A GEO communication satellite time synchronization method and system based on USB measurement and control signals

Abstract

The present invention relates to a GEO communication satellite timing method based on USB measurement and control signals. This method is a timing method based on the measurement, operation, and control of satellites by ground measurement and control stations. The measurement and control station accesses the standard time-frequency signal output from the NTSC master clock as the time-frequency reference of the station, and sends the uplink carrier signal modulated with ranging tones to the satellite. After being mixed and forwarded by the satellite measurement and control transponder, it is sent back to the ground. At this time, both the ground measurement and control station and the user receive this signal simultaneously. After demodulation, the total path propagation delay of the signal on the uplink and downlink can be obtained respectively. After correcting error terms such as atmospheric delay, satellite equipment delay, ground equipment delay, and satellite orbit error, the clock difference between the user and the measurement and control station is obtained, and satellite timing is completed. The timing method of the present invention can achieve high timing accuracy, and moreover, it can endow the satellite measurement and control system with new functions without increasing additional costs, realizing high-precision satellite timing based on measurement and control signals.

Description

Technical Field

[0001] The present invention belongs to the technical field of satellite time service, and particularly relates to a method and system for GEO communication satellite time service based on USB measurement and control signals. Background Art

[0002] High-precision time-frequency information is an important strategic resource of the country, playing an irreplaceable role in national defense security and people's livelihood. Since 2016, China has proposed to build a national integrated positioning, navigation and timing (PNT) system to achieve a higher-precision and more stable and reliable time and space reference. The research and construction of the integrated PNT system is bound to become the development trend of the global navigation satellite system (GNSS). As an important part of the PNT system, the time service system has also become a current research hotspot.

[0003] Time service refers to determining and maintaining the national time scale and transmitting the time information representing the national scale to users for their use through a certain method. Satellite time service has become one of the main services of major satellite navigation systems due to its large coverage area and high time service accuracy. The existing satellite time service methods can generally be divided into the transponder type and the direct transmission type. Among them, the transponder type of time service realizes time service by renting a satellite transponder to forward the time-frequency signal injected by the master station to the user. The direct transmission type is that the satellite itself is equipped with an on-board atomic clock and can directly provide time service.

[0004] The transponder type of common-view satellite time service has high accuracy, but the equipment price is expensive. The point-to-point time synchronization technology can obtain a time service accuracy at the nanosecond level, but the technology is complex and the cost is high, and it is only suitable for a few users with high-precision time service requirements. The broadcast (direct transmission) satellite time service is not limited by the number of ground users, but the GNSS one-way time service accuracy is relatively low. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a method and system for GEO communication satellite time service based on USB measurement and control signals. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0006] The present invention provides a method for GEO communication satellite time service based on USB measurement and control signals, including:

[0007] Step 1: Taking the standard time-frequency signal output by the NTSC master clock as the time-frequency reference of the measurement and control station, and sending the uplink carrier signal modulated with ranging tones to the satellite;

[0008] Step 2: Obtain the downlink telemetry signal after being mixed and forwarded by the satellite TT&C transponder. Among them, the downlink telemetry signal includes the user terminal downlink telemetry signal and the TT&C station downlink telemetry signal;

[0009] Step 3: Demodulate the user terminal downlink telemetry signal and the TT&C station downlink telemetry signal respectively to obtain the first total path propagation delay and the second total path propagation delay;

[0010] Step 4: Calculate the geometric path delay of the propagation between the satellite and the TT&C station, and the geometric path delay of the propagation between the satellite and the user terminal;

[0011] Step 5: Correct the propagation error term of the first total path propagation delay, and obtain the satellite TT&C transponder delay according to the correction result and the geometric path delay of the propagation between the satellite and the TT&C station;

[0012] Step 6: Correct the propagation error term of the second total path propagation delay, and obtain the clock difference between the user terminal and the TT&C station according to the correction result, the geometric path delay of the propagation between the satellite and the TT&C station, the geometric path delay of the propagation between the satellite and the user terminal, and the satellite TT&C transponder delay, so as to complete time service.

