CN110058287B - Low-orbit satellite orbit determination method, device and system - Google Patents

Low-orbit satellite orbit determination method, device and system Download PDF

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CN110058287B
CN110058287B CN201910406386.9A CN201910406386A CN110058287B CN 110058287 B CN110058287 B CN 110058287B CN 201910406386 A CN201910406386 A CN 201910406386A CN 110058287 B CN110058287 B CN 110058287B
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orbit
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navigation satellite
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CN110058287A (en
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王军
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Beijing Unistrong Science & Technology Co ltd
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Beijing Unistrong Science & Technology Co ltd
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Priority to PCT/CN2020/090127 priority patent/WO2020228754A1/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/40—Correcting position, velocity or attitude
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/42—Determining position
    • G01S19/45—Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement
    • G01S19/46—Determining position by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement the supplementary measurement being of a radio-wave signal type

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)

Abstract

The embodiment of the application discloses a low-orbit satellite orbit determination method and a low-orbit satellite orbit determination device. And then, receiving correction information of the positioning information sent by the ground system so as to correct the positioning information and obtain the corrected positioning information. And then the low orbit satellite is fixed by adopting the corrected positioning information and observation data. That is, the embodiment of the present application introduces correction information of positioning information, and performs orbit determination on a low-orbit satellite by using accurate corrected positioning information, thereby improving the orbit determination accuracy of the low-orbit satellite.

Description

Low-orbit satellite orbit determination method, device and system
Technical Field
The application relates to the technical field of satellite communication, in particular to a low-orbit satellite orbit determination method, device and system.
Background
With the continuous development of Global Navigation Satellite System (GNSS) technology, GNSS measurement technology is gradually becoming a main technical means for low-earth-orbit Satellite positioning due to the characteristics of globality, high precision, low cost and the like. The low earth orbit satellite carries a GNSS receiver to acquire GNSS observation data and broadcast ephemeris sent by the GNSS satellite in real time, wherein the GNSS observation data comprises pseudo-range observation values and carrier phase observation values. During actual orbit determination, the position and clock error of the navigation satellite are determined by using the broadcast ephemeris, and then the position of the low orbit satellite is determined according to the position, clock error and observation data of the navigation satellite. However, since the broadcast ephemeris itself has errors, when the low-orbit satellite performs the orbit determination by using the broadcast ephemeris and the observation data, the orbit determination accuracy can only reach 0.3-0.5 meter. With the continuous development of various fields, the requirement on low-orbit satellite orbit determination is higher, and the low-orbit satellite orbit determination usually reaches centimeter level. Obviously, the existing satellite orbit determination method is difficult to meet the development requirement of the industry.
Disclosure of Invention
In view of this, embodiments of the present disclosure provide a satellite orbit determination method, device and system to improve the satellite orbit determination accuracy.
In order to solve the above problem, the technical solution provided by the embodiment of the present application is as follows:
in a first aspect of the embodiments of the present application, there is provided a method for determining an orbit of a low-earth orbit satellite, where the method is applied to the low-earth orbit satellite, and the method includes:
acquiring broadcast ephemeris and observation data of a navigation satellite;
acquiring positioning information according to the broadcast ephemeris, and correcting the positioning information based on correction information of the positioning information acquired and transmitted by a ground system;
and adopting the corrected positioning information and the observation data to fix the orbit of the low-orbit satellite.
In one possible implementation, the correction information is obtained by the ground system through calculation according to the position of the ground system, the observation data of the navigation satellite and the broadcast ephemeris.
In a possible implementation manner, the positioning information includes an orbit and a clock error of a navigation satellite, and the correction information includes an orbit correction number and a clock error correction number of the navigation satellite; the corrected positioning information includes a corrected track and a corrected clock error.
In one possible implementation, the orbit correction number is obtained by the ground system according to a real-time precise orbit of a navigation satellite and an orbit of the navigation satellite;
the real-time precise orbit of the navigation satellite is obtained by the ground system according to the position of the ground system, the observation data and the broadcast ephemeris;
the orbit of the navigation satellite is obtained by the ground system according to the broadcast ephemeris;
the clock error correction number is obtained by the ground system according to the real-time precise clock error of the navigation satellite and the clock error of the navigation satellite;
the real-time precise clock error of the navigation satellite is obtained by the ground system according to the observation data and the real-time precise orbit;
the clock offset of the navigation satellite is obtained by the ground system from the broadcast ephemeris.
In a possible implementation manner, the orbit determination of the low-orbit satellite by using the corrected orbit and the corrected clock error and the observation data includes:
carrying out filtering calculation according to the corrected orbit, the corrected clock error and the observation data to obtain orbit parameters of the low-orbit satellite in each preset direction;
calculating the sum of variances of the orbit parameters of the low-orbit satellite in each preset direction;
and when the sum of the variances of the orbit parameters of the low-orbit satellite in the preset directions is smaller than a preset threshold value, determining the orbit of the low-orbit satellite according to the orbit parameters of the low-orbit satellite in the preset directions.
