A time calibration method, system, apparatus, device, and medium

Abstract

One or more embodiments of the present application provide a time calibration method, system, device, equipment and medium, a low-orbit satellite receives a first reference time, and calibrates a current first time using the first reference time; determines a clock difference with a GNSS according to at least one observation data sent by the GNSS, and calibrates the first time according to the clock difference to determine a second time; receives other clock differences sent by other low-orbit satellites, and calibrates the second time according to a clock difference average value of the other clock differences and the clock difference, and determines the calibrated second time as a calibrated current time. Since the low-orbit satellite determines a clock difference between the low-orbit satellite and the GNSS according to at least one observation data sent by the GNSS, and calibrates the time of the low-orbit satellite according to the clock difference and other clock differences sent by other low-orbit satellites, the time carried by the low-orbit satellite meets the timing accuracy required by GNSS navigation and positioning.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of satellite communication, and in particular to a time calibration method, system, device, equipment and medium. BACKGROUND

[0002] Currently, low-orbit satellite assisted global navigation satellite system (GNSS) is used to realize high-precision navigation and positioning. When low-orbit satellite assisted GNSS is used to realize high-precision positioning, there is a high requirement for the time reference of the low-orbit satellite. However, due to the complex space environment, high speed of operation, and short service life of the low-orbit satellite, the cost of launching the low-orbit satellite needs to be strictly controlled, which makes it impossible for the low-orbit satellite to carry an atomic clock with the same precision as the GNSS. Currently, most low-orbit satellites carry crystal oscillator clocks.

[0003] However, the frequency stability, frequency drift, and frequency accuracy of the crystal oscillator clock cannot fully meet the requirements of maintaining the time reference required for navigation and positioning. Therefore, it is necessary to correct and maintain the time reference of the low-orbit satellite so that the time reference of the low-orbit satellite can meet the timing accuracy required for GNSS navigation and positioning. SUMMARY

[0004] The present application provides a time calibration method, system, device, equipment and medium to solve the problem that the crystal oscillator clock carried by the low-orbit satellite cannot meet the timing accuracy required for GNSS navigation and positioning in the prior art.

[0005] In a first aspect, one or more embodiments of the present application provide a time calibration method applied to a low-orbit satellite, the method comprising:

[0006] receiving a first reference time sent by a ground tracking station, and using the first reference time to calibrate a first time of the low-orbit satellite at present;

[0007] determining a clock difference between the low-orbit satellite and a global navigation satellite system (GNSS) according to at least one observation data sent by the GNSS, and calibrating the first time according to the clock difference to determine a second time corresponding to the low-orbit satellite;

[0008] receiving other clock differences sent by other low-orbit satellites, determining a clock difference average value according to the other clock differences and the clock difference, and using the clock difference average value to calibrate the second time, and determining the calibrated second time as the calibrated current time of the low-orbit satellite.

[0009] In a second aspect, one or more embodiments of the present application further provide a time calibration system, the system comprising:

[0010] a ground tracking station configured to transmit a first reference time to a low earth orbit satellite;

[0011] the low earth orbit satellite is configured to receive the first reference time transmitted by the ground tracking station, and to calibrate a first time of the low earth orbit satellite using the first reference time;

[0012] a global navigation satellite system (GNSS) configured to transmit at least one observation data to the low earth orbit satellite;

[0013] the low earth orbit satellite is further configured to determine a clock difference between the low earth orbit satellite and the GNSS according to the at least one observation data transmitted by the GNSS, and to calibrate the first time according to the clock difference to determine a second time corresponding to the low earth orbit satellite;

[0014] another low earth orbit satellite configured to transmit another clock difference to the low earth orbit satellite;

[0015] the low earth orbit satellite is further configured to determine a clock difference average according to the another clock difference and the clock difference, and to calibrate the second time using the clock difference average, and to determine a calibrated second time as a calibrated current time of the low earth orbit satellite.

[0016] In a third aspect, one or more embodiments of the present application further provide a time calibration device applied to a low earth orbit satellite, the device comprising:

[0017] a receiving and processing module configured to receive a first reference time transmitted by a ground tracking station;

[0018] a calibration module configured to calibrate a first time of the low earth orbit satellite using the first reference time;

[0019] the receiving and processing module is further configured to determine a clock difference between the low earth orbit satellite and a global navigation satellite system (GNSS) according to at least one observation data transmitted by the GNSS;

[0020] the calibration module is further configured to calibrate the first time according to the clock difference to determine a second time corresponding to the low earth orbit satellite;

[0021] the receiving and processing module is further configured to receive another clock difference transmitted by another low earth orbit satellite, and to determine a clock difference average according to the another clock difference and the clock difference;

[0022] the calibration module is further configured to calibrate the second time using the clock difference average, and to determine a calibrated second time as a calibrated current time of the low earth orbit satellite.

[0023] In a fourth aspect, one or more embodiments of the present application further provide an electronic device, which comprises a processor configured to implement the steps of the time calibration method as described above when executing a computer program stored in a memory.

[0024] In a fifth aspect, one or more embodiments of the present application further provide a computer readable storage medium storing a computer program, which is configured to implement the steps of the time calibration method as described above when executed by a processor.

