up the ephemeris to obtain the real-time value of k i ; if the timekeeping device i orbits the celestial body with the satellite, when the satellite is not affected by other forces except gravity, the motion of the satellite is geodesic motion, also known as free-fall motion. At this time, the value of k i is a stable small quantity. Only when the orbital parameters change (such as orbit transfer or orbit maintenance) and the conversion coefficient k i ephemeris needs to be adjusted, perform a one-time adjustment of the conversion coefficient k i ephemeris. During normal operation, the k i ephemeris does not need to be adjusted.

[0103] In formula (1), the origin delay time t di is a real-time variable that can be found through the ephemeris. At initialization, the d i ephemeris of the timekeeping device i is known information. Using the proper time τ measured by the timekeeping device i as the time index, look up the table to obtain the real-time t di or d i value. If the timekeeping device i is fixed on the surface of the celestial body, then d i is a fixed value; if the timekeeping device i orbits the celestial body with the satellite, d i is expressed by the ephemeris. When the origin of the coordinate system is still uncertain, the d i ephemeris is also a quantity to be adjusted.

[0104] In formula (1), the initial time t 0i ​is the initialization time when other timekeeping devices j already exist in the coordinate system and timekeeping device i is added to the coordinate system to eliminate the initial clock error. When the proper times of all timekeeping devices are converted to the origin coordinates, they should all satisfy the simultaneity condition of four-dimensional spacetime. When timekeeping device i is newly added to the coordinate system, its initial time t 0i should be adjusted to

[0105]

[0106] In the formula: is the average value of the origin coordinates of other timekeeping devices in the coordinate system except timekeeping device i.

[0107] The simultaneity condition of four-dimensional spacetime is expressed as: the origin coordinates in the coordinate system are unique. At any moment, for any clock located at a non-origin position, after it is converted to the origin coordinates, it should ensure synchronization and simultaneity, expressed as:

[0108] t0 = t i -|R i | / c i = 1, 2, 3… (4)

[0109] In the formula: t0 is the unified origin coordinates in the ideal case, which is unique, with the unit of SI second; t i is the origin coordinates read by timekeeping device i at the position of R i ; |R i | is the distance from the clock of timekeeping device i to the coordinate origin, with the unit of m; R i is the position vector that can be found in the ephemeris, and c is the vacuum light speed constant.

[0110] The synchronization of the origin coordinates is the third term on the right side of equation (1), that is, guaranteed by the proper time definition and the coordinate time conversion coefficient, which is called the time scale conversion, converting from the SI second scale of the proper time to the coordinate time scale. The effect after conversion is to keep the clock speeds of the coordinate time clocks of each timekeeping device in the system synchronized.

[0111] The simultaneity of the origin coordinates is the first term on the right side of equation (1), guaranteed by the initial time t 0i . When a new timekeeping device is added, the initial time t 0i is assigned according to formula (3), inheriting the initial epoch of the existing timekeeping devices, eliminating the initial deviation, and making the newly added one have simultaneity with the existing ones.

[0112] Step S3: Regularly compare the origin coordinates pairwise through the timekeeping devices in the coordinate system to generate multiple clock difference data tables;

[0113] Comparing the origin coordinates is the process of pairwise comparing the origin coordinates of multiple timekeeping devices at different positions and establishing a clock difference data table after the comparison.

[0114] When comparing the origin coordinates, the timekeeping device i uses the relay satellite channel to bidirectionally compare the clocks with the timekeeping device j to eliminate the channel delay error. The direct comparison result is:

[0115] Δt ij = t i - t j i,j = 1,2,3… i≠j (5)

[0116] In the formula: Δt ij is the difference in origin coordinates between the timekeeping devices i and j; t i and t j are the converted origin coordinates of the timekeeping devices i and j respectively. When the simultaneity condition of the ideal four-dimensional spacetime is satisfied, the clock difference should be zero.

