Satellite two-way time comparison system and method

Abstract

The application discloses a satellite two-way time comparison system and method, and relates to the technical field of space. The system comprises a satellite, a master station and a slave station which are respectively connected with the satellite. The master station, the satellite and the slave station have a master long pseudo-range ranging signal and a slave long pseudo-range ranging signal. The master station receives and measures the master long pseudo-range ranging signal to obtain a master long pseudo-range ranging value, and the slave station receives and measures the slave long pseudo-range ranging signal to obtain a slave long pseudo-range ranging value. The master station and the satellite have a master retransmission ranging signal, and the slave station and the satellite have a slave retransmission ranging signal. A calculation device calculates a master ionospheric total electron number between the satellite and the master station, a slave ionospheric total electron number between the satellite and the slave station, and a clock difference between the master station and the slave station according to the master long pseudo-range ranging value, the slave long pseudo-range ranging value, the master retransmission ranging value and the slave retransmission ranging value. The ionospheric time delay error is overcome, and the time comparison precision is significantly improved compared with a traditional satellite two-way time comparison system.

Description

Technical Field

[0001] This invention relates to the field of time and frequency science and space science, specifically to a satellite two-way time comparison system.

[0002] This invention also relates to a satellite two-way time comparison method. Background Technology

[0003] Two-way satellite time synchronization is currently the most accurate method for long-distance time synchronization and is also a commonly used method for time synchronization among international time service centers. The basic principle of two-way satellite time synchronization is that two time stations, located far apart, send long pseudorange ranging signals to each other. Each station measures the long pseudorange ranging signal sent by the other, and then the difference between the two long pseudorange values ​​is the time difference between the two stations. The high accuracy of two-way satellite time synchronization is entirely due to the symmetry of the paths between the two long pseudorange ranging signals. For example, if the spatial geometric distance traversed is equal, the tropospheric delays of the two long pseudorange ranging signals are equal, but the ionospheric delays are unequal, producing an ionospheric residual. Current two-way satellite time synchronization methods use the Ku band, which produces a smaller ionospheric delay, thus achieving very high time synchronization accuracy.

[0004] When satellites and ground stations communicate via radio, the radio signals experience time delays as they pass through the atmosphere, including ionospheric and tropospheric delays. When the carrier frequency is less than 30 GHz, the tropospheric delay is considered equal to the radio signal delay. However, the ionospheric delay is inversely proportional to the square of the carrier frequency and directly proportional to the total number of electrons in the ionosphere along the transmission path. The mathematical expression for the time delay of a radio signal crossing the ionosphere can be:

[0005]

[0006] In the formula: dI is the time delay of the radio frequency signal (i.e., radio signal) when it travels through the ionospheric path of the satellite-to-ground connection, in meters; f is the carrier frequency of the radio signal, in Hertz; TEC is the total number of electrons in the ionosphere along the path between the satellite and the ground station, in electrons per square meter.

[0007] Radio signals from satellite two-way time comparisons also introduce ionospheric delay. Although international recommendations suggest using the Ku band for satellite two-way time comparisons, resulting in relatively small ionospheric delays, these ionospheric residuals are still significant for ultra-high-precision long-range time comparisons and need to be eliminated. A common method is ionospheric model estimation, which estimates the total number of ionospheric electrons along the long pseudorange ranging signal path and then eliminates the error. Another method is to use the total number of ionospheric electrons provided by a third party to eliminate the error; currently, the total number of ionospheric electrons provided by IGS (International GPS Service) is representative. When using ionospheric data provided by IGS, users need to download the ionospheric delay for the corresponding time period from the IGS website, which involves time lag and may even result in the data being unavailable.

[0008] Although satellite two-way time comparison is highly accurate, it still has errors due to ionospheric residuals. In addition, the cost of using satellite two-way time comparison is very high, including equipment costs and satellite communication costs. The terminal comparison equipment is also very expensive, which limits its scope of use.

[0009] If the ionospheric time delay error can be overcome while reducing the cost of use, the application scope of satellite two-way time comparison will be greatly expanded. Summary of the Invention

[0010] The purpose of this invention is to address the aforementioned problems by providing a satellite two-way time comparison system. This system solves the problems of the total number of ionospheric electrons between the master station and the satellite, and the total number of ionospheric electrons between the slave station and the satellite, through long pseudorange ranging signals and relay ranging signals. As a result, the satellite two-way time comparison system proposed in this invention can overcome ionospheric delay, improve the accuracy of satellite two-way time comparison, and the system no longer relies on the total number of ionospheric electrons provided by a third party, making the system safe and reliable.

[0011] The technical solution adopted in this invention is as follows:

[0012] A satellite two-way time comparison system, the system comprising a master station and a slave station respectively connected to a satellite for communication;

[0013] The master station, slave station and satellite are respectively connected by a master long pseudorange ranging signal and a slave long pseudorange ranging signal. The master station and slave station obtain the master long pseudorange ranging value and the slave long pseudorange ranging value through the master long pseudorange ranging signal and the slave long pseudorange ranging signal, respectively.

[0014] There is a primary relay ranging signal between the master station and the satellite, and the master station obtains the primary relay ranging value through the primary relay ranging signal;

[0015] There is a relay ranging signal between the slave station and the satellite, and the slave station obtains the relay ranging value through the relay ranging signal;

[0016] The total number of primary ionospheric electrons between the satellite and the master station, the total number of secondary ionospheric electrons between the satellite and the slave station, and the clock difference between the master station and the slave station are calculated using the primary long pseudorange ranging value, the secondary long pseudorange ranging value, the primary transponder ranging value, and the secondary transponder ranging value.

[0017] Furthermore, the number of signal channels for the main long pseudorange ranging signal, the secondary long pseudorange ranging signal, the main forwarding ranging signal, and the secondary forwarding ranging signal are m, v, h, and r, respectively; m and v are both integers greater than or equal to 1, h and r are both integers greater than or equal to 0, and m+h+r+v≥4.

[0018] Furthermore, the primary pseudorange ranging signal includes the primary pseudorange downlink signal broadcast by the slave station and relayed by the satellite to the master station;

[0019] The long pseudorange ranging signal includes the primary pseudorange uplink signal broadcast by the master station and relayed by the satellite to the slave station;

[0020] The main relay ranging signal includes a main uplink signal and a main downlink signal. The main station broadcasts the main uplink signal and receives the main downlink signal. The satellite receives the main uplink signal and forwards it to form the main downlink signal.

[0021] The relay ranging signal includes an uplink signal and a downlink signal. The slave station broadcasts the uplink signal and receives the downlink signal. The satellite receives the uplink signal and forwards it to form the downlink signal.

[0022] Furthermore, the satellite includes:

[0023] A repeater is used for communication between the primary uplink signal and the primary downlink signal, between the secondary uplink signal and the secondary downlink signal, between the primary pseudorange uplink signal and the secondary pseudorange downlink signal, and between the secondary pseudorange uplink signal and the primary pseudorange downlink signal;

[0024] Satellite time and frequency equipment is used to provide time and frequency signals to the transponder;

[0025] The main station, comprising:

[0026] A primary pseudorange ranging device is used to receive and synchronously measure the primary long pseudorange ranging signal to obtain the primary long pseudorange ranging value.

[0027] The main forwarding ranging device is used to generate and broadcast the main uplink signal and the main pseudorange uplink signal, and to receive and measure the main downlink signal to obtain the main forwarding ranging value.

[0028] At least one primary time-frequency device is used to provide time-frequency signals to the primary relay ranging device and the primary pseudorange ranging device;

[0029] Slave station, the slave station includes:

[0030] From the pseudorange ranging device, used to receive and synchronously measure the pseudorange ranging signal to obtain the pseudorange ranging value;

[0031] The forwarding ranging device is used to generate and broadcast the forwarding uplink signal, receive and measure the forwarding downlink signal to obtain the forwarding ranging value;

[0032] The master station and slave station each include at least one time-frequency device for providing time-frequency signals to the master relay ranging device, slave relay ranging device, master pseudorange ranging device, and slave pseudorange ranging device.

[0033] Furthermore, the primary pseudorange ranging device, the primary relay ranging device, the secondary pseudorange ranging device, and the secondary relay ranging device are all set to zero baseline.

[0034] Furthermore, the system also includes:

[0035] A computing device is communicatively connected to both the master station and the slave station. The computing device receives the main long pseudorange ranging value, the slave long pseudorange ranging value, the main relay ranging value, and the slave relay ranging value. Based on the main long pseudorange ranging value, the slave long pseudorange ranging value, the main relay ranging value, and the slave relay ranging value, the computing device determines the total number of primary ionospheric electrons between the master station and the satellite, the total number of secondary ionospheric electrons between the slave station and the satellite, and the clock difference between the master station and the slave station.

[0036] Furthermore, the main long pseudorange ranging signal, the secondary long pseudorange ranging signal, the main relay ranging signal, and the secondary relay ranging signal are all spread spectrum signals.

[0037] The second technical solution adopted in this invention is a satellite two-way time comparison method, which employs a satellite two-way time comparison system, the method comprising:

[0038] The computing device acquires data by communicating with the master station and the slave station respectively, and acquiring m master long pseudorange ranging values, v slave long pseudorange ranging values, h master forwarding ranging values ​​and r slave forwarding ranging values;

[0039] The calculation device obtains the total number of primary ionospheric electrons and / or the total number of secondary ionospheric electrons, as well as the clock difference between the master station and the slave station, based on m primary long pseudorange ranging values, v secondary long pseudorange ranging values, h primary relay ranging values, and r secondary relay ranging values. The total number of primary ionospheric electrons is the total number of ionospheric electrons on the ranging signal path between the master station and the satellite, and the total number of secondary ionospheric electrons is the total number of ionospheric electrons on the ranging signal path between the slave station and the satellite.