[0025] In one or more embodiments of the present application, the low-orbit satellite receives a first reference time sent by a ground tracking station, calibrates a current first time of the low-orbit satellite using the first reference time, determines a clock difference between the low-orbit satellite and a global navigation satellite system (GNSS) according to at least one observation data sent by the GNSS, calibrates the first time according to the clock difference to determine a second time corresponding to the low-orbit satellite, receives other clock differences sent by other low-orbit satellites, determines an average clock difference according to the other clock differences and the clock difference, and calibrates the second time using the average clock difference to determine a calibrated current time of the low-orbit satellite. In one or more embodiments of the present application, the low-orbit satellite determines the clock difference between the low-orbit satellite and the GNSS according to at least one observation data sent by the GNSS, and calibrates the time of the low-orbit satellite according to the clock difference and other clock differences sent by other low-orbit satellites, so that the time carried by the low-orbit satellite satisfies the timing accuracy required by GNSS navigation and positioning. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0027] Figure 1 A time calibration process schematic diagram provided for one or more embodiments of the present application;

[0028] Figure 2 A time calibration process schematic diagram provided for one or more embodiments of the present application;

[0029] Figure 3 A time calibration device structure schematic diagram provided for one or more embodiments of the present application;

[0030] Figure 4 An electronic device structure schematic diagram provided for one or more embodiments of the present application. DETAILED DESCRIPTION

[0031] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0032] In order to ensure that the crystal oscillator clocks carried by low-orbit satellites meet the timing accuracy required for GNSS navigation and positioning and improve the accuracy of low-orbit satellite time, one or more embodiments of the present invention provide a time calibration method, system, device, equipment and medium.

[0033] In one or more embodiments of the present invention, a low-orbit satellite receives a first reference time sent by a ground tracking station, and uses the first reference time to calibrate the current first time of the low-orbit satellite; determines the clock difference between the low-orbit satellite and the GNSS based on at least one observation data sent by the global navigation satellite system GNSS, and calibrates the first time based on the clock difference to determine the second time corresponding to the low-orbit satellite; receives other clock differences sent by other low-orbit satellites, and determines the average clock difference based on the other clock differences and the clock difference, and uses the average clock difference to calibrate the second time, and determines the calibrated second time as the current time of the low-orbit satellite after calibration.

[0034] Figure 1 A schematic diagram of a time calibration process provided for one or more embodiments of the present invention includes the following steps:

[0035] S101: Receive a first reference time sent by a ground tracking station, and use the first reference time to calibrate a current first time of a low-orbit satellite.

[0036] One or more embodiments of the present invention provide a time calibration method applied to a low-orbit satellite, wherein the low-orbit satellite is a satellite flying 1000 to 5000 km above the ground.

[0037] In one or more embodiments of the present invention, the low-orbit satellite receives the time sent by the ground tracking station before performing time calibration.

[0038] Specifically, in one or more embodiments of the present invention, a low-orbit satellite may communicate with a ground tracking station, and the low-orbit satellite may receive time from a ground-based atomic clock transmitted by the ground tracking station. In one or more embodiments of the present invention, this time is referred to as a first reference time. After receiving this first reference time, the low-orbit satellite may adjust the current first time of the low-orbit satellite based on this first reference time. That is, the low-orbit satellite uses the first reference time received from the ground tracking station to update the current first time of the low-orbit satellite.

[0039] S102: acquiring at least one observation data sent by a GNSS, determining a clock difference between the low-orbit satellite and the GNSS, and calibrating the first time according to the clock difference to determine a second time corresponding to the low-orbit satellite.

[0040] In one or more embodiments of the present application, a low-orbit satellite is provided with a satellite-borne GNSS receiver which can receive at least one observation data sent by a GNSS. After receiving the at least one observation data, the low-orbit satellite can determine a clock difference between the low-orbit satellite and the GNSS according to the at least one observation data. And the low-orbit satellite can calibrate the current first time according to the clock difference.

[0041] Specifically, in one or more embodiments of the present application, the low-orbit satellite can input the at least one observation data into an observation model, and acquire a clock difference output by the observation model. Of course, in one or more embodiments of the present application, the technician can also pre-configure a program for calculating the clock difference in the low-orbit satellite, and the low-orbit satellite can determine the clock difference according to the program and the at least one observation data.

[0042] S103: receiving other clock differences sent by other low-orbit satellites in the satellite system, determining a clock difference average value according to the other clock differences and the clock difference, and calibrating the second time according to the clock difference average value to determine a calibrated second time as a calibrated current time of the low-orbit satellite.

[0043] In the existing satellite system, a plurality of low-orbit satellites are usually used to assist GNSS, which leads to different clock differences calculated by different low-orbit satellites. In order to make the clock difference determined by each low-orbit satellite in the same satellite system the same, in one or more embodiments of the present application, for each low-orbit satellite, after the low-orbit satellite determines a clock difference according to target observation data corresponding to the low-orbit satellite, the low-orbit satellite will also receive other clock differences sent by other low-orbit satellites in the satellite system. The low-orbit satellite determines a final clock difference used for time calibration according to the other clock differences and the clock difference.

[0044] Specifically, in one or more embodiments of the present application, after receiving other clock differences sent by other low-orbit satellites in the satellite system, the low-orbit satellite calculates a clock difference average value of the other clock differences and the clock difference, calibrates the current second time according to the clock difference average value, and determines a calibrated second time as a calibrated current time of the low-orbit satellite.

[0045] In one or more embodiments of the present application, the low-orbit satellites in the same satellite system communicate through inter-satellite links, i.e., other low-orbit satellites can send other clock differences to the low-orbit satellite through the inter-satellite links.