[0117] Each timekeeping device needs to store the pairwise comparison results of all timekeeping devices to form a clock difference data table, and multiple clock difference data tables form a clock difference database. This clock difference ratio database is stored in each timekeeping device and has the characteristics of decentralization, being not easily modified and lost. During the comparison, the two timekeeping devices exchange the comparison data of all other timekeeping devices, and the formed clock difference data table is shown in Table 1 below:

[0118] Timekeeping device 1 Timekeeping device 2 Timekeeping device 3 …… Timekeeping device n Timekeeping device 1 - <![CDATA[Δt 12 > <![CDATA[Δt 13 > …… <![CDATA[Δt 1n > Timekeeping device 2 <![CDATA[Δt 21 > - <![CDATA[Δt 23 > …… <![CDATA[Δt 2n > Timekeeping device 3 <![CDATA[Δt 31 > <![CDATA[Δt 32 > - <![CDATA[Δt 3n > …… …… …… …… - …… Timekeeping device n <![CDATA[Δt n1 > <![CDATA[Δt n2 > <![CDATA[Δt n3 > …… -

[0119] Table 1

[0120] Pairwise comparisons are carried out in sequence until all timekeeping devices are traversed. The traversal order from smallest to largest is 12, 13, …, 1n, 21, 23, …, 2n, 31, 32, …, 3n, …, (n - 1)1, (n - 1)2, (n - 1)3, …, (n - 1)n, n1, n2, n3, …, n(n - 1).

[0121] When carrying out pairwise comparisons, the frequency or interval of the comparison activities should ensure that within the shortest ephemeris period, at least 2 traversals are made, and a new clock difference data table is generated after each pairwise comparison; to retain as much historical data as possible, the number of clock difference data tables retained by the clock difference comparison unit in the timekeeping device should at least satisfy spanning one longest ephemeris period. The shortest ephemeris period refers to the time for the fastest-moving timekeeping device among all timekeeping devices to rotate or revolve one week, and the longest ephemeris period respectively refers to the time for the slowest-moving timekeeping device among all timekeeping devices to rotate or revolve one week.

[0122] During the generation process of the clock difference data table, it is added in sequence according to the order in which the timekeeping devices are added. The serial number of the newly added timekeeping device (abbreviated as the new hand) is the largest; when the coordinate time clock of the original timekeeping device i in the coordinate system is adjusted, then the unit in the i-th row and i-th column is assigned to the initial clock difference t 0i。In this embodiment, the coordinate time clock adjustment of the timekeeping device is achieved by adjusting the calendar table.

[0123] The process of a novice joining should not affect the already operating timekeeping devices. It can be marked in the clock difference data table. For example, if the novice number is n, the cell in the nth row and nth column can be assigned the value n to indicate that this novice does not participate in the comparison. The novice does not participate in the initial clock difference adjustment during the joining process. During the joining process, the novice checks the clock difference change rate between itself and other timekeeping devices and repeatedly adjusts its conversion coefficient k n , so that its clock difference change rate is less than the clock difference change rate limit value. Until it converges and stabilizes within the range of the clock difference change rate limit value, the initial clock difference of novice n can be corrected according to formula (3), and the initial clock difference t 0n of novice n is placed in the cell of the nth row and nth column in the clock difference data table to indicate that this novice can participate in the comparison within the coordinate system. If it cannot converge, the clock difference data of novice n cannot be used by other timekeeping devices for inspection and adjustment. The timekeeping device should be replaced or the calendar table should be updated.

[0124] For a timekeeping device that performs coordinate time clock adjustment midway, the process of its coordinate time clock adjustment should ensure that it does not affect other timekeeping devices that are operating within the coordinate system. Except for inheriting the original serial number, the adjustment process of the timekeeping device that performs coordinate time clock adjustment is the same as the process of a novice joining.