[0040] Further, the total number of electrons in the primary ionosphere and / or the total number of electrons in the secondary ionosphere are specifically:

[0041] The m primary long pseudorange ranging values, v secondary long pseudorange ranging values, h primary forwarding ranging values, and r secondary forwarding ranging values ​​are corrected respectively to obtain m corrected primary long pseudorange ranging values, v corrected secondary long pseudorange ranging values, h corrected primary forwarding ranging values, and r corrected secondary forwarding ranging values.

[0042] The total number of electrons in the main ionosphere and / or the total number of electrons in the secondary ionosphere are determined based on the m corrected main long pseudorange ranging values, v corrected secondary long pseudorange ranging values, h corrected main forwarding ranging values, and r corrected secondary forwarding ranging values.

[0043] Furthermore, the clock difference between the master station and the slave station is specifically as follows:

[0044] The clock difference between the master station and the slave station is determined using the total number of electrons in the main ionosphere and / or the total number of electrons in the slave ionosphere, any of the corrected main long pseudorange distance measurement values, and any of the corrected slave long pseudorange distance measurement values.

[0045] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0046] This invention provides a satellite two-way time comparison system. By using long pseudorange ranging signals and relay ranging signals, it solves the problems of the total number of ionospheric electrons between the master station and the satellite, and the total number of ionospheric electrons between the slave station and the satellite. This allows the satellite two-way time comparison system proposed in this invention to overcome ionospheric delay and improve the accuracy of satellite two-way time comparison. The system no longer relies on the total number of ionospheric electrons provided by a third party, making the system safe and reliable. This invention overcomes ionospheric delay error and significantly improves the time comparison accuracy compared to traditional satellite two-way time comparison systems. Attached Figure Description

[0047] Figures 1-3 These are schematic diagrams of the first, second, and third simplified systems in the satellite two-way time comparison system provided in the embodiments of the present invention.

[0048] Figure 4 and Figure 5These are schematic diagrams of the first and second typical system structures in the satellite two-way time comparison system provided in the embodiments of the present invention.

[0049] Figure 6 This is a structural block diagram of a satellite two-way time comparison system according to an embodiment of the present invention;

[0050] Figure 7 This is a flowchart of a satellite two-way time comparison method according to an embodiment of the present invention. Detailed Implementation

[0051] The present invention will now be described in detail with reference to the accompanying drawings.

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0053] Example:

[0054] This embodiment provides a satellite two-way time comparison system, such as Figures 1 to 5 As shown, it includes a satellite, a master station, a slave station, and a computing device. The master station and slave station are both connected to the satellite for communication, and the computing device is connected to both the master station and the slave station for communication.

[0055] The computing device can communicate with the master station and the slave station respectively to obtain the master long pseudorange ranging value, the slave long pseudorange ranging value, the slave forwarding ranging value and the master forwarding ranging value, as well as the device latency, etc.

[0056] After obtaining the primary long pseudorange ranging value, secondary long pseudorange ranging value, primary relay ranging value, and secondary relay ranging value, the computing device calculates the total number of primary ionospheric electrons on the ranging signal path between the satellite and the master station and / or the total number of secondary ionospheric electrons on the ranging signal path between the satellite and the user, as well as the clock difference between the master station and the secondary station.

[0057] In this embodiment, the computing device can be integrated into the master station; or integrated into the slave station; or it can be independent of the master station and slave station; or it can be distributed among the master station and slave station to perform calculations; or it can be a separate device.

[0058] In actual use, the master station and slave station each have corresponding devices with computing capabilities to perform different computing tasks.

[0059] The computing device performs calculations based on the primary long pseudorange ranging value, the secondary long pseudorange ranging value, the primary forwarding ranging value, and the secondary forwarding ranging value, which is not the core function of this embodiment.

[0060] In this embodiment, system time refers to the time during which a system generates and maintains itself, such as the system composed of satellites, master stations, slave stations, and computing devices. In practical applications, BeiDou time is often used as the reference time and system time, and the clock difference of different devices is the clock difference of different devices relative to this BeiDou reference time.

[0061] In the satellite two-way time comparison system proposed in this embodiment, the number of primary long pseudorange ranging signals is m, the number of secondary long pseudorange ranging signals is v, the number of primary relay ranging signals is h, and the number of secondary relay ranging signals is r, and m+v+h+r≥4. There are multiple simplest satellite two-way time comparison systems that meet this condition.

[0062] Before introducing the simplest system, let's first explain a few basic signal structures.

[0063] The Y-type bifurcated long pseudorange ranging signal is: there is one pseudorange uplink signal and a pseudorange downlink signals with different carrier frequencies, where a is an integer greater than or equal to 2, denoted as Y(a).

[0064] The T-type converged long pseudorange ranging signal is defined as having at least b pseudorange uplink signals and b pseudorange downlink signals with different carrier frequencies, and all pseudorange downlink signals having the same carrier frequency, denoted as T(b).

[0065] The following is a simplified description of the system with reference to the accompanying drawings.

[0066] The first simplest system, such as Figure 1 As shown, the system has one primary long pseudorange ranging signal (m=1), one secondary long pseudorange ranging signal (v=1), two primary relay ranging signals (h=2), and two secondary relay ranging signals (r=2). The primary pseudorange uplink signal of the secondary long pseudorange ranging signal is the same as the uplink signal of the primary relay ranging signal. The satellite splits the primary pseudorange uplink signal into three parts, one of which is relayed as the secondary pseudorange downlink signal, and the other two are relayed to the master station as primary downlink signals. Carrier frequency reuse technology is used, and the carrier frequency of any one of the two primary relay ranging signals is the same as the carrier frequency of the primary pseudorange downlink signal. The master station uses the two primary relay ranging values ​​to calculate the total number of electrons in the primary ionosphere, and the slave station uses the two secondary relay ranging values ​​to calculate the total number of electrons in the secondary ionosphere.

[0067] The second simplest system, such as Figure 2As shown, the system has one main long pseudorange ranging signal (m=1), two secondary long pseudorange ranging signals (v=2), which are Y-shaped bifurcated long pseudorange ranging signals, two main relay ranging signals (h=2), and zero secondary relay ranging signals (r=0). The main pseudorange uplink signal transmitted by the master station 210 is split into four after reaching satellite 100. Two of them are pseudorange downlink signals that reach the slave station 220, and the other two are main downlink signals that reach the master station 210. The downlink signals of the main relay ranging signals of the master station and the main pseudorange downlink signals of the secondary long pseudorange ranging signals are multiplexed using the carrier frequency. The master station uses the two main relay ranging values ​​to obtain the total number of electrons in the main ionosphere, and the slave station uses the two Y-shaped bifurcated secondary long pseudorange ranging values ​​to obtain the total number of electrons in the secondary ionosphere.

[0068] The third simplest system, such as Figure 3 As shown, the system has one main long pseudorange ranging signal (m=1), two secondary long pseudorange ranging signals (v=2), and the secondary long pseudorange ranging signals are converged in a T-shape. There is also one main forwarding ranging signal (h=0) and two secondary forwarding ranging signals (r=2). The secondary forwarding ranging signals and the secondary pseudorange downlink signals utilize carrier frequency multiplexing technology. The slave station uses the two secondary forwarding ranging values ​​to obtain the total number of electrons in the ionosphere, and the slave station uses the two T-shaped converged secondary long pseudorange ranging signals to obtain the total number of electrons in the main ionosphere.

[0069] The first typical system, such as Figure 4 As shown, the system has one main long pseudorange ranging signal (m=1), one secondary long pseudorange ranging signal (v=1), zero main relay ranging signals (h=0), and two secondary relay ranging signals (r=2). The secondary relay ranging signals and the secondary pseudorange downlink signals use carrier frequency multiplexing technology; the secondary station uses the two secondary relay ranging values ​​to obtain the total number of electrons in the secondary ionosphere, but cannot obtain the total number of electrons in the main ionosphere.

[0070] The second typical system, such as Figure 5 As shown, the system has one main long pseudorange ranging signal (m=1), one secondary long pseudorange ranging signal (v=1), two main relay ranging signals (h=2), and zero secondary relay ranging signals (r=0). The main relay ranging signal and the main pseudorange downlink signal use carrier frequency multiplexing technology. The master station uses the two main relay ranging values ​​to obtain the total number of electrons in the main ionosphere, but cannot obtain the total number of electrons in the secondary ionosphere.

[0071] The satellite two-way time comparison system and method provided in this embodiment will be described in detail below with reference to the accompanying drawings.

[0072] like Figure 1 As shown, the satellite two-way time comparison system includes a master station 210, a satellite 100, a slave station 220, and computing equipment.

[0073] There are master long pseudorange ranging signals and slave long pseudorange ranging signals among master station 210, satellite 100 and slave station 220. The long pseudorange ranging signal consists of pseudorange uplink signal and pseudorange downlink signal.

[0074] like Figure 1 As shown, satellite 100 is used to forward the main pseudorange downlink signal of the main pseudorange ranging signal to the master station based on the received pseudorange uplink signal of the main long pseudorange ranging signal, and to forward the pseudorange downlink signal of the long pseudorange ranging signal to the slave station based on the received pseudorange uplink signal of the long pseudorange ranging signal.

[0075] The master station 210 is used to broadcast the main pseudorange uplink signal of the long pseudorange ranging signal to the satellite, receive the main pseudorange downlink signal of the main long pseudorange ranging signal, and synchronously measure the main long pseudorange ranging signal to obtain the main long pseudorange ranging value.