[0046] In addition, after obtaining the clock difference output by the observation model, the low-orbit satellite also sends the clock difference to other low-orbit satellites through the inter-satellite link, so that the updated clock difference of other low-orbit satellites is consistent with the updated clock difference of the low-orbit satellite, and the low-orbit satellites in the same satellite network maintain a unified time through the inter-satellite link.

[0047] In one or more embodiments of the present application, the clock taming module of the low-orbit satellite tames and corrects the second time of the local crystal oscillator clock according to the clock difference average.

[0048] In one or more embodiments of the present application, the low-orbit satellite determines the clock difference between the low-orbit satellite and the GNSS according to at least one observation data sent by the GNSS, and calibrates the time of the low-orbit satellite according to the clock difference, so that the time carried by the low-orbit satellite meets the timing accuracy required by GNSS navigation and positioning.

[0049] In one or more embodiments, before determining the clock difference between the low-orbit satellite and the GNSS according to the at least one observation data sent by the global navigation satellite system (GNSS), the method further comprises:

[0050] And according to the preset satellite elevation angle threshold, signal-to-noise ratio threshold, cycle slip threshold and satellite elevation angle, signal-to-noise ratio and cycle slip carried in each observation data, determine the target observation data that meets the threshold condition;

[0051] The determination of the clock difference between the low-orbit satellite and the GNSS according to the at least one observation data sent by the global navigation satellite system (GNSS) comprises:

[0052] According to the target observation data, determine the clock difference between the low-orbit satellite and the GNSS.

[0053] In one or more embodiments of the present application, a satellite-borne GNSS receiver is installed in the low-orbit satellite, which can receive the observation data sent by the GNSS. After receiving the observation data sent by the GNSS, the low-orbit satellite can preprocess the observation data to screen out the observation data that does not meet the requirements.

[0054] In one or more embodiments of the present application, the observation data at least contains GNSS pseudo-range observation value, carrier phase observation value, GNSS navigation message and navigation enhancement data, and the observation data also carries the satellite elevation angle when the GNSS collects the observation data, and the signal-to-noise ratio and cycle slip of the observation data.

[0055] In one or more embodiments of the present application, the operating environment of the low-orbit satellite and the GNSS is complex, which may cause the observation data received by the on-board GNSS receiver of the low-orbit satellite to be inaccurate and the like. Based on this, in one or more embodiments of the present application, the low-orbit satellite can further screen the observation data after obtaining the observation data.

[0056] Specifically, in one or more embodiments of the present application, the low-orbit satellite stores a satellite elevation angle threshold value, a signal-to-noise ratio threshold value, and a cycle slip threshold value. After obtaining the observation data, the low-orbit satellite can determine target observation data that satisfies a threshold condition according to the satellite elevation angle, the signal-to-noise ratio, and the cycle slip carried in the observation data, and the pre-stored satellite elevation angle threshold value, the signal-to-noise ratio threshold value, and the cycle slip threshold value.

[0057] The low-orbit satellite can determine the clock difference between the low-orbit satellite and the GNSS according to the target observation data.

[0058] In one or more embodiments, the determination of the clock difference between the low-orbit satellite and the GNSS according to the target observation data includes:

[0059] Inputting the target observation data into an observation model to obtain the clock difference between the low-orbit satellite and the GNSS output by the observation model.

[0060] In the prior art, when determining the clock difference between the low-orbit satellite and the GNSS, the GNSS usually monitors the low-orbit satellite and determines the clock difference according to the running track and angle of the low-orbit satellite. However, the clock difference determined in this way is low in accuracy and unreliable, which further affects the accuracy of subsequent navigation.

[0061] Based on this, in one or more embodiments of the present application, the low-orbit satellite is configured with an observation model. The low-orbit satellite can solve the target observation data according to the observation model, determine and output the clock difference between the low-orbit satellite and the GNSS.

[0062] Specifically, in one or more embodiments of the present application, after the low-orbit satellite screens the target observation data that satisfies the condition from the obtained observation data, the low-orbit satellite inputs the target observation data into an observation model. The observation model can determine and output the clock difference between the low-orbit satellite and the GNSS based on the target observation data.

[0063] In one or more embodiments of the present application, the observation model can be an ionosphere-free observation model or other observation models.

[0064] The training process of the observation model comprises: inputting sample target observation data carrying a sample true clock difference into the observation model to be trained, the observation model outputting a sample predicted clock difference, determining a loss value according to the sample true clock difference and the sample predicted clock difference, and adjusting parameters of the observation model according to the loss value, and if the sample quantity of the loss value less than a threshold value meets a requirement or the number of iterations of the observation model reaches a maximum value, it is considered that the training of the observation model is completed.

[0065] In one or more embodiments, the determining of the target observation data satisfying the threshold condition comprises:

[0066] The observation data carrying a satellite elevation angle exceeding the satellite elevation angle threshold value, a signal-to-noise ratio exceeding the signal-to-noise ratio threshold value, and a cycle slip lower than the cycle slip threshold value is determined as the target observation data.

[0067] In one or more embodiments of the present application, the low-orbit satellite stores the satellite elevation angle threshold value, the signal-to-noise ratio threshold value, and the cycle slip threshold value, and the low-orbit satellite can screen the obtained observation data according to the satellite elevation angle threshold value, the signal-to-noise ratio threshold value, and the cycle slip threshold value.

[0068] Specifically, in one or more embodiments of the present application, for each observation data, the low-orbit satellite compares the satellite elevation angle carried in the observation data with the satellite elevation angle threshold value, compares the signal-to-noise ratio carried in the observation data with the signal-to-noise ratio threshold value, and compares the cycle slip carried in the observation data with the cycle slip threshold value.