[0013] The present invention also provides a GEO communication satellite time service system based on USB TT&C signals, including:

[0014] A signal transmitting module, which is used to use the standard time-frequency signal output by the NTSC master clock as the time-frequency reference, and send the uplink carrier signal modulated with ranging tones to the satellite;

[0015] A signal receiving module, which is used to obtain the downlink telemetry signal after being mixed and forwarded by the satellite TT&C transponder. Among them, the downlink telemetry signal includes the user terminal downlink telemetry signal and the TT&C station downlink telemetry signal;

[0016] A total path delay module, which is used to demodulate the user terminal downlink telemetry signal and the TT&C station downlink telemetry signal respectively to obtain the first total path propagation delay and the second total path propagation delay;

[0017] A geometric path delay module, which is used to calculate the geometric path delay of the propagation between the satellite and the TT&C station, and the geometric path delay of the propagation between the satellite and the user terminal;

[0018] A propagation error term correction module, which corrects the propagation error term of the first total path propagation delay, and obtains the satellite TT&C transponder delay according to the correction result and the geometric path delay of the propagation between the satellite and the TT&C station; it is also used to correct the propagation error term of the second total path propagation delay;

[0019] A timing module, configured to obtain the clock difference between the user terminal and the TT&C station according to the correction result of the second total path, the geometric path delay propagated between the satellite and the user terminal, and the satellite TT&C transponder delay, and complete the timing of the user terminal according to the clock difference.

[0020] The present invention further provides an electronic device, including a processor, a communication interface, a memory, and a communication bus. Among them, the processor, the communication interface, and the memory complete mutual communication through the communication bus; the memory is used to store computer programs; the processor is used to implement the method steps described in any of the above embodiments when executing the programs stored on the memory.

[0021] The present invention further provides a computer-readable storage medium, in which a computer program is stored, and the computer program realizes the method steps described in any of the above embodiments when executed by a processor.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. The GEO communication satellite timing method based on USB TT&C signals of the present invention utilizes the ranging accuracy of USB technology and can achieve high timing accuracy through calculation. Moreover, on the premise that the positions of both the satellite and the ground station are known, due to the wide-area differential function, its timing accuracy is higher than that of satellite one-way timing, and what the user finally obtains will directly be the clock difference from the TT&C station UTC(NTSC).

[0024] 2. The GEO communication satellite timing method based on USB TT&C signals of the present invention can endow the satellite TT&C system with a new function, that is, to achieve high-precision satellite timing based on TT&C signals, without increasing additional costs.

[0025] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features, and advantages of the present invention more obvious and understandable, the following specifically gives preferred embodiments and, in conjunction with the drawings, details are described as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of a GEO communication satellite timing method based on USB TT&C signals provided by an embodiment of the present invention;

[0027] Figure 2 is a flowchart of a GEO communication satellite timing method based on USB TT&C signals provided by an embodiment of the present invention;

[0028] Figure 3This is a schematic diagram of satellite time synchronization based on measurement and control signals provided by an embodiment of the present invention. Detailed implementation manners

[0029] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following, in combination with the accompanying drawings and specific implementation manners, details a method and system for GEO communication satellite time synchronization based on USB measurement and control signals proposed according to the present invention.

[0030] The foregoing and other technical contents, features and effects of the present invention can be clearly presented in the following detailed description in conjunction with the accompanying drawings. Through the description of the specific implementation manners, a more in-depth and specific understanding of the technical means and effects adopted by the present invention to achieve the intended purpose can be obtained. However, the accompanying drawings are only for reference and illustration, and are not used to limit the technical solution of the present invention.

[0031] Embodiment 1

[0032] Please refer to Figure 1 and Figure 2 , Figure 1 which is a schematic diagram of a method for GEO communication satellite time synchronization based on USB measurement and control signals provided by an embodiment of the present invention; Figure 2 which is a flowchart of a method for GEO communication satellite time synchronization based on USB measurement and control signals provided by an embodiment of the present invention. As shown in the figure, the method for GEO communication satellite time synchronization based on USB measurement and control signals in this embodiment includes:

[0033] Step 1: Use the standard time-frequency signal output by the NTSC master clock as the time-frequency reference of the measurement and control station, and send the uplink carrier signal modulated with ranging tones to the satellite;

[0034] It should be noted that the method for GEO communication satellite time synchronization based on USB measurement and control signals is a time synchronization method based on the measurement, operation and control of the satellite by the ground measurement and control station. Therefore, the measurement and control station needs to access the standard time-frequency signal output by the NTSC master clock as the time-frequency reference of the measurement and control station.

