Ionospheric delay monitoring, orbit determination system and related methods

Abstract

The application discloses an ionosphere delay monitoring and orbiting system and a related method, belongs to the technical field of ionosphere delay monitoring, and relates to the ionosphere delay monitoring and orbiting system, which comprises a satellite and a monitoring station in communication connection. The monitoring station broadcasts at least one uplink signal to the satellite, the satellite forwards at least two downlink signals to the monitoring station based on the received at least one uplink signal, two forwarding distance measurement values are synchronously measured, the total electron number of the ionosphere on a distance measurement signal path between the satellite and the monitoring station and the space distance between the satellite and the monitoring station are determined based on the two forwarding distance measurement values. The ionosphere delay monitoring method provided by the application has the advantages of high real-time performance and accurate monitoring results.

Description

[0001] Cross-referencing

[0002] This disclosure claims application number 202410661194.3, filed on May 27, 2024, entitled "An Ionization..." Priority to the Chinese patent application for "Layer Delay Monitoring, Orbit Determination System and Related Methods", the full contents of which are described. All references are incorporated into this article. Technical Field

[0003] This application relates to the field of ionospheric time delay monitoring technology, and in particular to an ionospheric time delay monitoring and orbit determination system and related methods. Background Technology

[0004] Ionospheric delay is a major positioning error term in satellite navigation and positioning, and it also has a significant impact on satellite communication and satellite remote sensing. Currently, ionospheric delay monitoring commonly uses multi-frequency ranging signals broadcast by navigation satellites. Two different ranging signals are selected for pseudorange measurement, and then the dual-frequency method is used to calculate the ionospheric TEC value (total number of electrons in the ionosphere).

[0005] In related technologies, when satellites and ground stations conduct radio communication, the radio signals experience time delays as they pass through the atmosphere, including ionospheric and tropospheric delays. When the signal 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 caused by a radio signal crossing the ionosphere can be:

[0006]

[0007] Where: dI is the time delay of the radio frequency signal (i.e., radio signal) as it traverses the ionospheric path of the satellite-to-ground connection (unit: meters); f is the carrier frequency of the radio signal (unit: Hertz); TEC is the total number of electrons in the ionosphere along the path between the satellite and the ground station (unit: electrons / square meter).

[0008] The International GPS Service (IGS) uses a large network of ground stations to observe dual-frequency pseudoranges, calculates the TEC values ​​at different ionospheric penetration points, and generates global ionospheric data for use by a wide range of users.

[0009] Currently, some communication and remote sensing satellites use two main methods to correct ionospheric delay between themselves and specific ground stations: one is to directly obtain TEC values ​​from third-party organizations such as IGS for correction; the other is to add a payload, with the satellite broadcasting dual-frequency or even multi-frequency pseudorange signals, which are received by the earth station, and then the TEC value is obtained according to ionospheric calculation methods. It can be seen that the current methods for obtaining satellite-to-ground ionospheric delay mainly fall into two categories: obtaining it from third-party organizations such as IGS; and directly obtaining real-time ionospheric delay from dual frequencies.

[0010] 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 even the risk of not being able to obtain the data. When using a dual-frequency method to obtain ionospheric delay, the satellite needs to add a payload to broadcast multi-frequency ranging signals, increasing the satellite payload complexity and satellite development costs.

[0011] The above content is only used to help understand the technical solution of this application and does not represent an admission that the above content is prior art. Summary of the Invention

[0012] This application combines the characteristics of satellite transponders with the multiple access characteristics of spread spectrum signals. Leveraging the ability of a satellite transponder to forward one signal into at least two, and the carrier frequency reuse capability of at least two spread spectrum signals, it creatively proposes a system and method for using the total number of ionospheric electrons in the transponder ranging signal. The main objective of this application is to provide an ionospheric delay monitoring and orbit determination system and related methods, aiming to solve the problems of poor real-time performance, high cost, and time lag in existing ionospheric delay monitoring technologies.

[0013] To achieve the above objectives, this application provides an ionospheric delay monitoring system, comprising a satellite and a monitoring station connected by communication; the satellite forwards at least two downlink signals to the monitoring station based on at least one received uplink signal, wherein the at least one uplink signal and the at least two downlink signals constitute at least two forwarding ranging signals; the monitoring station is used to broadcast at least one of the uplink signals to the satellite, receive at least two of the downlink signals, and simultaneously measure at least two forwarding ranging values ​​corresponding to the at least two forwarding ranging signals.

[0014] Furthermore, to achieve the above objectives, this application also provides a satellite orbit determination system, comprising: an ionospheric delay monitoring system as described in any embodiment of this application, wherein the number of monitoring stations is greater than or equal to 3; wherein each monitoring station is communicatively connected to the satellite, and each monitoring station determines the space distance between itself and the satellite based on the total number of ionospheric electrons on the ranging signal path between itself and the satellite and at least one relay ranging value; and a computing device communicatively connected to the monitoring stations, wherein the computing device is used to determine the orbital parameters of the satellite based on the space distance between each monitoring station and the satellite and the coordinate information of each monitoring station.

[0015] Furthermore, to achieve the above objectives, this application also provides an ionospheric delay monitoring method, applied to the ionospheric delay monitoring system described in any embodiment of this application. The method is executed by a monitoring station and includes: broadcasting at least one uplink signal to a satellite; acquiring at least two downlink signals relayed by the satellite based on the at least one uplink signal; wherein the at least one uplink signal and the at least two downlink signals constitute at least two relay ranging signals; synchronously measuring each of the relay ranging signals to obtain x relay ranging values, and selecting y relay ranging values ​​from the x relay ranging values; or, selecting y relay ranging signals from the x relay ranging signals for synchronous measurement to obtain y relay ranging values. Ranging values; where x is a positive integer greater than or equal to 2, 2≤y≤x; each of the relay ranging values ​​is represented by a relay ranging expression; the y relay ranging values ​​are divided into two groups, one group including m relay ranging values ​​and the other group including h relay ranging values, where 2≤y≤x, m+h=y, and y, m, and h are all positive integers; the average of the two groups of relay ranging values ​​represented by each relay ranging expression is calculated to obtain a first corrected average relay ranging value and a second corrected average relay ranging value; the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station is determined based on the first corrected average relay ranging value and the second corrected average relay ranging value.

[0016] Furthermore, to achieve the above objectives, this application also provides a satellite orbit determination method, applied to the satellite orbit determination system described in any embodiment of this application. The method is executed by a computing device and includes: determining the coordinate information of the satellite based on the acquired coordinate information of a monitoring station and the space distance between the satellite and the monitoring station, wherein the space distance between the satellite and the monitoring station is determined according to the ionospheric delay monitoring method described in any embodiment of this application; there are multiple monitoring stations, and each monitoring station meets the time synchronization requirement; and the satellite's orbital parameters are determined based on the satellite's coordinate information.

[0017] The ionospheric delay monitoring method provided in this application involves a monitoring station broadcasting two uplink signals to a satellite. The satellite then forwards two downlink signals to the monitoring station, allowing the monitoring station to measure the first forwarding ranging signal to obtain a first forwarding ranging value and measure the second forwarding ranging signal to obtain a second forwarding ranging value. The monitoring station further characterizes the first forwarding ranging value using a first forwarding ranging expression and the second forwarding ranging value using a second forwarding ranging expression. The two forwarding ranging values, characterized by these two expressions, allow the calculation of the total number of ionospheric electrons along the ranging signal path between the satellite and the monitoring station. Furthermore, based on this total number of ionospheric electrons along the ranging signal path, the ionospheric delays of the two uplink signals and the two downlink signals can be calculated. After obtaining the aforementioned ionospheric delays, the monitoring station can further calculate the space distance between the satellite and the monitoring station using the two forwarding ranging values.