[0069] And the low-orbit satellite determines the observation data carrying a satellite elevation angle exceeding the satellite elevation angle threshold value, a signal-to-noise ratio exceeding the signal-to-noise ratio threshold value, and a cycle slip lower than the cycle slip threshold value, and determines the observation data as the target observation data.

[0070] In one or more embodiments, the calibration of the first time according to the clock difference comprises:

[0071] calculating a difference value between the first time and the clock difference;

[0072] calibrating the first time by using the difference value, and determining the calibrated first time as the second time.

[0073] In one or more embodiments of the present application, after the low-orbit satellite determines the clock difference between the low-orbit satellite and the GNSS, the low-orbit satellite obtains a first time displayed by a crystal oscillator clock, and calculates a difference value between the first time and the clock difference. The low-orbit satellite takes the difference value as a second time, and adjusts the time displayed by the crystal oscillator clock to the second time.

[0074] For example, in one or more embodiments of the present invention, the low-orbit satellite determines that the clock error is 5 minutes and 32 seconds, and the low-orbit satellite determines that the time displayed by the crystal oscillator clock is 3 hours, 37 minutes and 54 seconds. The low-orbit satellite determines that the difference between the time and the clock error is 3 hours, 32 minutes and 22 seconds, and the low-orbit satellite adjusts the time displayed by the crystal oscillator clock to 3 hours, 32 minutes and 22 seconds.

[0075] In one or more embodiments, the method further comprises:

[0076] Obtaining a preset number of clock differences determined before determining the clock difference;

[0077] Inputting the clock error and the preset number of clock errors into a clock error prediction model to obtain a predicted clock error output by the clock error prediction model;

[0078] According to the saved format of the GNSS navigation message, the predicted clock error is added to the preset position of the navigation message, and the navigation message with the predicted clock error added is sent to the terminal, so that the terminal subsequently navigates according to the navigation message with the predicted clock error added.

[0079] In one or more embodiments of the present invention, since low-orbit satellites do not calibrate time in real time, the clock difference between low-orbit satellites and GNSS accumulates with time. Based on this, in order to better provide navigation services for users, in one or more embodiments of the present invention, low-orbit satellites can predict the clock difference after a preset period of time based on the currently determined clock difference, and add the predicted clock difference to the navigation message and send it to the terminal, so that the terminal can make navigation based on the predicted clock difference, thereby further reducing the impact of the clock difference between the low-orbit satellite and GNSS on navigation.

[0080] Specifically, in one or more embodiments of the present invention, a clock error prediction model is also configured in the low-orbit satellite. After the low-orbit satellite determines the clock error between the low-orbit satellite and the GNSS, the low-orbit satellite will also input the clock error into the clock error prediction model. The clock error prediction model predicts and outputs the predicted clock error based on the clock error.

[0081] After determining the predicted clock error, the low-orbit satellite obtains the format of the saved GNSS navigation message and the navigation message carried in the target observation data, adds the predicted clock error to the preset position of the navigation message, and sends the navigation message with the predicted clock error added to the terminal, so that the terminal can subsequently navigate according to the navigation message with the predicted clock error added.

[0082] In one or more embodiments, before obtaining a preset number of clock differences determined before determining the clock difference, the method further includes:

[0083] receiving a second reference time sent by the ground tracking station, and determining whether a time difference between the second reference time and a current time of the low-orbit satellite after calibration is not more than a preset difference value;

[0084] If yes, a subsequent step of acquiring a preset number of clock differences determined before the clock difference is determined is executed.

[0085] In addition, in one or more embodiments of the present application, after the low-orbit satellite updates the clock difference by using the clock difference average value and calibrates the second time according to the updated clock difference, the low-orbit satellite can further acquire the time of the ground tracking station from the ground tracking station, and in one or more embodiments of the present application, the time acquired this time is taken as a second reference time. The low-orbit satellite takes the second reference time as a test time and tests the calibrated second time.

[0086] Specifically, if the calibrated second time is consistent with the second reference time, or a time difference between the calibrated second time and the second reference time does not exceed a preset time difference threshold value, it is determined that the calibrated second time is accurate, and then the low-orbit satellite continues to execute a subsequent step of acquiring a preset number of clock differences determined before the clock difference is determined.

[0087] Figure 2 A flowchart of time calibration provided by one or more embodiments of the present application is shown in the figure. Figure 2 As shown in the figure, the flowchart includes:

[0088] S201: receiving a first reference time sent by a ground tracking station, and calibrating a first time of a low-orbit satellite by using the first reference time.

[0089] S202: acquiring at least one observation data sent by a GNSS, and determining target observation data satisfying threshold conditions according to a preset satellite elevation angle threshold value, a signal-to-noise ratio threshold value, a cycle slip threshold value, and a satellite elevation angle, a signal-to-noise ratio, and a cycle slip carried in each observation data.

[0090] S203: inputting the target observation data into an observation model, acquiring a clock difference between the low-orbit satellite and the GNSS output by the observation model, and calibrating the first time according to the clock difference to determine a second time corresponding to the low-orbit satellite.

[0091] S204: receiving other clock differences emitted by other low-orbit satellites, determining a clock difference average value according to the other clock differences and the clock difference, and calibrating the second time by using the clock difference average value.

[0092] S205: acquiring a second reference time of the ground tracking station from the ground tracking station, and testing the calibrated second time by taking the time as a test time, and if the test is successful, executing S206.

[0093] S206: Obtain a preset number of clock differences determined before the clock difference is determined.