In a possible implementation manner, before the correction of the positioning information based on the correction information of the positioning information acquired and sent by the ground system, the method further includes:
judging whether the time information of the positioning information and the correction information is matched or not;
and if the positioning information is matched with the positioning information, correcting the positioning information.
In a possible implementation manner, before the correcting the positioning information, the method further includes:
judging whether the correction information is available or not according to the integrity information acquired and transmitted by the ground system; the integrity information includes an indication of whether the revision information is available;
and if so, correcting the positioning information.
In a second aspect of the embodiments of the present application, there is provided a method for determining an orbit of a low-orbit satellite, where the method is applied to a ground system, and the method includes:
acquiring observation data and broadcast ephemeris of a navigation satellite;
acquiring correction information of a navigation satellite according to the position of the ground system, the observation data and the broadcast ephemeris; the correction information is used for correcting the positioning information by the low-orbit satellite to obtain corrected positioning information; and the corrected positioning information and the observation data of the navigation satellite obtained by the low-orbit satellite are used for the low-orbit satellite to carry out real-time orbit determination.
In one possible implementation, the correction information includes an orbit correction number and a clock correction number of the navigation satellite; the positioning information comprises an orbit and a clock error of a navigation satellite, and the corrected positioning information comprises a corrected orbit and a corrected clock error.
In a possible implementation manner, the obtaining correction information of the navigation satellite according to the position of the ground system, the observation data and the broadcast ephemeris includes:
acquiring a real-time precise orbit of the navigation satellite according to the position of a ground system, the observation data and the broadcast ephemeris;
acquiring the orbit of the navigation satellite according to the broadcast ephemeris;
acquiring the orbit correction number of the navigation satellite according to the real-time precise orbit and the orbit of the navigation satellite;
acquiring real-time precision clock error of the navigation satellite according to the observation data and the real-time precision orbit;
acquiring the clock error of the navigation satellite according to the broadcast ephemeris;
and acquiring the clock error correction number of the navigation satellite according to the real-time precise clock error and the clock error of the navigation satellite.
In one possible implementation, the obtaining the real-time precise orbit of the navigation satellite according to the position of the ground system, the observation data and the broadcast ephemeris includes:
acquiring the orbit of the navigation satellite according to the broadcast ephemeris to determine the orbit as an initial value of the navigation satellite;
and correcting the initial value of the navigation satellite orbit according to the position of the ground system and the observation data, and determining the corrected navigation satellite orbit as the real-time precise orbit of the navigation satellite.
In one possible implementation, the positioning information is obtained by the low-earth satellite according to the acquired broadcast ephemeris of the navigation satellite.
In one possible implementation, the method further includes:
obtaining integrity information from the revision information, the integrity information including an indication of whether the revision information is available.
In a third aspect of the embodiments of the present application, there is provided a low earth orbit satellite determination system, including: ground system, low earth orbit satellite;
the surface system for performing the method of the first aspect;
the low-earth satellite is used for executing the method of the second aspect.
In a fourth aspect of the embodiments of the present application, there is provided an orbit determination device for a low-earth-orbit satellite, the device being applied to the low-earth-orbit satellite, the device including:
a first acquisition unit for acquiring broadcast ephemeris and observation data of a navigation satellite;
the correction unit is used for acquiring positioning information according to the broadcast ephemeris and correcting the positioning information based on the correction information of the positioning information acquired and sent by the ground system;
and the first calculation unit is used for performing orbit determination on the low-orbit satellite by adopting the corrected positioning information and the observation data.
In one possible implementation, the correction information is obtained by the ground system through calculation according to the position of the ground system, the observation data of the navigation satellite and the broadcast ephemeris.
In a possible implementation manner, the positioning information includes an orbit and a clock error of a navigation satellite, and the correction information includes an orbit correction number and a clock error correction number of the navigation satellite; the corrected positioning information includes a corrected track and a corrected clock error.
In one possible implementation, the orbit correction number is obtained by the ground system according to a real-time precise orbit of a navigation satellite and an orbit of the navigation satellite;
the real-time precise orbit of the navigation satellite is obtained by the ground system according to the position of the ground system, the observation data and the broadcast ephemeris;
the orbit of the navigation satellite is obtained by the ground system according to the broadcast ephemeris;
the clock error correction number is obtained by the ground system according to the real-time precise clock error of the navigation satellite and the clock error of the navigation satellite;
the real-time precise clock error of the navigation satellite is obtained by the ground system according to the observation data and the real-time precise orbit;
the clock offset of the navigation satellite is obtained by the ground system from the broadcast ephemeris.