[0035] In this embodiment, using the standard time-frequency signal output by the NTSC master clock as the time-frequency reference of the satellite measurement and control station realizes the synchronization of the atomic clock of the measurement and control station with UTC(NTSC).

[0036] Optionally, the uplink carrier signal modulated with ranging tones is a telecommand containing ranging tones, and the measurement and control station sends the telecommand containing ranging tones to the satellite.

[0037] Step 2: Obtain the downlink telemetry signal after being mixed and forwarded by the satellite measurement and control transponder, where the downlink telemetry signal includes the user terminal downlink telemetry signal and the measurement and control station downlink telemetry signal;

[0038] In this embodiment, after the uplink carrier signal modulated with ranging tones is mixed and forwarded by the satellite TT&C transponder, it is then sent to the ground. At this time, both the ground TT&C station and the user terminal receive the downlink telemetry signal simultaneously.

[0039] Step 3: Demodulate the downlink telemetry signal of the user terminal and the downlink telemetry signal of the TT&C station respectively to obtain the first total path propagation delay and the second total path propagation delay;

[0040] Among them, the first total path propagation delay is the path propagation delay of the signal from the TT&C station to the satellite and then back to the TT&C station; the second total path propagation delay is the path propagation delay of the signal from the TT&C station to the satellite and then back to the user terminal.

[0041] Step 4: Calculate the geometric path delay of the propagation between the satellite and the TT&C station, and the geometric path delay of the propagation between the satellite and the user terminal;

[0042] Specifically, Step 4 includes: using the satellite passive orbit determination system, according to the position coordinates of the TT&C station and the user terminal, calculate the geometric path delay of the propagation between the satellite and the TT&C station and the geometric path delay of the propagation between the satellite and the user terminal.

[0043] In this embodiment, by using the existing satellite passive orbit determination system of the National Time Service Center, an orbit with meter-level accuracy of the satellite can be obtained. At the same time, the positions of the ground TT&C station and the user terminal are also accurately known, meeting the basic conditions for single-satellite time service. According to the coordinates of the satellite and the ground stations (TT&C station and user terminal), the geometric distance between the satellite and the ground can be calculated, and the geometric path delay of the propagation between the satellite and the ground station, that is, the geometric path delay of the propagation between the satellite and the TT&C station, and the geometric path delay of the propagation between the satellite and the user terminal can be calculated using this geometric distance.

[0044] Step 5: Correct the propagation error term of the first total path propagation delay, and obtain the satellite TT&C transponder delay according to the correction result and the geometric path delay of the propagation between the satellite and the TT&C station;

[0045] Step 6: Correct the propagation error term of the second total path propagation delay, and obtain the clock difference between the user terminal and the TT&C station according to the correction result, the geometric path delay of the propagation between the satellite and the TT&C station, the geometric path delay of the propagation between the satellite and the user terminal, and the satellite TT&C transponder delay, so as to complete time service.

[0046] It should be noted that during the propagation of signals in free space, they will be affected by various error factors, such as atmospheric delay, satellite equipment time delay, ground equipment time delay, and satellite orbit error. By correcting the propagation error terms of the first total path propagation delay and the second total path propagation delay, the clock difference between the user terminal and the measurement and control station can be obtained, that is, the clock difference between the user and UTC(NTSC), thus completing satellite timekeeping.

[0047] In this embodiment, the propagation error terms include atmospheric delay, ground equipment time delay, and link Sagnac effect. Among them, the atmospheric delay includes ionospheric delay and tropospheric delay.