[0018] As can be seen, the ionospheric delay monitoring method provided in this application embodiment can accurately calculate the total number of ionospheric electrons and the space distance between the satellite and the ground simply by forwarding the ranging value. It has the characteristics of complete autonomy and controllability. The monitoring station can send uplink signals to the satellite at any time and calculate the real-time total number of ionospheric electrons and the space distance between the satellite and the ground based on the above method. It has the advantages of strong real-time performance and accurate monitoring results. Furthermore, the method in this application embodiment uses a satellite transponder instead of a satellite pseudorange signal broadcasting device, which can simplify the satellite structure and reduce the hardware cost and operating cost of the entire system. In addition, in this application embodiment, the monitoring station can use a directional antenna, which can further overcome the multipath effect error. Attached Figure Description

[0019] Figure 1 This is one of the structural schematic diagrams of the ionospheric delay monitoring system according to an embodiment of this application;

[0020] Figure 2 This is a second schematic diagram of the ionospheric delay monitoring system according to an embodiment of this application;

[0021] Figure 3 This is the third schematic diagram of the ionospheric time delay monitoring system according to the embodiments of this application;

[0022] Figure 4 This is a structural block diagram of a satellite and a monitoring station according to one embodiment of this application;

[0023] Figure 5 This is a schematic diagram of the structure of an ionospheric delay monitoring system according to another embodiment of this application;

[0024] Figure 6 This is a schematic diagram of the structure of an ionospheric time delay monitoring system according to another embodiment of this application;

[0025] Figure 7 This is a flowchart of an ionospheric time delay monitoring method according to one embodiment of this application;

[0026] Figure 8 This is a flowchart of a satellite orbit determination method according to one embodiment of this application.

[0027] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] This application creatively proposes a system and calculation method for obtaining the total number of ionospheric electrons using relay ranging signals by organically integrating relay ranging signals and satellite transponders. To achieve the functions of this application, the monitoring station broadcasts at least one uplink signal, the satellite transponder relays this at least one uplink signal into at least two downlink signals with different carrier frequencies, the monitoring station measures at least two relay ranging signals to obtain at least two relay ranging values, and uses these at least two relay ranging values ​​to calculate the total number of ionospheric electrons and the satellite-to-ground space distance.

[0030] The parameters involved in the embodiments of this application are explained in a unified manner below:

[0031] m represents the number of forwarded ranging values ​​in the first group; k represents the number of forwarded ranging values ​​in the first group; h represents the number of forwarded ranging values ​​in the second group; j represents the number of forwarded ranging values ​​in the second group; y represents the total number of forwarded ranging values ​​selected; x represents the total number of forwarded ranging signals or forwarded ranging values.

[0032] This represents the difference in forwarding distances, in meters. This represents the first corrected average forwarding distance, in meters. This represents the second corrected average forwarding distance, in meters. Represents the forwarding ranging value with ID i at time n, in meters; This represents the actual spatial distance traversed by the uplink signal numbered i at time n, i.e., the satellite-to-ground spatial distance, in meters; This represents the actual spatial distance traveled by the downlink signal numbered i at time n, i.e., the satellite-to-ground spatial distance, in meters; Represents the ionospheric delay of the uplink signal numbered i at time n, in meters; Represents the ionospheric delay of the downlink signal numbered i at time n, in meters; The tropospheric delay of the uplink signal numbered i at time n is represented in meters. The tropospheric delay of the downlink signal numbered i at time n is represented in meters. The hardware device delay for the forwarding ranging signal numbered i at time n is expressed in meters. The hardware device delay includes the transmission delay of the monitoring station for the uplink signal numbered i, the forwarding delay of the satellite when forwarding the downlink signal numbered i, and the reception delay of the monitoring station when receiving the downlink signal numbered i.

[0033] , Represents the forwarding ranging values ​​of numbers k and j at time n, in meters; , This represents the actual spatial distance traversed by the uplink signals numbered k and j at time n, i.e., the satellite-to-ground spatial distance, in meters; , This represents the actual spatial distance traversed by downlink signals numbered k and j at time n, i.e., the satellite-to-ground spatial distance, in meters. , Represents the ionospheric delay of the uplink signals numbered k and j at time n, in meters; , Represents the ionospheric delay of downlink signals numbered k and j at time n, in meters; , The tropospheric delay of the uplink signals numbered k and j at time n is represented in meters. , The unit represents the tropospheric delay of the downlink signals numbered k and j at time n, in meters. , The hardware device delay for forwarding ranging signals numbered k and j at time n is expressed in meters. The hardware device delay includes the transmission delay of the monitoring station for the uplink signals numbered k and j, the forwarding delay of the satellite when forwarding the downlink signals numbered k and j, and the reception delay of the monitoring station when receiving the downlink signals numbered k and j.

[0034] Represents the ionospheric time delay coefficient. The total number of ionospheric electrons along the ranging signal path between the satellite and the monitoring station at time n, in electrons per square meter; The carrier frequency of the uplink signal numbered k at time n is represented in Hertz. The carrier frequency of the downlink signal numbered k at time n is represented in Hertz. The carrier frequency of the uplink signal numbered j at time n is represented in Hertz. The carrier frequency of the downlink signal numbered j at time n is represented in Hertz. The carrier frequency of the uplink signal numbered i at time n is represented in Hertz. This represents the carrier frequency of the downlink signal numbered i at time n, in Hertz (Hz).

[0035] Special note: The 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 ionospheric time delay 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.

[0036] Furthermore, it should be noted that in this embodiment, since only two forwarding ranging signals are used for illustration, it can be understood that after dividing the two forwarding ranging values ​​into two groups, each group contains one forwarding ranging value. Then, the forwarding ranging values ​​of each group are averaged to obtain the first corrected average forwarding ranging value and the second corrected average forwarding ranging value.

[0037] To illustrate the method provided in this application more clearly and generally, this application uses a signal structure with two forwarding ranging signals, all of which have different carrier frequencies. Two forwarding ranging values ​​are selected for calculation as an example, where x=2, y=2, m=1, h=1, and x=m+h. Figure 1 As shown, two forwarding ranging values ​​are obtained through synchronous measurement, which illustrates the specific implementation of the method in this application.

[0038] The ionospheric time delay monitoring system and related methods provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0039] Figure 1 This is one of the structural schematic diagrams of the ionospheric time delay monitoring system according to an embodiment of this application, such as... Figure 1 As shown, the system includes a satellite 100 and a monitoring station 200 connected by communication. The ionospheric delay monitoring system provided in this embodiment will be described in detail below.

[0040] Satellite 100 forwards a first downlink signal to monitoring station 200 based on the received first uplink signal, and forwards a second downlink signal to monitoring station 200 based on the received second uplink signal. The first uplink signal and the first downlink signal constitute a first forwarding ranging signal, and the second uplink signal and the second downlink signal constitute a second forwarding ranging signal.

[0041] The monitoring station 200 is used to broadcast a first uplink signal and a second uplink signal to the satellite 100, receive a first downlink signal and a second downlink signal, and simultaneously measure the first and second relay ranging signals to obtain the first and second relay ranging values, as well as the total number of ionospheric electrons on the ranging signal path between the satellite 100 and the monitoring station 200 and the space distance between the satellite 100 and the monitoring station 200, determined based on the first and second relay ranging values.

[0042] The ionospheric delay monitoring system provided in this application can be applied to aerospace systems, such as satellite navigation, satellite communication, satellite remote sensing, satellite reconnaissance, and meteorological satellites. This application embodiment uses the example of a monitoring station determining the total number of ionospheric electrons and the space distance between the satellite and the ground along the ranging signal path for illustrative purposes.

[0043] Specifically, this embodiment provides multiple signal transmission methods between satellite 100 and monitoring station 200. The first method is as follows: Figure 1 As shown: Monitoring station 200 broadcasts two uplink signals to satellite 100, and satellite 100 forwards two downlink signals to monitoring station 200. The second type is as follows... Figure 2 As shown: Monitoring station 200 broadcasts an uplink signal to satellite 100, which satellite 100 then relays as two downlink signals with different carrier frequencies. The third type is as follows... Figure 3 As shown: The two uplink signals broadcast by monitoring station 200 to satellite 100 have different carrier frequencies, and the satellite uses carrier frequency reuse technology to forward them into two downlink signals with the same carrier frequency.

[0044] like Figures 1 to 3 As shown, because regardless of Figure 1 , Figure 2 , Figure 3 The signal transmission method shown in this ionospheric delay monitoring system has two relay ranging signals and two corresponding relay ranging values. Therefore, the space distance between satellite 100 and monitoring station 200 and the total number of ionospheric electrons along the ranging signal path can be determined. The following only uses... Figure 1 The ionospheric delay monitoring system of this application is illustrated by taking the example of monitoring station 200 broadcasting two uplink signals to the satellite and satellite 100 forwarding two downlink signals to the monitoring station.

[0045] In this embodiment, satellite 100 forwards the two received uplink signals into two downlink signals to monitoring station 200, enabling monitoring station 200 to determine the total number of ionospheric electrons and the satellite-to-ground distance along the ranging signal path between satellite 100 and monitoring station 200 based on the two forwarded ranging signals. In this exemplary embodiment, because satellite 100 does not need to broadcast pseudorange ranging signals, there is no need to include a device for transmitting pseudorange ranging signals in satellite 100, thus simplifying the structure of satellite 100 and reducing its equipment cost. The monitoring system provided in this application embodiment can obtain the total number of ionospheric electrons and the satellite-to-ground distance in real time, achieving complete autonomous control and independence from constraints from other organizations.