[0076] The slave station 220 is used to broadcast the slave pseudorange uplink signal of the main long pseudorange ranging signal to the satellite, receive the slave pseudorange downlink signal of the slave long pseudorange ranging signal, and synchronously measure the corresponding slave long pseudorange ranging signal to obtain the slave long pseudorange ranging value.

[0077] Since both the main long pseudorange ranging signal and the secondary long pseudorange ranging signal are long pseudorange ranging signals, the long pseudorange ranging signal can also be considered as being composed of the pseudorange uplink signal transmitted by the transmitter and the pseudorange downlink signal received by the receiver.

[0078] There is also a primary relay ranging signal between the master station and the satellite. The master station broadcasts the primary uplink signal, which is relayed by the satellite as the primary downlink signal, thus forming the primary relay ranging signal. There is also a secondary relay ranging signal between the slave station and the satellite. The slave station broadcasts the primary uplink signal, which is relayed by the satellite as the secondary downlink signal, thus forming the secondary relay ranging signal.

[0079] The computing device is used to calculate the total number of electrons in the main ionosphere and / or the total number of electrons in the secondary ionosphere based on the main long pseudorange ranging value, the secondary long pseudorange ranging value, the main relay ranging value, and the secondary relay ranging value. Then, based on any one of the main long pseudorange ranging values, any one of the secondary long pseudorange ranging values, the total number of electrons in the main ionosphere, and / or the total number of electrons in the secondary ionosphere, the clock difference between the master station and the slave station is calculated.

[0080] The satellite two-way time comparison system provided in this embodiment can be applied to international time comparison, inter-station time synchronization of satellite navigation systems, or other applications requiring high-precision time comparison. This embodiment only uses the example of the computing device 230 determining the clock difference between the master station 210 and the slave station 220 for illustrative purposes.

[0081] In this embodiment, the primary long pseudorange ranging signal, the secondary long pseudorange ranging signal, the primary forwarding ranging signal, and the secondary forwarding ranging signal all refer to signals obtained by modulating a ranging code signal onto a carrier signal. In some specific embodiments, the ranging code can be a pseudocode, a weil code, an M code, etc., and this application does not impose any special limitation on the specific ranging code used. It is also understood that all the primary long pseudorange ranging signals, secondary long pseudorange ranging signals, primary forwarding ranging signals, and secondary forwarding ranging signals described in this embodiment are spread spectrum signals. When multiple spread spectrum signals are transmitted and received, the relationship between the carrier frequency and the ranging code is processed according to spread spectrum communication technology and code division multiple access communication technology, which will not be elaborated here.

[0082] Since the main long pseudorange ranging signal, the secondary long pseudorange ranging signal, the main relay ranging signal, and the secondary relay ranging signal are all spread spectrum signals, they are collectively referred to as ranging signals for the sake of simplicity and convenience.

[0083] Furthermore, the primary pseudorange uplink signal, primary pseudorange downlink signal, and primary relay ranging signal between the master station and the satellite have at least three different carrier frequencies, and the secondary pseudorange uplink signal, secondary pseudorange downlink signal, and secondary relay ranging signal between the slave station and the satellite have at least three different carrier frequencies; or, the primary pseudorange uplink signal, primary pseudorange downlink signal, and primary relay ranging signal between the master station and the satellite have at least two different carrier frequencies, and the secondary pseudorange uplink signal, secondary pseudorange downlink signal, and secondary relay ranging signal between the slave station and the satellite have at least three different carrier frequencies; or, the primary pseudorange uplink signal, primary pseudorange downlink signal, and primary relay ranging signal between the master station and the satellite have at least three different carrier frequencies, and the secondary pseudorange uplink signal, secondary pseudorange downlink signal, and secondary relay ranging signal between the slave station and the satellite have at least two different carrier frequencies.

[0084] Figure 6 This is a structural block diagram of a satellite two-way time comparison system according to one embodiment of this invention, as shown below. Figure 6 As shown, satellite 100 may include transponder 101 and satellite time and frequency equipment 103. Satellite time and frequency equipment 103 can provide time and frequency signals to transponder 101. Transponder 101 can forward several pseudorange downlink signals to slave station 220 based on several received pseudorange uplink signals. It can forward the main uplink signal of the main forwarding ranging signal to the main downlink signal of the main forwarding ranging signal, and it can also forward the secondary uplink signal of the secondary forwarding ranging signal to the secondary downlink signal of the secondary forwarding ranging signal.

[0085] The repeater 101 can perform frequency conversion and power amplification on the acquired pseudorange uplink signal before forwarding it. In this embodiment, the repeater 101 performs frequency conversion and power amplification on the uplink signal in each long pseudorange ranging signal and forwards the corresponding pseudorange downlink signal to the slave station 220.

[0086] Furthermore, the transponder 101 performs frequency conversion and power amplification on the acquired uplink signal before forwarding the downlink signal to the slave station 220. Similarly, the transponder 101 performs frequency conversion and power amplification on the acquired master uplink signal before forwarding the master downlink signal to the master station 210.

[0087] It should be understood that the transponder 101 and the satellite time and frequency device 103 described in this embodiment can be set independently or integrated into a single hardware device, i.e., implemented through an integrated hardware device. These are all within the protection scope of this application.

[0088] Continue to refer to Figure 6 The master station 210 may include a master time-frequency device 213 and a master forwarding ranging device 211 that establish communication connections with each other, as well as a master pseudorange ranging device 212. The master forwarding ranging device 211 is used to broadcast pseudorange uplink signals and master uplink signals. The master time-frequency device 213 can provide time-frequency signals to the master forwarding ranging device 211 and the master pseudorange ranging device 212. The master forwarding ranging device 211 can be used to generate and broadcast pseudorange uplink signals derived from long pseudorange ranging signals, as well as uplink signals derived from master forwarding ranging signals; these two types of signals can be shared.

[0089] The main relay ranging device 211 broadcasts the main uplink signal and receives the main downlink signal, and measures the received main downlink signal to obtain the main relay ranging value.

[0090] The primary pseudorange measuring device 212 is used to receive the primary long pseudorange measuring signal and obtain the primary long pseudorange measuring value.

[0091] In this embodiment, the primary pseudorange ranging device 212 and the primary relay ranging device 211 are set to zero baseline.

[0092] In practice, in order to reduce system costs and save frequency resources, the main uplink signal of the main pseudorange uplink signal and the main relay ranging signal can be the same. That is, part of the main uplink signal broadcast by the main relay ranging device 211 is relayed by satellite 100 into a main downlink signal and received by the main relay ranging device 211, and part of it is relayed into a secondary pseudorange downlink signal and received by the secondary station 220.

[0093] In addition, it should be noted that the main time-frequency device 213, the main relay ranging device 211, and the main pseudorange ranging device 212 included in the main station 210 can be set up independently or integrated, and these are all within the scope of protection of this application.

[0094] Continue to refer to Figure 6 The slave station 220 may include a slave time-frequency device 223, a slave pseudorange ranging device 222, and a slave forwarding ranging device 221.

[0095] The pseudorange measuring device 222 is used to receive and measure the long pseudorange ranging signal to obtain the long pseudorange ranging value.

[0096] The relay ranging device 221 transmits uplink signals and receives downlink signals to measure and obtain the relay ranging value.

[0097] Time-frequency signal is provided from time-frequency device 223 to pseudorange ranging device 222 and from repeater ranging device 221.

[0098] In practice, in order to reduce system costs and save frequency resources, the uplink signals from pseudorange uplink signals and from relay ranging signals can be the same. That is, part of the uplink signal broadcast by relay ranging device 221 is relayed by satellite 100 into downlink signal and received by relay ranging device 221, and part of it is relayed into main pseudorange downlink signal and received by main station 210.

[0099] Furthermore, it should be noted that the slave station 220 includes the slave pseudorange ranging device 222, the slave time and frequency device 223, and the slave relay ranging device 221, which can be set up independently or integrated. All of these fall within the protection scope of this application.

[0100] The main pseudorange ranging device 222 includes a receiving antenna and a receiver. The receiving antenna receives long pseudorange ranging signals and performs measurements.

[0101] The primary relay ranging device 211 and the secondary relay ranging device 221 may include a modulator, a mixer, a demodulator, an antenna, a data acquisition unit, etc. The modulator generates an intermediate frequency spread spectrum signal; the mixer mixes the intermediate frequency spread spectrum signal to a radio frequency signal; the antenna transmits the radio frequency signal to the satellite 100 and receives the radio frequency signal relayed by the satellite 100; the antenna receives the radio frequency signal and mixes it to an intermediate frequency signal by the mixer; the demodulator demodulates the intermediate frequency signal and obtains the relay ranging value through ranging code correlation calculation; the data acquisition unit records and stores the relay ranging value.

[0102] The computing device is communicatively connected to the master station 210 and the slave station 220 respectively, obtains the main long pseudorange ranging value, the slave long pseudorange ranging value, the main relay ranging value, and the slave relay ranging value, and executes the method of this application to obtain the total number of primary ionospheric electrons between the master station 210 and the satellite 100 and / or the total number of secondary ionospheric electrons between the satellite 100 and the slave station 220, as well as the clock difference between the master station and the slave station.

[0103] In this embodiment, the pseudorange ranging device 222 and the relay ranging device 221 are set to zero baseline.

[0104] It is worth noting that the zero baseline setting proposed in this embodiment does not mean that the distance between the pseudorange ranging device 222 and the relay ranging device 221 is 0. Rather, the distance between them is set to ensure that the spatial paths traversed by each pseudorange downlink signal, pseudorange uplink signal, and relay ranging signal are approximately the same. For example, as the distance between the pseudorange ranging device 222 and the relay ranging device 221 becomes smaller and smaller, and they can be integrated into one device, the approximation gradually becomes identical, with the same satellite-to-ground space distance, the same tropospheric delay, and the same total number of ionospheric electrons.