[0048] In this embodiment, the atmospheric delay includes the atmospheric delay in the propagation between the satellite and the measurement and control station, and the atmospheric delay in the propagation between the satellite and the user terminal. The ground equipment time delay includes the transmitter equipment time delay and receiver equipment time delay of the measurement and control station, and the receiver equipment time delay of the user terminal. The link Sagnac effect includes the uplink Sagnac effect of the signal from the measurement and control station to the satellite, the downlink Sagnac effect of the signal from the satellite to the measurement and control station, and the downlink Sagnac effect of the signal from the satellite to the user terminal. Correspondingly, the corresponding propagation error term corrections are made to the first total path propagation delay and the second total path propagation delay.

[0049] Specifically, step 5 includes:

[0050] Step 5.1: Obtain the transmitter equipment time delay and receiver equipment time delay of the measurement and control station, and use the transmitter equipment time delay and receiver equipment time delay of the measurement and control station to correct the ground equipment time delay error of the first total path propagation delay, and obtain the first error correction result of the first total path;

[0051] In this embodiment, the transmitter equipment time delay and receiver equipment time delay of the measurement and control station can be directly calibrated.

[0052] Step 5.2: Use the model to correct the first error correction result of the first total path for atmospheric delay and link Sagnac effect, and obtain the second error correction result of the first total path;

[0053] In this embodiment, use the model to correct the first error correction result of the first total path for the atmospheric delay in the propagation between the satellite and the measurement and control station, the uplink Sagnac effect of the signal from the measurement and control station to the satellite, and the downlink Sagnac effect of the signal from the satellite to the measurement and control station, and obtain the second error correction result of the first total path.

[0054] It should be noted that the atmospheric delay mainly includes the ionospheric delay and the tropospheric delay. Optionally, the ionospheric delay can be obtained by interpolating the total electron content required for the ionospheric pierce point through the global ionospheric products provided by IGS, and is used for the ionospheric delay correction in this embodiment. The tropospheric delay can be calculated through meteorological data and the Saastamonien model, or a GNSS receiver can be configured at the station and calculated based on the IGS / iGMAS products. The Sagnac effect is due to the finiteness of the speed of light. The geometric distance between the satellite and the ground station at the signal emission time or reception time does not correspond to the actual signal propagation distance, and the influence of the earth's rotation also needs to be considered. This error can be calculated and corrected by establishing a geometric path model of signal transmission and calculating the projected area. The above correction methods for atmospheric delay and Sagnac effect can be implemented by existing correction methods, and the specific method steps are not elaborated here.

[0055] Step 5.3: Obtain the satellite TT&C transponder delay according to the second error correction result of the first total path and the geometric path delay of the propagation between the satellite and the TT&C station.

[0056] In this embodiment, the signal is transmitted from the TT&C station to the satellite and then returns to the TT&C station. The path propagation delay of this path is similar to the path propagation delay of "self-transmitting and self-receiving" of the signal in the transponder system. By using the obtained first total path propagation delay and correcting the propagation error terms (including atmospheric delay, ground equipment delay, and link Sagnac effect, etc.), the satellite TT&C transponder delay can be calculated.

[0057] Furthermore, step 6 includes:

[0058] Step 6.1: Obtain the receiver equipment delay of the user terminal, and use the transmitter equipment delay of the TT&C station and the receiver equipment delay of the user terminal to correct the ground equipment delay error of the second total path propagation delay, and obtain the first error correction result of the second total path;

[0059] In this embodiment, the receiver equipment delay of the user terminal can be directly calibrated.

[0060] Step 6.2: Use the model to correct the atmospheric delay and link Sagnac effect of the first error correction result of the second total path, and obtain the second error correction result of the second total path;

[0061] In this embodiment, the model is used to correct the atmospheric delay of the propagation between the satellite and the TT&C station, the atmospheric delay of the propagation between the satellite and the user terminal, the uplink Sagnac effect of the signal from the TT&C station to the satellite, and the downlink Sagnac effect of the signal from the satellite to the user terminal for the first error correction result of the second total path, and obtain the second error correction result of the second total path.

[0062] Step 6.3: Obtain the clock difference between the user terminal and the TT&C station based on the second error correction result of the second total path, the geometric path delay in the propagation between the satellite and the TT&C station, the geometric path delay in the propagation between the satellite and the user terminal, and the satellite TT&C transponder delay.