In one possible implementation manner, the first computing unit includes:
the first obtaining subunit is configured to perform filtering calculation according to the corrected orbit, the corrected clock error and the observation data, and obtain orbit parameters of the low-earth-orbit satellite in each preset direction;
the first calculating subunit is used for calculating the sum of variances of the orbit parameters of the low-orbit satellite in each preset direction;
the first determining subunit is configured to determine, when the sum of the variances of the orbit parameters of the low-orbit satellite in the preset directions is smaller than a preset threshold, the orbit of the low-orbit satellite according to the orbit parameters of the low-orbit satellite in the preset directions.
In one possible implementation, the apparatus further includes:
a first judgment unit configured to judge whether the time information of the positioning information and the time information of the correction information match;
the correcting unit is specifically configured to correct the positioning information by using the correction information when the determination result of the first determining unit is a match.
In one possible implementation, the apparatus further includes:
the second judgment unit is used for judging whether the correction information is available or not according to the integrity information acquired and sent by the ground system; the integrity information includes an indication of whether the revision information is available;
the correcting unit is specifically configured to correct the positioning information when the determination result of the second determining unit is that the correction information is available.
In a fifth aspect of the embodiments of the present application, there is provided a low earth orbit determination device for a ground system, the device including:
the second acquisition unit is used for acquiring the observation data and the broadcast ephemeris of the navigation satellite;
the second calculation unit is used for obtaining the correction information of the navigation satellite according to the position of the ground system, the observation data and the broadcast ephemeris; the correction information is used for correcting the positioning information by the low-orbit satellite to obtain corrected positioning information; and the corrected positioning information and the observation data of the navigation satellite obtained by the low-orbit satellite are used for the low-orbit satellite to carry out real-time orbit determination.
In one possible implementation, the correction information includes an orbit correction number and a clock correction number of the navigation satellite; the positioning information comprises an orbit and a clock error of a navigation satellite, and the corrected positioning information comprises a corrected orbit and a corrected clock error.
In one possible implementation manner, the second computing unit includes:
the second calculation subunit is used for obtaining the real-time precise orbit of the navigation satellite according to the position of a ground system, the observation data and the broadcast ephemeris;
a third computing subunit, configured to obtain the orbit of the navigation satellite according to the broadcast ephemeris;
the fourth calculation subunit is configured to obtain an orbit correction number of the navigation satellite according to the real-time precise orbit and the orbit of the navigation satellite;
the fifth calculating subunit is configured to obtain a real-time precision clock error of the navigation satellite according to the observation data and the real-time precision orbit;
a sixth calculating subunit, configured to obtain a clock offset of the navigation satellite according to the broadcast ephemeris;
and the seventh calculating subunit is used for obtaining the clock correction number of the navigation satellite according to the real-time precise clock correction and the clock correction of the navigation satellite.
In one possible implementation manner, the second computing subunit includes:
the second determining subunit is used for obtaining the orbit of the navigation satellite according to the broadcast ephemeris to determine the orbit as an initial value of the navigation satellite orbit;
and the third determining subunit is configured to modify the initial value of the navigation satellite orbit according to the position of the ground system and the observation data, and determine the modified navigation satellite orbit as the real-time precise orbit of the navigation satellite.
In one possible implementation, the positioning information is obtained by the low-earth satellite according to the acquired broadcast ephemeris of the navigation satellite.
In one possible implementation, the apparatus further includes:
a third obtaining unit, configured to obtain integrity information according to the correction information, where the integrity information includes a flag indicating whether the correction information is available.
Therefore, the embodiment of the application has the following beneficial effects:
according to the embodiment of the application, the low-orbit satellite firstly acquires the broadcast ephemeris and observation data of the navigation satellite, and the positioning information of the navigation satellite is obtained through calculation according to the broadcast ephemeris. And then, receiving correction information of the positioning information sent by the ground system, correcting the positioning information, and acquiring the corrected positioning information. And finally, adopting the corrected positioning information and observation data to fix the orbit of the low-orbit satellite. Therefore, the embodiment of the application introduces the correction information of the positioning information, and utilizes the corrected positioning information to fix the orbit of the low orbit satellite, thereby improving the orbit determination precision.
Drawings
Fig. 1 is a scene diagram illustrating an example of low-earth orbit satellite orbit determination provided in an embodiment of the present application;
fig. 2 is a flowchart of a low earth orbit satellite orbit determination method according to an embodiment of the present application;
fig. 3 is a flowchart of another low-earth orbit satellite positioning method according to an embodiment of the present application;
fig. 4 is a flowchart of another low-earth orbit satellite orbit determination method provided in the embodiment of the present application;
FIG. 5 is a diagram of a low earth orbit satellite positioning framework according to an embodiment of the present application;
fig. 6 is a structural diagram of a low earth orbit satellite positioning system according to an embodiment of the present application;
fig. 7 is a structural diagram of a low-earth orbit determination device according to an embodiment of the present application;
fig. 8 is a structural diagram of another low-earth orbit determination device according to an embodiment of the present application.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the drawings are described in detail below.