[0046] In this exemplary embodiment, the monitoring station 200 can send a first uplink signal and a second uplink signal to the satellite 100 based on its own time and frequency system, i.e., local time. After the satellite 100 obtains the first uplink signal and the second uplink signal, it performs frequency conversion processing and power amplification on the first uplink signal and the second uplink signal to obtain a first downlink signal and a second downlink signal with different carrier frequencies. Furthermore, the satellite 100 then forwards the first downlink signal and the second downlink signal to the monitoring station 200.

[0047] The first uplink signal and the first downlink signal constitute the first forwarding ranging signal, and the second uplink signal and the second downlink signal constitute the second forwarding ranging signal. Monitoring station 200 measures the first forwarding ranging signal to obtain the first forwarding ranging value, and measures the second forwarding ranging signal to obtain the second forwarding ranging value.

[0048] After obtaining the first and second transponder ranging values, monitoring station 200 uses the first transponder ranging expression to characterize the first transponder ranging value and the second transponder ranging expression to characterize the second transponder ranging value. Then, through mathematical calculations using these two transponder ranging expressions, the total number of ionospheric electrons along the ranging signal path between monitoring station 200 and satellite 100, as well as the space distance between monitoring station 200 and satellite 100, can be obtained.

[0049] Furthermore, it is worth noting that the monitoring station 200 in this embodiment can be one or more. When there are multiple monitoring stations 200, each monitoring station 200 can determine the total number of ionospheric electrons on the ranging signal path between itself and satellite 100, as well as the space distance between itself and satellite 100.

[0050] In some implementations, the carrier frequency of the first uplink signal, the carrier frequency of the first downlink signal, the carrier frequency of the second uplink signal, and the carrier frequency of the second downlink signal are frequency-hopped on the time axis according to a preset frequency-hopping pattern.

[0051] Specifically, the carrier frequencies of the first uplink signal and the second uplink signal at different times, and the first downlink signal and the second downlink signal, are not the same fixed frequency, but different frequencies are used at different times. Therefore, frequency hopping can improve the signal's anti-interference ability and enhance its anti-interception ability.

[0052] Of course, the carrier frequency of the first uplink signal, the carrier frequency of the first downlink signal, the carrier frequency of the second uplink signal, and the carrier frequency of the second downlink signal can also remain unchanged for a long time, that is, the time interval between the two frequency hopping is infinite.

[0053] Additionally, it should be noted that the first forwarding ranging signal and the second forwarding ranging signal mentioned in the embodiments of this application refer to the modulated signals obtained by modulating the ranging code signal into the carrier signal. In some specific embodiments, the ranging code can be a pseudo-code, a weil code, an M code, etc., and this application does not make any special limitation on which ranging code is specifically selected. Furthermore, it can be understood that the forwarding ranging signal mentioned in the embodiments of this application is a spread spectrum signal. 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.

[0054] For details regarding the process by which monitoring station 200 determines the total number of ionospheric electrons along the ranging signal path between itself and satellite 100, as well as the space distance between itself and satellite 100, please refer to the description of the subsequent method embodiments, which will not be elaborated here.

[0055] Figure 4 This is a structural block diagram of a satellite and monitoring station according to one embodiment of this application. Figure 4 As shown, in some embodiments, satellite 100 may include transponder 101 and satellite time and frequency equipment 103, wherein satellite time and frequency equipment 103 provides time and frequency signals to transponder 101, transponder 101 may be used to receive a first uplink signal and a second uplink signal, and after performing frequency conversion processing and power amplification on the first uplink signal, forward the first downlink signal to monitoring station 200, and after performing frequency conversion processing and power amplification on the second uplink signal, forward the second downlink signal to monitoring station 200.

[0056] Continue to refer to Figure 4 In some implementations, the monitoring station 200 may include a forwarding ranging device 201, a processing device 202, and a monitoring time and frequency device 203.

[0057] It should be noted that the monitoring station 200 can be equipped with one or more forwarding ranging devices 201. Taking the setup of two forwarding ranging devices 201 as an example, in this embodiment of the application, the two forwarding ranging devices 201 can be set independently, or they can be integrated into one hardware device, that is, one hardware device can implement the functions of two forwarding ranging devices 201. These are all within the protection scope of this application. Furthermore, it can be understood that... Figure 4 The monitoring station 200 shown includes a relay ranging device 201, a processing device 202, and a monitoring time and frequency device 203, which are modules divided according to function. In terms of hardware implementation, they can be implemented separately or integrated into a single device, all of which fall within the protection scope of this application.

[0058] In an exemplary embodiment, the transponder ranging device 201 may include a modulator, a mixer, a demodulator, an antenna, a data acquisition unit, etc. The modulator generates an intermediate frequency (IF) ranging code spread spectrum signal; the mixer mixes the IF ranging code spread spectrum signal to a radio frequency (RF) signal; the antenna transmits the RF signal to the satellite 100 and receives the RF signal transponded by the satellite 100, which is then mixed to an IF signal by the mixer; the demodulator demodulates the received IF signal and obtains the transponder ranging value through relevant mathematical operations; and the data acquisition unit records and stores the transponder ranging value.

[0059] The forwarding ranging device 201 generates and broadcasts a first uplink signal and a second uplink signal; and receives a first downlink signal and a second downlink signal; the forwarding ranging device 201 determines a first forwarding ranging value based on the first forwarding ranging signal and determines a second forwarding ranging value based on the second forwarding ranging signal.

[0060] The processing device 202 is communicatively connected to the transponder ranging device 201. The processing device 202 receives the first transponder ranging value and the second transponder ranging value, and determines the total number of electrons in the ionosphere and the space distance between the satellite and the ground based on the first transponder ranging value and the second transponder ranging value. The monitoring time and frequency device 203 can provide time and frequency signals to the transponder ranging device 201.

[0061] In some embodiments, the monitoring station 200 includes at least two forwarding ranging devices 201; when there are two forwarding ranging devices 201, one forwarding ranging device 201 receives a first downlink signal and determines a first forwarding ranging value based on the first forwarding ranging signal, and the other forwarding ranging device 201 receives a second downlink signal and determines a second forwarding ranging value based on the second forwarding ranging signal, and the two forwarding ranging devices are set to zero baseline.

[0062] It is worth noting that in this embodiment, when the monitoring station 200 includes two relay ranging devices 201, the two relay ranging devices 201 are set to zero baseline. This ensures that the first relay ranging signal and the second relay ranging signal have the same transmission path, that is, the two relay ranging signals have the same atmospheric path.

[0063] It is worth noting that the zero baseline setting mentioned in this application does not mean that the distance between two transponder ranging devices is zero. Rather, it means that the distance between the two transponder ranging devices is set such that the uplink signals transmitted and the downlink signals received by each transponder ranging device follow approximately the same spatial path. As the distance between the two transponder ranging devices decreases and they become essentially the same device, the approximation gradually becomes identical, resulting in the same satellite-to-ground distance, the same tropospheric delay, and the same total number of ionospheric electrons. This application can calculate this total number of ionospheric electrons. Of course, when there are multiple transponder ranging devices, a zero baseline setting is applied across all of them.

[0064] In some embodiments, when the monitoring station 200 includes two relay ranging devices 201, the two relay ranging devices 201 use at least one time-frequency system. When the two relay ranging devices 201 use the same time-frequency system, the two relay ranging devices 201 perform measurements at the same time to obtain two relay ranging values ​​at the same time.

[0065] It is worth noting that at least one time-frequency system in the embodiments of this application may include multiple clocks (crystal oscillators or atomic clocks) or a single clock (crystal oscillator or atomic clock). Generally, using a single clock is recommended. When the time-frequency system includes multiple clocks (crystal oscillators or atomic clocks), the multiple clocks provide time-frequency signals to the multiple relay ranging devices 201 respectively. In practical use, the preset time interval can be set to, for example, 1 second, and the two relay ranging devices 201 perform measurements at the rising or falling edge of their respective 1PPS (1 Pulse Per Second) signals. Preferably, it is generally recommended to use a single clock to synchronously measure the relay ranging signals at the rising or falling edge of the same 1PPS signal.

[0066] In some implementations, the transponder 101 of the satellite 100 has a forwarding delay, and the transponder ranging device 201 of the monitoring station 200 has a transmission delay and a reception delay; wherein, the forwarding delay is transmitted through an additional communication link, or the processing device 202 has a preset forwarding delay, transmission delay and reception delay.

