Ionized layer time delay monitoring and orbit determination system and related method

Abstract

The invention discloses an ionosphere time delay monitoring and orbit determination system and a related method, and belongs to the technical field of ionosphere time delay monitoring. The ionosphere time delay monitoring and orbit determination system comprises a satellite and a monitoring station which are 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 at least one received uplink signal, and two forwarding ranging values are obtained through synchronous measurement; and determining the total electron number of the ionized layer on the ranging signal path between the satellite and the monitoring station and the satellite-ground space distance between the satellite and the monitoring station based on the two forwarding ranging values. The ionosphere time delay monitoring method provided by the invention has the advantages of high real-time performance, accurate monitoring result and the like.

Description

[0001] Cross-references

[0002] This disclosure claims application number 202410661194.3 filed on May 27, 2024 and entitled "A Kind of Ionization The priority of the Chinese patent application entitled "Layer delay monitoring, orbit determination system and related methods", the entire content of the Chinese patent application Incorporated herein by reference in its entirety. Technical Field

[0003] The present application relates to the technical field of ionospheric time delay monitoring, and in particular to an ionospheric time delay monitoring, orbit determination system and related methods. Background Art

[0004] Ionospheric delay is a major positioning error term in satellite navigation and positioning, and also has an important impact in satellite communications and satellite remote sensing. In the current field of ionospheric delay monitoring, multi-frequency ranging signals broadcast by navigation satellites are commonly used, from which two different ranging signals are selected for pseudo-range measurement, and then the dual-frequency method is used to calculate the ionospheric TEC value (ionospheric total electron count).

[0005] In related technologies, when a satellite and a ground station communicate by radio, the radio signal will generate delays when passing through the atmosphere, including ionospheric delays and tropospheric delays. When the signal carrier frequency is less than 30GHz, the delay of the troposphere to the radio signal is considered equal; while the delay of the ionosphere to the radio signal is inversely proportional to the square of the carrier frequency and proportional to the total number of ionospheric electrons on the path. The mathematical expression of the delay generated by the radio signal passing through the ionosphere can be:

[0006]

[0007] Where: dI is the time delay of the RF signal (i.e., radio signal) when it passes through the ionosphere path of the satellite-to-ground line (unit: meter); f is the carrier frequency of the radio signal (unit: Hertz); TEC is the total number of ionosphere electrons on the path between the satellite and the ground station (unit: electrons / square meter);

[0008] The International GPS service (IGS) organization uses a large number of ground stations to observe dual-frequency pseudoranges, calculate the TEC values ​​of different ionospheric piercing points, and form data covering the global ionosphere for use by a wide range of users.

[0009] At present, some communication satellites and remote sensing satellites use two methods to correct the ionospheric delay between satellites and specific ground stations: one is to obtain TEC values ​​directly from third-party organizations such as IGS for correction; the other is to increase the payload, and the satellite can broadcast dual-frequency or even multi-frequency pseudo-range signals. The earth station receives this dual-frequency signal and then obtains the TEC value according to the ionospheric calculation method. It can be seen that there are two main methods for obtaining satellite-ground ionospheric delay: obtaining from third-party organizations represented by IGS; and obtaining real-time ionospheric delay directly by dual frequency.

[0010] When using the ionospheric data provided by IGS, users need to download the ionospheric delay of the corresponding time period from the IGS website, which may cause time lag or even the risk of not being able to obtain it. When using the dual-frequency method to obtain the ionospheric delay, the satellite needs to increase the payload of broadcasting multi-frequency ranging signals, which increases the complexity of the satellite payload and the cost of satellite development.

[0011] The above contents are only used to assist in understanding the technical solution of the present application and do not constitute an admission that the above contents are prior art. Summary of the invention

[0012] The present application combines the characteristics of satellite transponders with the multi-access characteristics of spread spectrum signals, and utilizes the characteristics of satellite transponders that one signal can be forwarded into at least two signals, and the characteristics that at least two spread spectrum signals can be carrier frequency multiplexed, and creatively proposes a system and method for using the forwarded ranging signal to measure the total number of ionospheric electrons. The main purpose of the present application is to provide an ionospheric delay monitoring, orbit determination system and related methods, aiming to solve the problems of poor real-time performance, high cost and time lag of ionospheric delay monitoring in the prior art.

[0013] To achieve the above-mentioned purpose, the present application provides an ionospheric delay monitoring system, comprising a satellite and a monitoring station in communication connection; 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 synchronously measure at least two of the forwarding ranging signals to obtain at least two forwarding ranging values.

[0014] In addition, to achieve the above-mentioned purpose, the present application also provides a satellite orbit determination system, including: the ionospheric delay monitoring system described in any embodiment of the present application, and the number of monitoring stations is greater than or equal to 3; wherein each of the monitoring stations is respectively connected to the satellite in communication, and each of the monitoring stations determines the satellite-to-earth 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 forwarded ranging value; a computing device is connected to the monitoring station in communication, and the computing device is used to determine the orbital parameters of the satellite based on the satellite-to-earth space distance between each of the monitoring stations and the satellite and the coordinate information of each of the monitoring stations.

[0015] In addition, to achieve the above-mentioned purpose, the present application also provides an ionospheric delay monitoring method, which is applied to the ionospheric delay monitoring system described in any embodiment of the present application, and the method is executed by a monitoring station, and the method includes: broadcasting at least one uplink signal to a satellite; obtaining at least two downlink signals forwarded 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 forwarding ranging signals; synchronously measuring each of the forwarding ranging signals to obtain x forwarding ranging values, and selecting y forwarding ranging values ​​from the x forwarding ranging values; or selecting y from the x forwarding ranging signals for synchronous measurement to obtain y forwarding ranging values. Ranging value; wherein x is a positive integer greater than or equal to 2, 2≤y≤x; each of the forward ranging values ​​is represented by a forward ranging expression; y forward ranging values ​​are divided into two groups, one group includes m forward ranging values, and the other group includes h forward ranging values, wherein 2≤y≤x, m+h=y, y, m, h are all positive integers; the two groups of forward ranging values ​​represented by each forward ranging expression are respectively averaged to obtain a first corrected average forward ranging value and a second corrected average forward ranging value; based on the first corrected average forward ranging value and the second corrected average forward ranging value, the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station is determined.

[0016] In addition, to achieve the above-mentioned purpose, the present application also provides a satellite orbit determination method, which is applied to the satellite orbit determination system described in any embodiment of the present application, and the method is executed by a computing device, and the method includes: determining the coordinate information of the satellite based on the acquired coordinate information of the monitoring station and the satellite-to-ground space distance between the satellite and the monitoring station, wherein the satellite-to-ground space distance between the satellite and the monitoring station is determined according to the ionospheric delay monitoring method described in any embodiment of the present application; there are multiple monitoring stations, and each of the monitoring stations meets the time synchronization requirements; and determining the orbital parameters of the satellite based on the coordinate information of the satellite.

[0017] The ionospheric delay monitoring method provided by the present application is that the monitoring station broadcasts two uplink signals to the satellite, and the satellite forwards two downlink signals to the monitoring station respectively for the two uplink signals, so that the monitoring station can measure the first forwarding ranging signal to obtain the first forwarding ranging value, and measure the second forwarding ranging signal to obtain the second forwarding ranging value; the monitoring station further characterizes the first forwarding ranging value by the first forwarding ranging expression, and characterizes the second forwarding ranging value by the second forwarding ranging expression, so that the two forwarding ranging values ​​represented by the two forwarding ranging expressions can calculate the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station, and further, the ionospheric delays of the two uplink signals and the ionospheric delays of the two downlink signals can be calculated respectively according to the total number of ionospheric electrons on the ranging signal path, and after obtaining the above-mentioned ionospheric delay, the monitoring station can further use the two forwarding ranging values ​​to calculate the satellite-to-ground space distance between the satellite and the monitoring station.