[0105] In this embodiment, at least one time-frequency device is used from both the pseudorange ranging device 222 and the relay ranging device 221. One time-frequency device provides a time-frequency signal to the pseudorange ranging device 222, while the remaining time-frequency devices provide time-frequency signals to the relay ranging device 221. In practical use, the pseudorange ranging device 222 and the relay ranging device 221 perform ranging measurements at a preset time interval, which can be set to, for example, 1 second. The pseudorange ranging device 222 performs synchronous measurements on the rising or falling edge of its own 1PPS signal, where 1PPS stands for 1 Pulse Per Second. The relay ranging device 221 operates under its own time-frequency signal. Preferably, it is generally recommended to use a single clock, meaning that the relay ranging device 221 and the pseudorange ranging device 222 use a common time-frequency signal for measurement.

[0106] The primary pseudorange ranging device 212 and the primary relay ranging device 211 are set to zero baseline, for the same reason as the secondary pseudorange ranging device 222 and the secondary relay ranging device 221.

[0107] In an exemplary embodiment, the satellite transponder generates a forwarding delay when forwarding a signal. The forwarding delay includes the forwarding delay generated by the satellite 100 in the process of forwarding the uplink signal of the long pseudorange ranging signal sent by the master station 210 to obtain the downlink signal of the long pseudorange ranging signal.

[0108] Similarly, the forwarding delay also includes the forwarding delay generated when satellite 100 receives the uplink signal of the primary long pseudorange ranging signal sent by slave station 220 and forwards the pseudorange uplink signal to obtain the downlink signal of the primary long pseudorange ranging signal.

[0109] Furthermore, in this exemplary embodiment, the primary pseudorange generator 211 in the master station 210 has a transmission delay, and the primary pseudorange ranging device 212 has a reception delay. Specifically, the transmission delay of the primary pseudorange generator 211 refers to the delay in generating and broadcasting the uplink signal of the long pseudorange ranging signal; the reception delay of the primary pseudorange ranging device 212 refers to the delay in receiving the downlink signal of the primary long pseudorange ranging signal.

[0110] Similarly, the slave pseudorange generator 221 in the slave station has a transmission delay, and the slave pseudorange ranging device 222 has a reception delay. Specifically, the transmission delay of the slave pseudorange generator 221 refers to the delay in generating and broadcasting the uplink signal of the main long pseudorange ranging signal; the reception delay of the slave pseudorange ranging device 222 refers to the delay in receiving the downlink signal of the main long pseudorange ranging signal.

[0111] In this embodiment, the computing device 230 acquires the transmission delay, forwarding delay, and reception delay of all primary long pseudorange ranging signals, as well as the transmission delay, forwarding delay, and reception delay of all secondary long pseudorange ranging signals, through communication.

[0112] It is worth noting that, in this exemplary embodiment, during communication between the master station 210 and the satellite 100, the satellite 100 can first transmit all satellite forwarding delays to the master station 210 by adding a communication signal. Thus, the master station 210 can obtain the forwarding delays of the satellite 100, which include the forwarding delays of the satellite 100 for the uplink signals of the long pseudorange ranging signal and the uplink signals of the main long pseudorange ranging signal. Then, the master station 210 sends all satellite forwarding delays to the computing device 230.

[0113] At the same time, the computing device also obtains the device latency of the master station 210 and the slave station 220.

[0114] Furthermore, in this exemplary embodiment, the main relay ranging device 211 in the main station 210 has a relay signal transmission delay and a relay signal reception delay.

[0115] The pseudorange ranging device 222 at station 220 has a receiving delay, and the relay ranging device 221 has both a transmitting delay and a receiving delay.

[0116] The aforementioned forwarding delay, transmission delay, and reception delay are collectively referred to as device delay.

[0117] It is worth noting that, in this exemplary embodiment, during communication between the master station 210 and the satellite 100, the satellite 100 can first transmit all forwarding delays to the master station 210 by adding a communication signal. Thus, the master station 210 can obtain the various forwarding delays of the satellite 100, and the computing device can obtain its device delay by communicating with the master station 210. Of course, the computing device can also directly communicate with the satellite 100 to obtain the various forwarding delays.

[0118] In this exemplary embodiment, the carrier frequencies of all primary long pseudorange ranging signals, all secondary long pseudorange ranging signals, all primary forwarding ranging signals, and all secondary forwarding ranging signals are frequency-hopped on the time axis according to a preset frequency hopping pattern, which can improve the anti-interference capability and anti-interception capability of the signals.

[0119] Of course, the carrier frequency of each signal in all the master long pseudorange ranging signals, all the slave long pseudorange ranging signals, all the master relay ranging signals, and all the slave relay ranging signals can remain unchanged for a long time, that is, the time interval between the two frequency hopping is infinite.

[0120] In an exemplary embodiment, the satellite two-way time comparison system provided in this application also has a satellite-to-ground communication function. The satellite 100 uses an additional communication signal to interact with the master station 210. The additional communication signal can be a remote control and telemetry signal.

[0121] When the master station 210 and the slave station 220 communicate, they can directly connect. For example, in a city, the master station 210 and the slave station 220 can communicate directly via a 4G or 5G network. Of course, if... Figure 1 As shown, the master station 210 can also communicate with the slave station 220 via satellite 100. For example, at sea or in the desert, both the master station 210 and the slave station 220 can communicate directly with satellite 100, thereby enabling communication between the master station 210 and the slave station 220 via satellite 100.

[0122] In this embodiment, the slave station 220 can be a base station, radar, or a satellite surveillance system. Furthermore, there can be multiple slave stations 220 in this embodiment. For example, a telecommunications operator can build a communication network based on this satellite two-way time comparison system. In this case, the slave station 220 can be a communication base station. The telecommunications operator controls each communication base station through the master station 210 and obtains relevant information about each communication base station based on the communication results between the master station 210 and the communication base stations.

[0123] It should be noted that in this embodiment, the Sagnac effect delay needs to be obtained when calculating the clock difference between the master station and the slave station. The calculation of the Sagnac effect delay requires the coordinates of the master station 210, the slave station 220 and the satellite 100. The coordinates of the satellite 100 can be obtained from the known ephemeris of the satellite 100. The coordinates of the master station 210 and the slave station 220 can be obtained from existing positioning methods. In this way, the coordinate information required by the method of this embodiment is obtained, and then the Sagnac effect delay is obtained.

[0124] When using the forwarding ranging expression to characterize the master and slave forwarding ranging values, the Sagnac effect delay is not included in the expression because the signs of the uplink and downlink Sagnac effect delays are opposite, and their absolute values ​​differ very little. Therefore, these two Sagnac effect delays can be approximately canceled out, and thus the Sagnac effect delay term is not reflected in the forwarding ranging expression. Of course, in other embodiments of this application, the Sagnac effect delay can also be considered, i.e., the uplink and downlink Sagnac effect delays can be added to the forwarding ranging expression to achieve better measurement accuracy of the forwarding ranging value. These are all within the scope of protection of this application.

[0125] Furthermore, the master station 210 communicates with the satellite 100 based on the added communication signal. The master station 210 obtains the forwarding delay of the satellite 100 based on the communication result. The forwarding delay of the satellite 100 includes the forwarding delay of the satellite 100 for the primary forwarding ranging signal and the forwarding delay for the secondary forwarding ranging signal.

[0126] The main pseudorange uplink signal, main pseudorange downlink signal, and main relay ranging signal traverse the exact same atmospheric path, and the total number of electrons in the ionosphere traversed by the ranging signals is exactly the same. The ionosphere is a diffuse medium, meaning that the time delay produced by the ionosphere for radio frequency signals of different carrier frequencies varies depending on the carrier frequency. In contrast, the troposphere is a non-diffuse medium, meaning that the troposphere produces the same time delay for radio frequency signals of different carrier frequencies.

[0127] The uplink and downlink signals of the primary relay ranging signal traverse the same space path. However, the moment the primary uplink signal crosses the ionosphere differs from the moment the primary downlink signal, relayed by satellite 100, crosses the ionosphere, exhibiting a certain time difference. Within a short period, such as a few seconds, the ionosphere is stable, and the total number of electrons in the ionosphere remains almost constant. It can be calculated that the round-trip time of radio frequency signals between almost all spacecraft and ground stations currently does not exceed a few seconds, fully meeting the requirements. Combining the spatial relationship of zero baseline setting and the very short time difference, the downlink signals of the primary relay ranging signal and the primary long pseudorange ranging signal, as well as the uplink signal from the long pseudorange ranging signal, traverse the exact same space path, as shown in the following equation:

[0128] R true,zu,1 (n)=R true,zd,1 (n)=R xu,1 (n)=R xd,1 (n)=R xu,2 (n)=R xd,2 (n) (2)

[0129] T duiliu,zu,1 (n)=T duiliu,zd,1 (n)=Tduiliu,xu,1 (n)=T duiliu,xd,1 (n)=T duiliu,xu,2 (n)=T duiliu,xd,2 (n) (3)

[0130] In this embodiment, the pseudorange ranging device 222 and the relay ranging device 221 are set to zero baseline. The pseudorange uplink signal, the pseudorange downlink signal, the relay ranging signal from the uplink signal, and the downlink signal also have similar spatial path relationships as described above. Therefore, the following equation applies:

[0131] R true,cd,1 (n)=R true,cu,1 (n)=R uu,1 (n)=R ud,1 (n)=R uu,2 (n)=R ud,2 (n) (4)

[0132] T duiliu,cd,1 (n)=T duiliu,cu,1 (n)=T duiliu,uu,1 (n)=T duiliu,ud,1 (n)=T duiliu,uu,2 (n)=T duiliu,ud,2 (n) (5)

[0133] Based on the above introduction, in this embodiment, the process by which the main station obtains the main forwarding ranging value and the main long pseudorange ranging value can be summarized as follows:

[0134] Transmit the main uplink signal that relays the ranging signal;

[0135] Receive the h-channel main relay ranging signal relayed back by the satellite;

[0136] Acquire m main-length pseudorange ranging signals;

[0137] By synchronously measuring each main relay ranging signal and each main long pseudorange ranging signal, h main relay ranging values ​​and m main long pseudorange ranging values ​​are obtained;

[0138] Similarly, the process of obtaining forwarding ranging values ​​and long pseudorange ranging values ​​from the station can be summarized as follows:

[0139] Broadcast uplink signals to satellites;

[0140] The satellite acquires downlink signals relayed from uplink signals, wherein the uplink and downlink signals constitute r-path relay ranging signals.