[0125] Step S4: The timekeeping device checks the conversion coefficient according to multiple clock difference data tables and adjusts the calendar table of the conversion coefficient according to the inspection results;

[0126] In step S4, it specifically includes:

[0127] Step S41: Perform conversion coefficient check: The timekeeping device calculates the clock difference change rate between itself and other timekeeping devices within the coordinate system according to multiple clock difference data tables and generates a clock difference change rate table;

[0128] Step S42: The timekeeping device calculates and determines whether the average value of the clock difference change exceeds the clock difference change rate limit value according to the clock difference change rate table;

[0129] Step S43: If so, execute step S44; otherwise, execute step S5;

[0130] Step S44: The timekeeping device adjusts the calendar table of the conversion coefficient and checks the conversion coefficient of the timekeeping device that has completed the adjustment of the calendar table of the conversion coefficient, and assigns an initial time to the timekeeping device that passes the conversion coefficient check.

[0131] In step S44, it specifically includes:

[0132] Adjust the conversion coefficient ephemeris of the timekeeping device once and repeatedly, and check the conversion coefficient of the adjusted timekeeping device to make the clock error change rate of the adjusted timekeeping device less than the limit value of the clock error change rate until it converges and stabilizes, so that the timekeeping device that has completed the adjustment of the conversion coefficient ephemeris passes the conversion coefficient check; correct the initial clock error of the timekeeping device that has passed the conversion coefficient check.

[0133] The clock error change rate refers to the difference between the clock error data at the same position in the clock error data table formed by two adjacent pairwise comparisons. Each timekeeping device finds its own serial number from the clock error database. For example, taking the serial number i as the object of investigation, list the comparison clock error data of the timekeeping device i in the order of traversal time to form the following clock error change rate table:

[0134] Timekeeping device 1 Timekeeping device 2 Timekeeping device 3 ...... Timekeeping device n The m-th traversal <![CDATA[Δt i1 (m) > <![CDATA[Δt i2 (m) > <![CDATA[Δt i3 (m) > <![CDATA[...... (m) > <![CDATA[Δt in (m) > The (m - 1)-th traversal <![CDATA[Δt i1 (m-1) > <![CDATA[Δt i2 (m-1) > <![CDATA[Δt i3 (m-1) > <![CDATA[...... (m-1) > <![CDATA[Δt in (m-1) > The (m - 2)-th traversal <![CDATA[Δt i1 (m-2) > <![CDATA[Δt i2 (m-2) > <![CDATA[Δt i3 (m-2) > <![CDATA[...... (m-2) > <![CDATA[Δt in (m-2) > ...... ...... ...... ...... - ...... The (m - k)-th traversal <![CDATA[Δt i1 (m-n) > <![CDATA[Δt i2 (m-n) > <![CDATA[Δt i3 (m-n) > <![CDATA[...... (m-n) > <![CDATA[Δt in (m-n) >

[0135] Table 2

[0136] Then the clock error change rate is calculated as:

[0137] Di j (m) =Δti j (m) -Δti j (m-1) i≠j, (6)

[0138] In the formula: D ij (m) is the clock error change rate of Δt ij ; Δt ij (m) is the difference between the origin coordinates of the timekeeping devices i and j in the clock error data table formed by the mth pairwise comparison; Δt ij (m-1) is the difference between the origin coordinates of the timekeeping devices i and j in the clock error data table formed by the (m - 1)th pairwise comparison.

[0139] Checking and adjusting the conversion coefficient is that each timekeeping device checks the clock error database. After each pairwise comparison traversal, a new clock error change rate table is formed, and the clock error change rate between itself and other timekeeping devices is calculated. For example, for the serial number i, if the average value of the clock error change rate exceeds the limit value according to formula (5), the conversion coefficient ephemeris needs to be adjusted. It is also possible to assign the value i to the i-th row and i-th column of the clock error data table to mark the timekeeping device i. The marked timekeeping device i does not participate in the initial time adjustment of other timekeeping devices in the coordinate system.