[0018] It can be seen that the ionospheric delay monitoring method provided in the embodiment of the present application only needs to forward the ranging value to accurately calculate the total number of ionospheric electrons and the satellite-to-earth space distance, and is fully autonomous and controllable. The monitoring station can send an uplink signal to the satellite at any time and calculate the real-time total number of ionospheric electrons and the satellite-to-earth space distance based on the above method. It has the advantages of strong real-time performance and accurate monitoring results. In addition, based on the method of the embodiment of the present application, a satellite-borne transponder is used to replace the satellite-borne pseudo-range signal broadcasting equipment, which can simplify the structure of the satellite and reduce the hardware cost and use cost of the entire system. In the embodiment of the present application, the monitoring station can use a directional antenna to further overcome the multipath effect error. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 One of the structural schematic diagrams of the ionospheric delay monitoring system according to the implementation mode of the present application;

[0020] Figure 2 This is a second structural diagram of the ionospheric delay monitoring system according to an implementation mode of the present application;

[0021] Figure 3 The third structural diagram of the ionospheric delay monitoring system according to the implementation mode of the present application;

[0022] Figure 4 is a structural block diagram of a satellite and a monitoring station according to an implementation mode of the present application;

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

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

[0025] Figure 7 It is a flow chart of an ionospheric delay monitoring method according to an embodiment of the present application;

[0026] Figure 8 The present invention is a flowchart of a satellite orbit determination method according to one embodiment of the present application.

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

[0028] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

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

[0030] First, various parameters involved in the embodiments of the present application are described as follows:

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

[0032] dL(n) represents the forwarding ranging difference, unit: meter; L 1,mean (n) represents the first corrected average forwarding ranging value, unit: meter; L 2,mean (n) represents the second corrected average forwarding ranging value, unit: meter; L zi (n) represents the forwarding ranging value of the number i at the nth time, in meters; R true,ziu (n) represents the real space distance that the uplink signal numbered i has traveled at the nth moment, i.e., the satellite-to-ground space distance, in meters; R true,zid(n) represents the real space distance, i.e., the satellite-to-ground space distance, traversed by the downlink signal numbered i at the nth moment, in meters; Iziu(n) represents the ionospheric delay of the uplink signal numbered i at the nth moment, in meters; I zid (n) represents the ionospheric delay of the downlink signal numbered i at the nth time, in meters; T duiliu,ziu (n) represents the tropospheric delay of the uplink signal numbered i at the nth time, in meters; T duiliu,zid (n) represents the tropospheric delay of the downlink signal numbered i at the nth time, in meters; Y i (n) represents the hardware device delay of the forwarding ranging signal numbered i at the nth moment, in meters, wherein 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] L zk (n), L zj (n) represents the forwarding ranging value of k and j at the nth moment, in meters; R true,zku (n), R true,zju (n) represents the real space distance that the uplink signal numbered k or j has traveled at the nth moment, i.e., the satellite-to-ground space distance, in meters; R true,zkd (n), R true,zjd (n) represents the real space distance that the downlink signal numbered k, j has traveled at the nth moment, i.e., the satellite-to-ground space distance, in meters; I zku (n), I zju (n) represents the ionospheric delay of the uplink signal numbered k, j at the nth moment, in meters; I zkd (n), I zjd (n) represents the ionospheric delay of the downlink signal numbered k, j at the nth time, in meters; T duiliu,zku (n), T duiliu,zju (n) represents the tropospheric delay of the uplink signal numbered k, j at the nth time, in meters; T duiliu,zkd (n), T duiliu,zjd (n) represents the tropospheric delay of the downlink signal numbered k, j at the nth moment, in meters; Y k (n), Y j (n) represents the hardware device delay of the forwarding ranging signal numbered k and j at the nth moment, in meters. The hardware device delay includes the transmission delay of the monitoring station for the uplink signal numbered k and j, the forwarding delay of the satellite when forwarding the downlink signal numbered k and j, and the reception delay of the monitoring station when receiving the downlink signal numbered k and j;

[0034] Q ion represents the ionospheric delay coefficient, TEC(n) represents the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station at the nth moment, unit: electron / square meter; f zku (n) represents the carrier frequency of the uplink signal numbered k at the nth time, in Hertz; f zkd (n) represents the carrier frequency of the downlink signal numbered k at the nth time, in Hertz; f zju (n) represents the carrier frequency of the uplink signal numbered j at the nth time, in Hertz; f zjd (n) represents the carrier frequency of the downlink signal numbered j at the nth time, in Hertz; f ziu (n) represents the carrier frequency of the uplink signal numbered i at the nth time, in Hertz; f zid (n) represents the carrier frequency of the downlink signal numbered i at the nth moment, in Hertz.

[0035] Special mention: Q ion is the ionospheric delay coefficient, which is published by some international organizations. With the in-depth study of ionospheric delay, the ionospheric delay coefficient is becoming more and more accurate. The ionospheric delay coefficient used to be 40.28, 40.30, and is currently 40.309. There may be more accurate ionospheric delay coefficients in the future. This application does not specifically limit the ionospheric delay coefficient, and takes the latest published value. In this embodiment, Q ion The value is 40.309.

[0036] In addition, it should be noted that in this embodiment, since only two forwarding ranging signals are used for explanation, it can be known that after the two forwarding ranging values ​​are divided into two groups, each group includes a forwarding ranging value, and then the forwarding ranging values ​​of each group are averaged to obtain a first corrected average forwarding ranging value and a second corrected average forwarding ranging value.

[0037] In order to explain the method provided by the present application more clearly and generally, the present application uses two forwarding ranging signals, and the carrier frequencies of all signals are different from each other. Two forwarding ranging values ​​are selected for calculation as an exemplary explanation. At this time, x=2, y=2, m=1, h=1, x=m+h, such as Figure 1 As shown, two forwarding ranging values ​​are obtained by synchronous measurement, so as to illustrate the specific implementation of the method of the present application.

[0038] The ionospheric delay monitoring system and related methods provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0039] Figure 1 This is one of the structural schematic diagrams of the ionospheric delay monitoring system according to the implementation mode of the present application, such as Figure 1 As shown, the system includes a satellite 100 and a monitoring station 200 which are in communication connection. The ionospheric delay monitoring system provided in this embodiment is described in detail below.

[0040] The satellite 100 forwards the first downlink signal to the monitoring station 200 based on the received first uplink signal, and forwards the second downlink signal to the monitoring station 200 based on the received second uplink signal, wherein 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 synchronously measure the first forwarding ranging signal and the second forwarding ranging signal to obtain a first forwarding ranging value and a second forwarding ranging value, as well as a total number of ionospheric electrons on the ranging signal path between the satellite 100 and the monitoring station 200 and a satellite-to-earth space distance between the satellite 100 and the monitoring station 200 determined based on the first forwarding ranging value and the second forwarding ranging value.

[0042] The ionospheric delay monitoring system provided in the embodiment of the present application can be applied to aerospace systems, for example, satellite navigation, satellite communication, satellite remote sensing, satellite reconnaissance, and meteorological satellites. The embodiment of the present application only takes the monitoring station to determine the total number of ionospheric electrons and the satellite-to-ground space distance on the ranging signal path as an example for exemplary description.