[0094] S207: Input the clock difference and the preset number of clock differences into a clock difference prediction model to obtain a predicted clock difference output by the clock difference prediction model.

[0095] S208: According to the format of the saved navigation message of the GNSS, add the predicted clock difference to a preset position of the navigation message, and send the navigation message with the predicted clock difference added to the terminal, so that the terminal subsequently performs navigation according to the navigation message with the predicted clock difference added.

[0096] In one or more embodiments of the present application, the ground tracking station transmits a first reference time displayed by a ground atomic clock to a low-orbit satellite, thereby achieving initial time service for the low-orbit satellite. The low-orbit satellite receives at least one observation data transmitted by a GNSS through a local on-board GNSS receiver, and determines target observation data meeting a requirement from the at least one observation data. The low-orbit satellite determines a clock difference between the low-orbit satellite and the GNSS through an observation model and the target observation data. The low-orbit satellite calibrates a first time of the low-orbit satellite according to the clock difference, and generates a predicted clock difference according to the clock difference and a clock difference prediction model, and then adjusts a navigation message according to the predicted clock difference. Based on this, the time calibration method provided by one or more embodiments of the present application can establish a high-precision time reference required for the low-orbit satellite to broadcast a navigation ranging signal for positioning, realize the function of signal enhancement in low-orbit satellite navigation enhancement, and reduce the clock cost of the low-orbit satellite, and achieve a higher precision time service requirement.

[0097] One or more embodiments of the present application also provide a time calibration system, which comprises:

[0098] a ground tracking station configured to transmit a first reference time to a low-orbit satellite;

[0099] the low-orbit satellite is configured to receive the first reference time transmitted by the ground tracking station, and calibrate a current first time of the low-orbit satellite by using the first reference time;

[0100] a GNSS configured to transmit at least one observation data to the low-orbit satellite;

[0101] the low-orbit satellite is further configured to determine a clock difference between the low-orbit satellite and the GNSS according to the at least one observation data transmitted by the GNSS, calibrate the first time according to the clock difference, and determine a second time corresponding to the low-orbit satellite;

[0102] another low-orbit satellite configured to transmit another clock difference to the low-orbit satellite;

[0103] The low-orbit satellite is further configured to determine a clock difference average value according to the other clock difference and the clock difference, and calibrate the second time according to the clock difference average value, so as to determine the calibrated second time as the calibrated current time of the low-orbit satellite.

[0104] In one or more embodiments of the present application, the low-orbit satellite is specifically configured to determine target observation data that meets threshold conditions according to a preset satellite elevation angle threshold, a signal-to-noise ratio threshold, a cycle slip threshold, and a satellite elevation angle, a signal-to-noise ratio, and a cycle slip carried in each observation data; and determine the clock difference between the low-orbit satellite and the GNSS according to the target observation data.

[0105] In one or more embodiments of the present application, the low-orbit satellite is specifically configured to input the target observation data into an observation model, and obtain the clock difference between the low-orbit satellite and the GNSS output by the observation model.

[0106] In one or more embodiments of the present application, the low-orbit satellite is specifically configured to determine observation data that carries a satellite elevation angle exceeding the satellite elevation angle threshold, a signal-to-noise ratio exceeding the signal-to-noise ratio threshold, and a cycle slip lower than the cycle slip threshold as the target observation data.

[0107] In one or more embodiments of the present application, the low-orbit satellite is specifically configured to calculate a difference value between the first time and the clock difference; calibrate the first time according to the difference value, and determine the calibrated first time as the second time.

[0108] In one or more embodiments of the present application, the low-orbit satellite is further configured to obtain a preset number of clock differences determined before the clock difference is determined; input the clock difference and the preset number of clock differences into a clock difference prediction model, obtain a predicted clock difference output by the clock difference prediction model; add the predicted clock difference to a preset position of a navigation message according to a saved format of the navigation message of the GNSS, and send the navigation message with the predicted clock difference added to a terminal, so that the terminal subsequently performs navigation according to the navigation message with the predicted clock difference added.

[0109] In one or more embodiments of the present application, the ground tracking station is further configured to send a second reference time to the low-orbit satellite.

[0110] The low-orbit satellite is further configured to receive the second reference time sent by the ground tracking station, and determine whether a time difference between the second reference time and the calibrated current time of the low-orbit satellite is not more than a preset difference value; if yes, perform a subsequent step of obtaining a preset number of clock differences determined before the clock difference is determined.

[0111] Figure 3A time calibration device structure schematic diagram is provided for one or more embodiments of the application, and the device comprises:

[0112] The receiving processing module 301 is configured to receive a first reference time sent by a ground tracking station.

[0113] The calibration module 302 is configured to calibrate a first time of a low-orbit satellite at present by using the first reference time.

[0114] The receiving processing module 301 is further configured to determine a clock difference between the low-orbit satellite and a global navigation satellite system (GNSS) according to at least one observation data sent by the GNSS.

[0115] The calibration module 302 is further configured to calibrate the first time according to the clock difference, and determine a second time corresponding to the low-orbit satellite.

[0116] The receiving processing module 301 is further configured to receive other clock differences sent by other low-orbit satellites, and determine a clock difference average value according to the other clock differences and the clock difference.

[0117] The calibration module 302 is further configured to calibrate the second time by using the clock difference average value, and determine a calibrated second time as a calibrated current time of the low-orbit satellite.