In order to facilitate understanding of the technical solutions provided in the embodiments of the present application, a discovery process of the technical solutions of the present application is described below.
The inventor finds that, when the low-orbit satellite is fixed by using the GNSS, the orbit and the clock error of the navigation satellite are usually obtained by using the broadcast ephemeris calculation, and then the orbit of the low-orbit satellite is determined according to the orbit, the clock error and the GNSS observation data of the navigation satellite, because the low-orbit satellite is limited by the conditions of real-time performance and autonomy. However, the broadcast ephemeris itself has a large error, which causes the low-orbit satellite to perform real-time orbit determination by using inaccurate reference information (orbit and clock error of the navigation satellite), and affects the orbit determination accuracy of the low-orbit satellite.
Based on this, an embodiment of the present application provides a low earth orbit satellite orbit determination method, specifically, a low earth orbit satellite obtains positioning information of a navigation satellite by using a broadcast ephemeris sent by the navigation satellite, and receives correction information of the positioning information sent by a ground system, so as to correct the positioning information and obtain corrected positioning information. And then the low orbit satellite is fixed by adopting the corrected positioning information and observation data. Namely, the low orbit satellite is fixed by accurate positioning information, thereby improving the orbit determination precision of the low orbit satellite.
In order to facilitate understanding of the technical solutions of the embodiments of the present application, a practical application scenario of the embodiments of the present application will be described below.
Referring to fig. 1, this figure is an exemplary diagram of an application scenario for low-earth orbit satellite orbit determination provided in this embodiment of the present application, and in this embodiment, in order to implement low-earth orbit satellite orbit determination, a ground system and a low-earth orbit satellite may be included.
The ground system can acquire observation data and broadcast ephemeris of the navigation satellite in real time through the global GNSS tracking station, then calculate and acquire correction information about the navigation satellite according to the position of the ground system, the observation data and the broadcast ephemeris, and send the correction information to the low-orbit satellite, so that the low-orbit satellite corrects the positioning information of the navigation satellite acquired by calculation according to the correction information, and acquires the corrected positioning information. And finally, the low-orbit satellite performs orbit determination according to the corrected positioning information and observation data.
In consideration of the fact that the effective time of the correction information is very limited, the correction information needs to be frequently updated. Because the low-orbit satellite has a high operation speed, the track of the sub-satellite points extends all over the world, and if the ground system is directly communicated with the low-orbit satellite, the ground system is required to be capable of continuously communicating with the low-orbit satellite in a short time at a plurality of places all over the world, so that a large amount of communication resources are occupied. Therefore, in one possible implementation manner in this embodiment, the communication satellite is used as a relay station between the ground system and the low-earth satellite to perform data forwarding.
It can be understood that, in the embodiment of the present application, the low earth orbit satellite corrects the positioning information of the navigation satellite obtained by calculating itself according to the correction information provided by the ground system, and in order to facilitate understanding of the technical solution provided by the embodiment of the present application, a method for determining the correction information by the ground system in the present application will be described first.
Method embodiment one
Referring to fig. 2, which is a flowchart of a low-earth orbit satellite positioning method provided in an embodiment of the present application, as shown in fig. 2, the method is applied to a ground system, and the method may include:
s201: and acquiring observation data and broadcast ephemeris of the navigation satellite.
In this embodiment, the ground system may obtain GNSS observation data and broadcast ephemeris in real time through a global GNSS tracking station. In particular implementations, each GNSS tracking station may be onboard a GNSS receiver to obtain GNSS observation data and broadcast ephemeris via the GNSS receiver. The GNSS observation data is obtained by the ground system by analyzing satellite signals transmitted by the navigation satellites.
The observation data may include information such as a carrier phase observation value and a pseudo-range observation value. The carrier phase observation value refers to an instantaneous carrier phase value of the GNSS receiver at the moment of receiving the carrier signal of the navigation satellite; pseudorange means that the navigation satellite transmits a signal structured as a "pseudo-random noise code" called a ranging code signal (i.e., a coarse code C/a code or a fine code P code) according to an on-board clock. The signal is transmitted from the navigation satellite for a time delta t and then reaches the antenna of the receiver; the distance from the satellite to the receiver is obtained by multiplying the signal propagation time Δ t by the speed c of the electromagnetic wave in vacuum. Since the propagation time Δ t includes an error of the satellite clock not being synchronized with the receiver clock, a satellite ephemeris error, a receiver measurement noise, a delay error of the ranging code propagating through the atmosphere, and the like, the obtained range value is not a true geometric range of the satellite, and is called a "pseudorange".
The broadcast ephemeris is a telegraph text message which is carried on a radio signal transmitted by a navigation satellite and forecasts the number of satellites in a certain time, and can be used for calculating the orbit, namely the position, of the navigation satellite.
S202: and acquiring the correction information of the navigation satellite according to the position of the ground system, the observation data and the broadcast ephemeris.