[0043] Specifically, this embodiment provides a variety of signal transmission methods between the satellite 100 and the monitoring station 200. The first method is as follows: Figure 1 As shown in FIG. 1 , the monitoring station 200 broadcasts two uplink signals to the satellite 100, and the satellite 100 forwards two downlink signals to the monitoring station 200. Figure 2 As shown in FIG. 1 , the monitoring station 200 broadcasts an uplink signal to the satellite 100, and the satellite 100 forwards it as two downlink signals with different carrier frequencies. Figure 3 As shown, the carrier frequencies of the two uplink signals broadcast by the monitoring station 200 to the satellite 100 are different, and the satellite uses carrier frequency multiplexing technology to forward them into two downlink signals with the same carrier frequency.

[0044] like Figures 1 to 3 As shown, because either Figure 1 , Figure 2 , Figure 3 According to the signal transmission mode shown in FIG. 1 , the ionospheric delay monitoring system has two forwarding ranging signals and two corresponding forwarding ranging values, so the space distance between the satellite 100 and the monitoring station 200 and the total number of ionospheric electrons on the ranging signal path can be determined. Figure 1The ionospheric delay monitoring system of the present application is illustrated by taking the example that the monitoring station 200 broadcasts two uplink signals to the satellite and the satellite 100 forwards two downlink signals to the monitoring station.

[0045] In this embodiment, the satellite 100 forwards the two received uplink signals into two downlink signals to the monitoring station 200, so that the monitoring station 200 can determine the total number of ionospheric electrons and the satellite-to-ground space distance on the ranging signal path between the satellite 100 and the monitoring station 200 based on the two forwarded ranging signals. In this exemplary embodiment, since the satellite 100 does not need to broadcast a pseudo-range ranging signal, there is no need to set up a device for sending a pseudo-range ranging signal in the satellite 100, so that the structure of the satellite 100 is simplified and the equipment cost of the satellite 100 is reduced. The monitoring system provided in the embodiment of the present application can obtain the total number of ionospheric electrons and the satellite-to-ground space distance in real time, and realizes full autonomous control without being restricted by 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, that is, based on the local time; after acquiring the first uplink signal and the second uplink signal, the satellite 100 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; further, the satellite 100 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 a first forwarding ranging signal, and the second uplink signal and the second downlink signal constitute a second forwarding ranging signal. The monitoring station 200 measures the first forwarding ranging signal to obtain a first forwarding ranging value, and measures the second forwarding ranging signal to obtain a second forwarding ranging value.

[0048] After obtaining the first forwarding ranging value and the second forwarding ranging value, the monitoring station 200 uses the first forwarding ranging expression to represent the first forwarding ranging value, and uses the second forwarding ranging expression to represent the second forwarding ranging expression. Then, the total number of ionospheric electrons on the ranging signal path between the monitoring station 200 and the satellite 100 and the satellite-to-earth space distance between the monitoring station 200 and the satellite 100 can be obtained by mathematical calculation through the two forwarding ranging expressions.

[0049] In addition, it is worth noting that the monitoring station 200 in the embodiment of the present application may be one or more. When there are multiple monitoring stations 200, the multiple monitoring stations 200 can each determine the total number of ionospheric electrons on the ranging signal path between themselves and the satellite 100 and the satellite-to-earth space distance between each of them and the 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 according to a preset frequency-hopping pattern on the time axis.

[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 do not use the same fixed frequency, but signals of different frequencies are used at different times. Therefore, frequency hopping of the signal can improve the signal's anti-interference ability and enhance the signal's 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 may also remain unchanged for a long time, that is, the time interval between two frequency hoppings is infinite.

[0053] In addition, it should be noted that the first forwarding ranging signal and the second forwarding ranging signal described in the embodiment of the present application refer to the modulated signals obtained after modulating the ranging code signal in the carrier signal. In some specific embodiments, the ranging code can be selected from pseudo code, weil code, M code, etc., and this application does not specifically limit the specific selection of the ranging code. And it can be understood that the forwarding ranging signal described in the embodiment of the present application is a spread spectrum signal. When multiple spread spectrum signals are sent and received, the relationship between the carrier frequency and the ranging code is processed according to the spread spectrum communication technology and the code division multiple access communication technology, which will not be repeated here.

[0054] The specific process of the monitoring station 200 determining the total number of ionospheric electrons on the ranging signal path between it and the satellite 100 and the satellite-to-earth space distance between it and the satellite 100 can be found in the introduction of the subsequent method embodiments, which will not be expanded here.

[0055] Figure 4 FIG. 1 is a structural block diagram of a satellite and a monitoring station according to an embodiment of the present application. Figure 4 As shown, in some embodiments, the satellite 100 may include a transponder 101 and a satellite time and frequency device 103, wherein the satellite time and frequency device 103 provides a time and frequency signal for the transponder 101, and the transponder 101 may be used to receive a first uplink signal and a second uplink signal, and perform frequency conversion processing and power amplification on the first uplink signal and then forward the first downlink signal to the monitoring station 200, and perform frequency conversion processing and power amplification on the second uplink signal and then forward the second downlink signal to the monitoring station 200.

[0056] Continue to refer 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 one or more forwarding and ranging devices 201 may be set in the monitoring station 200. Taking the setting of two forwarding and ranging devices 201 as an example, the two forwarding and ranging devices 201 in the embodiment of the present application may be set independently, or may be integrated in one hardware device, that is, one hardware device realizes the functions of the two forwarding and ranging devices 201, which all belong to the protection scope of the present application. And it can be understood that, Figure 4 The monitoring station 200 shown includes a forwarding ranging device 201, a processing device 202 and a monitoring time and frequency device 203, which are modules divided by function. Specifically, in terms of hardware implementation, they can be implemented separately or integrated into one device, which all belong to the protection scope of this application.

[0058] In an exemplary embodiment, the forwarding ranging device 201 may include a modulator, a mixer, a demodulator, an antenna, a data collector, etc. The modulator generates an intermediate frequency ranging code spread spectrum signal; the mixer mixes the intermediate frequency ranging code spread spectrum signal into a radio frequency signal, the antenna sends the radio frequency signal to the satellite 100, and receives the radio frequency signal forwarded by the satellite 100, which is mixed into an intermediate frequency signal by the mixer; the demodulator demodulates the received intermediate frequency signal, and obtains the forwarding ranging value through relevant mathematical operations; the data collector records and stores the forwarding 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 in communication connection with the forwarding ranging device 201, and the processing device 202 receives the first forwarding ranging value and the second forwarding ranging value, and determines the total number of ionospheric electrons and the satellite-to-earth space distance based on the first forwarding ranging value and the second forwarding ranging value. The monitoring time-frequency device 203 can provide a time-frequency signal for the forwarding 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 with a zero baseline.

[0062] It is worth noting that in the embodiment of the present application, when the monitoring station 200 includes two forwarding ranging devices 201, the two forwarding ranging devices 201 are set with a zero baseline, so that the first forwarding ranging signal and the second forwarding ranging signal have the same transmission path, that is, the two forwarding ranging signals have the same atmospheric path.

[0063] It is worth pointing out that the zero baseline setting mentioned in this application does not mean that the distance between the two forwarding ranging devices is 0, but that the distance setting between the two forwarding ranging devices must satisfy the requirement that the spatial paths experienced by the uplink signal transmitted and the downlink signal received by each forwarding ranging device are approximately the same. When the distance between the two forwarding ranging devices becomes smaller and smaller and becomes one device, the approximately same gradually becomes the same, with the same satellite-to-ground space distance, the same tropospheric delay, and the same total number of ionospheric electrons. This application can calculate the total number of ionospheric electrons. Of course, when there are multiple forwarding ranging devices, a zero baseline is set between the multiple forwarding ranging devices.

