Time comparison method and device, electronic equipment and storage medium

Abstract

The application provides a time comparison method and device, electronic equipment and storage medium, and relates to the technical field of satellite navigation and timing. The method comprises the following steps: extracting the observation value of the total delay of the oblique path of the RDSS signal by using the fixed elevation penetration path of the RDSS signal; decomposing the theoretical value of the total delay of the oblique path of the RDSS signal into a zenith delay variable and a horizontal gradient variable; minimizing the difference between the theoretical value and each observation value to obtain the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector, and constructing the target constraint function of the tropospheric delay in the double-difference carrier phase observation equation of the RNSS signal; calculating the estimated value of the double-difference phase ambiguity based on the double-difference carrier phase observation equation and the target constraint function, and calculating the time bias based on the estimated value of the double-difference phase ambiguity. The application can not only maintain the high precision close to the TWSTFT method, but also has the advantages of low cost and high availability of the GNSS PPP method.

Description

Technical Field

[0001] This invention relates to the field of satellite navigation and timing technology, and in particular to a time comparison method, apparatus, electronic device, and storage medium. Background Technology

[0002] High-precision time comparison technology has permeated many aspects of national science and technology, economy, military and social life. With the development of science and technology, the requirements for time comparison accuracy are also getting higher and higher.

[0003] Currently, the commonly used high-precision long-distance time comparison methods mainly include the following.

[0004] 1) The Two-Way Time-Frequency Transfer (TWSTFT) method involves two ground stations transmitting and receiving time signals from the same communication satellite. By calculating and eliminating common path errors, high-precision clock matching between the two locations is achieved. TWSTFT is currently recognized internationally as one of the most accurate long-distance time transfer technologies, with a time matching uncertainty typically better than 1 nanosecond, and is often used as the "gold standard" for verifying other methods. However, TWSTFT relies on expensive ground station equipment and dedicated satellite communication resources, resulting in extremely high system construction and maintenance costs, which significantly limits its large-scale adoption and application.

[0005] 2) The Global Navigation Satellite System Precise Point Positioning (GNSS PPP) method utilizes precise satellite ephemeris and clock bias products provided by a globally continuously operating network of reference stations. A single receiver at the user end can correct observations using complex error models (such as ionospheric and tropospheric delays) to achieve high-precision absolute positioning and time recovery. The GNSS PPP method eliminates the dependence on common-view satellites found in traditional common-view methods, offering high flexibility. However, its final accuracy heavily depends on the accuracy of tropospheric delay modeling and involves a convergence process ranging from tens of minutes to several hours, making it difficult to achieve high-precision real-time or near-real-time time transfer.

[0006] Specifically, the GNSS PPP method typically relies on carrier phase observations of Radio Navigation Satellite Service (RNSS) signals. However, this method is significantly affected by time-varying tropospheric delays; in long-baseline scenarios, this error can reach the centimeter level (equivalent to tens of nanoseconds), and the low efficiency and difficulty in ambiguity resolution become the main bottlenecks restricting its accuracy and reliability.

[0007] 3) In addition to providing RNSS services, my country's global satellite navigation system, the BeiDou Navigation Satellite System, also uniquely offers Radio Determination Satellite Service (RDSS). While providing communication services, it can also perform time transfer using a two-way pseudorange comparison method. However, the accuracy of this method is limited by pseudorange observation noise (typically 10 ns), making it difficult to meet the requirements for precise time and frequency transfer at the nanosecond level.

[0008] Furthermore, existing PPP technologies widely employ empirical tropospheric models (such as Saastamoinen and UNB3m) for delay correction. However, these models do not adequately consider the spatiotemporal variations in water vapor content, especially the changes in the horizontal gradient, resulting in measured residuals greater than 5 cm. Under severe weather conditions, the error will further increase, introducing significant systematic bias.

[0009] Therefore, there is an urgent need to develop a new long-distance time comparison method that can maintain the high accuracy close to that of the TWSTFT method while possessing the advantages of low cost and high availability of the GNSS PPP method. Summary of the Invention

[0010] This invention provides a time comparison method, apparatus, electronic device, and storage medium that can maintain the high accuracy close to the TWSTFT method while possessing the low cost and high availability advantages of the GNSS PPP method.

[0011] This invention provides a time comparison method, comprising:

[0012] The observation value of the total slant path delay of the satellite radio determination service signal is extracted using the fixed elevation angle penetration path of the satellite radio determination service signal;

[0013] The theoretical value of the total slant path delay of the satellite radio determination service signal is decomposed into a zenith delay variable and a horizontal gradient variable; the zenith delay variable includes the tropospheric vertical path delay in the zenith direction, and the horizontal gradient variable includes the horizontal gradient vector.