In this embodiment, after acquiring the observation data and the broadcast ephemeris of the navigation satellite, since the position of the ground system is known, the correction information of the navigation satellite may be calculated and acquired according to the position of the ground system, the observation data, and the broadcast ephemeris. The corrected positioning information and observation data of the navigation satellite obtained by the low-orbit satellite are used for the low-orbit satellite to carry out real-time orbit determination. Wherein the positioning information is obtained by the low-orbit satellite according to the acquired broadcast ephemeris of the navigation satellite.
In practical applications, the correction information may include an orbit correction number and a clock error correction number of the navigation satellite, the positioning information may include an orbit and a clock error of the navigation satellite, and the corrected positioning information includes a corrected orbit and a corrected clock error. The orbit correction number is used for correcting the orbit of the navigation satellite by the low-orbit satellite so as to obtain a corrected orbit; the clock error correction number is used for correcting the clock error of the navigation satellite by the low orbit satellite so as to obtain the corrected clock error. And the low-orbit satellite carries out real-time orbit determination by utilizing the corrected orbit, the corrected clock error and the observation data. Wherein the orbit of the navigation satellite and the clock error of the navigation satellite are obtained by the low-orbit satellite according to the broadcast ephemeris of the navigation satellite obtained by the low-orbit satellite.
It should be noted that, the following embodiments will be described with respect to a specific implementation in which the ground system calculates and obtains the orbit correction number and the clock error correction number of the navigation satellite according to the position of the ground system, the observation data, and the broadcast ephemeris, and with respect to a specific implementation in which the low-orbit satellite corrects the orbit and the clock error of the navigation satellite by using the orbit correction number and the clock error correction number, and performs orbit determination according to the corrected orbit, the corrected clock error, and the observation data.
It can be understood that, in order to ensure that the low-earth satellite can timely obtain the orbit correction number and the clock correction number obtained by the ground system, the low-earth satellite and the ground system can be used for forwarding, that is, the ground system sends the orbit correction number and the clock correction number to the communication satellite, so as to send the orbit correction number and the clock correction number to the low-earth satellite through the communication satellite. That is, the orbit correction number and the clock correction number transmitted by the ground system are transmitted to the low orbit satellite by the communication satellite, so that the real-time performance of the orbit correction number and the clock correction number is ensured.
According to the above description, the ground system can calculate and obtain the correction information of the navigation satellite according to the self-position information, the observation data of the navigation satellite and the broadcast ephemeris, so as to send the correction information to the low-orbit satellite, so that the low-orbit satellite corrects the positioning information of the navigation satellite obtained by the broadcast ephemeris calculation by using the correction information, so as to obtain the corrected positioning information, and then performs orbit determination according to the corrected positioning information and the observation data, thereby improving the orbit determination precision.
Method embodiment two
The following describes an implementation of calculating and obtaining the orbit correction number and the clock correction number of the navigation satellite by the ground system with reference to the accompanying drawings.
Referring to fig. 3, which is a flowchart of a method for obtaining track corrections and clock correction counts according to an embodiment of the present application, as shown in fig. 3, the method is applied to a ground system, and the method may include:
s301: and acquiring the real-time precise orbit of the navigation satellite according to the position of the ground system, the observation data and the broadcast ephemeris.
In this embodiment, after receiving the GNSS observation data and the broadcast ephemeris, the ground system calculates and obtains the real-time precise orbit of the navigation satellite by using the position of the ground system, the observation data, and the broadcast ephemeris.
During specific implementation, firstly, the orbit of the navigation satellite is calculated by using the broadcast ephemeris and is determined as an initial value of the orbit of the navigation satellite, then the initial value of the orbit of the navigation satellite is corrected by using the position and observation data of the ground system, and the corrected orbit of the navigation satellite is determined as a real-time precise orbit of the navigation satellite.
It is understood that, since the position of the ground system is known and accurate, that is, the position of the GNSS receiver is known and accurate, and the GNSS observation data represents the distance between the GNSS receiver and the navigation satellite, the more accurate position of the navigation satellite can be calculated and obtained according to the position of the ground system and the observation data. When the position of the navigation satellite is calculated by using the broadcast ephemeris, the determined position of the navigation satellite has a certain error due to the error of the broadcast ephemeris. In order to eliminate errors, the position of the navigation satellite obtained by the broadcast ephemeris is corrected by using the position of the navigation satellite obtained by the observation data, so that the accurate position of the navigation satellite, that is, the real-time precise orbit is obtained.
In real-time application, a least square batch processing method can be used for calculating and obtaining a real-time precise orbit of a navigation satellite, specifically, (1) the orbit of the navigation satellite is calculated by using a broadcast ephemeris and is used as an orbit initial value; (2) and when the observation data acquired by the global GNSS tracking station is accumulated for a certain time length, iteratively updating the initial orbit value by adopting a least square batch processing method until the sum of the residual errors of the observation values is less than a preset limit value. Wherein, the observed value residual error can be a residual error between the actual position of the ground system and the estimated value.