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

[0065] It is worth noting that at least one time-frequency system in the embodiments of the present application may include multiple clocks (crystal oscillators or atomic clocks) or one clock (crystal oscillator or atomic clock). It is generally recommended to use one clock. When the time-frequency system includes multiple clocks (crystal oscillators or atomic clocks), the multiple clocks provide time-frequency signals for multiple forwarding ranging devices 201 respectively. In actual use, the preset time interval can be set to 1s, for example, and the two forwarding ranging devices 201 measure at the rising edge or falling edge of their respective 1PPS (1Pulse PerSecond, second pulse) signals. Preferably, it is generally recommended to use one clock to perform synchronous measurement of the forwarding ranging signal at the rising edge or falling edge of the same 1PPS signal.

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

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

[0068] In addition, the transmission delay of the forwarding and ranging device 201 refers to the delay generated in the process of the forwarding and ranging device 201 sending the first uplink signal and the second uplink signal to the satellite 100. The reception delay of the forwarding and ranging device 201 refers to the delay generated in the process of the forwarding and ranging device 201 receiving the first downlink signal and the second downlink signal sent by the satellite 100.

[0069] In this exemplary embodiment, the monitoring station 200 and the satellite 100 may use an additional communication link to transmit the forwarding delay of the repeater 101. For example, the satellite 100 may be provided with a telemetry unit, and the forwarding delay of the repeater 101 may be transmitted through a telemetry signal broadcast by the telemetry unit; or, the forwarding delay of the repeater 101 may be transmitted to the monitoring station 200 through other user-defined communication link signals. The present application does not specifically limit the specific signal used to transmit the forwarding delay of the repeater 101. Alternatively, because the change in the forwarding delay of the repeater 101 is very small and known, the known forwarding delay of the repeater 101 can be regarded as a certain amount, so that in actual use, the forwarding delay can also be preset in the processing device 202 in the monitoring station 200.

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

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

[0072] like Figure 5 As shown, the ionospheric delay monitoring system may further include a central station 210 , wherein the central station 210 is in communication connection with the monitoring station 200 ; the central station 210 may obtain 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, and the monitoring station 200 and the central station 210 can be directly connected in communication. For example, in a city, the monitoring station 200 and the central station 210 can communicate directly through a 4G network or a 5G network. Of course, the monitoring station 200 can also be connected in communication with the central station 210 through a satellite 100. For example, at sea or in a desert, the central station 210 and the monitoring station 200 both communicate directly through the satellite 100, thereby realizing communication between the monitoring station 200 and the central station 210 through the satellite 100.

[0074] In addition, continue to refer to Figure 5 When the central station 210 and the satellite 100 are connected for communication via the satellite 100, there may be a main feeder link between the central station 210 and the satellite 100, and there may be a slave feeder link between the monitoring station 200 and the satellite 100; wherein the main feeder link includes a main feeder link uplink signal and a main feeder link downlink signal, and the slave feeder link includes a slave feeder link uplink signal and a slave feeder link downlink signal, the main feeder link uplink signal and the slave feeder link downlink signal constitute a forward communication link, and the main feeder link downlink signal and the slave feeder link uplink signal constitute a return communication link.

[0075] Specifically, taking the case where the central station 210 is located on the ground as an example, during the communication process between the central station 210 and the monitoring station 200, the central station 210 broadcasts the main feed link uplink signal fu1 to the satellite 100. After receiving the uplink communication signal fu1, the satellite 100 forwards the signal to obtain the slave feed link downlink signal fd2 and transmits the downlink communication signal fd2 to the monitoring station 200. The monitoring station 200 broadcasts the slave feed link uplink signal fu2 to the satellite 100. After receiving the uplink communication signal fu2, the satellite 100 forwards the signal to obtain the main feed link downlink signal fd1 and transmits the downlink communication signal fd1 to the central station 210. The monitoring station 200 and the central station 210 communicate with each other through forwarding by the satellite 100, and the satellite 100 does not need to perform modulation, demodulation and other processing on the signal. In this way, the communication between the monitoring station 200 and the central station 210 is realized through the forwarding communication link, which can simplify the structure of the satellite 100, reduce the complexity of the satellite 100, and further reduce the cost of the satellite 100. Of course, it should be understood that when the central station 210 is integrated into the satellite, Figure 5 The main feed link and the slave feed link in the system are combined into one.

[0076] In this embodiment, the monitoring station 200 can exchange data with the central station 210 based on the communication link, so that the central station 210 can obtain other parameters such as the total number of ionosphere electrons of each monitoring station 200. The central station 210 summarizes the total number of ionosphere electrons of each monitoring station 200, processes it accordingly, and then publishes it, thereby improving positioning and navigation accuracy. For the method for determining the total number of ionosphere electrons, please refer to the introduction of the subsequent method embodiment, which will not be expanded here.

[0077] Further, continue to refer to Figure 5 There is also a forwarding ranging signal link between the monitoring station 200 and the satellite 100, and the forwarding ranging signal link includes two forwarding uplink signals and two forwarding downlink signals; wherein the carrier frequency of the uplink signal from the feeder link can be the same as the carrier frequency of any of the forwarding uplink signals; or different from the carrier frequencies of the two forwarding uplink signals. The carrier frequency of the downlink signal from the feeder link is the same as the carrier frequency of any of the forwarding downlink signals; or different from the carrier frequencies of the two forwarding downlink signals.

[0078] Specifically, when the carrier frequency of the forwarded uplink signal is different from the carrier frequency of the uplink signal from the feeder link, the forwarded uplink signal and the uplink signal from the feeder link use different carrier frequencies. When the carrier frequency of any forwarded uplink signal is the same as the carrier frequency of the uplink signal from the feeder link, it is equivalent to carrier frequency multiplexing the forwarded uplink signal and the uplink signal from the feeder link, and using code division multiple access technology for communication. In this way, frequency resources can be saved and the use and operation costs of the equipment can be reduced. In addition, the carrier frequency of any forwarded downlink signal and the carrier frequency of the downlink signal from the feeder link can be set with reference to the aforementioned relationship between the carrier frequencies of the forwarded uplink signal and the uplink signal from the feeder link, which will not be repeated here.

[0079] The monitoring station 200 in the embodiment of the present application may be a base station, a radar, etc. Figure 6 As shown, the number of monitoring stations 200 in the embodiment of the present application can be one or more. For example, by deploying multiple monitoring stations 200 covering the world, the country, or different cities, each monitoring station 200 can monitor the ionospheric delay within its coverage area, and 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, so that the central station 210 can obtain the ionospheric delay of different locations around the world or the country. When performing navigation or remote sensing monitoring, the corresponding equipment manufacturer or user can obtain the corresponding ionospheric delay according to its own regional location to perform position correction and improve 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 system can be constructed based on the communication system provided in the embodiment of the present application. The specific content of the operating parameters can be determined according to the needs of the user. 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] On the basis of the above embodiments, the embodiments of the present application further provide an ionospheric delay monitoring method. The ionospheric delay monitoring method provided in the embodiments of the present application determines the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station by forwarding ranging signals in two paths. The ionospheric delay monitoring method can be applied to the ionospheric delay monitoring system described in any of the above embodiments, and the 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 by the present application includes y forwarding ranging values ​​involved in the calculation, where y is at least 2 and at most x, and the y forwarding ranging values ​​are divided into two groups, one of which has m forwarding ranging values ​​and the other has h forwarding ranging values, y=m+h. Each group of forwarding ranging values ​​is first averaged to obtain a corrected average forwarding ranging value, and the two corrected average forwarding ranging values ​​are then subtracted to calculate 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, there are two average forwarding ranging values, two forwarding ranging values ​​are selected for calculation, divided into two groups, the first group has only one forwarding ranging value, the corrected average value is itself minus the hardware device delay, the second group also has only one forwarding ranging value, the corrected average value is itself minus the hardware device delay. Then the total number of electrons in the ionosphere is calculated based on the two corrected average forwarding ranging values.