[0067] It should be noted that the forwarding delay of transponder 101 refers to the delay generated when satellite 100 receives the first uplink signal and the second uplink signal sent by monitoring station 200 and forwards the first uplink signal and the second uplink signal to obtain the corresponding first downlink signal and the second downlink signal.

[0068] In addition, the transmission delay of the transponder ranging device 201 refers to the delay incurred by the transponder ranging device 201 in the process of transmitting the first uplink signal and the second uplink signal to the satellite 100. The reception delay of the transponder ranging device 201 refers to the delay incurred by the transponder ranging device 201 in the process of receiving the first downlink signal and the second downlink signal transmitted by the satellite 100.

[0069] In this exemplary embodiment, the relay delay of the transponder 101 can be transmitted between the monitoring station 200 and the satellite 100 via an additional communication link. For example, the satellite 100 may be equipped with a telemetry unit, and the relay delay of the transponder 101 can be transmitted through telemetry signals broadcast by the telemetry unit; alternatively, the relay delay of the transponder 101 can be transmitted to the monitoring station 200 through other user-defined communication link signals. This application does not specifically limit which signal is used to transmit the relay delay of the transponder 101. Alternatively, since the variation in the relay delay of the transponder 101 is very small and known, the known relay delay of the transponder 101 can be treated as a constant. Therefore, in practical use, the relay delay can also be preset in the processing device 202 in the monitoring station 200.

[0070] The above is an embodiment of an ionospheric delay monitoring system provided in this application. The ionospheric delay monitoring system determines the total number of ionospheric electrons on the ranging signal path between satellite 100 and monitoring station 200 and the space distance between the satellite and the monitoring station by two forwarding ranging signals.

[0071] Figure 5 This is a schematic diagram of the structure of an ionospheric delay monitoring system according to another embodiment of this application.

[0072] like Figure 5 As shown, the ionospheric time delay monitoring system may also include a central station 210, wherein the central station 210 is communicatively connected to the monitoring station 200; the central station 210 can obtain the monitoring parameters of the monitoring station 200 based on the communication results with the monitoring station 200.

[0073] Specifically, the central station 210 can be located on the ground or integrated into a satellite. The monitoring station 200 and the central station 210 can communicate directly. For example, in a city, the monitoring station 200 and the central station 210 can communicate directly via a 4G or 5G network. Of course, the monitoring station 200 can also communicate with the central station 210 via satellite 100. For example, at sea or in a desert, the central station 210 and the monitoring station 200 can communicate directly via satellite 100, thus enabling communication between the monitoring station 200 and the central station 210 through satellite 100.

[0074] In addition, continue to refer to Figure 5 When the central station 210 and satellite 100 communicate via satellite 100, there can be a main feed link between the central station 210 and satellite 100, and a secondary feed link between the monitoring station 200 and satellite 100. The main feed link includes an uplink signal and a downlink signal, and the secondary feed link includes an uplink signal and a downlink signal. The uplink signal of the main feed link and the downlink signal of the secondary feed link constitute a forward communication link, and the downlink signal of the main feed link and the uplink signal of the secondary feed link constitute a return communication link.

[0075] Specifically, taking the example of a central station 210 located on the ground, during communication between the central station 210 and the monitoring station 200, the central station 210 broadcasts the uplink signal fu1 of the main feed link to the satellite 100. After receiving the uplink communication signal fu1, the satellite 100 forwards it to obtain the downlink signal fd2 of the feed link and transmits the downlink communication signal fd2 to the monitoring station 200. The monitoring station 200 broadcasts the uplink signal fu2 of the feed link to the satellite 100. After receiving the uplink communication signal fu2, the satellite 100 forwards it to obtain the downlink signal fd1 of the main feed link and transmits the downlink communication signal fd1 to the central station 210. Communication between the monitoring station 200 and the central station 210 is achieved through forwarding by the satellite 100, and the satellite 100 does not need to perform modulation and demodulation processing on the signal. In this way, communication between the monitoring station 200 and the central station 210 is realized through this forwarding communication link, which simplifies the structure of the satellite 100, reduces the complexity of the satellite 100, and thus reduces the cost of the satellite 100. Of course, it should be understood that when the central station 210 is integrated into the satellite, then... Figure 5 The main power supply link and the slave power supply link are combined into one.

[0076] In this embodiment, monitoring station 200 can interact with central station 210 via a communication link, allowing central station 210 to obtain other parameters such as the total number of ionospheric electrons from each monitoring station 200. Central station 210 then aggregates and processes the total number of ionospheric electrons from each monitoring station 200 before publishing the data, thereby improving positioning and navigation accuracy. The method for determining the total number of ionospheric electrons will be described in subsequent method embodiments and will not be elaborated here.

[0077] Further reference Figure 5 The monitoring station 200 and satellite 100 also have a relay ranging signal link, which includes two relay uplink signals and two relay downlink signals. The carrier frequency of the uplink signal from the feed link can be the same as the carrier frequency of any one of the relay uplink signals, or different from the carrier frequencies of both relay uplink signals. Similarly, the carrier frequency of the downlink signal from the feed link can be the same as the carrier frequency of any one of the relay downlink signals, or different from the carrier frequencies of both relay downlink signals.

[0078] Specifically, when the carrier frequency of the forwarded uplink signal is different from the carrier frequency of the feeder link uplink signal, that is, the forwarded uplink signal and the feeder link uplink signal use different carrier frequencies. When the carrier frequency of any forwarded uplink signal is the same as the carrier frequency of the feeder link uplink signal, it is equivalent to multiplexing the carrier frequencies of the forwarded uplink signal and the feeder link uplink signal, and using code division multiple access (CDMA) technology for communication. This can save frequency resources and reduce the usage and operating costs of the equipment. In addition, the carrier frequency of any forwarded downlink signal and the carrier frequency of the feeder link downlink signal can be set with reference to the aforementioned relationship between the carrier frequencies of the forwarded uplink signal and the feeder link uplink signal, which will not be elaborated here.

[0079] The monitoring station 200 in this embodiment can be a base station, radar, etc. Furthermore, as... Figure 6 As shown, the number of monitoring stations 200 in this embodiment can be one or more. For example, by deploying multiple monitoring stations 200 covering the globe, the entire country, or different cities, each monitoring station 200 can monitor the ionospheric delay within its coverage area. Each monitoring station 200 communicates with the central station 210 to send the ionospheric delay of its respective monitoring area to the central station 210, thereby allowing the central station 210 to obtain the ionospheric delay at different locations globally or nationwide. When performing navigation or remote sensing monitoring, the corresponding equipment manufacturers or users can obtain the corresponding ionospheric delay based on their own regional location for position correction, thereby improving navigation and positioning accuracy.

[0080] It should be understood that in this exemplary embodiment, the central station 210 communicates with the monitoring station 200 to control the monitoring station 200 to perform corresponding actions. Typically, an Internet of Things (IoT) system can be built based on the communication system provided in this application embodiment. The specific content of the operating parameters can be determined according to the user's needs. For example, the operating parameters may include the location information of the monitoring station 200, the current temperature information of the location of the monitoring station 200, etc.

[0081] Based on the above embodiments, this application also provides an ionospheric delay monitoring method. The ionospheric delay monitoring method provided in this application determines the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station by using two forwarded ranging signals. This ionospheric delay monitoring method can be applied to the ionospheric delay monitoring system described in any of the above embodiments, and this ionospheric delay monitoring method can be executed by the monitoring station.

[0082] The method for calculating the total number of electrons in the ionosphere provided in this application involves y transponder ranging values, where y is at least 2 and at most x. These y transponder ranging values ​​are divided into two groups: one group has m transponder ranging values, and the other group has h transponder ranging values, where y = m + h. Each group of transponder ranging values ​​is first averaged to obtain a corrected average transponder ranging value. The difference between the two corrected average transponder ranging values ​​is then calculated to obtain the total number of electrons in the ionosphere.

[0083] To illustrate the use of this method, here x=2, y=2, m=1, h=1, providing two average forwarding ranging values. These two values ​​are selected for calculation, divided into two groups. The first group contains only one forwarding ranging value, and the corrected average is calculated by subtracting the hardware latency from the original value. The second group also contains only one forwarding ranging value, and the corrected average is calculated by subtracting the hardware latency from the original value. Then, the total number of electrons in the ionosphere is calculated based on these two corrected average forwarding ranging values.