[0118] In one or more embodiments of the application, the receiving processing module 301 is specifically configured to determine target observation data satisfying threshold conditions according to a preset satellite elevation angle threshold, a signal-to-noise ratio threshold, a cycle slip threshold, and a satellite elevation angle, a signal-to-noise ratio, and a cycle slip carried in each observation data; and determine the clock difference between the low-orbit satellite and the GNSS according to the target observation data.

[0119] In one or more embodiments of the application, the receiving processing module 301 is specifically configured to input the target observation data into an observation model, and obtain the clock difference between the low-orbit satellite and the GNSS output by the observation model.

[0120] In one or more embodiments of the application, the receiving processing module 301 is specifically configured to determine observation data with a satellite elevation angle exceeding the satellite elevation angle threshold, a signal-to-noise ratio exceeding the signal-to-noise ratio threshold, and a cycle slip lower than the cycle slip threshold as the target observation data.

[0121] In one or more embodiments of the application, the calibration module 302 is specifically configured to calculate a difference value between the first time and the clock difference; calibrate the first time by using the difference value, and determine a calibrated first time as the second time.

[0122] In one or more embodiments of the present application, the receiving processing module 301 is further configured to obtain a preset number of clock differences determined before the clock difference is determined; input the clock difference and the preset number of clock differences into a clock difference prediction model to obtain a predicted clock difference output by the clock difference prediction model; add the predicted clock difference to a preset position of a navigation message according to a format of the saved navigation message of the GNSS; and send the navigation message with the predicted clock difference added to a terminal, so that the terminal subsequently performs navigation according to the navigation message with the predicted clock difference added.

[0123] In one or more embodiments of the present application, the receiving processing module 301 is further configured to receive a second reference time sent by the ground tracking station, and determine whether a time difference between the second reference time and a current time of the low-orbit satellite after calibration exceeds a preset difference value.

[0124] If not, the subsequent step of obtaining a preset number of clock differences determined before the clock difference is determined is performed. Based on the above-mentioned embodiments, one or more embodiments of the present application further provide an electronic device, Figure 4 A structural schematic diagram of an electronic device provided by one or more embodiments of the present application is shown in FIG. 1, which includes a processor 41, a communication interface 42, a memory 43 and a communication bus 44, wherein the processor 41, the communication interface 42 and the memory 43 complete mutual communication through the communication bus 44. Figure 4

[0125] The memory 43 stores a computer program, and when the program is executed by the processor 41, the processor 41 performs the following steps:

[0126] receive a first reference time sent by a ground tracking station, and calibrate a current first time of a low-orbit satellite by using the first reference time;

[0127] determine a clock difference between the low-orbit satellite and a global navigation satellite system (GNSS) according to at least one observation data sent by the GNSS, and calibrate the first time according to the clock difference to determine a corresponding second time of the low-orbit satellite;

[0128] receive other clock differences sent by other low-orbit satellites, determine a clock difference average value according to the other clock differences and the clock difference, and calibrate the second time by using the clock difference average value to determine a current time of the low-orbit satellite after calibration.

[0129] In one or more embodiments of the present application, before the clock difference between the low-orbit satellite and the GNSS is determined according to the at least one observation data sent by the GNSS, the method further includes: ​

[0130] determine target observation data meeting threshold conditions according to a preset satellite elevation angle threshold, a signal-to-noise ratio threshold, a cycle slip threshold, and a satellite elevation angle, a signal-to-noise ratio, and a cycle slip carried in each observation data;

[0131] The method further includes:

[0132] The method further includes:

[0133] In one or more embodiments of the present application, the determining of the clock difference between the low-orbit satellite and the GNSS according to the target observation data includes:

[0134] The method further includes:

[0135] In one or more embodiments of the present application, the determining of the target observation data meeting threshold conditions according to a preset satellite elevation angle threshold, a signal-to-noise ratio threshold, a cycle slip threshold, and a satellite elevation angle, a signal-to-noise ratio, and a cycle slip carried in each observation data includes:

[0136] The observation data carrying a satellite elevation angle exceeding the satellite elevation angle threshold, a signal-to-noise ratio exceeding the signal-to-noise ratio threshold, and a cycle slip lower than the cycle slip threshold is determined as the target observation data.

[0137] In one or more embodiments of the present application, the calibrating of the first time according to the clock difference and the determining of the second time corresponding to the low-orbit satellite include:

[0138] The difference between the first time and the clock difference is calculated.

[0139] The first time is calibrated by using the difference, and the calibrated first time is determined as the second time.

[0140] The method further includes:

[0141] A preset number of clock differences determined before the clock difference is determined are acquired.

[0142] The clock difference and the preset number of clock differences are input into a clock difference prediction model, and a predicted clock difference output by the clock difference prediction model is acquired.

[0143] According to a format of the saved navigation message of the GNSS, the predicted clock difference is added to a preset position of the navigation message, and the navigation message with the added predicted clock difference is sent to the terminal, so that the terminal performs navigation according to the navigation message with the added predicted clock difference subsequently.

[0144] In one or more embodiments of the present application, before the step of determining the preset number of clock differences determined before the clock difference is determined, the method further comprises:

[0145] receiving a second reference time sent by the ground tracking station, and determining whether a time difference between the second reference time and the current time of the low-orbit satellite after calibration exceeds a preset difference value;

[0146] If not, the step of subsequently determining the preset number of clock differences determined before the clock difference is determined is executed.

[0147] Since the principle of solving the problem of the electronic device is similar to the time calibration method, the implementation of the electronic device can refer to the embodiments of the method, and the repeated parts will not be described again.