[0084] It should be noted that, because the relay ranging device is set with a zero baseline, the satellite-to-ground space distances of the two relay ranging signals are exactly the same, so there is equation (11):

[0085] R true,z1u (n) = R true,z2u (n) = R true,z1d (n) = R true,z2d (n)(11);

[0086] In addition, because the zero baseline setting of the forwarding ranging equipment is still in place, the atmospheric layers that the forwarding ranging signals pass through are exactly the same, so the tropospheric delays they experience are exactly the same, and the ionospheric delays are different due to different carrier frequencies. That is, the tropospheric delays of the two forwarding ranging signals are the same, so there is equation (12):

[0087] Tduiliu,z1u (n) = T duiliu,z2u (n) = T duiliu,z1d (n) = T duiliu,z2d (n)(12);

[0088] When there are x forwarding ranging signals, the uplink and downlink signals of the x forwarding ranging signals experience the same spatial distance and the same tropospheric delay.

[0089] It should also be noted that, in this embodiment, the satellite-to-earth space distance, tropospheric delay, and ionospheric delay are all unknown quantities. When calculating the total number of ionospheric electrons on the ranging signal path, the satellite-to-earth space distance and tropospheric delay are eliminated due to the zero baseline setting; after the total number of ionospheric electrons is calculated, the satellite-to-earth space distance can be calculated in reverse based on the total number of ionospheric electrons.

[0090] The ionospheric delay monitoring method provided by the present application is described in detail below with reference to the accompanying drawings.

[0091] Figure 7 Flow chart of an ionospheric delay monitoring method according to an embodiment of the present application, as shown in FIG. Figure 7 As shown, the ionospheric delay monitoring method may include the following steps:

[0092] Step 910: broadcast at least one uplink signal to a satellite;

[0093] Step 920: Acquire at least two downlink signals forwarded 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 forwarding ranging signals;

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

[0095] Step 940: using forwarding ranging expressions to represent each of the forwarding ranging values;

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

[0097] Step 960: Calculate the averages of the two groups of forwarding ranging values ​​represented by the forwarding ranging expressions to obtain a first corrected average forwarding ranging value and a 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 forward ranging value and the second corrected average forward ranging value.

[0099] Among them, 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 in the two forwarded ranging signals are different from each other or partially the same.

[0100] For example, the carrier frequency of the first uplink signal and the carrier frequency of the second uplink signal are the same, and the carrier frequency of the first downlink signal and the carrier frequency of the second downlink signal are different from each other.

[0101] Alternatively, the carrier frequency of the first downlink signal and the carrier frequency of the second downlink signal are the same, and the carrier frequency of the first uplink signal and the carrier frequency of the second uplink signal are different from each other.

[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, the monitoring station may, in step 940, use a first forwarding ranging expression to represent the first forwarding ranging value, and use a 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 ranging value and the second forwarding ranging value of the specific embodiment according to the forwarding ranging value numbered i among the y forwarding ranging values ​​shown in formula (1), where i is 1 and 2 respectively.

[0105] L zi (n) = R true,ziu (n)+R true,zid (n)+I ziu (n)+I zid (n)+T duiliu,ziu (n)+T duiliu,zid (n)+Y i (n)(1);

[0106] The monitoring station may use the first forwarding ranging expression shown in the following formula (1-1) to represent the first forwarding ranging value:

[0107] L z1 (n) = R true,z1u (n)+R true,z1d (n)+I z1u (n)+I z1d (n)+Tduiliu,z1u (n)+T duiliu,z1d (n)+Y1(n)(1-1);

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

[0109] L z2 (n) = R true,z2u (n)+R true,z2d (n)+I z2u (n)+I z2d (n)+T duiliu,z2u (n)+T duiliu,z2d (n)+Y2(n)(1-2);

[0110] It is worth noting that in the embodiment of the present application, when the forward ranging expression is used to characterize the forward ranging value, there is no Sagnac effect delay in the forward ranging expression because the Sagnac effect delay of the uplink signal is opposite to the Sagnac effect delay of the downlink signal, and the absolute value difference between the two is very small, so the two Sagnac effect delays can be approximately offset, so that the Sagnac effect delay term is not reflected in the forward ranging expression. Of course, in some other embodiments of the present 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 are added to the forward ranging expression, so as to obtain better ionospheric delay monitoring accuracy, which all belong to the protection scope of the present application.

[0111] In the embodiment of the present application, the forwarding ranging value represented by the two forwarding ranging expressions of the monitoring station can be mathematically calculated in subsequent steps to obtain the total number of ionospheric electrons and the satellite-to-earth 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 steps: using a pseudorange smoothing algorithm to perform pseudorange smoothing correction on the first forwarding ranging value and the second forwarding ranging value, so as to reduce the random error of the forwarding ranging value, which is conducive to improving the accuracy of the final determined total number of ionospheric electrons, thereby improving the accuracy of the ionospheric delay between the satellite and the monitoring station and the satellite-to-ground space distance. The specific content of the pseudorange smoothing algorithm will not be repeated here.

[0113] As described above, the first forwarding ranging signal and the second forwarding ranging signal include the same satellite-to-earth space distance delay and tropospheric delay. Therefore, in subsequent steps, the monitoring station uses the two forwarding ranging values ​​to determine the total number of ionospheric electrons and the satellite-to-earth space distance between the satellite and the monitoring station.

[0114] Step 950 and step 960 are to group the two forwarding ranging values ​​obtained in the previous steps, and respectively calculate the corrected average forwarding ranging value represented by the forwarding ranging expression. For example, when x=2, it is the first forwarding ranging value and the second forwarding ranging value. In this step, all forwarding ranging values ​​are selected, x=y=2, and 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 two-path forwarding ranging signals are used to calculate the total number of electrons in the ionosphere, step 960 may specifically include the following process:

[0116] Step 960: Because the embodiment of the present application takes two forwarding ranging values ​​as an example for explanation, the two forwarding ranging values ​​are divided into two groups, each group having one forwarding ranging value, so the first corrected average forwarding ranging value calculated using formula (2) is as shown in formula (2-1):

[0117]

[0118] At this time, m=1.

[0119] L 1,mean (n) = L z1 (n)-Y1(n)=R true,z1u (n)+R true,z1d (n)+I z1u (n)+I z1d (n)+T duiliu,z1u (n)+T duiliu,z1d (n)(2-1);

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

[0121] At this time, h=1, y=2.

[0122] L 2,mean (n) = L z2 (n)-Y2(n)=R true,z2u (n)+R true,z2d (n)+I z2u (n)+I z2d (n)+T duiliu,z2u (n)+T duiliu,z2d (n) (3-1);

[0123] Step 970 may specifically include the following process:

[0124] Step 971: Determine a forwarding ranging difference using the first corrected average forwarding ranging value and the second corrected average forwarding ranging value.

[0125] Step 972: Determine the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station based on the forwarded ranging difference.