[0084] It should be noted that because the relay ranging device is set to zero baseline, the space distance between the two relay ranging signals and the ground is exactly the same, therefore equation (11) holds:

[0085] (11);

[0086] Furthermore, because the ranging relay equipment is set to zero baseline, the atmospheric layers traversed by the ranging relay signals are exactly the same, and therefore the tropospheric delays are exactly the same. The ionospheric delays differ due to the different carrier frequencies. That is, the tropospheric delays of the two ranging relay signals are the same, therefore we have equation (12):

[0087] (12);

[0088] When there are x forwarded ranging signals, the uplink and downlink signals of the x forwarded ranging signals experience equal spatial distances and equal tropospheric delays.

[0089] It should also be noted that in this embodiment, the space distance between the satellite and the ground, the tropospheric delay, and the ionospheric delay are all unknowns. When calculating the total number of electrons in the ionospheric region along the ranging signal path, the space distance between the satellite and the ground and the tropospheric delay are eliminated due to the zero baseline setting. After calculating the total number of electrons in the ionospheric region, the space distance between the satellite and the ground can be calculated in reverse based on the total number of electrons in the ionospheric region.

[0090] The ionospheric time delay monitoring method provided in this application will be described in detail below with reference to the accompanying drawings.

[0091] Figure 7 Here is a flowchart of an ionospheric time delay monitoring method according to one embodiment of this application, as follows: Figure 7 As shown, the ionospheric time delay monitoring method may include the following steps:

[0092] Step 910: Broadcast at least one uplink signal to the satellite;

[0093] Step 920: Obtain at least two downlink signals that the satellite forwards based on the at least one uplink signal; wherein the at least one uplink signal and the at least two downlink signals constitute at least two forwarding ranging signals;

[0094] Step 930: Synchronously measure each of the aforementioned forwarding ranging signals to obtain x forwarding ranging values, and select y forwarding ranging values ​​from the x forwarding ranging values; or, select y forwarding ranging signals from the x forwarding ranging signals for synchronous measurement to obtain y forwarding ranging values; where x is a positive integer greater than or equal to 2, and 2≤y≤x;

[0095] Step 940: Characterize each of the forwarding ranging values ​​using the forwarding ranging expression;

[0096] Step 950: Divide the y forwarding ranging values ​​into two groups, one group including m forwarding ranging values ​​and the other group including h forwarding ranging values, where 2≤y≤x, m+h=y, m and h are both greater than or equal to 1, and y, m and h are all positive integers.

[0097] Step 960: Calculate the mean of the two sets of forwarding ranging values ​​represented by each forwarding ranging expression to obtain the first corrected average forwarding ranging value and the second corrected average forwarding ranging value;

[0098] Step 970: Determine the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station based on the first corrected average relay ranging value and the second corrected average relay ranging value.

[0099] Among them, the carrier frequencies of the first uplink signal, the first downlink signal, the second uplink signal, and the second downlink signal in the two forwarding ranging signals are different from each other or partially the same.

[0100] For example, the carrier frequencies of the first uplink signal and the second uplink signal are the same, while the carrier frequencies of the first downlink signal and the second downlink signal are different.

[0101] Alternatively, the carrier frequencies of the first downlink signal and the second downlink signal are the same, while the carrier frequencies of the first uplink signal and the second uplink signal are different.

[0102] In step 930, y=2 forwarding ranging values ​​are obtained. The monitoring station measures the first forwarding ranging signal to obtain the first forwarding ranging value, and measures the second forwarding ranging signal to obtain the second forwarding ranging value.

[0103] After obtaining the two forwarding ranging values, in step 940, the monitoring station can use the first forwarding ranging expression to represent the first forwarding ranging value and the second forwarding ranging expression to represent the second forwarding ranging value.

[0104] In an exemplary embodiment, the monitoring station can obtain the formula expression of the first forwarding range value and the second forwarding range value of this embodiment based on the forwarding range value numbered i among the y forwarding range values ​​shown in formula (1), where i is 1 and 2 respectively.

[0105] (1);

[0106] The monitoring station can characterize the first forwarding ranging value using the first forwarding ranging expression shown in the following formula (1-1):

[0107] (1-1);

[0108] The second forwarding ranging value is characterized by the second forwarding ranging expression shown in the following formula (1-2):

[0109] (1-2);

[0110] It is worth noting that in the embodiments of this application, when using the forwarding ranging expression to characterize the forwarding ranging value, the forwarding ranging expression does not include the Sagnac effect delay. This is because the Sagnac effect delay of the uplink signal and the Sagnac effect delay of the downlink signal have opposite signs, 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, that is, the Sagnac effect delay of the uplink signal and the Sagnac effect delay of the downlink signal can be added to the forwarding ranging expression to achieve better ionospheric delay monitoring accuracy. These are all within the protection scope of this application.

[0111] In this embodiment of the application, the monitoring station can use the relay ranging values ​​represented by the two relay ranging expressions to perform mathematical calculations in subsequent steps to obtain the total number of ionospheric electrons and the space distance between the satellite and the monitoring station.

[0112] In some embodiments, after step 940, the ionospheric delay monitoring method may further include the following step: using a pseudorange smoothing algorithm to perform pseudorange smoothing correction on the first and second transponder ranging values. This can reduce the random error of the transponder ranging values, which is beneficial to improving the accuracy of the finally determined total number of ionospheric electrons, thereby improving the accuracy of the ionospheric delay between the satellite and the monitoring station, as well as the accuracy of the satellite-to-ground spatial distance. The specific details of the pseudorange smoothing algorithm will not be elaborated here.

[0113] As mentioned above, the first and second relay ranging signals contain the same satellite-to-ground spatial distance delay and tropospheric delay. Therefore, in subsequent steps, the monitoring station uses the two relay ranging values ​​to determine the total number of ionospheric electrons and the satellite-to-ground spatial distance between the satellite and the monitoring station.

[0114] Steps 950 and 960 involve grouping the two forwarding ranging values ​​obtained in the preceding steps and calculating the corrected average forwarding ranging value represented by the forwarding ranging expression. For example, when x=2, which represents the first forwarding ranging value and the second forwarding ranging value, in this step, all forwarding ranging values ​​are selected, x=y=2. The first forwarding ranging value can be divided into the first group, and the first corrected average forwarding ranging value can be calculated. The second forwarding ranging value can be divided into the second group, and the second corrected average forwarding ranging value can be calculated.

[0115] In an exemplary embodiment, when calculating the total number of electrons in the ionosphere using two relay ranging signals, step 960 may specifically include the following process:

[0116] Step 960: Since this application embodiment uses two forwarding ranging values ​​as an example for illustration, the two forwarding ranging values ​​are divided into two groups, with one forwarding ranging value in each group. Therefore, the first corrected average forwarding ranging value calculated using formula (2) is as shown in formula (2-1):

[0117] (2);

[0118] At this point, m=1.

[0119] (2-1);

[0120] The second corrected average forwarding ranging value calculated using formula (3) is shown in formula (3-1):

[0121] (3);

[0122] At this point, h=1, y=2.

[0123] (3-1);

[0124] Step 970 may specifically include the following process:

[0125] Step 971: Determine the forwarding ranging difference using the first corrected average forwarding ranging value and the second corrected average forwarding ranging value.

[0126] Step 972: Determine the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station based on the relay ranging difference.

[0127] In an exemplary embodiment, when calculating the total number of electrons in the ionosphere using two relay ranging signals, step 970 may specifically include the following process:

[0128] The forwarding ranging difference is determined using the first corrected average forwarding ranging value and the second corrected average forwarding ranging value;

[0129] The total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station is determined based on the relay ranging difference.

[0130] In this process, the monitoring station calculates the difference between the first corrected average forwarding distance value and the second corrected average forwarding distance value according to the formula (5). At the same time, using the zero baseline setting relationship of the forwarding distance equipment shown in formulas (11) and (12), the forwarding distance difference value of this embodiment is obtained as shown in formula (5-1):

[0131] (5);

[0132] (5-1);

[0133] Then, based on the carrier frequency of each signal in the relay ranging signal and the preset ionospheric delay coefficient, as well as formula (6), the monitoring station can use the relay ranging difference shown in formula (5-1) to determine the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station as shown in formula (6-1):

[0134] (6);

[0135] (6-1);

[0136] In some embodiments, the ionospheric delay coefficient can be 40.309. In other embodiments, the ionospheric delay coefficient can also be 40.28 or 40.30. Other more precise ionospheric delay coefficients may be used in the future, and these are all within the scope of protection of this application.