[0141] Acquire the v-path from the long pseudorange ranging signal;

[0142] By synchronously measuring each slave relay ranging signal and each slave long pseudorange ranging signal, r slave relay ranging values ​​and v slave long pseudorange ranging values ​​are obtained;

[0143] Where m and v are integers greater than or equal to 1, h and r are integers greater than or equal to 0, and m+h+r+v≥4.

[0144] It should be noted that since the master station and slave station measure the master long pseudorange ranging value, the master forwarding ranging value, the slave long pseudorange ranging value, and the slave forwarding ranging value under their respective clock signals, the master station and slave station need to meet the coarse synchronization requirement in time, which is generally required to be on the order of milliseconds. It can be considered that the master station and slave station are measuring synchronously before executing the method of this application.

[0145] Based on the above embodiments, this embodiment also provides a satellite two-way time comparison method, which is applied to the satellite two-way time comparison system described in any of the above embodiments. This method is executed by a computing device.

[0146] Figure 7 This is a flowchart of a satellite two-way time comparison method according to one embodiment of this application. The satellite two-way time comparison method may include the following steps:

[0147] S200. Communicate with the master station to obtain m main long pseudorange ranging values ​​and h main forwarding ranging values; communicate with the slave station to obtain v secondary long pseudorange ranging values ​​and r secondary forwarding ranging values. The main long pseudorange ranging values ​​and the main forwarding ranging values ​​are obtained by the master station measuring the main long pseudorange ranging signal and the main forwarding ranging signal, respectively. The secondary long pseudorange ranging values ​​and the secondary forwarding ranging values ​​are obtained by the slave station measuring the secondary long pseudorange ranging signal and the secondary forwarding ranging signal respectively. m and v are both integers greater than or equal to 1, h and r are both integers greater than or equal to 0, and m + h + r + v ≥ 4.

[0148] S210. Each of the primary long pseudorange ranging values ​​and secondary long pseudorange ranging values ​​is represented by a long pseudorange ranging expression, and each of the primary forwarding ranging values ​​and secondary forwarding ranging values ​​is represented by a forwarding ranging expression.

[0149] S220. Based on the main long pseudorange ranging value represented by m long pseudorange ranging expressions, the secondary long pseudorange ranging value represented by v long pseudorange ranging expressions, the main relay ranging value represented by h relay ranging expressions, and the secondary relay ranging value represented by r relay ranging expressions, determine the total number of primary ionospheric electrons and / or the total number of secondary ionospheric electrons, as well as the clock difference between the master station and the secondary station. The total number of primary ionospheric electrons is the total number of ionospheric electrons along the ranging signal path between the master station and the satellite, and the total number of secondary ionospheric electrons is the total number of ionospheric electrons along the ranging signal path between the secondary station and the satellite.

[0150] S230. Determine the clock difference between the master station and the slave station using the total number of electrons in the main ionosphere and / or the total number of electrons in the slave ionosphere, any of the corrected main long pseudorange ranging values ​​and any of the corrected slave long pseudorange ranging values;

[0151] The satellite two-way time comparison system provided in this embodiment has five systems that can achieve high-precision time comparison services. The master station and slave station measure the following five systems: master long pseudorange ranging value, slave long pseudorange ranging value, master relay ranging value, and slave relay ranging value.

[0152] First simplest system ( Figure 1 ): m=1, v=1, h=2, r=2; The system has one main long pseudorange ranging signal, one secondary long pseudorange ranging signal, two main forwarding ranging signals, and two secondary forwarding ranging signals;

[0153] Second simplest system ( Figure 2 ): m=1, v=2, h=2, r=0; The system has one main long pseudorange ranging signal, two Y-branched secondary long pseudorange ranging signals, and two main forwarding ranging signals;

[0154] The third simplest system ( Figure 3 ): m=1, v=2, h=0, r=2; The system has one main long pseudorange ranging signal, two T-type converged slave long pseudorange ranging signals, and two slave relay ranging signals;

[0155] First typical system ( Figure 4 ): m=1, v=1, h=0, r=2; The slave station obtains the total number of electrons in the ionosphere using two slave relay ranging signals, but cannot obtain the total number of electrons in the main ionosphere;

[0156] Second typical system ( Figure 5 ): m=1, v=1, h=2, r=0; The main station uses two main relay ranging signals to obtain the total number of electrons in the main ionosphere, but cannot obtain the total number of electrons in the secondary ionosphere;

[0157] The maximum envelope of the above systems is one primary long pseudorange ranging value + two secondary long pseudorange ranging values ​​+ two primary forwarding ranging values ​​+ two secondary forwarding ranging values. The required measurement values ​​are used for calculation and explanation according to different systems.

[0158] In S210, the computing device can characterize the primary long pseudorange ranging value using the following equation (6), the primary relay ranging value using the following equation (7), the secondary long pseudorange ranging value using the following equation (8), and the secondary relay ranging value using the following formula (9):

[0159]

[0160] In the formula, i = 1, 2, ..., m, where i and m are integers;

[0161] The primary forwarding ranging value is obtained using the following formula:

[0162] L z,j (n)=R true,xu,j (n)+R true,xd,j (n)+I xu,j (n)+I xd,j (n)+T duiliu,xu,j (n)+T duiliu,xd,j (n)+Y z,j (n) (7)

[0163] In the formula, j = 1, 2, ..., h, and j and h are integers;

[0164] The distance measured from the long pseudorange is obtained by the following formula:

[0165]

[0166] In the formula, x = 1, 2, ..., v, where x and v are integers;

[0167] The forwarding ranging value is obtained using the following formula:

[0168] L c,k (n)=R true,uu,k (n)+R true,ud,k (n)+I uu,k (n)+I ud,k (n)+T duiliu,uu,k (n)+T duiliu,ud,k (n)+Y c,k (n) (9)

[0169] In the formula, k = 1, 2, ..., r, where k and r are integers;

[0170] In the formula, ρ z,i (n) represents the principal pseudorange value numbered i at time n, in meters; R true,cu,i (n) represents the actual spatial distance traversed by the pseudorange uplink signal of the main long-range pseudorange ranging signal numbered i at time n, in meters; cu,i (n) represents the ionospheric delay of the primary long pseudorange uplink signal numbered i at time n, in meters (T). duiliu,cu,i (n) represents the tropospheric delay of the primary pseudorange uplink signal of the primary long pseudorange ranging signal numbered i at time n, in meters; R true,zd,i (n) represents the actual spatial distance traversed by the primary pseudorange downlink signal of the primary long pseudorange ranging signal numbered i at time n, in meters; zd,i(n) represents the ionospheric delay of the main pseudorange downlink signal of the main long pseudorange ranging signal numbered i at time n, in meters (T). duiliu,zd,i (n) represents the tropospheric delay of the main pseudorange downlink signal of the main long pseudorange ranging signal numbered i at time n, in meters; c represents the speed of light, in meters per second; δt z (n) represents the clock difference between the master station and the system time at time n, in seconds; δt c (n) represents the clock difference between the slave station and the system time at time n, in seconds; sagnac csu (n) represents the Sagnac effect delay of the primary long pseudorange ranging signal at time n, relative to the secondary pseudorange uplink signal, in meters; zsd (n) represents the Sagnac effect delay of the main pseudorange downlink signal from the main long pseudorange ranging signal at time n, in meters; X z,i (n) represents the hardware delay of the primary long pseudorange ranging signal numbered i at time n, in meters. The hardware delay of the primary long pseudorange ranging signal includes the transmission delay of the slave station for the pseudorange uplink signal of the primary long pseudorange ranging signal numbered i, the forwarding delay of the satellite for forwarding the pseudorange uplink signal to the primary pseudorange downlink signal, and the reception delay of the primary station for the primary pseudorange downlink signal of the primary long pseudorange ranging signal numbered i.

[0171] ρ c,x (n) represents the distance measured from the long pseudorange at time n, with the number x, in meters; R true,zu,x (n) represents the actual spatial distance traversed by the main pseudorange uplink signal numbered x from the long pseudorange ranging signal at time n, in meters; zu,x (n) represents the ionospheric delay of the primary pseudorange uplink signal with ID x from the long pseudorange ranging signal at time n, in meters (T). duiliu,zu,x (n) represents the tropospheric delay of the main pseudorange uplink signal with ID x from the long pseudorange ranging signal at time n, in meters; R true,cd,x (n) represents the actual spatial distance traversed by the pseudorange downlink signal of the long pseudorange ranging signal numbered x at time n, in meters; cd,x (n) represents the ionospheric delay of the pseudorange downlink signal from the long pseudorange ranging signal numbered x at time n, in meters (T). duiliu,cd,x (n) represents the tropospheric delay of the pseudorange downlink signal from the long pseudorange ranging signal numbered x at time n, in meters; sagnac zsu (n) represents the Sagnac effect delay of the main pseudorange uplink signal from the long pseudorange ranging signal at time n, in meters; csd(n) represents the Sagnac effect delay of the downlink signal from the long pseudorange ranging signal at time n, in meters; X c,x (n) represents the hardware delay of the long pseudorange ranging signal numbered x at time n, in meters. The hardware delay of the long pseudorange ranging signal includes the transmission delay of the master station for the main pseudorange uplink signal of the long pseudorange ranging signal numbered x, the forwarding delay of the satellite forwarding the main pseudorange uplink signal into the pseudorange downlink signal, and the reception delay of the slave station for the pseudorange downlink signal of the long pseudorange ranging signal numbered x.