[0063] Specifically, in this embodiment, by using the obtained second total path propagation delay, after correcting the propagation error terms (including atmospheric delay, ground equipment delay, and link Sagnac effect, etc.), and based on the satellite TT&C transponder delay obtained in Step 5, the clock difference between the user terminal and the TT&C station can be obtained, that is, the clock difference between the user and UTC(NTSC) can be obtained.

[0064] Step 6.4: Perform time synchronization on the user terminal according to the clock difference.

[0065] The GEO communication satellite time synchronization method based on USB TT&C signals in this embodiment utilizes the ranging accuracy of USB technology and can achieve high time synchronization accuracy through calculation. Moreover, on the premise that the positions of both the satellite and the ground station are known, due to the wide-area differential function, its time synchronization accuracy is higher than that of satellite one-way time synchronization, and what the user finally obtains will directly be the clock difference with the UTC(NTSC) of the TT&C station.

[0066] The GEO communication satellite time synchronization method based on USB TT&C signals in this embodiment can endow the satellite TT&C system with a new function, that is, to achieve high-precision satellite time synchronization based on TT&C signals, without increasing additional costs.

[0067] Furthermore, with reference to Figure 3 the schematic diagram of satellite time synchronization based on TT&C signals, the specific implementation principle of the GEO communication satellite time synchronization method based on USB TT&C signals in the above embodiment will be further described in detail.

[0068] Specifically, as Figure 3 shown, for the convenience of explanation, the delays of each main link in the signal transmission process are shown.

[0069] From Figure 3 it can be seen that the uplink carrier signal sent by TT&C station A is received by user B after being relayed by the satellite TT&C transponder, and the time relationship of signal transmission is expressed as:

[0070]

[0071] where, t AB is the measured path propagation delay of the signal from TT&C station A to the satellite and then back to user B, that is, the second total path propagation delay; and are the time scales of the local atomic clocks of TT&C station A and user B respectively; is the time delay of the transmitter equipment of the measurement and control station A; is the uplink propagation time delay of the signal from the measurement and control station A to the satellite; is the Sagnac effect of the uplink from the measurement and control station A to the satellite; is the time delay of the satellite measurement and control transponder on the ASB path; is the downlink propagation time delay of the signal from the satellite to the user B; is the Sagnac effect of the downlink from the satellite to the user B; is the time delay of the receiver equipment of the user B.

[0072] In formula (1), t AB can be directly measured; the clock difference between the measurement and control station A and the user B is the unknown quantity to be solved in the GEO communication satellite time synchronization method based on USB measurement and control signals in this embodiment. Since it is difficult to directly calibrate the satellite measurement and control transponder equipment in the air, the equipment time delay of the satellite measurement and control transponder needs to be corrected by an algorithm, which is also another unknown quantity to be solved. The specific solution will be described below.

[0073] In addition, the path propagation time delay of the signal not only includes the geometric path time delay, but also includes the atmospheric delay. Among them, the atmospheric delay includes the ionospheric delay and the tropospheric delay. The uplink propagation time delay of the signal from the measurement and control station A to the satellite, and the downlink propagation time delay of the signal from the satellite to the user B are expressed by the following formula:

[0074]

[0075]

[0076] Among them, c is the speed of light; respectively represent the coordinates of the satellite, the measurement and control station A, and the user B in the ground fixed coordinate system; represents the geometric path time delay of the propagation between the satellite and the measurement and control station A; represents the geometric path time delay of the propagation between the satellite and the user B; is the ionospheric delay of the uplink from the measurement and control station A to the satellite; is the ionospheric delay of the downlink from the satellite to the user B; is the tropospheric delay of the uplink from the measurement and control station A to the satellite; is the tropospheric delay of the downlink from the satellite to the user B.

[0077] It should be noted that and constitute the atmospheric delay of the propagation between the satellite and the user terminal.