[0140] The timekeeping device that has passed the conversion coefficient check should satisfy:

[0141]

[0142] In the formula: is the average value of the clock difference change rate of the timekeeping device i after the m-th pairwise comparison; D lim is the limit value of the clock difference change rate, and the limit value D of the clock difference change rate is set at the beginning of the coordinate system establishment lim is the maximum value of the clock difference change rates of the first three timekeeping devices. When the 4th and more new devices are added later, the limit value D lim gradually decreases, but the number of timekeeping devices in the system should always be kept no less than three.

[0143] The i-th timekeeping device exceeding the limit value D of the clock difference change rate lim exits the simultaneity check, but the pairwise comparison work continues, continues to generate clock difference comparison data, and adjusts k i After the ephemeris, referring to the new device addition procedure, after checking and meeting the requirements, modify the assignment of the i-th row and i-th column to the initialization time t calculated according to (3) 0i . How to adjust k i Many technologies for adjusting the ephemeris are already mature, such as the PID adjustment algorithm, the Kalman filtering algorithm, the AI algorithm, the neural network algorithm, etc. The technical details are not involved in this embodiment.

[0144] Step S5: The timekeeping device performs a deviation check according to the latest clock difference data table, and adjusts the ephemeris of the deviation according to the check result to complete the unification of the four-dimensional space-time reference;

[0145] In step S5, it specifically includes:

[0146] Step S51: According to the latest clock difference data table, calculate the average deviation of the timekeeping device, and select the timekeeping device with the largest average deviation and greater than the deviation limit value as the over-deviation device;

[0147] Step S52: The over-deviation device actively adjusts the distance d from the position of the broadcast antenna in its ephemeris to the origin of the coordinate system i until the average deviation of the over-deviation device does not exceed the deviation limit value.

[0148] Checking the deviation is a process where each timekeeping device discovers the deviation and adjusts the ephemeris. The adjustment object should be selected according to the principle of "the largest average deviation".

[0149] The principle of the largest average deviation means that in the clock difference data table, calculate the average value of the absolute values of each row, and select the row where the largest average value is located.

[0150]

[0151] In the formula: is the average value of the absolute values of the clock differences in the i-th row of the clock difference data table, which is also called the average deviation of the timekeeping device i; Δt ijis the clock error data at the i-th row and j-th column in the clock error data table, representing the difference between the origin coordinates of the timekeeping devices i and j; M is the row number in the clock error data table, and it is selected from the rows where i = 1, 2,... n and deviates from the average value The row number M where the maximum value is located; is the average value of the absolute values of the clock errors in the M-th row; T lim is the deviation limit.

[0152] If the condition of formula (9) is satisfied, the timekeeping device corresponding to the M-th row in the clock error data table is called an over-deviator. The over-deviator M that appears should actively adjust the parameter d of the distance from the origin in the ephemeris M , and other timekeeping devices do not need to be adjusted. The over-deviator should assign the value T to the unit at the M-th row and M-th column in the clock error data table lim , as a mark, indicating that the over-deviator does not participate in the initial time adjustment of other timekeeping devices in the coordinate system.

[0153] Each time an over-deviation adjustment is performed, only 1 timekeeping device performs the over-deviation adjustment to ensure the stability of the coordinate system and avoid chaos caused by multiple timekeeping devices being adjusted simultaneously. When the value of T lim appears in a certain row and column of the clock error data table, other timekeeping devices should work normally and do not perform the deviation check represented by formulas (8), (9), and (10). Until the ephemeris of the timekeeping device M is adjusted and the requirement of formula (9) is met, the unit at the M-th row and M-th column in the table is assigned zero, and then the deviation check and adjustment procedure are restarted. When the coordinate system is initialized, there are only three timekeeping devices in the clock error data table, and T lim is set to

[0154] The method for the timekeeping device M to adjust d M in the ephemeris can use the trial-and-error method, which is not described in detail in this embodiment.