[0137] In this embodiment, when the ionospheric delay monitoring method is applied to the communication system described in the above embodiments, after the monitoring station determines the total number of ionospheric electrons, the monitoring station can interact with the central station via a communication link. The central station can then obtain the total number of ionospheric electrons from each monitoring station. By summarizing and publishing the total number of ionospheric electrons from each monitoring station, the central station can improve satellite positioning and navigation accuracy. The central station obtains the total number of ionospheric electrons determined by the monitoring stations based on the data interaction results. The communication link includes a forward communication link and a return communication link.

[0138] After obtaining the total number of electrons in the ionosphere, since the two relay signals between the satellite and the monitoring station follow the same path, the total number of electrons in the ionosphere on the ranging signal paths between the first uplink signal, the second uplink signal, the first downlink signal, and the second downlink signal between the satellite and the monitoring station is the same. Thus, the monitoring station can further determine the space distance between the satellite and the monitoring station based on the obtained total number of electrons in the ionosphere.

[0139] In an exemplary embodiment, the monitoring station may specifically include the following steps to calculate the space distance between itself and the satellite:

[0140] Step 9741: Determine the ionospheric delay of each signal in the corresponding forwarding ranging signal based on the total number of electrons in the ionosphere, the preset ionospheric delay coefficient, and the carrier frequency of each signal in at least one forwarding ranging signal.

[0141] Step 9742: Determine the sum of the satellite-to-ground spatial distance and tropospheric delay between the satellite and the monitoring station using at least one transponder ranging value characterized by the transponder ranging expression.

[0142] Step 9743: Determine the tropospheric delay on the ranging signal path between the satellite and the monitoring station based on the tropospheric delay model.

[0143] Step 9744: Determine the space distance between the satellite and the monitoring station based on the determined tropospheric delay of the corresponding signal and the sum of the satellite-to-ground space distance and the tropospheric delay.

[0144] In this exemplary embodiment, the ionospheric delay of two uplink signals and two downlink signals in two forwarding ranging signals is used as an example for illustrative purposes.

[0145] (8);

[0146] (9);

[0147] In step 9741, the monitoring station calculates the ionospheric delay of any relay ranging signal according to formulas (8) and (9), where i is equal to 1 and 2 respectively. The monitoring station can determine the ionospheric delay of the first uplink signal using the following formula (15) based on the total number of ionospheric electrons along the ranging signal path between the satellite and the monitoring station; determine the ionospheric delay of the first downlink signal using the following formula (16); determine the ionospheric delay of the second uplink signal using the following formula (17); and determine the ionospheric delay of the second downlink signal using the following formula (18):

[0148] (15);

[0149] (16);

[0150] (17);

[0151] (18);

[0152] Then, in step 9742, as described above, since the satellite-to-ground spatial distances of the two forwarding ranging signals are exactly the same, we have equation (11):

[0153] (11);

[0154] Furthermore, since the signals traverse the same atmospheric layers, the tropospheric delays are identical, while the ionospheric delays differ due to the different carrier frequencies. That is, the tropospheric delays of the two relay ranging signals are identical, thus equation (12) holds:

[0155] (12);

[0156] Based on this, the monitoring station can use the first transponder ranging value shown in formula (1-1), the second transponder ranging value shown in formula (1-2), formulas (15) to (18), and formula (10) to obtain the average value of the sum of the satellite-ground spatial distance and tropospheric delay between the satellite and the monitoring station, as shown in formula (20):

[0157] (20);

[0158] In steps 9743-9744, the tropospheric delay T between the satellite and the monitoring station can be obtained by correcting using a tropospheric delay model. The calculation of the tropospheric delay requires meteorological parameters. In the absence of real-time meteorological parameters, a simple model that only depends on the satellite elevation angle can be used for calculation, as shown in formula (T1):

[0159] T = 2.47 / (sinθ + 0.0121) (T1)

[0160] In the formula: T represents the tropospheric time delay, in meters; θ represents the satellite elevation angle, in radians.

[0161] Currently, there are relatively many models for calculating tropospheric delay based on meteorological parameters. The differences between them are about a few millimeters to a few centimeters as the satellite elevation angle decreases, which is more accurate than this simple model.

[0162] Common models for determining tropospheric delay corrections include the Saastamoinen model and the Hopfield model. Studies have shown that when the elevation angle is greater than or equal to 15°, the results obtained by different models are in good agreement, and any model can be selected. However, when the station elevation is very large, the tropospheric delay calculated by the two models in the zenith direction can differ by tens of centimeters. After comparison with measured meteorological data, it is recommended to use the Saastamoinen model.

[0163] Thus, after obtaining the tropospheric delay, the monitoring station can use the known tropospheric delay elimination formula (20) to obtain the space distance between the satellite and the monitoring station.

[0164] In some implementations, after determining the total number of ionospheric electrons along the ranging signal path between the satellite and the monitoring station, the method further includes: performing data interaction with a central station based on a communication link, wherein the central station obtains the total number of ionospheric electrons and the satellite-to-ground space distance along the ranging signal path between the satellite and the monitoring station based on the data interaction results, and the communication link includes a forward communication link and a return communication link.

[0165] In this embodiment, after determining the total number of ionospheric electrons, the monitoring station can interact with the central station via a communication link. The central station can then obtain the total number of ionospheric electrons from each monitoring station. By summarizing and publishing the total number of ionospheric electrons from all monitoring stations, the central station can improve satellite positioning and navigation accuracy. The central station obtains the total number of ionospheric electrons determined by the monitoring stations based on the data interaction results. The communication link includes a forward communication link and a return communication link.

[0166] Based on the above embodiments, this application also provides a satellite orbit determination system, which may include: a satellite, multiple monitoring stations, and a computing device. The multiple monitoring stations are communicatively connected to the satellite, and the number of monitoring stations is greater than or equal to three. Each monitoring station can determine the space distance between the satellite and the monitoring station according to the ionospheric delay monitoring method provided in the above embodiments. The computing device is communicatively connected to the monitoring stations and is used to determine the satellite's orbital parameters based on the space distance between the monitoring stations and the satellite and the coordinate information of the monitoring stations. Specific methods for the computing device to determine the satellite's orbital parameters can be found in the subsequent method embodiments, and will not be detailed here.

[0167] In addition, in this embodiment of the application, the satellite orbit determination system may also include a central station 210, which is communicatively connected to the monitoring station. For details of the specific functions of the central station 210, please refer to the description of the above embodiments, which will not be detailed here.

[0168] Furthermore, in this embodiment of the application, the computing device may be integrated into the monitoring station 200, or integrated into the central station 210, or it may be an independent device independent of the monitoring station 200 and the central station 210.

[0169] Based on the above embodiments, this application also provides a satellite orbit determination method. Figure 8 This is a flowchart of a satellite orbit determination method according to one embodiment of this application, the method being executed by a computing device, such as... Figure 8 As shown, this satellite orbit determination method may include the following steps:

[0170] Step 1110: Based on the obtained coordinate information of the monitoring station and the space distance between the satellite and the monitoring station, determine the coordinate information of the satellite.

[0171] Step 1120: Determine the satellite's orbital parameters based on the satellite's coordinate information.

[0172] In step 1110, the space distance between the satellite and the monitoring station can be determined according to the ionospheric delay monitoring method provided in the above embodiment. Furthermore, there are multiple monitoring stations, and each monitoring station meets the time synchronization requirement. Thus, the computing device can perform orbit determination processing on the satellite based on the corresponding space distance to obtain the satellite orbit parameters.

[0173] In summary, the ionospheric delay monitoring method provided in this application can accurately calculate the total number of ionospheric electrons and the satellite-to-ground spatial distance when using relay ranging values, exhibiting complete autonomous controllability. The monitoring station can send uplink signals to the satellite at any time and calculate the real-time total number of ionospheric electrons and the satellite-to-ground spatial distance based on the above method, offering advantages such as strong real-time performance and accurate monitoring results. Furthermore, the method in this application uses a satellite-borne transponder instead of a satellite-borne pseudorange signal broadcasting device, simplifying the satellite structure, reducing the overall system hardware and operating costs, and improving system reliability. In addition, in this application embodiment, the monitoring station can use a directional antenna, further overcoming multipath effect errors.

[0174] Furthermore, the monitoring station can further calculate the tropospheric delay using the tropospheric delay model, thereby obtaining the satellite-to-ground spatial distance. With multiple monitoring stations having known coordinates and meeting the time synchronization requirements between them, the computing equipment can perform orbit determination processing on the satellite based on the monitoring station coordinate information and the corresponding satellite-to-ground spatial distance to obtain the satellite's orbital parameters.