[0078] Substituting formulas (2) and (3) into formula (1), the clock difference between the measurement and control station A and the user B can be obtained as follows:

[0079]

[0080] In formula (4), the atmospheric delay and Sagnac effect during the signal transmission process can be corrected through models; the ground equipment time delay (the transmitter equipment time delay and receiver equipment time delay of the measurement and control station A, as well as the receiver equipment time delay of the user B) can also be directly calibrated. Using the passive orbit determination system of the National Time Service Center, the meter-level orbit of the satellite can be obtained, and thus the geometric path time delay of the signal propagation between the satellite and the ground station can be directly calculated (the geometric path time delay of the signal propagation from the satellite to the measurement and control station A, as well as the geometric path time delay of the signal propagation from the satellite to the user B).

[0081] Through the above analysis, only the time delay of the satellite measurement and control transponder is unknown in formula (4). After deducting this item of time delay, the clock difference between the user and the measurement and control station can be obtained, and satellite time transfer is completed. Since the USB ranging accuracy is at the meter level, the satellite time transfer method based on USB measurement and control signals in this embodiment can achieve a time transfer accuracy at the nanosecond level.

[0082] It can be seen from formula (4) that to obtain the accurate clock difference between the user and the measurement and control station, the influence of the satellite measurement and control transponder time delay needs to be deducted. Since the position of the satellite measurement and control transponder itself cannot be directly calibrated like the ground station equipment, this embodiment uses a measurement mode similar to the "self-transmitting and self-receiving" of the transponder system to calibrate the time delay of the satellite measurement and control transponder.

[0083] Specifically, from Figure 2 it can be seen that when the measurement and control station sends a measurement and control signal to the satellite, and after being relayed by the satellite and then received by the measurement and control station, the time relationship of the signal transmission of the measurement and control station A can be expressed as:

[0084]

[0085] Among them, t AA is the path propagation time delay of the signal measured from the measurement and control station A to the satellite and then back to the measurement and control station A, that is, the first total path propagation time delay; is the time scale of the local atomic clock of the measurement and control station A; is the transmitter equipment time delay of the measurement and control station A; is the uplink propagation time delay of the signal from the measurement and control station A to the satellite; is the uplink Sagnac effect of the signal from the measurement and control station A to the satellite; is the time delay of the satellite measurement and control transponder in the ASA path; is the downlink propagation time delay of the signal from the satellite to the measurement and control station A; is the Sagnac effect of the downlink from the satellite to TT&C station A; is the receiver equipment delay of TT&C station A.

[0086] Similar to formula (3), the propagation delay of the downlink from the satellite to TT&C station A is as follows:

[0087]

[0088] where, is the ionospheric delay of the downlink from the satellite to TT&C station A; is the tropospheric delay of the downlink from the satellite to TT&C station A.

[0089] It should be noted that and constitute the atmospheric delay in the propagation between the satellite and the TT&C station.

[0090] Substitute formulas (2) and (6) into formula (5), and after combination, the satellite TT&C transponder delay can be obtained as follows:

[0091]

[0092] For GEO satellites, the same TT&C transponder can meet the full coverage of TT&C stations and users. Therefore,

[0093] Substitute formula (7) into formula (4), and the clock difference between the user and the TT&C station can be calculated, that is, the clock difference between the user and UTC(NTSC), to complete the timing of the user.

[0094] The timing method of this embodiment meets the construction requirements of the current integrated PNT system to realize the fusion of multiple information sources based on different principles to generate a more accurate and stable spatio-temporal reference. Without increasing additional costs, it can endow the satellite TT&C system with a new function, that is, to realize high-precision satellite timing based on TT&C signals.

[0095] Embodiment 2

[0096] This embodiment provides a GEO communication satellite timing system based on USB TT&C signals. The timing system includes: a signal transmission module, a signal reception module, a total path delay module, a geometric path delay module, a propagation error term correction module, and a timing module. Among them,

[0097] The signal transmission module is used to use the standard time-frequency signal output by the NTSC master clock as the time-frequency reference and send the uplink carrier signal modulated with ranging tones to the satellite;

[0098] The signal receiving module is used to obtain the downlink telemetry signal after being mixed and forwarded by the satellite TT&C transponder. Among them, the downlink telemetry signal includes the user terminal downlink telemetry signal and the TT&C station downlink telemetry signal;