[0155] Step S6: Through the timekeeping device, according to the ephemeris that completes the four-dimensional space-time reference unification and the local measured proper time, convert the proper time into the broadcast coordinate time, and use the broadcast coordinate time to time other time users.

[0156] In step S6, using the broadcast coordinate time to time other time users specifically includes:

[0157] Through the timekeeping device, form a time stamp according to the broadcast coordinate time and the position coordinates of the broadcast antenna, and broadcast it through the broadcast antenna to provide time for other time users.

[0158] As Figure 3 shown, this embodiment also provides a timekeeping device for implementing the above decentralized four-dimensional space-time reference unification method, including:

[0159] The original time clock is a time measurement device that reproduces the SI second according to the SI second definition and locally measures the original time of the timekeeping device. The current technical status is that the SI second is reproduced by a cesium atomic clock. If the SI second is redefined in the International System of Units, it will be updated to the measurement device newly recommended by the International System of Units accordingly.

[0160] The coordinate time clock is a time measurement device that obtains the origin coordinate time through the calculation of formula (1) and the broadcast coordinate time through the calculation of formula (2) based on the original time clock. The initialization time t used in the calculation 0i is assigned by formula (3) when the timekeeping device i newly joins the coordinate system. The distance d to the origin and the conversion coefficient k used in the calculation i are obtained from the ephemeris unit indexed by the original time τ i . i

[0161] The ephemeris unit is used to record the ephemeris of the timekeeping device and adjust the ephemeris according to the inspection results of the conversion coefficient inspection and the deviation inspection. The ephemeris is a list of position coordinates and conversion coefficients indexed by the original time τ. When calculating formulas (1), (2), and (3), data can be found in the column of the conversion coefficient (k value) corresponding to the original time τ in the ephemeris and the column of the broadcast antenna coordinates (R) for the calculation of the formulas. i i

[0162] The comparison antenna is used to communicate with other timekeeping devices in the coordinate system to obtain the comparison information of the origin coordinate time. The comparison antenna is a radio transceiver antenna or an antenna for receiving and transmitting optical signals using laser communication, and it is required that the transceiver channel delays are symmetric.

[0163] The time service unit is used to generate a time stamp for broadcasting to other time users for time service. The time service unit obtains the broadcast coordinate time from the coordinate time clock, then obtains the position coordinate of the broadcast antenna from the ephemeris, and forms a time stamp (t xi , R i ) by combining the broadcast coordinate time t and the position coordinate R of the broadcast antenna. The time stamp is broadcast through the broadcast antenna, enabling the time users within the broadcast coverage area to receive the time stamp information and achieving the purpose of time and space unification. x i

[0164] The broadcast antenna is used to broadcast the time stamp information. The spatial coordinates of the broadcast antenna are represented in the ephemeris and are the reference benchmark for the space of the broadcast coverage area.

[0165] The clock difference comparison unit is to save the clock difference data of pairwise comparisons of all timekeeping devices to form a clock difference data table and a clock difference change rate table, and perform conversion coefficient inspection and deviation inspection based on the clock difference data table and the clock difference change rate table. It can have the ability to save long-term historical data and retain a certain capacity for expanding the number of timekeeping devices. ​​​​​

[0166] As Figure 2 shown Figure 2 is a schematic diagram of the distribution of timekeeping devices in a four-dimensional space-time coordinate system. The origin of the coordinate system is at the mass center of the system. There are three or more timekeeping devices distributed at different positions in the coordinate system. For example, timekeeping device 1 is fixed on the surface of the celestial body and moves with the celestial body. For example, timekeeping device 2 is in free fall on a circular orbit near the celestial body. For example, timekeeping device 3 is in free fall on an elliptical orbit near the celestial body. They all have their own ephemerides and know their spatial coordinates at different times By adjusting their respective conversion coefficients and deviation amounts to meet the four-dimensional space-time simultaneity condition of formula (4), the timekeeping devices can achieve a decentralized unification of the four-dimensional space-time reference