[0148] The communication bus mentioned in the electronic device can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus can be divided into an address bus, a data bus, a control bus, etc. For the convenience of representation, only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus. The communication interface 42 is used for communication between the electronic device and other devices. The memory can include a Random Access Memory (RAM) and can also include a Non-Volatile Memory (NVM), such as at least one disk memory. Optionally, the memory can also be at least one storage device located away from the aforementioned processor.

[0149] The processor mentioned above can be a general-purpose processor, including a central processing unit, a network processor (NP), etc.; can also be a Digital Signal Processing (DSP), an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, etc.

[0150] On the basis of the above-mentioned embodiments, the embodiment of the present application further provides a computer readable storage medium, the computer readable storage medium stores a computer program executable by a processor, when the program runs on the processor, the processor executes the following steps:

[0151] Receiving a first reference time sent by a ground tracking station, and calibrating a first time of the low-orbit satellite at present by using the first reference time;

[0152] According to at least one observation data sent by a global navigation satellite system (GNSS), determining a clock difference between the low-orbit satellite and the GNSS, and calibrating the first time according to the clock difference to determine a second time corresponding to the low-orbit satellite;

[0153] Receiving other clock differences sent by other low-orbit satellites, determining a clock difference average value according to the other clock differences and the clock difference, and calibrating the second time by using the clock difference average value, and determining the calibrated second time as the calibrated current time of the low-orbit satellite.

[0154] In one or more embodiments of the present application, before the clock difference between the low-orbit satellite and the GNSS is determined according to the at least one observation data sent by the global navigation satellite system (GNSS), the method further comprises:

[0155] According to a preset satellite elevation angle threshold, a signal-to-noise ratio threshold, a cycle slip threshold and a satellite elevation angle, a signal-to-noise ratio and a cycle slip carried in each observation data, determining target observation data satisfying a threshold condition;

[0156] The clock difference between the low-orbit satellite and the GNSS is determined according to the at least one observation data sent by the global navigation satellite system (GNSS) includes:

[0157] According to the target observation data, the clock difference between the low-orbit satellite and the GNSS is determined.

[0158] In one or more embodiments of the present application, the clock difference between the low-orbit satellite and the GNSS is determined according to the target observation data, which includes:

[0159] The target observation data is input into an observation model, and the clock difference between the low-orbit satellite and the GNSS output by the observation model is obtained.

[0160] In one or more embodiments of the present application, the target observation data satisfying the threshold condition is determined according to the preset satellite elevation angle threshold, the signal-to-noise ratio threshold, the cycle slip threshold and the satellite elevation angle, the signal-to-noise ratio and the cycle slip carried in each observation data, which includes:

[0161] The observation data carrying a satellite elevation angle exceeding the satellite elevation angle threshold, a signal-to-noise ratio exceeding the signal-to-noise ratio threshold, and a cycle slip lower than the cycle slip threshold are determined as the target observation data.

[0162] In one or more embodiments of the present application, the determining the second time corresponding to the low-orbit satellite according to the clock difference includes:

[0163] calculating a difference between the first time and the clock difference;

[0164] calibrating the first time by using the difference, and determining the calibrated first time as the second time.

[0165] In one or more embodiments of the present application, the method further includes:

[0166] acquiring a preset number of clock differences determined before the clock difference is determined;

[0167] inputting the clock difference and the preset number of clock differences into a clock difference prediction model to acquire a predicted clock difference output by the clock difference prediction model;

[0168] adding the predicted clock difference to a preset position of a navigation message according to a format of the saved navigation message of the GNSS, and sending the navigation message with the predicted clock difference added to a terminal, so that the terminal performs navigation according to the navigation message with the predicted clock difference added subsequently.

[0169] In one or more embodiments of the present application, before the acquiring the preset number of clock differences determined before the clock difference is determined, the method further includes:

[0170] receiving a second reference time sent by the ground tracking station, and judging whether a time difference between the second reference time and the calibrated current time of the low-orbit satellite is not more than a preset difference value;

[0171] If yes, the subsequent step of acquiring the preset number of clock differences determined before the clock difference is determined is executed. Since the principle of solving the problem by the above computer readable storage medium is similar to that of the time calibration method, the implementation of the above computer readable storage medium can be referred to the implementation of the method, and the repeated parts will not be described here.

[0172] Those skilled in the art will appreciate that embodiments of the present application can be devised for a variety of applications. It is therefore intended that the present application cover all such modifications and variations of this application provided they come within the scope of the appended claims and their equivalents. It is intended to embrace all alternatives, modifications and variations of this application within the scope of the following claims.

[0173] The present application is described in reference to the drawings using a flowchart and / or a block diagram of the method, apparatus (system) and computer program product according to the present application. It will be understood that each block of the flowchart and / or block diagram, and combinations of blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks. Figure 1 means for performing the function specified by the flowchart and / or block diagram block or blocks.

[0174] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks. Figure 1 means for performing the function specified by the flowchart and / or block diagram block or blocks.

[0175] The computer program instructions can also be loaded into a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks. Figure 1 means for performing the function specified by the flowchart and / or block diagram block or blocks.