[0099] The total path delay module is used to demodulate the user terminal downlink telemetry signal and the TT&C station downlink telemetry signal respectively to obtain the first total path propagation delay and the second total path propagation delay;

[0100] The geometric path delay module is used to calculate the geometric path delay of the propagation between the satellite and the TT&C station, and the geometric path delay of the propagation between the satellite and the user terminal;

[0101] The propagation error term correction module corrects the propagation error term of the first total path propagation delay, and obtains the satellite TT&C transponder delay according to the correction result and the geometric path delay of the propagation between the satellite and the TT&C station; It is also used to correct the propagation error term of the second total path propagation delay;

[0102] The timing module is used to obtain the clock difference between the user terminal and the TT&C station according to the correction result of the second total path, the geometric path delay of the propagation between the satellite and the user terminal, and the satellite TT&C transponder delay, and complete the timing of the user terminal according to the clock difference.

[0103] The GEO communication satellite timing system based on USB TT&C signals provided by the embodiments of the present invention can execute the GEO communication satellite timing method based on USB TT&C signals in the above-mentioned Embodiment 1. Its specific implementation steps, implementation principles, and technical effects are similar, and will not be elaborated here.

[0104] This embodiment also provides an electronic device, including a processor, a communication interface, a memory, and a communication bus. Among them, the processor, the communication interface, and the memory complete mutual communication through the communication bus; the memory is used to store computer programs; the processor is used to implement the steps of the above-mentioned GEO communication satellite timing method based on USB TT&C signals when executing the programs stored on the memory.

[0105] This embodiment also provides an electronic device, a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above-mentioned GEO communication satellite timing method based on USB TT&C signals are implemented.

[0106] It should be noted that the systems, electronic devices, and storage media in the embodiments of the present invention are respectively devices, electronic devices, and storage media applying the above-mentioned GEO communication satellite timing method based on USB TT&C signals. Then all embodiments of the above-mentioned GEO communication satellite timing method based on USB TT&C signals are applicable to this device, electronic device, and storage medium, and can achieve the same or similar beneficial effects.

[0107] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant are intended to cover non-exclusive inclusion, so that an article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the article or device comprising the element.

[0108] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for timing a GEO communication satellite based on USB measurement and control signals, characterized in that, it includes: Step 1: Use the standard time-frequency signal output by the NTSC master clock as the time-frequency reference of the measurement and control station, and send the uplink carrier signal modulated with ranging tones to the satellite; Step 2: Obtain the downlink telemetry signal after being mixed and forwarded by the satellite measurement and control transponder, where the downlink telemetry signal includes the user terminal downlink telemetry signal and the measurement and control station downlink telemetry signal; Step 3: Demodulate the user terminal downlink telemetry signal and the measurement and control station downlink telemetry signal respectively to obtain the first total path propagation delay and the second total path propagation delay; Step 4: Calculate the geometric path delay of the propagation between the satellite and the measurement and control station, and the geometric path delay of the propagation between the satellite and the user terminal; Step 5: Correct the propagation error terms of the first total path propagation delay, and obtain the satellite measurement and control transponder delay according to the correction result and the geometric path delay of the propagation between the satellite and the measurement and control station; Step 6: Correct the propagation error terms of the second total path propagation delay, and obtain the clock difference between the user terminal and the measurement and control station according to the correction result, the geometric path delay of the propagation between the satellite and the measurement and control station, the geometric path delay of the propagation between the satellite and the user terminal, and the satellite measurement and control transponder delay, so as to complete timing.

2. The method for timing a GEO communication satellite based on USB measurement and control signals according to claim 1, characterized in that, the first total path propagation delay is the path propagation delay of the signal from the measurement and control station to the satellite and then back to the measurement and control station; the second total path propagation delay is the path propagation delay of the signal from the measurement and control station to the satellite and then back to the user terminal.

3. The method for timing a GEO communication satellite based on USB measurement and control signals according to claim 1, characterized in that, the propagation error terms include atmospheric delay, ground equipment delay, and link Sagnac effect.