It can be understood that the observation data obtained by the GNSS tracking station also has a certain degree of error, and in order to ensure the accuracy of the position correction of the navigation satellite obtained by using the broadcast ephemeris calculation, the position of the navigation satellite is usually corrected for multiple times by using multiple sets of observation data. The method is realized by firstly correcting the position of the navigation satellite obtained by the broadcast ephemeris by using the actual position value of the ground system and the first group of observation data to obtain a first position. And then, calculating an estimated value of the position of the ground system by using the first position and the observation data, obtaining a first residual error according to the actual value of the position of the ground system and the estimated value of the position of the ground system, and if the first residual error meets a preset threshold value, indicating that the first position is accurate. And if the first residual error does not meet the preset threshold value, correcting the first position by using the actual position value of the ground system and the second group of observation data to obtain a second position. And then calculating an estimated value of the position of the ground system by using the second position and the observation data, obtaining a second residual error according to the actual value of the position of the ground system and the estimated value of the position of the ground system, and if the root mean square of the first residual error and the second residual error meets a preset threshold value, indicating that the second position is accurate. And if the root mean square of the first residual error and the second residual error does not meet the preset threshold value, correcting the second position by using the actual position value of the ground system and the third group of observation data to obtain a third position. And then calculating an estimated value of the position of the ground system by using the third position and the observation data, obtaining a third residual error according to the actual value of the position of the ground system and the estimated value of the position of the ground system, and if the root mean square of the second residual error and the third residual error meets a preset threshold value, indicating that the third position is accurate. And if the root mean square of the second residual error and the third residual error does not meet the preset threshold value, continuously utilizing other groups of observation data to carry out iterative updating until the root mean square of the two adjacent residual errors meets the preset threshold value.
S302: and acquiring the orbit of the navigation satellite according to the broadcast ephemeris.
S303: and acquiring the orbit correction number of the navigation satellite according to the real-time precise orbit and the orbit of the navigation satellite.
In this embodiment, after the real-time precise orbit and the orbit of the navigation satellite are obtained, the orbit correction number related to the navigation satellite may be obtained according to the real-time precise orbit and the orbit of the navigation satellite.
S304: and acquiring the real-time precise clock error of the navigation satellite according to the observation data and the real-time precise orbit.
S305: and acquiring the clock error of the navigation satellite according to the broadcast ephemeris.
S306: and acquiring the clock error correction number of the navigation satellite according to the real-time precise clock error and the clock error of the navigation satellite.
In this embodiment, after the ground system calculates and obtains the real-time precise orbit of the navigation satellite, the ground system calculates and obtains the real-time precise clock error of the navigation satellite according to the real-time precise orbit and the observation data, and calculates and obtains the clock error of the navigation satellite by using the broadcast ephemeris. In specific implementation, when the real-time precise clock error of the navigation satellite is obtained by using the observation data, the real-time precise orbit can be used as a constraint condition to calculate and obtain the real-time precise clock error of the navigation satellite. And then, acquiring the clock error correction number of the navigation satellite according to the real-time precise clock error and the clock error of the navigation satellite.
In a possible implementation manner of the embodiment of the application, the ground system may obtain the correction information through calculation, and may also obtain the integrity information according to the correction information, where the integrity information may include a flag indicating whether the correction information is available, so that after the low earth orbit satellite receives the integrity information sent by the ground system, the low earth orbit satellite may determine whether the currently received correction information may be used to correct the positioning information according to the flag included in the integrity information. In specific implementation, the integrity monitoring system in the ground system can judge the correction information, then the usable or unusable mark of the correction information is given according to the judgment result, and then the ground system sends the usable or unusable mark of the correction information to the low-orbit satellite through the integrity information.
It can be understood that, in order to ensure that the low-earth satellite can timely acquire the integrity information sent by the ground system, the ground system sends the integrity information to the low-earth satellite through the communication satellite, so that the low-earth satellite determines whether to correct by using the orbit correction number and the clock correction number according to the integrity information, thereby ensuring the real-time performance of the integrity information acquired by the low-earth satellite.
In specific implementation, the ground system may first send the orbit correction number and the clock correction number to the satellite upper station, and then the satellite upper station uploads the orbit correction number, the clock correction number, and the integrity information to the communication satellite, and when the communication satellite receives the orbit correction number and the clock correction number, the communication satellite sends the orbit correction number and the clock correction number to the low orbit satellite.
As can be seen from the above description, the ground system can provide the orbit correction number and the clock error correction number for the low-orbit satellite, and when the low-orbit satellite performs orbit determination according to the parameters sent by the navigation satellite, the orbit correction number and the clock error correction number can be used to correct the orbit and the clock error of the navigation satellite obtained by the broadcast ephemeris calculation, so as to perform self orbit determination by using the relatively accurate orbit and clock error of the navigation satellite, thereby improving the accuracy of orbit determination.