[0126] In an exemplary embodiment, when two-path forwarding ranging signals are used to calculate the total number of ionospheric electrons, step 970 may specifically include the following process:

[0127] Determine a forwarding ranging difference using the first corrected average forwarding ranging value and the second corrected average forwarding ranging value;

[0128] Determine the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station based on the forwarded ranging difference;

[0129] The monitoring station calculates the difference between the first corrected average forwarding ranging value and the second corrected average forwarding ranging value according to the formula for calculating the forwarding ranging difference value in formula (5), and uses the forwarding ranging device zero baseline setting relationship shown in formulas (11) and (12) to obtain the forwarding ranging difference value of this embodiment shown in the following formula (5-1):

[0130]

[0131] dL(n)=L 1,mean (n)-L 2,mean (n) = I z1u (n)+I z1d (n)-(I z2u (n)+I z2d (n)) (5-1);

[0132] Then, the monitoring station can determine the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station as shown in the following formula (6-1) using the forwarding ranging difference shown in the formula (5-1) based on the carrier frequency of each signal in the forwarding ranging signal and the preset ionospheric delay coefficient and the formula (6):

[0133]

[0134] In some embodiments, the value of the ionospheric delay coefficient may be 40.309. In other embodiments, the ionospheric delay coefficient may also be 40.28 or 40.30. In the future, there may be other more precise ionospheric delay coefficients, all of which fall within the scope of protection of this application.

[0135] In this embodiment, when the ionospheric delay monitoring method is applied to the communication system described in the above embodiment, after the monitoring station determines the total number of ionospheric electrons, the monitoring station can exchange data with the central station based on the communication link, so that the central station can obtain the total number of ionospheric electrons of each monitoring station, and the central station can improve satellite positioning, navigation accuracy, etc. by summarizing the total number of ionospheric electrons of each monitoring station and publishing it. Among them, the central station obtains the total number of ionospheric electrons determined by the monitoring station based on the data interaction result, and the communication link includes a forward communication link and a return communication link.

[0136] After obtaining the total number of ionospheric electrons, because the two forwarding signals between the satellite and the monitoring station pass through the same path, the total number of ionospheric electrons 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 are the same. In this way, the monitoring station can further determine the space distance between the satellite and the monitoring station based on the obtained total number of ionospheric electrons.

[0137] In an exemplary embodiment, the monitoring station may specifically include the following steps to calculate the space distance between itself and the satellite:

[0138] Step 9741: Based on the total number of ionosphere electrons, the preset ionosphere delay coefficient and the carrier frequency of each signal in at least any one of the forwarded ranging signals, the ionosphere delay of each signal in the corresponding forwarded ranging signal is determined respectively.

[0139] Step 9742: Determine the sum of the satellite-to-ground space distance and the tropospheric delay between the satellite and the monitoring station using at least one forward ranging value represented by the forward ranging expression.

[0140] Step 9743: Determine the tropospheric delay on the ranging signal path between the satellite and the monitoring station based on the tropospheric delay model.

[0141] Step 9744: Determine the satellite-to-ground 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.

[0142] In this exemplary embodiment, the ionospheric delays of two uplink signals and two downlink signals in the two forwarding ranging signals are obtained by taking two forwarding ranging signals as an example for exemplary description.

[0143]

[0144] Then in step 9741, the monitoring station calculates the ionospheric delay of any forwarded 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), 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) based on the determined total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station:

[0145]

[0146] Then, in step 9742, as described above, because the satellite-to-ground space distances of the two forwarded ranging signals are exactly the same, equation (11) is obtained:

[0147] R true,z1u (n) = R true,z2u (n) = R true,z1d (n) = R true,z2d (n)(11);

[0148] In addition, the signals pass through the same atmospheric layer, so the tropospheric delays they experience are exactly the same, and the ionospheric delays are different due to different carrier frequencies. That is, the tropospheric delays of the two forwarding ranging signals are the same, so there is equation (12):

[0149] T duiliu,z1u (n) = T duiliu,z2u (n) = T duiliu,z1d (n) = T duiliu,z2d (n)(12);

[0150] On this basis, the monitoring station can use the first forwarding ranging value shown in formula (1-1), the second forwarding ranging value shown in formula (1-2), formula (15) to formula (18) and formula (10) to obtain the average value of the sum of the satellite-to-ground space distance and the tropospheric delay between the satellite and the monitoring station as shown in the following formula (20):

[0151]

[0152] In steps 9743 to 9744, the tropospheric delay T between the satellite and the monitoring station can be corrected using the tropospheric delay model. The tropospheric delay calculation requires the help of meteorological parameters. In the absence of real-time meteorological parameters, a simple model related only to the satellite elevation angle can be used for calculation, as shown in formula (T1):

[0153] T=2.47 / (sinθ+0.0121)(T1)

[0154] Where: T is the tropospheric delay, unit: meter; θ is the satellite elevation angle, unit: radian.

[0155] There are relatively many models for calculating tropospheric delay based on meteorological parameters. The differences between them decrease with the satellite elevation angle by about a few millimeters to a few centimeters, which is more accurate than that calculated by this simple model.

[0156] Common models for determining tropospheric delay correction include the Saastamoinen model and the Hopfield model. Studies have shown that when the altitude angle is greater than or equal to 15°, the results obtained by different models are consistent with each other, and the model can be selected arbitrarily. However, when the value of the station elevation is large, the tropospheric delay in the zenith direction calculated by the two models can differ by tens of centimeters. After comparison with the measured meteorological data, it is recommended to use the Saastamoinen model.

[0157] In this way, after obtaining the tropospheric delay, the monitoring station can use the known tropospheric delay to eliminate the tropospheric delay in formula (20) to obtain the satellite-to-ground space distance between the satellite and the monitoring station.

[0158] In some embodiments, after determining the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station, the method further includes: performing data exchange with a central station based on a communication link, wherein the central station obtains the total number of ionospheric electrons and the satellite-to-earth space distance on the ranging signal path between the satellite and the monitoring station based on the data exchange result, and the communication link includes a forward communication link and a return communication link.

[0159] In this embodiment, after the monitoring station determines the total number of electrons in the ionosphere, the monitoring station can exchange data with the central station based on the communication link, so that the central station can obtain the total number of electrons in the ionosphere of each monitoring station. The central station can improve satellite positioning, navigation accuracy, etc. by summarizing the total number of electrons in the ionosphere of each monitoring station and publishing it. The central station obtains the total number of electrons in the ionosphere determined by the monitoring station based on the data interaction result, and the communication link includes a forward communication link and a return communication link.

[0160] On the basis of the above embodiments, the embodiments of the present application also provide a satellite orbit determination system, which may include: a satellite, multiple monitoring stations and a computing device, wherein the multiple monitoring stations are respectively connected to the satellite in communication, the number of the monitoring stations is greater than or equal to 3, and each of the monitoring stations can determine the satellite-to-ground 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 connected to the monitoring station in communication, and the computing device is used to determine the orbital parameters of the satellite according to the satellite-to-ground space distance between the monitoring station and the satellite and the coordinate information of the monitoring station. The specific method for determining the orbital parameters of the satellite by the computing device can be found in the introduction of the subsequent method embodiments, which will not be described in detail here.

[0161] In addition, in an embodiment of the present application, the satellite orbit determination system may further include a central station 210, which is communicatively connected with the monitoring station. For specific functions of the central station 210, reference may be made to the introduction of the above embodiment and will not be described in detail here.

[0162] Furthermore, in the embodiment of the present application, the computing device may be integrated into the monitoring station 200, or integrated into the central station 210, or may be independent of the monitoring station 200 and the central station 210, that is, an independent device.

[0163] Based on the above embodiments, the present application also provides a satellite orbit determination method. Figure 8 is a flowchart of a satellite orbit determination method according to an embodiment of the present application, wherein the method is executed by a computing device, such as Figure 8 As shown, the satellite orbit determination method may include the following steps:

[0164] Step 1110: Determine the coordinate information of the satellite based on the acquired coordinate information of the monitoring station and the satellite-to-ground space distance between the satellite and the monitoring station.

[0165] Step 1120: Determine the orbital parameters of the satellite based on the coordinate information of the satellite.