[0175] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An ionospheric time delay monitoring system, characterized in that, This includes satellites and monitoring stations with communication connections; The satellite forwards at least two downlink signals to the monitoring station based on at least one received uplink signal, wherein the at least one uplink signal and the at least two downlink signals constitute at least two forwarded ranging signals; The monitoring station is used to: broadcast at least one uplink signal to the satellite, and acquire at least two downlink signals that the satellite forwards based on the at least one uplink signal; The forwarding ranging signals are measured synchronously to obtain x forwarding ranging values, and y forwarding ranging values ​​are selected from the x forwarding ranging values; or, y forwarding ranging signals are selected from the x forwarding ranging signals and measured synchronously to obtain y forwarding ranging values; where x is a positive integer greater than or equal to 2, and 2≤y≤x; Each of the aforementioned forwarding ranging values ​​is represented by a forwarding ranging expression; Divide the y forwarding ranging values ​​into two groups, one group including m forwarding ranging values ​​and the other group including h forwarding ranging values, where 2≤y≤x, m+h=y, m and h are both greater than or equal to 1, and y, m and h are all positive integers. The average value of the two sets of forwarding ranging values ​​represented by each forwarding ranging expression is calculated to obtain the first corrected average forwarding ranging value and the second corrected average forwarding ranging value. The forwarding ranging difference is determined using the first corrected average forwarding ranging value and the second corrected average forwarding ranging value; The total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station is determined based on the relay ranging difference. The ionospheric delay of each signal in the corresponding forwarding ranging signal is determined based on the total number of electrons in the ionosphere, the preset ionospheric delay coefficient, and the carrier frequency of each signal in at least one forwarding ranging signal. The sum of the satellite-to-ground spatial distance and tropospheric delay between the satellite and the monitoring station is determined using at least one of the forwarding ranging values ​​characterized by the forwarding ranging expression; The tropospheric delay on the ranging signal path between the satellite and the monitoring station was determined based on the tropospheric delay model. The satellite-to-ground spatial distance between the satellite and the monitoring station is determined based on the tropospheric delay of the corresponding signal and the sum of the satellite-to-ground spatial distance and the tropospheric delay.

2. The ionospheric time delay monitoring system according to claim 1, characterized in that, The forwarded ranging signal is a spread spectrum signal, and spread spectrum technology, carrier frequency reuse, and code division multiple access technology are used for corresponding processing in signal transmission, forwarding, and reception.

3. The ionospheric time delay monitoring system according to claim 1, characterized in that, In each of the uplink signals and each of the downlink signals, the carrier frequency of at least a portion of the uplink signals and / or the carrier frequency of at least a portion of the downlink signals are frequency-hopping according to a preset frequency-hopping pattern on the time axis.

4. The ionospheric time delay monitoring system according to claim 1, characterized in that, The satellite includes satellite time and frequency equipment and a transponder, and the monitoring station includes monitoring time and frequency equipment, transponder ranging equipment, and processing equipment; The satellite time and frequency equipment is used to provide time and frequency signals to the transponder; The repeater is used to receive the uplink signal, and after performing frequency conversion and power amplification on the uplink signal, it forwards the downlink signal to the monitoring station. The monitoring time-frequency device is used to provide time-frequency signals to the forwarding ranging device and / or the processing device; The forwarding ranging device is used to generate and broadcast the uplink signal, receive the downlink signal, and simultaneously measure at least two forwarding ranging signals to obtain at least two forwarding ranging values. The processing device is communicatively connected to the relay ranging device. The processing device is used to acquire at least two relay ranging values ​​and determine the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station and the space distance between the satellite and the monitoring station based on each relay ranging value. The satellite time and frequency equipment and transponder are either integrated or separate. The monitoring time-frequency device, the forwarding ranging device, and the processing device are either integrated or separate.

5. The ionospheric time delay monitoring system according to claim 4, characterized in that, The repeater has a forwarding delay, and the forwarding ranging device of the monitoring station has a transmission delay and a reception delay; The forwarding delay is transmitted through an additional communication link, or the processing device has the forwarding delay, the transmission delay of the forwarding ranging device, and the reception delay preset therein.

6. The ionospheric time delay monitoring system according to claim 4, characterized in that, The monitoring station includes one or more of the aforementioned forwarding ranging devices, and when there are multiple forwarding ranging devices, the multiple forwarding ranging devices are set to zero baseline.

7. The ionospheric time delay monitoring system according to claim 6, characterized in that, The multiple relay ranging devices use at least one time-frequency system.

8. The ionospheric time delay monitoring system according to claim 6, characterized in that, The monitoring station synchronously measures the forwarding ranging signal at preset time intervals to obtain the forwarding ranging value.

9. The ionospheric time delay monitoring system according to claim 1, characterized in that, The system also includes: The central station is communicatively connected to the monitoring station, and the central station obtains the monitoring parameters of the monitoring station based on the communication results with the monitoring station.

10. The ionospheric time delay monitoring system according to claim 9, characterized in that, The central station is directly connected to the monitoring station; or, the central station is connected to the monitoring station via the satellite. When the central station communicates with the monitoring station via the satellite, there is a main power supply link between the central station and the satellite, and a slave power supply link between the monitoring station and the satellite; The main power supply link includes a main power supply link uplink signal and a main power supply link downlink signal, and the slave power supply link includes a slave power supply link uplink signal and a slave power supply link downlink signal. The main power supply link uplink signal and the slave power supply link downlink signal constitute a forward communication link, and the slave power supply link uplink signal and the main power supply link downlink signal constitute a reverse communication link. The monitoring station and the central station are connected via satellite communication through the forward communication link and the return communication link, or the monitoring station and the central station are directly connected via communication.

11. A satellite orbit determination system, characterized in that, include: The ionospheric time delay monitoring system according to any one of claims 1-10, wherein the number of monitoring stations is greater than or equal to 3; Each of the monitoring stations is connected to the satellite in communication. Each monitoring station determines the space distance between itself and the satellite based on the total number of ionospheric electrons on the ranging signal path between itself and the satellite and at least one relay ranging value. A computing device, communicatively connected to the monitoring station, is used to determine the orbital parameters of the satellite based on the space distance between each monitoring station and the satellite and the coordinate information of each monitoring station.

12. The satellite orbit determination system according to claim 11, characterized in that, The computing device is integrated into the monitoring station; Alternatively, the satellite orbit determination system may further include a central station, which is communicatively connected to the monitoring station, and the computing device is integrated into the central station.

13. A method for monitoring ionospheric time delay, characterized in that, Applied to the ionospheric time delay monitoring system according to any one of claims 1-10, the method is performed by a monitoring station, and the method includes: Broadcast at least one uplink signal to the satellite; The satellite acquires at least two downlink signals that it forwards based on the at least one uplink signal; wherein the at least one uplink signal and the at least two downlink signals constitute at least two forwarding ranging signals. The forwarding ranging signals are measured synchronously to obtain x forwarding ranging values, and y forwarding ranging values ​​are selected from the x forwarding ranging values; or, y forwarding ranging signals are selected from the x forwarding ranging signals and measured synchronously to obtain y forwarding ranging values; where x is a positive integer greater than or equal to 2, and 2≤y≤x; Each of the aforementioned forwarding ranging values ​​is represented by a forwarding ranging expression; Divide the y forwarding ranging values ​​into two groups, one group including m forwarding ranging values ​​and the other group including h forwarding ranging values, where 2≤y≤x, m+h=y, m and h are both greater than or equal to 1, and y, m and h are all positive integers. The average value of the two sets of forwarding ranging values ​​represented by each forwarding ranging expression is calculated to obtain the first corrected average forwarding ranging value and the second corrected average forwarding ranging value. The forwarding ranging difference is determined using the first corrected average forwarding ranging value and the second corrected average forwarding ranging value; The total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station is determined based on the relay ranging difference. The ionospheric delay of each signal in the corresponding forwarding ranging signal is determined based on the total number of electrons in the ionosphere, the preset ionospheric delay coefficient, and the carrier frequency of each signal in at least one forwarding ranging signal. The sum of the satellite-to-ground spatial distance and tropospheric delay between the satellite and the monitoring station is determined using at least one of the forwarding ranging values ​​characterized by the forwarding ranging expression; The tropospheric delay on the ranging signal path between the satellite and the monitoring station was determined based on the tropospheric delay model. The satellite-to-ground spatial distance between the satellite and the monitoring station is determined based on the tropospheric delay of the corresponding signal and the sum of the satellite-to-ground spatial distance and the tropospheric delay.