[0014] By minimizing the difference between the theoretical value and each of the observed values, the optimal solution for the tropospheric vertical path delay in the zenith direction and the optimal solution for the horizontal gradient vector are obtained.

[0015] Using the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector as prior values, the target constraint function of the tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal is constructed.

[0016] The estimated value of the double-difference phase ambiguity is calculated based on the double-difference carrier phase observation equation and the target constraint function, and the time deviation is calculated based on the estimated value of the double-difference phase ambiguity.

[0017] According to a time comparison method provided by the present invention, the step of extracting the observed value of the slant path total delay of the satellite radio determination service signal using the fixed elevation angle penetration path of the satellite radio determination service signal includes:

[0018] Acquire multiple pseudorange observations of the satellite radio ranging service signal;

[0019] For each pseudorange observation, the corresponding geometric distance between the satellite and the receiver, as well as the pseudorange coarse synchronization clock error of the satellite radio navigation service signal, are extracted from the pseudorange observation to obtain the observed value of the total slant path delay of the satellite radio determination service signal.

[0020] According to a time comparison method provided by the present invention, minimizing the difference between the theoretical value and each of the observed values ​​to obtain the optimal solution for the tropospheric vertical path delay in the zenith direction and the optimal solution for the horizontal gradient vector includes:

[0021] Construct an objective function that minimizes the square of the Euclidean norm of the difference between each observed value and the theoretical value;

[0022] The objective function is solved using the least squares method to obtain the optimal solution for the vertical path delay of the troposphere in the zenith direction and the optimal solution for the horizontal gradient vector.

[0023] According to a time comparison method provided by the present invention, the step of constructing a target constraint function for the tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal by using the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector as prior values ​​includes:

[0024] Obtain the observation vector composed of the double-difference carrier phase observations of the satellite radio navigation service signal at multiple epochs;

[0025] The parameter vector to be estimated is constructed based on the optimal solution of double-difference hardware delay, double-difference phase ambiguity, the optimal solution of the tropospheric vertical path delay in the zenith direction, and the optimal solution of the horizontal gradient vector.

[0026] Calculate the Jacobian matrix of the observation vector relative to the parameter vector based on the observation equation;

[0027] Obtain the tropospheric delay vector composed of tropospheric delays from multiple epochs;

[0028] Obtain tropospheric prior values ​​retrieved from the satellite radio ranging service signals;

[0029] The first regularization term is constructed based on the observation vector, the parameter vector to be estimated, and the Jacobian matrix;

[0030] A second regularization term is constructed based on the tropospheric delay vector, the tropospheric prior value, and the constraint weights;

[0031] The target constraint function is constructed based on the first regularization term and the second regularization term.

[0032] According to a time alignment method provided by the present invention, the step of constructing a first regularization term based on the observation vector, the parameter vector to be estimated, and the Jacobian matrix includes:

[0033] Construct a first regularization term that minimizes the square of the Euclidean norm of the product between the observed vector and the parameter vector to be estimated and the Jacobian matrix.

[0034] According to a time comparison method provided by the present invention, the step of constructing a second regularization term based on the tropospheric delay vector, the tropospheric prior value, and the constraint weights includes:

[0035] The second regularization term is constructed by multiplying the square of the Euclidean norm of the difference between the tropospheric delay vector and the tropospheric prior value with the constraint weight.

[0036] The present invention also provides a time comparison device, comprising:

[0037] The extraction module is used to extract the observed value of the total slant path delay of the satellite radio determination service signal using the fixed elevation angle penetration path of the satellite radio determination service signal;

[0038] The decomposition module is used to decompose the theoretical value of the total oblique path delay of the satellite radio determination service signal into a zenith delay variable and a horizontal gradient variable; the zenith delay variable includes the tropospheric vertical path delay in the zenith direction, and the horizontal gradient variable includes a horizontal gradient vector.

[0039] The solution module is used to minimize the difference between the theoretical value and each of the observed values, and to obtain the optimal solution for the vertical path delay of the troposphere in the zenith direction and the optimal solution for the horizontal gradient vector.

[0040] A construction module is used to construct the target constraint function for tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal by using the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector as prior values.

[0041] The calculation module is used to calculate the estimated value of the double-difference phase ambiguity based on the double-difference carrier phase observation equation and the target constraint function, and to calculate the time deviation based on the estimated value of the double-difference phase ambiguity.

[0042] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the time comparison method as described above.

[0043] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the time comparison method as described above.