Method embodiment three
The above embodiments describe the acquisition of the correction information, and a method for determining an orbit by using the correction information for a low-orbit satellite according to an embodiment of the present application will be described below with reference to the accompanying drawings.
Referring to fig. 4, which is a flowchart of a method for determining an orbit of a low earth orbit satellite according to an embodiment of the present application, as shown in fig. 4, the method is applied to a low earth orbit satellite, and the method may include:
s401: broadcast ephemeris and observation data for the navigation satellites is obtained.
S402: and obtaining positioning information according to the broadcast ephemeris, and correcting the positioning information based on the correction information of the positioning information obtained and sent by the ground system.
In this embodiment, the low earth orbit satellite may receive the broadcast ephemeris sent by the navigation satellite, obtain the positioning information according to the broadcast ephemeris, and receive the correction information of the positioning information sent by the ground system, so as to correct the positioning information by using the correction information, and obtain the corrected positioning information. The correction information is obtained by the ground system through calculation according to the position of the ground system, the observation data of the navigation satellite and the broadcast ephemeris, and for obtaining the correction information, reference may be made to method embodiment one.
In a specific implementation, the positioning information may include an orbit and a clock error of the navigation satellite, and the correction information includes an orbit correction number and a clock error correction number of the navigation satellite; the corrected positioning information may include a corrected orbit and a corrected clock offset. For obtaining the track correction number and the clock correction number, reference may be made to method embodiment two.
In practical applications, the low earth orbit satellite may be equipped with a GNNS receiver to acquire the broadcast ephemeris and GNSS observations of the navigation satellites in real time using a GNSS receiver. The GNSS observation data is obtained by analyzing satellite signals transmitted by a navigation satellite by a low earth orbit satellite.
S403: and adopting the corrected positioning information and observation data to fix the orbit of the low-orbit satellite.
In this embodiment, after the corrected positioning information is obtained in S402, the low earth orbit satellite is orbit-determined by using the corrected positioning information and the observation data.
In a specific implementation, since the positioning information may include the orbit and clock error of the navigation satellite, and the correction information may include the orbit correction number and clock error correction number of the navigation satellite, the low-orbit satellite may be orbit-determined by using the corrected orbit and clock error and the observation data. A specific implementation of the orbit determination of the low-orbit satellite by using the corrected orbit and the corrected clock error and the observation data will be described in the following embodiments.
According to the above description, the low earth orbit satellite obtains the broadcast ephemeris and the observation data of the navigation satellite, and receives the correction information of the positioning information sent by the ground system while obtaining the positioning information of the navigation satellite according to the broadcast ephemeris, and corrects the positioning information to obtain the corrected positioning information. And then the low orbit satellite is fixed by adopting the corrected positioning information and observation data. Therefore, the embodiment of the application introduces the correction information of the positioning information acquired by the ground system, and utilizes the corrected positioning information to fix the orbit of the low-orbit satellite, so that the orbit fixing precision is improved.
In a possible implementation manner of the embodiment of the application, the orbit correction number is obtained by the ground system according to the real-time precise orbit of the navigation satellite and the orbit of the navigation satellite; the real-time precise orbit of the navigation satellite is obtained by a ground system according to the position of the ground system, observation data and broadcast ephemeris; the orbit of the navigation satellite is obtained by the ground system according to the broadcast ephemeris; the clock error correction number is obtained by the ground system according to the real-time precise clock error of the navigation satellite and the clock error of the navigation satellite; the real-time precise clock error of the navigation satellite is obtained by a ground system according to observation data and a real-time precise orbit; the clock error of the navigation satellite is obtained by the ground system from the broadcast ephemeris.
For specific implementation of the track correction number and the clock correction number obtained by the ground system through calculation, reference may be made to method embodiment two.
In practical applications, the low earth orbit satellite may be provided with a communication satellite receiver, so that the communication satellite receiver is used to receive the orbit correction number and the clock error correction number forwarded by the communication satellite. In specific implementation, the low earth orbit satellite can be provided with an integrated receiving device which has the functions of receiving navigation satellite signals and communication satellite signals, and can also be provided with a plurality of independent devices for receiving different signals.
In a specific implementation, when the low-earth orbit satellite acquires the orbit and clock error of the navigation satellite and the orbit correction number and clock error correction number, the corrected orbit and clock error of the navigation satellite can be calculated and obtained through the following formulas:
[R T N]precise＝[R T N]brdc±[dR dT dN]SSR-orbit (1)
dtprecise＝dtbrdc±dtSSR-clock (2)
wherein R/T/N is the component of the satellite orbit in Radial (Radial)/Tangential (Tangential)/Normal (Normal), respectively, [ R T N]preciseFor the recovered high precision real time orbit, [ R T N]brdcThe orbit of the navigation satellite, [ dR dT dN ] calculated for the broadcast ephemeris]SSR-orbitThe correction numbers of the track in three directions of R/T/N. dtpreciseFor high precision real time clock difference of recovery, dtbrdcClock error, dt, of navigation satellites calculated for broadcast ephemerisSSR-clockIs the clock error correction number. It should be noted that the three directions of R/T/N can also be changed into X/Y/Z directions, only multiplication by the corresponding rotation matrix is needed, and the right side of the equation adopts a "+" or "-" sign, which is related to the correction number calculation method.