4. The method for timing a GEO communication satellite based on USB measurement and control signals according to claim 3, characterized in that, the atmospheric delay includes the atmospheric delay of the propagation between the satellite and the measurement and control station, and the atmospheric delay of the propagation between the satellite and the user terminal; the ground equipment delay includes the transmitter equipment delay and receiver equipment delay of the measurement and control station, and the receiver equipment delay of the user terminal; the link Sagnac effect includes the uplink link Sagnac effect of the signal from the measurement and control station to the satellite, the downlink link Sagnac effect of the signal from the satellite to the measurement and control station, and the downlink link Sagnac effect of the signal from the satellite to the user terminal.

5. The method for timing a GEO communication satellite based on USB measurement and control signals according to claim 4, characterized in that, Step 4 includes: Using the satellite passive orbit determination system, calculate the geometric path delay of the propagation between the satellite and the measurement and control station and the geometric path delay of the propagation between the satellite and the user terminal according to the position coordinates of the measurement and control station and the user terminal.

6. The GEO communication satellite time synchronization method based on USB measurement and control signals according to claim 5, characterized in that, step 5 includes: Step 5.1: Obtain the transmitter device delay and receiver device delay of the measurement and control station, and use the transmitter device delay and receiver device delay of the measurement and control station to correct the ground device delay error of the first total path propagation delay, and obtain the first error correction result of the first total path; Step 5.2: Use the model to correct the atmospheric delay and link Sagnac effect of the first error correction result of the first total path, and obtain the second error correction result of the first total path; Step 5.3: According to the second error correction result of the first total path and the geometric path delay propagated between the satellite and the measurement and control station, obtain the satellite measurement and control transponder delay.

7. The GEO communication satellite time synchronization method based on USB measurement and control signals according to claim 5, characterized in that, step 6 includes: Step 6.1: Obtain the receiver device delay of the user terminal, and use the transmitter device delay of the measurement and control station and the receiver device delay of the user terminal to correct the ground device delay error of the second total path propagation delay, and obtain the first error correction result of the second total path; Step 6.2: Use the model to correct the atmospheric delay and link Sagnac effect of the first error correction result of the second total path, and obtain the second error correction result of the second total path; Step 6.3: According to the second error correction result of the second total path, the geometric path delay propagated between the satellite and the measurement and control station, the geometric path delay propagated between the satellite and the user terminal, and the satellite measurement and control transponder delay, obtain the clock difference between the user terminal and the measurement and control station; Step 6.4: Complete the time synchronization of the user terminal according to the clock difference.

8. A GEO communication satellite time synchronization system based on USB measurement and control signals, characterized in that, it includes: A signal transmission module, which uses the standard time-frequency signal output by the NTSC master clock as the time-frequency reference, and sends the uplink carrier signal modulated with the ranging tone to the satellite; A signal reception module, which is used to obtain the downlink telemetry signal mixed and forwarded by the satellite measurement and control transponder, wherein the downlink telemetry signal includes the user terminal downlink telemetry signal and the measurement and control station downlink telemetry signal; A total path delay module, which is used to demodulate the user terminal downlink telemetry signal and the measurement and control station downlink telemetry signal respectively, and obtain the first total path propagation delay and the second total path propagation delay; A geometric path delay module, which is used to calculate the geometric path delay propagated between the satellite and the measurement and control station, and the geometric path delay propagated between the satellite and the user terminal; A propagation error term correction module, which corrects the propagation error term of the first total path propagation delay, and obtains the satellite measurement and control transponder delay according to the correction result and the geometric path delay propagated between the satellite and the measurement and control station; it is also used to correct the propagation error term of the second total path propagation delay; A time service module, which is used to obtain the clock difference between the user terminal and the TT&C station according to the correction result of the second total path, the geometric path delay propagated between the satellite and the user terminal, and the satellite TT&C transponder delay, and complete the time service for the user terminal according to the clock difference.

9. An electronic device, characterized in that, it includes a processor, a communication interface, a memory, and a communication bus. Among them, the processor, the communication interface, and the memory complete communication with each other through the communication bus; the memory is used to store computer programs; when the processor is used to execute the programs stored on the memory, it realizes the steps of the method described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, it realizes the steps of the method described in any one of claims 1-7.

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