[0172] L z,j (n) represents the primary relay ranging value numbered j at time n, in meters; R true,xu,j (n), R true,xd,j (n) represents the actual spatial distance traversed by the main uplink and main downlink signals of the main relay ranging signal numbered j at time n, in meters; xu,j (n), I xd,j (n) represents the ionospheric delay of the main uplink and main downlink signals of the main relay ranging signal numbered j at time n, in meters (T). duiliu,xu,j (n), T duiliu,xd,j (n) represents the tropospheric delay of the main uplink and main downlink signals of the main relay ranging signal numbered j at time n, in meters; Y z,j (n) represents the hardware device delay of the primary relay ranging signal numbered j at time n, in meters. The hardware device delay of the primary relay ranging signal includes the transmission delay of the primary uplink signal of the primary relay ranging signal numbered j by the master station, the forwarding delay of the primary downlink signal of the primary relay ranging signal numbered j generated by the satellite, and the reception delay of the primary downlink signal of the primary relay ranging signal numbered j by the master station.

[0173] L c,k (n) represents the ranging value of the slave relay with ID k at time n, in meters; R true,uu,k (n), R true,ud,k (n) represents the actual spatial distance traversed by the uplink and downlink signals numbered k at time n, in meters; uu,k (n), I ud,k (n) represents the ionospheric delay of the uplink and downlink signals numbered k at time n, in meters (T). duiliu,uu,k (n), T duiliu,ud,k (n) represents the tropospheric delay of the uplink and downlink signals numbered k at time n, in meters; Y c,k(n) represents the hardware device delay of the k-th slave ranging signal at time n, in meters. The hardware device delay of the slave ranging signal includes the transmission delay of the slave ranging device for the k-th slave uplink signal, the forwarding delay of the satellite generating the k-th slave downlink signal, and the reception delay of the slave ranging device receiving the k-th slave downlink signal.

[0174] As analyzed above, the maximum envelope of the above system is one primary long pseudorange ranging value + two secondary long pseudorange ranging values ​​+ two primary forwarding ranging values ​​+ two secondary forwarding ranging values. Thus, the computing device further obtains the specific first primary long pseudorange ranging value based on formula (10):

[0175]

[0176] Similarly, the computing device obtains the specific first primary forwarding ranging value and the second primary forwarding ranging value according to formula (6), as shown in formulas (11) and (12);

[0177] L z,1 (n)=R true,xu,1 (n)+R true,xd,1 (n)+I xu,1 (n)+I xd,1 (n)+T duiliu,xu,1 (n)+T duiliu,xd,1 (n)+Y z,1 (n) (11)

[0178] L z,2 (n)=R true,xu,2 (n)+R true,xd,2 (n)+I xu,2 (n)+I xd,2 (n)+T duiliu,xu,2 (n)+T duiliu,xd,2 (n)+Y z,2 (n) (12)

[0179] The computing device further obtains the specific first long pseudorange measurement value and the second long pseudorange measurement value based on formula (8), as shown in formulas (13) and (14):

[0180]

[0181] The computing device obtains the specific first and second slave relay ranging values ​​according to formula (9), as shown in formulas (15) and (16):

[0182] L c,1 (n)=R true,uu,1 (n)+R true,ud,1 (n)+I uu,1 (n)+Iud,1 (n)+T duiliu,uu,1 (n)+T duiliu,ud,1 (n)+Y c,1 (n) (15)

[0183] L c,2 (n)=R true,uu,2 (n)+R true,ud,2 (n)+I uu,2 (n)+I ud,2 (n)+T duiliu,uu,2 (n)+T duiliu,ud,2 (n)+Y c,2 (n) (16)

[0184] In this embodiment, step S220 specifically includes the following process:

[0185] S2201. The m primary long pseudorange ranging values ​​and v secondary long pseudorange ranging values, represented by the long pseudorange ranging expression, are corrected to obtain m corrected primary long pseudorange ranging values ​​and v corrected secondary long pseudorange ranging values; the h primary forwarding ranging values ​​and r secondary forwarding ranging values, represented by the forwarding ranging expression, are corrected to obtain h corrected primary forwarding ranging values ​​and r corrected secondary forwarding ranging values.

[0186] The m primary pseudorange values ​​shown in formula (17) are corrected to obtain the m corrected primary pseudorange values ​​shown in formula (18):

[0187]

[0188]

[0189] Where i = 1, 2, ..., m, i is an integer;

[0190] The h primary forwarding ranging values ​​shown in formula (19) are corrected to obtain the h corrected primary forwarding ranging values ​​shown in formula (20):

[0191]

[0192] Where j = 1, 2, ..., h, j and h are integers;

[0193] By correcting the v long pseudorange ranging values ​​shown in the following formula (21), we obtain the v corrected master-slave pseudorange ranging values ​​shown in the following formula (22):

[0194]

[0195] Where x = 1, 2, ..., v, x and v are integers;

[0196] Furthermore, by modifying the r slave forwarding ranging values ​​represented by the forwarding ranging expression shown in formula (23), we obtain the r modified slave forwarding ranging values ​​shown in formula (24):

[0197]

[0198] Where k = 1, 2, ..., r, and k and r are integers;

[0199] In the formula: ρ z,i,a (n) represents the corrected principal pseudorange value numbered i at time n, in meters; ρ z,i (n) represents the principal pseudorange value numbered i at time n, in meters; R true,cu,i (n) represents the actual spatial distance traversed by the pseudorange uplink signal of the main long-range pseudorange ranging signal numbered i at time n, in meters; cu,i (n) represents the ionospheric delay of the primary long pseudorange uplink signal numbered i at time n, in meters (T). duiliu,cu,i (n) represents the tropospheric delay of the primary pseudorange uplink signal of the primary long pseudorange ranging signal numbered i at time n, in meters; R true,zd,i (n) represents the actual spatial distance traversed by the primary pseudorange downlink signal of the primary long pseudorange ranging signal numbered i at time n, in meters; zd,i (n) represents the ionospheric delay of the main pseudorange downlink signal of the main long pseudorange ranging signal numbered i at time n, in meters (T). duiliu,zd,i (n) represents the tropospheric delay of the main pseudorange downlink signal of the main long pseudorange ranging signal numbered i at time n, in meters; c represents the speed of light, in meters per second; δt z (n) represents the clock difference between the master station and the system time at time n, in seconds; δt c (n) represents the clock difference between the slave station and the system time at time n, in seconds; sagnac csu (n) represents the Sagnac effect delay of the primary long pseudorange ranging signal at time n, relative to the secondary pseudorange uplink signal, in meters; zsd (n) represents the Sagnac effect delay of the main pseudorange downlink signal from the main long pseudorange ranging signal at time n, in meters; X z,i (n) represents the hardware delay of the primary long pseudorange ranging signal numbered i at time n, in meters. The hardware delay of the primary long pseudorange ranging signal includes the transmission delay of the slave station for the pseudorange uplink signal of the primary long pseudorange ranging signal numbered i, the forwarding delay of the satellite for forwarding the pseudorange uplink signal to the primary pseudorange downlink signal, and the reception delay of the primary station for the primary pseudorange downlink signal of the primary long pseudorange ranging signal numbered i.

[0200] ρ c,x,a (n) represents the corrected distance measurement value from the long pseudorange at time n, numbered i, in meters; ρ c,x (n) represents the distance measured from the long pseudorange at time n, with the number x, in meters; R true,zu,x (n) represents the actual spatial distance traversed by the main pseudorange uplink signal numbered x from the long pseudorange ranging signal at time n, in meters; zu,x (n) represents the ionospheric delay of the primary pseudorange uplink signal with ID x from the long pseudorange ranging signal at time n, in meters (T). duiliu,zu,x (n) represents the tropospheric delay of the main pseudorange uplink signal with ID x from the long pseudorange ranging signal at time n, in meters; R true,cd,x (n) represents the actual spatial distance traversed by the pseudorange downlink signal of the long pseudorange ranging signal numbered x at time n, in meters; cd,x (n) represents the ionospheric delay of the pseudorange downlink signal from the long pseudorange ranging signal numbered x at time n, in meters (T). duiliu,cd,x (n) represents the tropospheric delay of the pseudorange downlink signal from the long pseudorange ranging signal numbered x at time n, in meters; sagnac zsu (n) represents the Sagnac effect delay of the main pseudorange uplink signal from the long pseudorange ranging signal at time n, in meters; csd (n) represents the Sagnac effect delay of the downlink signal from the long pseudorange ranging signal at time n, in meters; X c,x (n) represents the hardware delay of the long pseudorange ranging signal numbered x at time n, in meters. The hardware delay of the long pseudorange ranging signal includes the transmission delay of the master station for the main pseudorange uplink signal of the long pseudorange ranging signal numbered x, the forwarding delay of the satellite forwarding the main pseudorange uplink signal into the pseudorange downlink signal, and the reception delay of the slave station for the pseudorange downlink signal of the long pseudorange ranging signal numbered x.