[0167] It should be noted that the above description is the preferred embodiment of the present invention. It should be pointed out that although the preferred embodiments of the present invention have been described, for those skilled in the art of this technology, once they know the basic creative concept of the present invention, without departing from the principle described in the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention

Claims

1. A decentralized four-dimensional spacetime benchmark unification method, characterized in that, It includes the following steps: Step S1: Set at least three timekeeping devices at different positions in the coordinate system; Step S2: Locally measure the proper time through the timekeeping devices, and convert the locally measured proper time into the origin coordinate time according to the ephemeris of the timekeeping devices; Step S3: Regularly compare the origin coordinate times of the timekeeping devices in pairs through the timekeeping devices to generate multiple clock difference data tables; Step S4: Check the conversion coefficients according to multiple clock difference data tables through the timekeeping devices, and adjust the ephemeris of the conversion coefficients according to the inspection results; Step S5: Check the deviation amount according to the latest clock difference data table through the timekeeping devices, and adjust the ephemeris of the deviation amount according to the inspection results to complete the unification of the four-dimensional space-time reference; Step S6: Convert the proper time into the broadcast coordinate time through the timekeeping devices according to the ephemeris of the completed four-dimensional space-time reference unification and the locally measured proper time, and use the broadcast coordinate time to time other time users.

2. The decentralized four-dimensional space-time reference unified method according to claim 1, wherein The calculation formula for converting the proper time into the origin coordinate time is: t i = t 0i + t di +(1 + k i )τ i where t i is the origin coordinate converted by the punctuality device i; t 0i is the initial time of the timekeeping device i, which is a fixed quantity after initialization; t di is the coordinate origin delay time of the timekeeping device i, obtained through the ephemeris of the timekeeping device, t di = d i / c, where c is the speed of light in vacuum in m / s, and d i is the distance from the position of the broadcast antenna of the timekeeping device i to the origin of the coordinate system, with the unit of m; k i is a conversion coefficient obtained from the ephemeris of the timekeeping device, with the unit being dimensionless relative value; τ i is the local measurement of the proper time on the timekeeping device i, in SI seconds; The calculation formula for converting the proper time into the broadcast coordinate time is: t xi = t i -t di = t 0i +(1 + k i )τ i where t xi is the broadcast coordinate time of the timing device i; The d in the above two equations i and k i are indexed by the local measurement τ of proper time in the ephemeris of the timing device i i .

3. The decentralized four-dimensional spacetime reference unification method according to claim 2, wherein In the step S3, the pairwise comparison of the origin coordinate times includes: Each timekeeping device traverses other timekeeping devices in the coordinate system twice, calculates the difference between the origin coordinate times of the timekeeping device and other timekeeping devices in the coordinate system, obtains the difference between the origin coordinate times of other timekeeping devices, and forms a clock difference data table; the calculation formula for the difference between the origin coordinate times of the timekeeping device and other timekeeping devices in the coordinate system is: Δt ij = t i - t j i, j = 1, 2, 3… i ≠ j where: Δt ij is the difference between the origin coordinates of the timekeeping devices i and j in the coordinate system; t i and t j are the origin coordinates of the timekeeping devices i and j, respectively.

4. The decentralized four-dimensional spacetime reference unified method according to claim 3, characterized in that, In the step S3, the setting principle of the frequency of the pairwise comparison is: The frequency of the pairwise comparison satisfies that within the shortest ephemeris period, at least traverse the timekeeping devices in the coordinate system 2 times; the number of clock difference data tables retained by the timekeeping devices at least satisfies spanning one longest ephemeris period.