[0044] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the time comparison method as described above.

[0045] The time comparison method, apparatus, electronic device, and storage medium provided by this invention firstly extract the observed value of the total oblique path delay of the satellite radio determination service signal by utilizing the fixed elevation angle penetration path of the signal. This enables independent measurement of tropospheric delay, overcoming the limitations of traditional models that rely on meteorological parameters and avoiding the introduction of significant systematic biases, thereby improving the accuracy of time comparison. The theoretical value of the total oblique path delay of the satellite radio determination service signal is decomposed into a zenith delay variable and a horizontal gradient variable. The zenith delay variable includes the tropospheric vertical path delay in the zenith direction, and the horizontal gradient variable includes the horizontal gradient vector. Then, by minimizing the difference between the theoretical value and each observed value, the optimal solutions for the tropospheric vertical path delay in the zenith direction and the horizontal gradient vector are obtained. Using the optimal solutions for the tropospheric vertical path delay in the zenith direction and the horizontal gradient vector as prior values, a target constraint function for the tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal is constructed. Based on the double-difference carrier phase observation equation and the target constraint function... The calculation of the estimated value of double-difference phase ambiguity has several advantages. First, by using satellite radio determination service signal measurements to constrain the correction of tropospheric delay, the accuracy of tropospheric delay correction can be improved. Second, the target constraint function considers horizontal gradient changes, which can reduce errors and thus improve the accuracy of time comparison. Third, using the target constraint function can narrow the ambiguity search range, thereby increasing the success rate of ambiguity fixation, which in turn improves the accuracy and reliability of time comparison, and reduces the dimensionality of the parameters to be estimated, thus improving the efficiency of ambiguity resolution. Fourth, instead of directly using satellite radio determination service signal measurements for time comparison, a tropospheric correction model (i.e., double-difference carrier phase observation equation and target constraint function) is established using these measurements, and parameters are estimated through observations from multiple epochs, which is equivalent to smoothing, thereby suppressing the influence of pseudorange noise and meeting the requirements of precise time and frequency transmission at the nanosecond level. Fifth, finally, the time deviation is calculated based on the estimated value of double-difference phase ambiguity, which can realize the resolution of sub-nanosecond time deviation between receivers. Furthermore, RDSS and RNSS dual-mode receivers are less expensive than those used in the TWSTFT method, reducing system construction and maintenance costs and facilitating large-scale adoption and application. Therefore, the time comparison method of this invention maintains near-TWSTFT accuracy while also possessing the low cost and high availability advantages of the GNSS PPP method. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0047] Figure 1 This is a flowchart illustrating the time comparison method provided in an embodiment of the present invention.

[0048] Figure 2 This is a system composition block diagram provided in the embodiments of the present invention.

[0049] Figure 3 This is a schematic diagram of the joint calculation process of the time comparison method provided in the embodiment of the present invention.

[0050] Figure 4 This is a timing diagram of two sets of clock differences provided in an embodiment of the present invention.

[0051] Figure 5 This is a schematic diagram of the Allan variance of two sets of clock errors provided in an embodiment of the present invention.

[0052] Figure 6 This is a schematic diagram of the time comparison device provided in an embodiment of the present invention.

[0053] Figure 7 This is a schematic diagram of the structure of the electronic device provided in an embodiment of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0055] The following is combined Figures 1-4 The time comparison method of the present invention is described.

[0056] Please refer to Figure 1 , Figure 1 This is a flowchart illustrating the time comparison method provided in an embodiment of the present invention. Figure 1 As shown, the method includes the following steps 101-105.

[0057] Step 101: Extract the observed value of the total slant path delay of the satellite radio measurement service signal using the fixed elevation angle penetration path of the satellite radio measurement service signal.

[0058] Specifically, by utilizing the physical characteristics of the fixed elevation angle penetration path of Radio Determination Satellite Service (RDSS) signals, the slant total delay (STD) of RDSS signals was measured independently for the first time, obtaining the observed value of the slant total delay of RDSS signals. This can overcome the limitations of traditional models that rely on meteorological parameters.

[0059] In one embodiment, step 101 includes: acquiring multiple pseudorange observations of the satellite radio determination service signal; for each pseudorange observation, extracting the corresponding geometric distance between the satellite and the receiver and the pseudorange coarse synchronization clock error of the satellite radio navigation service signal from the pseudorange observation to obtain the observation of the total slant path delay of the satellite radio determination service signal.