[0176] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A time calibration method, characterized in that: Applied to a low-orbit satellite, the method includes: Receiving a first reference time sent by a ground tracking station, and calibrating a current first time of the low-orbit satellite using the first reference time; Determining a clock difference between the low-orbit satellite and the GNSS based on at least one acquired observation data sent by a global navigation satellite system (GNSS), and calibrating the first time based on the clock difference to determine a second time corresponding to the low-orbit satellite; receiving other clock errors sent by other low-orbit satellites, determining an average clock error based on the other clock errors and the clock error, calibrating the second time using the average clock error, and determining the calibrated second time as the current time after the calibration of the low-orbit satellite; Before determining the clock difference between the low-orbit satellite and the GNSS based on the acquired at least one observation data sent by the global navigation satellite system (GNSS), the method further includes: Determining observation data whose satellite elevation angle exceeds a satellite elevation angle threshold, whose signal-to-noise ratio exceeds a signal-to-noise ratio threshold, and whose cycle slip is lower than a cycle slip threshold, and determining the observation data as target observation data; The determining, based on the acquired at least one observation data sent by the global navigation satellite system (GNSS), the clock difference between the low-orbit satellite and the GNSS comprises: The clock difference between the low-orbit satellite and the GNSS is determined based on the target observation data.

2. The method according to claim 1, characterized in that Determining the clock difference between the low-orbit satellite and the GNSS according to the target observation data includes: The target observation data is input into an observation model to obtain the clock difference between the low-orbit satellite and the GNSS output by the observation model.

3. The method according to claim 1, characterized in that The step of determining target observation data that meets the threshold conditions based on a preset satellite elevation angle threshold, a signal-to-noise ratio threshold, a cycle slip threshold, and the satellite elevation angle, signal-to-noise ratio, and cycle slip carried in each observation data includes: Observation data whose satellite elevation angle exceeds the satellite elevation angle threshold, whose signal-to-noise ratio exceeds the signal-to-noise ratio threshold, and whose cycle slip is lower than the cycle slip threshold is determined to be the target observation data.

4. The method according to claim 1, wherein The calibrating the first time according to the clock difference to determine the second time corresponding to the low-orbit satellite includes: Calculating a difference between the first time and the clock difference; The first time is calibrated using the difference, and the calibrated first time is determined as the second time.

5. The method according to claim 1, wherein The method further comprises: Obtaining a preset number of clock differences determined before determining the clock difference; Inputting the clock error and the preset number of clock errors into a clock error prediction model to obtain a predicted clock error output by the clock error prediction model; According to the saved format of the GNSS navigation message, the predicted clock error is added to the preset position of the navigation message, and the navigation message with the predicted clock error added is sent to the terminal, so that the terminal subsequently navigates according to the navigation message with the predicted clock error added.

6. The method according to claim 5, characterized in that Before obtaining a preset number of clock differences determined before determining the clock difference, the method further includes: receiving a second reference time sent by the ground tracking station, and determining whether a time difference between the second reference time and the current time after calibration of the low-orbit satellite does not exceed a preset difference; If so, a subsequent step of obtaining a preset number of clock differences determined before determining the clock difference is performed.

7. A time calibration system, characterized in that: The system comprises: Ground tracking station for transmitting the first reference time to the low-orbit satellite; The low-orbit satellite is configured to receive the first reference time sent by the ground tracking station, and use the first reference time to calibrate a current first time of the low-orbit satellite; A global navigation satellite system (GNSS), configured to send at least one piece of observation data to the low-orbit satellite; The low-orbit satellite is further configured to determine a clock difference between the low-orbit satellite and the GNSS based on at least one acquired observation data sent by the GNSS, and calibrate the first time based on the clock difference to determine a second time corresponding to the low-orbit satellite; other low-orbit satellites, used to send other clock errors to the low-orbit satellites; The low-orbit satellite is further configured to determine a clock difference average value based on the other clock differences and the clock difference, calibrate the second time using the clock difference average value, and determine the calibrated second time as the calibrated current time of the low-orbit satellite; Among them, the low-orbit satellite is specifically used to determine the observation data carried by the satellite, whose satellite altitude angle exceeds the satellite altitude angle threshold, the signal-to-noise ratio exceeds the signal-to-noise ratio threshold, and the cycle slip is lower than the cycle slip threshold, and determine the observation data as the target observation data; based on the target observation data, determine the clock difference between the low-orbit satellite and the GNSS.

8. A time calibration device, characterized in that: Applied to low-orbit satellites, the device comprises: A receiving and processing module, configured to receive a first reference time sent by a ground tracking station; a calibration module, configured to calibrate a current first time of the low-orbit satellite using the first reference time; The receiving and processing module is further configured to determine a clock difference between the low-orbit satellite and the GNSS based on at least one acquired observation data sent by the GNSS; The calibration module is further configured to calibrate the first time according to the clock error to determine a second time corresponding to the low-orbit satellite; The receiving and processing module is further configured to receive other clock errors sent by other low-orbit satellites, and determine an average clock error value based on the other clock errors and the clock error; The calibration module is further configured to calibrate the second time using the clock difference average value, and determine the calibrated second time as the current time of the low-orbit satellite after calibration; Among them, the receiving and processing module is specifically used to determine the observation data carried by the satellite elevation angle exceeding the satellite elevation angle threshold, the signal-to-noise ratio exceeding the signal-to-noise ratio threshold, and the cycle slip lower than the cycle slip threshold, and determine the observation data as the target observation data; based on the target observation data, determine the clock difference between the low-orbit satellite and the GNSS.

9. An electronic device, characterized in that: The electronic device includes a processor, and the processor is configured to implement the steps of the time calibration method according to any one of claims 1 to 6 when executing a computer program stored in a memory.

10. A computer-readable storage medium, characterized in that The device stores a computer program, which, when executed by a processor, implements the steps of the time calibration method according to any one of claims 1 to 6.

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