[0201] L z,j,a (n) represents the corrected primary relay ranging value with number j at time n, in meters; L z,j (n) represents the primary relay ranging value numbered j at time n, in meters; R true,xu,j (n), R true,xd,j (n) represents the actual spatial distance traversed by the main uplink and main downlink signals of the main relay ranging signal numbered j at time n, in meters; xu,j (n), I xd,j (n) represents the ionospheric delay of the main uplink and main downlink signals of the main relay ranging signal numbered j at time n, in meters (T).duiliu,xu,j (n), T duiliu,xd,j (n) represents the tropospheric delay of the main uplink and main downlink signals of the main relay ranging signal numbered j at time n, in meters; Y z,j (n) represents the hardware device delay of the primary relay ranging signal numbered j at time n, in meters. The hardware device delay of the primary relay ranging signal includes the transmission delay of the primary uplink signal of the primary relay ranging signal numbered j by the master station, the forwarding delay of the primary downlink signal of the primary relay ranging signal numbered j generated by the satellite, and the reception delay of the primary downlink signal of the primary relay ranging signal numbered j by the master station.

[0202] L c,k,a (n) represents the corrected relay ranging value with number k at time n, in meters; L c,k (n) represents the ranging value of the slave relay with ID k at time n, in meters; R true,uu,k (n), R true,ud,k (n) represents the actual spatial distance traversed by the uplink and downlink signals numbered k at time n, in meters; uu,k (n), I ud,k (n) represents the ionospheric delay of the uplink and downlink signals numbered k at time n, in meters (T). duiliu,uu,k (n), T duiliu,ud,k (n) represents the tropospheric delay of the uplink and downlink signals numbered k at time n, in meters; Y c,k (n) represents the hardware device delay of the k-th slave ranging signal at time n, in meters. The hardware device delay of the slave ranging signal includes the transmission delay of the slave ranging device for the k-th slave uplink signal, the forwarding delay of the satellite generating the k-th slave downlink signal, and the reception delay of the slave ranging device receiving the k-th slave downlink signal.

[0203] S2202. Based on the m corrected primary long pseudorange ranging values, the v corrected secondary long pseudorange ranging values, the h corrected primary forwarding ranging values, and the r corrected secondary forwarding ranging values, determine the total number of electrons in the primary ionosphere and / or the total number of electrons in the secondary ionosphere, and use the total number of electrons in the primary ionosphere, the total number of electrons in the secondary ionosphere, and any corrected primary long pseudorange ranging value and any corrected secondary long pseudorange ranging value to determine the clock difference between the master station and the slave station.

[0204] Specifically, in step S2201, the computing device corrects the obtained primary long pseudorange ranging value, secondary long pseudorange ranging value, primary forwarding ranging value, and secondary forwarding ranging value to obtain the corrected primary long pseudorange ranging value, corrected secondary long pseudorange ranging value, corrected primary forwarding ranging value, and corrected secondary forwarding ranging value as follows:

[0205]

[0206]

[0207] In S230, the clock difference between the master station and the slave station is determined using the total number of electrons in the main ionosphere and / or the total number of electrons in the slave ionosphere, any of the corrected main pseudorange distance measurement values, and any of the corrected slave pseudorange distance measurement values, to obtain the clock difference between the master station and the slave station as shown in formula (30), formula (31), or formula (32):

[0208]

[0209]

[0210] Specifically, using the first primary long pseudorange measurement value, the first secondary long pseudorange measurement value, and the total number of electrons in the primary ionosphere and / or the total number of electrons in the secondary ionosphere, the clock difference between the master station and the secondary station is calculated to obtain the specific clock difference, as shown in formula (33), formula (34), or formula (35):

[0211]

[0212] In step S230, the calculation method for the total number of electrons in the main ionosphere and / or the total number of electrons in the secondary ionosphere is based on the signals from different systems:

[0213] The calculation process for each system will be described below.

[0214] The first simplest system, such as Figure 1 As shown, the system has one main long pseudorange ranging signal (m=1), one secondary long pseudorange ranging signal (v=1), two main relay ranging signals (h=2), and two secondary relay ranging signals (r=2). The main pseudorange uplink signal of the secondary long pseudorange ranging signal is the same as the uplink signal of the main relay ranging signal. The satellite splits the main pseudorange uplink signal into three parts, one of which is relayed as the secondary pseudorange downlink signal, and the other two are relayed to the master station as main downlink signals. The carrier frequencies used are reused, and the carrier frequency of any one of the two main relay ranging signals is the same as the carrier frequency of the main pseudorange downlink signal. The master station uses the two main relay ranging signals to calculate the total number of electrons in the main ionosphere, and the slave station uses the two secondary relay ranging signals to calculate the total number of electrons in the secondary ionosphere.

[0215] Specifically, the total number of electrons in the main ionosphere is calculated based on the two main relay ranging values ​​and the following formula.

[0216]

[0217] The total number of electrons from the ionosphere is calculated based on two forward ranging values ​​and the following formula.

[0218]

[0219] The second simplest system: such as Figure 2 As shown, the system has one main long pseudorange ranging signal (m=1), two secondary long pseudorange ranging signals (v=2), which are Y-shaped bifurcated long pseudorange ranging signals, two main relay ranging signals (h=2), and zero secondary relay ranging signals (r=0). The main pseudorange uplink signal transmitted by the master station 210 is split into four after reaching satellite 100. Two of them are used as pseudorange downlink signals to reach the slave station 220, and the other two are used as main downlink signals to reach the master station 210. The downlink signals of the main relay ranging signals of the master station and the main pseudorange downlink signals of the secondary long pseudorange ranging signals are multiplexed using the carrier frequency. The master station uses the two main relay ranging signals to obtain the total number of electrons in the main ionosphere, and the slave station uses the two Y-shaped bifurcated secondary long pseudorange ranging signals to obtain the total number of electrons in the secondary ionosphere.

[0220] The total number of electrons in the main ionosphere is calculated based on the two main relay ranging values ​​and the following formula.

[0221]

[0222] The total number of electrons in the ionosphere is calculated from the long pseudorange measurement values ​​of the two Y-shaped bifurcations and the following formula.

[0223]

[0224] The third simplest system: such as Figure 3 As shown, the system has one main long pseudorange ranging signal (m=1), two secondary long pseudorange ranging signals (v=2), and the secondary long pseudorange ranging signals are converged in a T-shape. There is also one main forwarding ranging signal (h=0) and two secondary forwarding ranging signals (r=2). The secondary forwarding ranging signals and the secondary pseudorange downlink signals utilize carrier frequency multiplexing technology. The slave station uses the two secondary forwarding ranging signals to obtain the total number of electrons in the ionosphere, and the slave station uses the two T-shaped converged secondary long pseudorange ranging signals to obtain the total number of electrons in the main ionosphere.

[0225] The total number of electrons in the main ionosphere can be calculated from long pseudorange measurements using two T-shaped convergences and the following formula:

[0226]

[0227] The total number of electrons from the ionosphere is calculated based on two forward ranging values ​​and the following formula.

[0228]

[0229] The first typical system, such as Figure 4As shown, the system has one main long pseudorange ranging signal (m=1), one secondary long pseudorange ranging signal (v=1), zero main relay ranging signals (h=0), and two secondary relay ranging signals (r=2). The secondary relay ranging signals and the secondary pseudorange downlink signals use carrier frequency multiplexing technology; the secondary station uses the two secondary relay ranging signals to obtain the total number of electrons in the secondary ionosphere, but cannot obtain the total number of electrons in the primary ionosphere.

[0230] The total number of electrons from the ionosphere is calculated based on two forward ranging values ​​and the following formula.

[0231]

[0232] The second typical system, such as Figure 5 As shown, the system has one main long pseudorange ranging signal (m=1), one secondary long pseudorange ranging signal (v=1), two main relay ranging signals (h=2), and zero secondary relay ranging signals (r=0). The main relay ranging signals and the main pseudorange downlink signal utilize carrier frequency multiplexing technology. The master station uses the two main relay ranging signals to obtain the total number of electrons in the main ionosphere, but cannot obtain the total number of electrons in the secondary ionosphere.

[0233] Specifically, the total number of electrons in the main ionosphere is calculated based on the two main relay ranging values ​​and the following formula.

[0234]

[0235] In addition, it should be noted that in the field of satellite two-way time comparison, counters and their readings are often used to obtain the clock difference between two stations. Typically, the time comparison relationship between satellite two-way time transfer station 1 and station 2 is expressed as the counter reading of station 1, as shown in the following formula (44):

[0236]

[0237] The counter reading at station 2 is expressed as shown in the following formula (61):

[0238]

[0239] In the formula, TS(k): represents the clock bias of station k; TI(k): represents the time scale of station k; TX(k): represents the instrument transmission delay of station k; RX(k): represents the instrument reception delay of station k; SGU(k): represents the geometric path delay of the uplink signal of station k; SGD(k): represents the geometric path delay of the downlink signal of station k; STU(k): represents the tropospheric delay of the uplink signal of station k; STD(k): represents the tropospheric delay of the downlink signal of station k; SIU(k): represents the ionospheric delay of the uplink signal of station k; SID(k): represents the ionospheric delay of the downlink signal of station k; SPT(k): represents the satellite relay delay; SCU(k): represents the sagnac delay of the uplink signal of station k; SCD(k): represents the sagnac delay of the downlink signal of station k.

[0240] In fact, formula (40) or formula (45) is essentially the same as formula (6) or formula (8) of this application, both of which are long pseudorange distance measurement value expressions.