14. The ionospheric time delay monitoring method according to claim 13, characterized in that, The method of representing each forwarding ranging value using a forwarding ranging expression includes: The forwarding ranging value with number i is represented by the forwarding ranging expression shown in the following formula (1): （1）； Where i = 1, 2, ..., y, and i is a positive integer; In the formula: Represents the forwarding ranging value with ID i at time n, in meters; This represents the actual spatial distance traversed by the uplink signal numbered i at time n, i.e., the satellite-to-ground spatial distance, in meters; This represents the actual spatial distance traveled by the downlink signal numbered i at time n, i.e., the satellite-to-ground spatial distance, in meters; Represents the ionospheric delay of the uplink signal numbered i at time n, in meters; Represents the ionospheric delay of the downlink signal numbered i at time n, in meters; The tropospheric delay of the uplink signal numbered i at time n is represented in meters. The tropospheric delay of the downlink signal numbered i at time n is represented in meters. The hardware device delay for forwarding the ranging signal numbered i at time n is expressed in meters. The hardware device delay includes the transmission delay of the monitoring station for the uplink signal numbered i, the forwarding delay of the satellite when forwarding the downlink signal numbered i, and the reception delay of the monitoring station when receiving the downlink signal numbered i.

15. The ionospheric time delay monitoring method according to claim 13, characterized in that, The determination of the total number of ionospheric electrons along the ranging signal path between the satellite and the monitoring station based on the relay ranging difference includes: Based on the carrier frequency of each signal in the relay ranging signal and the preset ionospheric delay coefficient, as well as the relay ranging difference, the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station is determined by the following formula (6): （6）； In the formula: m represents the number of forwarding ranging values ​​in the first group; k represents the number of forwarding ranging values ​​in the first group; h represents the number of forwarding ranging values ​​in the second group; j represents the number of forwarding ranging values ​​in the second group; y represents the total number of forwarding ranging values ​​selected. This represents the difference in forwarding distances, in meters. Indicates the ionospheric time delay coefficient; The total number of ionospheric electrons along the ranging signal path between the satellite and the monitoring station at time n, in electrons per square meter; The carrier frequency of the uplink signal numbered k at time n is represented in Hertz. The carrier frequency of the downlink signal numbered k at time n is represented in Hertz. The carrier frequency of the uplink signal numbered j at time n is represented in Hertz. This represents the carrier frequency of the downlink signal numbered j at time n, in Hertz (Hz).

16. The ionospheric time delay monitoring method according to claim 15, characterized in that, The step of averaging the two sets of forwarding ranging values ​​represented by each forwarding ranging expression to obtain the first corrected average forwarding ranging value and the second corrected average forwarding ranging value includes: The average of the m forwarding ranging values ​​in the first group is calculated to obtain the first corrected average forwarding ranging value as shown in formula (2): （2）； Where k is a positive integer from 1 to m; The average of the h forwarding ranging values ​​in the second group is calculated to obtain the second corrected average forwarding ranging value as shown in formula (3): （3）； Where j is a positive integer from m+1 to y; The step of determining the forwarding ranging difference using the first corrected average forwarding ranging value and the second corrected average forwarding ranging value includes: The first corrected average forwarding ranging value and the second corrected average forwarding ranging value are mathematically calculated to obtain the forwarding ranging difference shown in the following formula (5): （5）； In the formula: m represents the number of forwarding ranging values ​​in the first group; k represents the number of forwarding ranging values ​​in the first group; h represents the number of forwarding ranging values ​​in the second group; j represents the number of forwarding ranging values ​​in the second group; y represents the total number of forwarding ranging values ​​selected. This represents the difference in forwarding distances, in meters. This represents the first corrected average forwarding distance, in meters. This represents the second corrected average forwarding distance, in meters. , Represents the forwarding ranging values ​​of numbers k and j at time n, in meters; , This represents the actual spatial distance traversed by the uplink signals numbered k and j at time n, i.e., the satellite-to-ground spatial distance, in meters; , This represents the actual spatial distance traversed by downlink signals numbered k and j at time n, i.e., the satellite-to-ground spatial distance, in meters. , Represents the ionospheric delay of the uplink signals numbered k and j at time n, in meters; , Represents the ionospheric delay of downlink signals numbered k and j at time n, in meters; , The tropospheric delay of the uplink signals numbered k and j at time n is represented in meters. , The tropospheric delay of downlink signals numbered k and j at time n is expressed in meters. , The hardware device delay for forwarding ranging signals numbered k and j at time n is expressed in meters. The hardware device delay includes the transmission delay of the monitoring station for the uplink signals numbered k and j, the forwarding delay of the satellite when forwarding the downlink signals numbered k and j, and the reception delay of the monitoring station when receiving the downlink signals numbered k and j.

17. The ionospheric time delay monitoring method according to claim 13, characterized in that, After determining the total number of ionospheric electrons along the ranging signal path between the satellite and the monitoring station, the method further includes: Data interaction is conducted with the central station based on the communication link. The central station obtains the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station based on the data interaction results. The communication link includes a forward communication link and a return communication link.

18. The ionospheric time delay monitoring method according to claim 13, characterized in that, At least one forwarding ranging signal includes any forwarding ranging signal numbered i, wherein the forwarding ranging signal numbered i is composed of an uplink signal numbered i and a downlink signal numbered i; the step of determining the ionospheric delay of each signal in the corresponding forwarding ranging signal based on the total number of electrons in the ionosphere, a preset ionospheric delay coefficient, and the carrier frequency of each signal in at least one forwarding ranging signal includes: Based on the total number of ionospheric electrons along the ranging signal path between the satellite and the monitoring station, the ionospheric delay of the uplink signal numbered i is determined using the following formula (8), and the ionospheric delay of the downlink signal numbered i is determined using the following formula (9): （8）； （9）； The determination of the sum of the satellite-to-ground spatial distance and tropospheric delay between the satellite and the monitoring station using at least one of the forwarding ranging values ​​characterized by the forwarding ranging expression includes: Using any relay ranging value numbered i as shown in the following formula (1), the sum of the satellite-to-ground spatial distance and tropospheric delay between the satellite and the monitoring station, as shown in the following formula (10), can be obtained: （1）； （10）； In the formula: Represents the forwarding ranging value with ID i at time n, in meters; This represents the actual spatial distance traversed by the uplink signal numbered i at time n, i.e., the satellite-to-ground spatial distance, in meters; This represents the actual spatial distance traveled by the downlink signal numbered i at time n, i.e., the satellite-to-ground spatial distance, in meters; Represents the ionospheric delay of the uplink signal numbered i at time n, in meters; Represents the ionospheric delay of the downlink signal numbered i at time n, in meters; The tropospheric delay of the uplink signal numbered i at time n is represented in meters. The tropospheric delay of the downlink signal numbered i at time n is represented in meters. The hardware device delay for the forwarding ranging signal numbered i at time n is expressed in meters. The hardware device delay includes the transmission delay of the monitoring station for the uplink signal numbered i, the forwarding delay of the satellite when forwarding the downlink signal numbered i, and the reception delay of the monitoring station when receiving the downlink signal numbered i. Represents the ionospheric time delay coefficient. The total number of ionospheric electrons along the ranging signal path between the satellite and the monitoring station at time n, in electrons per square meter; The carrier frequency of the uplink signal numbered i at time n is represented in Hertz. This represents the carrier frequency of the downlink signal numbered i at time n, in Hertz (Hz).

19. The ionospheric time delay monitoring method according to claim 13, characterized in that, The determination of the sum of the satellite-to-ground spatial distance and tropospheric delay between the satellite and the monitoring station using at least one of the forwarding ranging values ​​characterized by the forwarding ranging expression includes: Multiple forwarding ranging values, characterized by multiple forwarding ranging expressions, are used to determine the sum of multiple satellite-to-ground spatial distances and tropospheric delays; The sum of the multiple satellite-to-ground spatial distances and tropospheric delays is averaged, and the average result is determined as the sum of the satellite-to-ground spatial distance and convective delay between the satellite and the monitoring station.

20. A satellite orbit determination method, characterized in that, Applied to the satellite orbit determination system of claim 11 or 12, the method is executed by a computing device, and the method includes: Based on the obtained coordinate information of the monitoring station and the space distance between the satellite and the monitoring station, the coordinate information of the satellite is determined. The space distance between the satellite and the monitoring station is determined according to any one of claims 13-19 of the ionospheric time delay monitoring method. There are multiple monitoring stations, and each monitoring station meets the time synchronization requirement. The orbital parameters of the satellite are determined based on the satellite's coordinate information.

Images