[0060] Specifically, the observed value of the total slant path delay of the RDSS signal can be extracted using the following expression (1):

[0061] (1)

[0062] in, The observed value representing the total slant path delay of the RDSS signal. This represents the pseudorange observation of the RDSS signal. This represents the geometric distance between the corresponding satellite and the receiver (calculated from RDSS positioning coordinates). Represents the speed of light. This represents the pseudorange coarse synchronization clock error (accuracy 5ns) of the Radio Navigation Satellite Service (RNSS) signal.

[0063] Step 102: Decompose the theoretical value of the total slant path delay of the satellite radio determination service signal into zenith delay variable and horizontal gradient variable; the zenith delay variable includes the tropospheric vertical path delay in the zenith direction, and the horizontal gradient variable includes the horizontal gradient vector.

[0064] Specifically, it can be decomposed using the following expression (1):

[0065] (2)

[0066] In this diagram, the variable to the left of the plus sign represents the zenith component, and the variable to the right of the plus sign represents the horizontal gradient component. This represents the theoretical value of the total skew path delay of the RDSS signal. This indicates the vertical path delay of the troposphere in the zenith direction. and This represents the components of the horizontal gradient in the north and east directions. Indicates the satellite azimuth angle. This indicates the fixed elevation angle of the satellite (values ​​range from 30° to 40°, with a typical value of around 35° in China).

[0067] Step 103: Minimize the difference between the theoretical value and each observed value to obtain the optimal solution for the vertical path delay of the troposphere in the zenith direction and the optimal solution for the horizontal gradient vector.

[0068] In one embodiment, step 103 includes: constructing an objective function that minimizes the square of the Euclidean norm of the difference between each observed value and the theoretical value; and solving the objective function using the least squares method to obtain the optimal solution for the vertical path delay of the troposphere in the zenith direction and the optimal solution for the horizontal gradient vector.

[0069] Specifically, the objective function is constructed using the following expression (3):

[0070] (3)

[0071] in, Represents the horizontal gradient vector. .

[0072] The least squares method is used to solve expression (3) to obtain the following results. The optimal solution and The optimal solution.

[0073] Step 104: Using the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector as prior values, construct the target constraint function of the tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal.

[0074] Specifically, the double-difference carrier phase observation equation for the RNSS signal is shown in expression (4):

[0075] (4)

[0076] in, This indicates the physical parameters that have undergone double-difference (inter-satellite and inter-station difference) processing. Indicates the wavelength of the RNSS signal. This represents the carrier phase observation of the RNSS signal. This represents the geometric distance between the phase centers of the satellite and the station antenna. Indicates hardware latency. Indicates phase ambiguity. This represents the tropospheric delay, which is the part that can be constrained by prior values. This indicates measurement noise.

[0077] In one embodiment, step 104 includes substeps 1041-1048.

[0078] Step 1041: Obtain double-difference carrier phase observations of satellite radio navigation service signals at multiple epochs. Observation vector (in meters) , This represents the double-difference carrier phase observation of the RNSS signal (in cycles, i.e., the number of electromagnetic wave cycles).

[0079] Step 1042, based on double-difference hardware delay Double-difference phase ambiguity The optimal solution for the vertical path delay of the troposphere in the zenith direction The optimal solution of the horizontal gradient vector Construct the parameter vector to be estimated , .

[0080] Step 1043, based on the observation equation Calculate the observation vector Relative to parameter vector Jacobian matrix (i.e., the partial derivative matrix).

[0081] Step 1044: Obtain tropospheric delays for multiple epochs. Constructed tropospheric delay vector .

[0082] Step 1045: Obtain the tropospheric prior values ​​obtained from the inversion of satellite radio determination service signals. .

[0083] Step 1046, Based on observation vectors The parameter vector to be estimated And Jacobi matrix Construct the first regular expression term.

[0084] Optionally, step 1046 includes: constructing a minimized observation vector With the parameter vector to be estimated And Jacobi matrix The first regular term of the square of the Euclidean norm of the difference between the products. .

[0085] Step 1047: Based on tropospheric delay vector Tropospheric prior values and constraint weights Construct the second regularization term.

[0086] Optionally, step 1047 includes: constructing a tropospheric delay vector. and tropospheric prior values The square of the Euclidean norm of the difference between the two and the constraint weights The second regularization term of the product between .

[0087] Step 1048: Construct the objective constraint function based on the first regularization term and the second regularization term.

[0088] Alternatively, the objective constraint function can be constructed using the following expression (5):

[0089] (5)

[0090] in, yes The value calculated relative to expression (4) The Jacobian matrix, optionally, =0.7, which is used as an empirical value for the constraint weight.