[0166] In step 1110, the satellite-to-ground space distance between the satellite and the monitoring station can be determined according to the ionospheric delay monitoring method provided in the above embodiment. In addition, there are multiple monitoring stations, and the time synchronization requirements are met between the monitoring stations. In this way, the computing device can perform orbit determination processing on the satellite according to the corresponding satellite-to-ground space distance to obtain satellite orbit parameters.

[0167] In summary, it can be seen that the ionospheric delay monitoring method provided in the embodiment of the present application can accurately calculate the total number of ionospheric electrons and the satellite-to-ground space distance when using the forwarding ranging value, and has the characteristics of being completely autonomous and controllable. The monitoring station can send an uplink signal to the satellite at any time and calculate the real-time total number of ionospheric electrons and the satellite-to-ground space distance based on the above method, which has the advantages of strong real-time performance and accurate monitoring results. In addition, based on the method of the embodiment of the present application, the satellite-borne transponder is used to replace the satellite-borne pseudo-range signal broadcasting equipment, which can simplify the structure of the satellite, reduce the hardware cost and use cost of the entire system, and improve the system reliability. In the embodiment of the present application, the monitoring station can use a directional antenna to further overcome the multipath effect error.

[0168] In addition, the monitoring station can further use the tropospheric delay model to calculate the tropospheric delay, and then obtain the satellite-to-earth space distance. For multiple monitoring stations with known coordinates and time synchronization requirements between the monitoring stations, the computing equipment can perform orbit determination on the satellite based on the monitoring station coordinate information and the corresponding satellite-to-earth space distance to obtain the satellite's orbital parameters.

[0169] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An ionospheric delay monitoring system, characterized in that: Satellites and monitoring stations including communications links; The satellite forwards at least two downlink signals to the monitoring station based on the received at least one 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 of the uplink signals to the satellite, receive at least two of the downlink signals, and synchronously measure at least two of the forwarding ranging signals to obtain at least two forwarding ranging values.

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

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

4. The ionospheric delay monitoring system according to claim 1, characterized in that: The satellite includes satellite time and frequency equipment and a repeater, and the monitoring station includes monitoring station time and frequency equipment, repeater ranging equipment and processing equipment; The satellite time and frequency equipment is used to provide a time and frequency signal to the repeater; The repeater is used to receive the uplink signal, and perform frequency conversion and power amplification on the uplink signal, and then forward the downlink signal to the monitoring station; The monitoring time and frequency device is used to provide a time and frequency signal 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 synchronously measure at least two of the forwarding ranging signals to obtain at least two forwarding ranging values; The processing device is communicatively connected with the forwarding ranging device, and the processing device is used to obtain at least two forwarding ranging values, and determine the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station and the satellite-to-ground space distance between the satellite and the monitoring station based on each of the forwarding ranging values; Wherein, the satellite time and frequency equipment and the repeater are integrated or separately arranged; The monitoring time and frequency device, the forwarding ranging device and the processing device are integrated or separately arranged.

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

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

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

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

9. The ionospheric delay monitoring system according to claim 1, characterized in that: The system further comprises: The central station is connected to the monitoring station for communication. The central station obtains the monitoring parameters of the monitoring station based on the communication result with the monitoring station.

10. The ionospheric delay monitoring system according to claim 9, characterized in that: The central station is directly connected to the monitoring station for communication; or, the central station is connected to the monitoring station for communication via the satellite; When the central station is in communication connection with the monitoring station via the satellite, there is a main feeder link between the central station and the satellite, and there is a slave feeder link between the monitoring station and the satellite; The main feeder link includes a main feeder link up signal and a main feeder link down signal, the slave feeder link includes a slave feeder link up signal and a slave feeder link down signal, the main feeder link up signal and the slave feeder link down signal constitute a forward communication link, and the slave feeder link up signal and the main feeder link down signal constitute a return communication link; The monitoring station and the central station are connected by satellite communication via the forward communication link and the return communication link, or the monitoring station and the central station are directly connected by communication.

11. A satellite orbit determination system, characterized in that: include: The ionospheric delay monitoring system according to any one of claims 1 to 10, wherein the number of monitoring stations is greater than or equal to 3; Each of the monitoring stations is respectively connected to the satellite for communication, and each of the monitoring stations determines the space distance between the satellite 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 forwarded ranging value; A computing device is communicatively connected to the monitoring station, and 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 in the monitoring station; Alternatively, the satellite orbit determination system further includes a central station, and the central station is communicatively connected to the monitoring station, and the computing device is integrated in the central station.

13. A method for monitoring ionospheric delay, characterized in that: Applied to the ionospheric delay monitoring system according to any one of claims 1 to 10, the method is performed by a monitoring station, and the method comprises: broadcasting at least one uplink signal to a satellite; Acquire at least two downlink signals forwarded 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 forwarding ranging signals; Synchronously measuring each of the forwarding ranging signals to obtain x forwarding ranging values, and selecting y forwarding ranging values ​​from the x forwarding ranging values; or, selecting y forwarding ranging values ​​from the x forwarding ranging signals for synchronous measurement to obtain y forwarding ranging values; wherein x is a positive integer greater than or equal to 2, and 2≤y≤x; Using forwarding ranging expressions to represent each of the forwarding ranging values; Divide the y forwarding ranging values ​​into two groups, one group includes m forwarding ranging values, and the other group includes h forwarding ranging values, wherein 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 two groups of forwarding ranging values ​​represented by each forwarding ranging expression are respectively averaged to obtain a first corrected average forwarding ranging value and a 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 first corrected average forward ranging value and the second corrected average forward ranging value.

14. The ionospheric delay monitoring method according to claim 13, characterized in that: The using forwarding ranging expressions to represent each of the forwarding ranging values ​​respectively includes: The forwarding ranging expression shown in the following formula (1) is used to represent the forwarding ranging value numbered i: L zi (n)=R true,ziu (n)+R true,zid (n)+I ziu (n)+I zid (n)+T duiliu,ziu (n)+T duiliu,zid (n)+Y i (n)(1); Wherein, i=1, 2, ..., y, i is a positive integer; Where: L zi (n) represents the forwarding ranging value of the number i at the nth time, in meters; R true,ziu (n) represents the real space distance that the uplink signal numbered i has traveled at the nth moment, i.e., the satellite-to-ground space distance, in meters; R true,zid (n) represents the real space distance that the downlink signal numbered i has traveled at the nth moment, i.e., the satellite-to-ground space distance, in meters; I ziu (n) represents the ionospheric delay of the uplink signal numbered i at the nth time, in meters; I zid (n) represents the ionospheric delay of the downlink signal numbered i at the nth time, in meters; T duiliu,ziu (n) represents the tropospheric delay of the uplink signal numbered i at the nth time, in meters; T duiliu,zid (n) represents the tropospheric delay of the downlink signal numbered i at the nth time, in meters; Y i (n) represents the hardware equipment delay of the forwarding ranging signal numbered i at the nth moment, in meters. The hardware equipment 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 delay monitoring method according to claim 13, characterized in that: The determining, based on the first corrected average forward ranging value and the second corrected average forward ranging value, the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station comprises: Determine a forwarding ranging difference 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 forwarded ranging difference.