[0241] Subtracting formula (45) from formula (44) and rearranging, we get the following formula (46):

[0242]

[0243] Therefore, based on the satellite two-way time comparison system of this application, the method of using the long pseudorange ranging value obtained by the reading meter and the method of calculating the clock difference using the long pseudorange ranging value should also be protected within the scope of protection of this application.

[0244] In summary, it can be seen that the satellite two-way time comparison system and method provided in this application, compared with traditional satellite two-way time comparison systems, can eliminate both the primary ionospheric delay between the satellite and the master station, and the secondary ionospheric delay between the satellite and the slave station, which is beneficial to improving the accuracy of time comparison. The satellite two-way time comparison system and method provided in this application have the following characteristics:

[0245] 1. The system of the present invention can independently obtain the total number of ionospheric electrons on the ranging signal path between the satellite and the main station without the need for ionospheric electron count data provided by a third party. It has the advantages of high real-time performance and independence from third-party ionospheric electron count data.

[0246] 2. The master station or slave station can use bidirectional time comparison to compare existing industry resources, which can reduce the complexity and cost of the master station and slave station.

[0247] The parameters involved in this embodiment are uniformly explained as follows:

[0248] Q ion Indicates the ionospheric time delay factor; TEC z(n) represents the total number of electrons in the main ionosphere along the ranging signal path between the satellite and the master station at time n, in electrons per square meter; TEC u (n) represents the total number of electrons in the ionosphere along the ranging signal path between the satellite and the slave station at time n, in electrons per square meter.

[0249] f zu,1 (n),f zu,2 (n) represents the carrier frequency of the main pseudorange uplink signal of the first and second long pseudorange ranging signals at time n, respectively, in Hertz; f cd,1 (n),f cd,2 (n) represents the carrier frequency of the downlink signal from the first long pseudorange ranging signal and the second long pseudorange ranging signal at time n, respectively, in Hertz;

[0250] f cu,1 (n),f cu,2 (n) represents the carrier frequencies of the slave pseudorange uplink signals of the first and second main long pseudorange ranging signals at time n, respectively, in Hertz; f zd,1 (n),f zd,2 (n) represents the carrier frequency of the primary pseudorange downlink signal of the first primary long pseudorange ranging signal and the second primary long pseudorange ranging signal at time n, respectively, in Hertz.

[0251] f xu,1 (n), f xd,1 (n) represents the carrier frequencies of the main uplink and main downlink signals of the main relay ranging signal numbered 1 at time n, respectively, in Hertz; f xu,2 (n), f xd,2 (n) represents the carrier frequencies of the main uplink and main downlink signals of the main relay ranging signal numbered 2 at time n, respectively, in Hertz; f uu,1 (n), f ud,1 (n) represents the carrier frequencies of the uplink and downlink signals of the slave relay ranging signal numbered 1 at time n, respectively, in Hertz; f uu,2 (n), f ud,2 (n) represents the carrier frequencies of the uplink and downlink signals of the forwarding ranging signal numbered 2 at time n, respectively, in Hertz;

[0252] It is worth noting, and specifically pointed out: Q ionThe ionospheric time delay coefficient is published by certain international organizations. With in-depth research on ionospheric time delay, the coefficient has become increasingly accurate. Previously, the coefficient was 40.28, 40.30, and currently it is 40.309. More precise coefficients may be available in the future. This application does not impose any specific limitations on the ionospheric time delay coefficient and uses the latest published value. In this embodiment, the value is 40.309.

[0253] This article uses specific embodiments to illustrate the principles and implementation methods of the present invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A satellite two-way time comparison system, the system comprising a master station and a slave station respectively connected to a satellite for communication, characterized in that: The master station, slave station and satellite are respectively connected by a master long pseudorange ranging signal and a slave long pseudorange ranging signal. The master station and slave station obtain the master long pseudorange ranging value and the slave long pseudorange ranging value through the master long pseudorange ranging signal and the slave long pseudorange ranging signal, respectively. There is a primary relay ranging signal between the master station and the satellite, and the master station obtains the primary relay ranging value through the primary relay ranging signal; There is a relay ranging signal between the slave station and the satellite, and the slave station obtains the relay ranging value through the relay ranging signal; The total number of primary ionospheric electrons between the satellite and the master station, the total number of secondary ionospheric electrons between the satellite and the slave station, and the clock difference between the master station and the slave station are calculated using the primary long pseudorange ranging value, the secondary long pseudorange ranging value, the primary transponder ranging value, and the secondary transponder ranging value.

2. The satellite two-way time comparison system according to claim 1, characterized in that, The number of signals for the main long pseudorange ranging signal, the secondary long pseudorange ranging signal, the main relay ranging signal, and the secondary relay ranging signal are m, v, h, and r, respectively. m and v are both integers greater than or equal to 1, h and r are both integers greater than or equal to 0, and m + h + r + v ≥ 4.

3. A satellite two-way time comparison system according to claim 1, characterized in that, The main pseudorange ranging signal includes the main pseudorange downlink signal broadcast by the slave station and relayed by the satellite to the master station; The long pseudorange ranging signal includes the primary pseudorange uplink signal broadcast by the master station and relayed by the satellite to the slave station; The main relay ranging signal includes a main uplink signal and a main downlink signal. The main station broadcasts the main uplink signal and receives the main downlink signal. The satellite receives the main uplink signal and forwards it to form the main downlink signal. The relay ranging signal includes an uplink signal and a downlink signal. The slave station broadcasts the uplink signal and receives the downlink signal. The satellite receives the uplink signal and forwards it to form the downlink signal.

4. A satellite two-way time comparison system according to claim 3, characterized in that, The satellites include: A repeater is used for forwarding between the primary uplink signal and the primary downlink signal, between the secondary uplink signal and the secondary downlink signal, between the primary pseudorange uplink signal and the secondary pseudorange downlink signal, and between the secondary pseudorange uplink signal and the primary pseudorange downlink signal; Satellite time and frequency equipment is used to provide time and frequency signals to the transponder; The main station, comprising: A primary pseudorange ranging device is used to receive and synchronously measure the primary long pseudorange ranging signal to obtain the primary long pseudorange ranging value. The main forwarding ranging device is used to generate and broadcast the main uplink signal and the main pseudorange uplink signal, and to receive and measure the main downlink signal to obtain the main forwarding ranging value. At least one time-frequency device is used to provide time-frequency signals to the main relay ranging device and the main pseudorange ranging device; Slave station, the slave station includes: From the pseudorange ranging device, used to receive and synchronously measure the pseudorange ranging signal to obtain the pseudorange ranging value; The forwarding ranging device is used to generate and broadcast the forwarding uplink signal and the forwarding pseudorange uplink signal, and to receive and measure the forwarding downlink signal to obtain the forwarding ranging value. At least one time-frequency device is used to provide time-frequency signals to the relay ranging device and the pseudorange ranging device.

5. A satellite two-way time comparison system according to claim 4, characterized in that, The primary pseudorange ranging device and the primary relay ranging device are set to zero baseline, and the secondary pseudorange ranging device and the secondary relay ranging device are also set to zero baseline.

6. A satellite two-way time comparison system according to claim 1, characterized in that, The system also includes: The computing device is communicatively connected to both the master station and the slave station. The computing device receives the main long pseudorange ranging value, the slave long pseudorange ranging value, the main relay ranging value, and the slave relay ranging value. Based on the main long pseudorange ranging value, the slave long pseudorange ranging value, the main relay ranging value, and the slave relay ranging value, the computing device determines the total number of primary ionospheric electrons between the master station and the satellite, the total number of secondary ionospheric electrons between the slave station and the satellite, and the clock difference between the master station and the slave station.

7. A satellite two-way time comparison system according to claim 1, characterized in that, The main long pseudorange ranging signal, the secondary long pseudorange ranging signal, the main relay ranging signal, and the secondary relay ranging signal are all spread spectrum signals.

8. A satellite two-way time comparison method, employing a satellite two-way time comparison system as described in any one of claims 1 to 7, characterized in that, The method includes: The computing device acquires data by communicating with the master station and the slave station respectively, and acquiring m master long pseudorange ranging values, v slave long pseudorange ranging values, h master forwarding ranging values ​​and r slave forwarding ranging values; The calculation device obtains the total number of primary ionospheric electrons and / or the total number of secondary ionospheric electrons, as well as the clock difference between the master station and the slave station, based on m primary long pseudorange ranging values, v secondary long pseudorange ranging values, h primary relay ranging values, and r secondary relay ranging values. The total number of primary ionospheric electrons is the total number of ionospheric electrons on the ranging signal path between the master station and the satellite, and the total number of secondary ionospheric electrons is the total number of ionospheric electrons on the ranging signal path between the slave station and the satellite.

9. A satellite two-way time comparison method according to claim 8, characterized in that, The total number of electrons in the primary ionosphere and / or the total number of electrons in the secondary ionosphere are specifically: The m primary long pseudorange ranging values, v secondary long pseudorange ranging values, h primary forwarding ranging values, and r secondary forwarding ranging values ​​are corrected respectively to obtain m corrected primary long pseudorange ranging values, v corrected secondary long pseudorange ranging values, h corrected primary forwarding ranging values, and r corrected secondary forwarding ranging values. The total number of electrons in the main ionosphere and / or the total number of electrons in the secondary ionosphere are determined based on the m corrected main long pseudorange ranging values, v corrected secondary long pseudorange ranging values, h corrected main forwarding ranging values, and r corrected secondary forwarding ranging values.

10. A satellite two-way time comparison method according to claim 9, characterized in that, The clock difference between the master station and the slave station is specifically as follows: The clock difference between the master station and the slave station is determined using the total number of electrons in the main ionosphere and / or the total number of electrons in the slave ionosphere, any of the corrected main long pseudorange distance measurement values, and any of the corrected slave long pseudorange distance measurement values.

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