[0091] Step 105: Calculate the estimated value of the double-difference phase ambiguity based on the double-difference carrier phase observation equation and the target constraint function, and calculate the time deviation based on the estimated value of the double-difference phase ambiguity.

[0092] Specifically, the classic LAMBDA method can be used to calculate the estimated value of the double-difference phase ambiguity based on the double-difference carrier phase observation equation and the target constraint function. .

[0093] Tropospheric prior values ​​obtained from RDSS inversion As a priori constraint, embedding the double-difference carrier phase observation equation can reduce the dimension of the parameters to be estimated by 50% and improve the efficiency of ambiguity resolution.

[0094] The time deviation is calculated using the following expression (6):

[0095] (6)

[0096] in, Indicates time deviation.

[0097] In practical implementation, the time comparison accuracy calculated using the time comparison method of this embodiment reaches 0.98 ns (3000 km baseline), which meets the sub-nanosecond requirements of quantum communication, gravitational wave detection, etc.

[0098] The time comparison method provided in this invention first extracts the observed value of the total slant path delay of the satellite radio determination service signal by utilizing the fixed elevation angle penetration path of the signal. This enables independent measurement of tropospheric delay, overcoming the limitations of traditional models that rely on meteorological parameters and avoiding the introduction of significant systematic biases, thereby improving the accuracy of time comparison. The theoretical value of the total slant path delay of the satellite radio determination service signal is decomposed into a zenith delay variable and a horizontal gradient variable. The zenith delay variable includes the tropospheric vertical path delay in the zenith direction, and the horizontal gradient variable includes the horizontal gradient vector. Then, by minimizing the difference between the theoretical value and each observed value, the optimal solutions for the tropospheric vertical path delay in the zenith direction and the horizontal gradient vector are obtained. Using these optimal solutions as prior values, a target constraint function for the tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal is constructed. Based on the double-difference carrier phase observation equation and the target constraint function, the double-difference phase... The estimation of tropospheric ambiguity has several advantages. First, by using satellite radio determination service signal measurements to constrain tropospheric delay correction, the accuracy of tropospheric delay correction can be improved. Second, the target constraint function considers horizontal gradient changes, which can reduce errors and thus improve the accuracy of time comparison. Third, using the target constraint function can narrow the ambiguity search range, thereby increasing the success rate of ambiguity fixation, which in turn improves the accuracy and reliability of time comparison, and reduces the dimensionality of the parameters to be estimated, thus improving the efficiency of ambiguity resolution. Fourth, instead of directly using satellite radio determination service signal measurements for time comparison, the measurement values ​​are used to establish a tropospheric correction model (i.e., the double-difference carrier phase observation equation and the target constraint function), and parameter estimation is performed through observations from multiple epochs, which is equivalent to smoothing, thereby suppressing the influence of pseudorange noise and meeting the requirements of precise time and frequency transmission at the nanosecond level. Fifth, finally, the time deviation is calculated based on the estimated value of double-difference phase ambiguity, which can realize the resolution of sub-nanosecond time deviation between receivers. Furthermore, RDSS and RNSS dual-mode receivers are less expensive than those used in the TWSTFT method, reducing system construction and maintenance costs and facilitating large-scale adoption and application. Therefore, the time comparison method in this embodiment maintains near-TWSTFT accuracy while also offering the low cost and high availability advantages of the GNSS PPP method.

[0099] The following is combined Figure 2-4 Using data from a specific region within a certain timeframe in 2021, the accuracy (including precision and stability) of the time comparison method provided in this embodiment of the invention is verified.

[0100] like Figure 2 As shown, the time comparison system includes an STD extraction module, a joint solver, and a time deviation output interface.

[0101] For the STD extraction module, such as Figure 2 and 3 As shown, firstly, multiple pseudorange observations of the input RDSS signal are... Specifically, the system receives RDSS signals from a Geostationary Earth Orbit (GEO) satellite (PRN C01, the BeiDou C01 satellite). The master control station sends the signal, which is relayed by the satellites. The RDSS receiver receives the signal from one satellite and then transmits it to multiple satellites, which then relay it back to the master control station for measurement. Therefore, a single measurement can simultaneously obtain measurements from multiple satellites, i.e., multiple pseudorange observations of the RDSS signal. Then, based on the RDSS signal, elevation data transmitted by the barometer / digital elevation model (DEM), and satellite ephemeris, the user's position (i.e., RDSS positioning coordinates) is calculated. Based on the RDSS positioning coordinates, the geometric distance between the satellite and the receiver is then calculated. Next, the pseudorange coarse synchronization clock difference of the input RNSS signal is... Finally, the observed value of the total slant path delay of the RDSS signal is extracted using expression (1). .