16. The ionospheric delay monitoring method according to claim 15, characterized in that: The determining, based on the forwarded ranging difference, the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station comprises: Based on the carrier frequency of each signal in the forwarded ranging signal and the preset ionospheric delay coefficient, as well as the forwarded ranging difference, the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station is determined as shown in the following formula (6): Where: m represents the number of the first group of forwarding ranging values; k represents the number of the first group of forwarding ranging values; h represents the number of the second group of forwarding ranging values; j represents the number of the second group of forwarding ranging values; y represents the total number of selected forwarding ranging values; dL(n) represents the forwarding ranging difference, in meters; Q ion represents the ionospheric delay coefficient; TEC(n) represents the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station at the nth moment, unit: electron / square meter; f zku (n) represents the carrier frequency of the uplink signal numbered k at the nth time, in Hertz; f zkd (n) represents the carrier frequency of the downlink signal numbered k at the nth time, in Hertz; f zju (n) represents the carrier frequency of the uplink signal numbered j at the nth time, in Hertz; f zjd (n) represents the carrier frequency of the downlink signal numbered j at the nth moment, in Hertz.

17. The ionospheric delay monitoring method according to claim 16, characterized in that: The method of respectively calculating the averages of the two groups of forwarding ranging values ​​represented by the forwarding ranging expressions to obtain the first corrected average forwarding ranging value and the second corrected average forwarding ranging value comprises: The m forwarding ranging values ​​of the first group are averaged to obtain the first corrected average forwarding ranging value as shown in formula (2): Wherein, k is a positive integer from 1 to m; The h forwarding ranging values ​​of the second group are averaged to obtain the second corrected average forwarding ranging value as shown in formula (3): Wherein, j is a positive integer from m+1 to y; The determining a forwarding ranging difference by using the first corrected average forwarding ranging value and the second corrected average forwarding ranging value comprises: The first corrected average forwarding ranging value and the second corrected average forwarding ranging value are mathematically calculated to obtain a forwarding ranging difference value as shown in the following formula (5): Where: m represents the number of the first group of forwarding ranging values; k represents the number of the first group of forwarding ranging values; h represents the number of the second group of forwarding ranging values; j represents the number of the second group of forwarding ranging values; y represents the total number of selected forwarding ranging values; dL(n) represents the forwarding ranging difference, in meters; L 1,mean (n) represents the first corrected average forwarding ranging value, unit: meter; L 2,mean (n) represents the second corrected average forwarding ranging value, unit: meter; L zk (n), L zj (n) represents the forwarding ranging value of k and j at the nth moment, in meters; R true,zku (n), R true,zju (n) represents the real space distance that the uplink signal numbered k or j has traveled at the nth moment, i.e., the satellite-to-ground space distance, in meters; R true,zkd (n), R true,zjd (n) represents the real space distance that the downlink signal numbered k, j has traveled at the nth moment, i.e., the satellite-to-ground space distance, in meters; I zku (n), I zju (n) represents the ionospheric delay of the uplink signal numbered k, j at the nth moment, in meters; I zkd (n), I zjd (n) represents the ionospheric delay of the downlink signal numbered k, j at the nth time, in meters; T duiliu,zku (n), T duiliu,zju (n) represents the tropospheric delay of the uplink signal numbered k, j at the nth time, in meters; T duiliu,zkd (n), T duiliu,zjd (n) represents the tropospheric delay of the downlink signal numbered k, j at the nth moment, in meters; Y k (n), Y j (n) represents the hardware equipment delay of the forwarding ranging signal numbered k and j at the nth moment, in meters. The hardware equipment delay includes the transmission delay of the monitoring station for the uplink signal numbered k and j, the forwarding delay of the satellite when forwarding the downlink signal numbered k and j, and the reception delay of the monitoring station for receiving the downlink signal numbered k and j.

18. The ionospheric delay monitoring method according to claim 13, characterized in that: After determining the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station, the method further includes: Data is exchanged with a central station based on a communication link, wherein 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 result, and the communication link includes a forward communication link and a return communication link.

19. The ionospheric delay monitoring method according to claim 15, characterized in that: After determining the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station, the method further includes: Determine the ionospheric delay of each signal in the corresponding forwarding ranging signal based on the total number of ionospheric electrons, a preset ionospheric delay coefficient, and a carrier frequency of each signal in at least one forwarding ranging signal; Determine the sum of the satellite-to-ground space distance and the tropospheric delay between the satellite and the monitoring station by using at least one of the forward ranging values ​​represented by the forward ranging expression; Determine the tropospheric delay on the ranging signal path between the satellite and the monitoring station based on the tropospheric delay model; The satellite-to-earth space distance between the satellite and the monitoring station is determined based on the determined tropospheric time delay of the corresponding signal and the sum of the satellite-to-earth space distance and the tropospheric time delay.

20. The ionospheric delay monitoring method according to claim 19, characterized in that: At least one forward ranging signal includes any forward ranging signal numbered i, and any forward ranging signal numbered i is composed of an uplink signal numbered i and a downlink signal numbered i; and the ionospheric delay of each signal in the corresponding forward ranging signal is determined based on the total number of ionosphere electrons, a preset ionosphere delay coefficient, and a carrier frequency of each signal in at least one forward ranging signal, including: Based on the determined total number of ionospheric electrons on 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): Determining the sum of the satellite-to-ground space distance and the tropospheric delay between the satellite and the monitoring station by using at least one of the forward ranging values ​​represented by the forward ranging expression includes: Using any forwarding ranging value numbered i as shown in the following formula (1), the sum of the satellite-to-ground space distance and the tropospheric delay between the satellite and the monitoring station as shown in the following formula (10) is obtained: L zi (n)=R true,ziu (n)+R true,zid (n)+I ziu (n)+I zid (n)+T duiliu,ziu (n)+T duiliu,zid (n)+Y i (n)(1); Where: L zi (n) represents the forwarding ranging value of the number i at the nth time, in meters; R true,ziu (n) represents the real space distance that the uplink signal numbered i has traveled at the nth moment, i.e., the satellite-to-ground space distance, in meters; R true,zid (n) represents the real space distance that the downlink signal numbered i has traveled at the nth moment, i.e., the satellite-to-ground space distance, in meters; I ziu (n) represents the ionospheric delay of the uplink signal numbered i at the nth time, in meters; I z1d (n) represents the ionospheric delay of the downlink signal numbered i at the nth time, in meters; T duiliu,z1u (n) represents the tropospheric delay of the uplink signal numbered i at the nth time, in meters; T duiliu,z1d (n) represents the tropospheric delay of the downlink signal numbered i at the nth time, in meters; Y i (n) represents the hardware device delay of the forwarding ranging signal numbered i at the nth moment, in meters, wherein 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; Q ion represents the ionospheric delay coefficient, TEC(n) represents the total number of ionospheric electrons on the ranging signal path between the satellite and the monitoring station at the nth moment, unit: electron / square meter; f ziu (n) represents the carrier frequency of the uplink signal numbered i at the nth time, in Hertz; f zid (n) represents the carrier frequency of the downlink signal numbered i at the nth moment, in Hertz.

21. The ionospheric delay monitoring method according to claim 19, characterized in that: Determining the sum of the satellite-to-ground space distance and the tropospheric delay between the satellite and the monitoring station by using at least one of the forward ranging values ​​represented by the forward ranging expression includes: The sum of multiple satellite-to-ground space distances and tropospheric delays is determined using multiple forwarding ranging values ​​represented by multiple forwarding ranging expressions; The sums of the plurality of satellite-to-ground space distances and the tropospheric time delays are averaged, and the average result is determined as the sum of the satellite-to-ground space distance and the convective time delay between the satellite and the monitoring station.

22. 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 comprises: Based on the acquired coordinate information of the monitoring station and the satellite-to-ground space distance between the satellite and the monitoring station, the coordinate information of the satellite is determined, wherein the satellite-to-ground space distance between the satellite and the monitoring station is determined according to the ionospheric delay monitoring method according to any one of claims 19 to 21; there are multiple monitoring stations, and time synchronization requirements are met between the monitoring stations; The orbital parameters of the satellite are determined based on the coordinate information of the satellite.

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