5. The decentralized four-dimensional space-time reference unified method according to claim 3, wherein In the step S4, it specifically includes: Step S41: Conduct conversion coefficient inspection: The timekeeping device calculates the clock difference change rate between it and other timekeeping devices in the coordinate system according to multiple clock difference data tables, and generates a clock difference change rate table; The calculation formula for the clock difference change rate is: Where: D ij (m) is the rate of change of the clock difference between the timekeeping devices i and j; Δt ij (m) is the difference in the origin coordinates between the timekeeping devices i and j in the clock difference data table formed by the m-th pairwise comparison; Δt ij (m-1) is the difference in the origin coordinates between the timekeeping devices i and j in the clock difference data table formed by the (m - 1)-th pairwise comparison; Step S42: The timekeeping device calculates and judges whether the average clock difference change exceeds the clock difference change rate limit according to the clock difference change rate table; Step S43: If so, execute step S44; otherwise, execute step S5; Step S44: The timekeeping device adjusts the ephemeris of the conversion coefficient, checks the conversion coefficient of the timekeeping device after completing the adjustment of the ephemeris of the conversion coefficient, and assigns an initial time to the timekeeping device that meets the conversion coefficient inspection limit condition after adjustment.

6. The decentralized four-dimensional space-time reference unified method according to claim 5, characterized in that In the step S44, it specifically includes: Repeatedly adjust the ephemeris of the conversion coefficient of the timekeeping device multiple times, and check the conversion coefficient of the adjusted timekeeping device, so that the clock difference change rate of the adjusted timekeeping device is less than the clock difference change rate limit until it converges and stabilizes, and make the timekeeping device that completes the adjustment of the ephemeris of the conversion coefficient meet the conversion coefficient inspection limit condition; The conversion coefficient inspection limit condition is: In the formula: is the average value of the clock error change rate of the timekeeping device i after the m-th pairwise comparison; D lim is the limit value of the clock error change rate; For the timekeeping device that meets the conversion coefficient inspection limit condition after adjustment, correct the initial clock difference according to the following formula: Where: i is the serial number of the timekeeping device, is the average value of the origin coordinates of other timekeeping devices in the coordinate system except the timekeeping device i.

7. The decentralized four-dimensional space-time reference unified method according to claim 6, characterized in that In the step S5, it specifically includes: Step S51: Calculate the deviation average value of the timekeeping device according to the latest clock error data table, and screen out the timekeeping device with the largest deviation average value and greater than the deviation limit value as the over-deviation device; Step S52: The over-deviation device actively adjusts the distance from the broadcast antenna position in its ephemeris to the origin of the coordinate system until the deviation average value of the over-deviation device does not exceed the deviation limit value.

8. The decentralized four-dimensional spacetime reference unified method according to claim 1, wherein In the said Step S6, the broadcast coordinate time is used to time other time users, specifically including: The timekeeping device forms a timestamp according to the broadcast coordinate time and the position coordinates of the broadcast antenna, and broadcasts it through the broadcast antenna, providing it to other time users for timing.

9. A punctuality device for implementing the decentralized four-dimensional space-time reference unification method according to any one of claims 1 to 8, characterized in that, Including: A local clock, which is used to locally measure the local time of the timekeeping device; A coordinate clock, which is used to convert the local time measured by the local clock into the origin coordinate time and the broadcast coordinate time; A comparison antenna, which is used to communicate with other timekeeping devices to obtain the origin coordinate time comparison information; A timing unit, which is used to generate a timestamp according to the broadcast coordinate time and the position coordinates of the broadcast antenna of the timekeeping device; A broadcast antenna, which is used to unidirectionally broadcast the timestamp to the time users in its nearby area, and time other time users through the timestamp; A clock error comparison unit, which is used to generate a clock error data table and a clock error change rate table according to the origin coordinate time comparison information, and perform conversion coefficient check and deviation amount check; An ephemeris unit, which is used to record the ephemeris of the timekeeping device, and adjust the ephemeris according to the check results of the conversion coefficient check and the deviation amount check.

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