[0102] For joint solvers, such as Figure 3 As shown, the observed values ​​of the total slant path delay of the extracted RDSS signal are... Next, set up the search space: , The least squares method is used to solve the expression (3) to solve the tropospheric parameters: , , Prior values ​​for injection into the flow layer This refers to prior constraints. The dual-frequency RNSS carrier phase is acquired, and the double-difference carrier phase observations of the RNSS signal are input. Construct the double-difference carrier phase observation equation for the RNSS signal as shown in expression (4). Solve the target constraint function as shown in expression (5) to obtain the estimated value of the double-difference phase ambiguity. The time deviation is calculated using expression (6). .

[0103] For the time deviation output interface, output time deviation .

[0104] With the assistance of RDSS signals, the success rate of fixing double-difference phase ambiguity increased from 89% to 93%, while the convergence time was reduced from 34 minutes to 26 minutes.

[0105] In practice, the clock difference results of the integrated inter-satellite link and C-band inter-station time synchronization between the two locations are used as a reference benchmark for verification. Figure 4 This is a timing diagram of two sets of clock differences provided in an embodiment of the present invention. For example... Figure 4 As shown, blue represents the clock difference result calculated by the time comparison method of this embodiment of the invention, and red represents the clock difference result of C-band inter-station time synchronization. The horizontal axis represents the number of days in 2021, and the vertical axis represents the clock difference result (diff Clk). From Figure 4 As can be seen, the clock difference result (diff Clk) calculated by the time comparison method of the present invention is consistent with the clock difference of the reference standard, and the root mean square error of the clock difference is 0.96 ns, which can verify the accuracy of the time comparison method of the present invention. Figure 5 This is a schematic diagram of the Allan deviation of two sets of clock errors provided in an embodiment of the present invention. Figure 5 As shown, blue represents the clock difference result calculated by the time comparison method in this embodiment of the invention, and red represents the clock difference result of C-band inter-station time synchronization. The horizontal axis represents the averaging time, and the vertical axis represents the Allan variance. Figure 5 As can be seen, the clock difference results calculated by the time comparison method in this embodiment of the invention have better frequency stability than the clock difference results of C-band inter-station time synchronization, especially in terms of short-term stability.

[0106] The time comparison device provided by the present invention is described below. The time comparison device described below and the time comparison method described above can be referred to in correspondence.

[0107] Please refer to Figure 6 , Figure 6 This is a schematic diagram of the time comparison device provided in an embodiment of the present invention. Figure 6 As shown, the device may include:

[0108] Extraction module 10 is used to extract the observed value of the total slant path delay of the satellite radio measurement service signal using the fixed elevation angle penetration path of the satellite radio measurement service signal;

[0109] The decomposition module 20 is used to decompose the theoretical value of the total oblique path delay of the satellite radio determination service signal into a zenith delay variable and a horizontal gradient variable; the zenith delay variable includes the tropospheric vertical path delay in the zenith direction, and the horizontal gradient variable includes a horizontal gradient vector.

[0110] The solution module 30 is used to minimize the difference between the theoretical value and each of the observed values, and to obtain the optimal solution for the vertical path delay of the troposphere in the zenith direction and the optimal solution for the horizontal gradient vector.

[0111] The construction module 40 is used to construct the target constraint function for tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal by using the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector as prior values.

[0112] The calculation module 50 is used to calculate the estimated value of the double-difference phase ambiguity based on the double-difference carrier phase observation equation and the target constraint function, and to calculate the time deviation based on the estimated value of the double-difference phase ambiguity.

[0113] In one embodiment, the extraction module 10 is specifically used for:

[0114] Acquire multiple pseudorange observations of the satellite radio ranging service signal;

[0115] For each pseudorange observation, the corresponding geometric distance between the satellite and the receiver, as well as the pseudorange coarse synchronization clock error of the satellite radio navigation service signal, are extracted from the pseudorange observation to obtain the observed value of the total slant path delay of the satellite radio determination service signal.

[0116] In one embodiment, the solving module 30 is specifically used for:

[0117] Construct an objective function that minimizes the square of the Euclidean norm of the difference between each observed value and the theoretical value;

[0118] The objective function is solved using the least squares method to obtain the optimal solution for the vertical path delay of the troposphere in the zenith direction and the optimal solution for the horizontal gradient vector.

[0119] In one embodiment, the construction module 40 includes:

[0120] The first acquisition unit is used to acquire an observation vector composed of double-difference carrier phase observations of the satellite radio navigation service signal at multiple epochs.

[0121] The first construction unit is used to construct the parameter vector to be estimated based on the double-difference hardware delay, the double-difference phase ambiguity, the optimal solution of the tropospheric vertical path delay in the zenith direction, and the optimal solution of the horizontal gradient vector.

[0122] A computational unit is used to calculate the Jacobian matrix of the observation vector relative to the parameter vector based on the observation equation;

[0123] The second acquisition unit is used to acquire the tropospheric delay vector composed of tropospheric delays from multiple epochs.

[0124] The third acquisition unit is used to acquire the tropospheric prior value obtained by inversion from the satellite radio measurement service signal;

[0125] The second construction unit is used to construct a first regularization term based on the observation vector, the parameter vector to be estimated, and the Jacobian matrix;

[0126] The third construction unit is used to construct a second regularization term based on the tropospheric delay vector, the tropospheric prior value, and the constraint weights.

[0127] The fourth construction unit is used to construct the target constraint function based on the first regularization term and the second regularization term.

[0128] In one embodiment, the second building unit is specifically used for:

[0129] Construct a first regularization term that minimizes the square of the Euclidean norm of the product between the observed vector and the parameter vector to be estimated and the Jacobian matrix.

[0130] In one embodiment, the third building unit is specifically used for:

[0131] The second regularization term is constructed by multiplying the square of the Euclidean norm of the difference between the tropospheric delay vector and the tropospheric prior value with the constraint weight.

[0132] Figure 7 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 7As shown, the electronic device may include: a processor 710, a communications interface 720, a memory 730, and a communications bus 740, wherein the processor 710, the communications interface 720, and the memory 730 communicate with each other through the communications bus 740. The processor 710 can call logical instructions in the memory 730 to execute a time comparison method, which includes: extracting the observed value of the total slant path delay of the satellite radio determination service signal using the fixed elevation angle penetration path of the satellite radio determination service signal; decomposing the theoretical value of the total slant path delay of the satellite radio determination service signal into a zenith delay variable and a horizontal gradient variable; the zenith delay variable includes the tropospheric vertical path delay in the zenith direction, and the horizontal gradient variable includes the horizontal gradient vector; minimizing the difference between the theoretical value and each observed value to obtain the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector; using the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector as prior values, constructing a target constraint function for the tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal; calculating the estimated value of the double-difference phase ambiguity based on the double-difference carrier phase observation equation and the target constraint function, and calculating the time deviation based on the estimated value of the double-difference phase ambiguity.

[0133] Furthermore, the logical instructions in the aforementioned memory 730 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0134] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the time comparison method provided by the above methods. The method includes: extracting the observed value of the total slant path delay of the satellite radio determination service signal using the fixed elevation angle penetration path of the satellite radio determination service signal; decomposing the theoretical value of the total slant path delay of the satellite radio determination service signal into a zenith delay variable and a horizontal gradient variable; the zenith delay variable includes the tropospheric vertical path delay in the zenith direction, and the horizontal gradient variable includes a horizontal gradient vector; minimizing the difference between the theoretical value and each observed value to obtain the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector; using the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector as prior values, constructing a target constraint function for the tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal; calculating the estimated value of the double-difference phase ambiguity based on the double-difference carrier phase observation equation and the target constraint function, and calculating the time deviation based on the estimated value of the double-difference phase ambiguity.

[0135] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the time comparison method provided by the methods described above. This method includes: extracting observed values ​​of the total slant path delay of the satellite radio determination service signal using a fixed elevation angle penetration path; decomposing the theoretical value of the total slant path delay of the satellite radio determination service signal into a zenith delay variable and a horizontal gradient variable; the zenith delay variable includes the tropospheric vertical path delay in the zenith direction, and the horizontal gradient variable includes a horizontal gradient vector; minimizing the difference between the theoretical value and each observed value to obtain the optimal solution for the tropospheric vertical path delay in the zenith direction and the optimal solution for the horizontal gradient vector; using the optimal solution for the tropospheric vertical path delay in the zenith direction and the optimal solution for the horizontal gradient vector as prior values, constructing a target constraint function for the tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal; calculating an estimated value of the double-difference phase ambiguity based on the double-difference carrier phase observation equation and the target constraint function, and calculating the time deviation based on the estimated value of the double-difference phase ambiguity.

[0136] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0137] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0138] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A time comparison method, characterized in that, include: The observation value of the total slant path delay of the satellite radio determination service signal is extracted using the fixed elevation angle penetration path of the satellite radio determination service signal; The theoretical value of the total slant path delay of the satellite radio determination service signal is decomposed into a zenith delay variable and a horizontal gradient variable; the zenith delay variable includes the tropospheric vertical path delay in the zenith direction, and the horizontal gradient variable includes the horizontal gradient vector. By minimizing the difference between the theoretical value and each of the observed values, the optimal solution for the tropospheric vertical path delay in the zenith direction and the optimal solution for the horizontal gradient vector are obtained. Using the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector as prior values, the target constraint function of the tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal is constructed. The estimated value of the double-difference phase ambiguity is calculated based on the double-difference carrier phase observation equation and the target constraint function, and the time deviation is calculated based on the estimated value of the double-difference phase ambiguity.

2. The time comparison method according to claim 1, characterized in that, The method of extracting the total path delay of the satellite radio determination service signal using the fixed elevation angle penetration path of the satellite radio determination service signal includes: Acquire multiple pseudorange observations of the satellite radio ranging service signal; For each pseudorange observation, the corresponding geometric distance between the satellite and the receiver, as well as the pseudorange coarse synchronization clock error of the satellite radio navigation service signal, are extracted from the pseudorange observation to obtain the observed value of the total slant path delay of the satellite radio determination service signal.

3. The time comparison method according to claim 1 or 2, characterized in that, Minimizing the difference between the theoretical value and each of the observed values ​​to obtain the optimal solution for the vertical path delay of the troposphere in the zenith direction and the optimal solution for the horizontal gradient vector includes: Construct an objective function that minimizes the square of the Euclidean norm of the difference between each observed value and the theoretical value; The objective function is solved using the least squares method to obtain the optimal solution for the vertical path delay of the troposphere in the zenith direction and the optimal solution for the horizontal gradient vector.

4. The time comparison method according to claim 1 or 2, characterized in that, The step of using the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector as prior values ​​to construct the target constraint function for the tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal includes: Obtain the observation vector composed of the double-difference carrier phase observations of the satellite radio navigation service signal at multiple epochs; The parameter vector to be estimated is constructed based on the optimal solution of double-difference hardware delay, double-difference phase ambiguity, the optimal solution of the tropospheric vertical path delay in the zenith direction, and the optimal solution of the horizontal gradient vector. The Jacobian matrix of the observation vector relative to the parameter vector is calculated based on the observation equation; Obtain the tropospheric delay vector composed of tropospheric delays from multiple epochs; Obtain tropospheric prior values ​​retrieved from the satellite radio ranging service signals; The first regularization term is constructed based on the observation vector, the parameter vector to be estimated, and the Jacobian matrix; A second regularization term is constructed based on the tropospheric delay vector, the tropospheric prior value, and the constraint weights; The target constraint function is constructed based on the first regularization term and the second regularization term.

5. The time comparison method according to claim 4, characterized in that, The construction of the first regularization term based on the observation vector, the parameter vector to be estimated, and the Jacobian matrix includes: Construct a first regularization term that minimizes the square of the Euclidean norm of the difference between the observation vector and the product of the parameter vector to be estimated and the Jacobian matrix.

6. The time comparison method according to claim 4, characterized in that, The construction of the second regularization term based on the tropospheric delay vector, the tropospheric prior value, and the constraint weights includes: The second regularization term is constructed by multiplying the square of the Euclidean norm of the difference between the tropospheric delay vector and the tropospheric prior value with the constraint weight.

7. A time comparison device, characterized in that, include: The extraction module is used to extract the observed value of the total slant path delay of the satellite radio determination service signal using the fixed elevation angle penetration path of the satellite radio determination service signal; The decomposition module is used to decompose the theoretical value of the total oblique path delay of the satellite radio determination service signal into a zenith delay variable and a horizontal gradient variable; the zenith delay variable includes the tropospheric vertical path delay in the zenith direction, and the horizontal gradient variable includes a horizontal gradient vector. The solution module is used to minimize the difference between the theoretical value and each of the observed values, and to obtain the optimal solution for the vertical path delay of the troposphere in the zenith direction and the optimal solution for the horizontal gradient vector. The module is used to construct the target constraint function for tropospheric delay in the double-difference carrier phase observation equation of the satellite radio navigation service signal by using the optimal solution of the tropospheric vertical path delay in the zenith direction and the optimal solution of the horizontal gradient vector as prior values. The calculation module is used to calculate the estimated value of the double-difference phase ambiguity based on the double-difference carrier phase observation equation and the target constraint function, and to calculate the time deviation based on the estimated value of the double-difference phase ambiguity.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the time comparison method as described in any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the time comparison method as described in any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the time comparison method as described in any one of claims 1 to 6.

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