It can be understood that, when the low-orbit satellite is in real-time orbit determination, after acquiring the orbit and clock error of the navigation satellite calculated by using the broadcast ephemeris and the orbit correction number and clock error correction number transmitted from the ground system, the corrected orbit and clock error of the navigation satellite can be calculated and obtained by using the formula (1) and the formula (2), and then the orbit, the corrected clock error and the observation data are used for performing the orbit determination.
As can be seen from the above description, the low earth orbit satellite receives the broadcast ephemeris transmitted by the navigation satellite and acquires the observation data, and calculates and acquires the orbit and the clock error of the navigation satellite according to the broadcast ephemeris, and at the same time receives the orbit correction number and the clock error correction number of the navigation satellite acquired and transmitted by the ground system. And then respectively correcting the orbit of the navigation satellite obtained by the calculation according to the broadcast ephemeris by using the orbit correction number, and correcting the clock error of the navigation satellite obtained by the calculation according to the broadcast ephemeris by using the clock error correction number, thereby obtaining the corrected orbit and the corrected clock error of the navigation satellite. And determining the orbit and the speed of the low orbit satellite according to the corrected orbit of the navigation satellite, the corrected clock error and the observation data. Therefore, the orbit correction number and the clock correction number are introduced in the embodiment of the application, so that the overall accuracy of the orbit and the clock correction of the navigation satellite is improved, and the orbit determination accuracy is improved when the orbit of the low-orbit satellite is positioned according to the orbit and the clock correction of the navigation satellite.
In a possible implementation manner of the embodiment of the application, in order to ensure the accuracy of low-orbit satellite orbit determination by using the corrected orbit, the corrected clock error and the observation data, after each step of filtering is finished, whether the filtering is converged is judged by combining the sum of variances of orbit parameters, and if the filtering equation is converged, it is shown that the currently obtained orbit determination result of the low-orbit satellite is reliable. Specifically, filtering calculation is carried out according to the corrected orbit, the corrected clock error and observation data to obtain orbit parameters of the low-orbit satellite in each preset direction; calculating the sum of variances of the orbit parameters of the low-orbit satellite in preset directions; and when the sum of the variances of the orbit parameters of the low-orbit satellite in the preset directions is smaller than a preset threshold value, determining the orbit of the low-orbit satellite according to the orbit parameters of the low-orbit satellite in the preset directions.
During specific implementation, the corrected orbit, the corrected clock error and the observation data are input into a filter equation, and when the sum of the variances of the orbit parameters of the low-orbit satellite output by the filter equation in each preset direction is smaller than a preset threshold value, the position of the low-orbit satellite is determined according to the orbit parameters of the low-orbit satellite output by the filter equation in each preset direction. The filter equation may be a kalman filter equation.
In practical application, initial values of state parameters and initial values of a covariance matrix can be preset for a filter equation, the covariance matrix is used for representing position errors of the low-orbit satellite in three directions, then the initial state parameters and the covariance matrix are updated by using the corrected orbit, the corrected clock error, the observation data, and the initial state parameters, and when the sum of the position variances of the low-orbit satellite in the three directions in the updated covariance matrix is smaller than a preset threshold value, the convergence of filtering is represented, and the orbit parameters of the low-orbit satellite output at the moment are determined as the position of the low-orbit satellite.
During specific implementation, state updating is carried out on a filtering equation by using a satellite-borne GNSS observation value obtained at the current moment, a corrected track and a corrected clock error to obtain updated covariance information, and if the sum of variances of position parameters is smaller than a preset limit value, filtering convergence is considered; and if not, the filtering is not converged, and the position and speed parameters obtained by the filtering calculation are utilized, and the dynamic model is adopted to predict the position and speed information of the low-orbit satellite at the next moment and serve as the prior value of the filtering parameter at the next moment. In practical application, the filtering algorithm may be extended kalman filtering based on the UD decomposition, and the filtering is continued until kalman filtering converges by using the on-board GNSS observation value, the corrected orbit of the navigation satellite, and the corrected clock error as inputs.
In a possible implementation manner of the embodiment of the application, since the orbit of the navigation satellite is constantly changing, in order to ensure that the time information of the broadcast ephemeris and the observation data of the navigation satellite, on which the correction information is obtained by the ground system, matches with the time information of the broadcast ephemeris and the observation data of the navigation satellite, on which the positioning information is obtained by the low-orbit satellite, it is further ensured that the low-orbit satellite can correct the matched positioning information according to the correction information sent by the ground system, before the correction, the low-orbit satellite can determine whether the time information of the positioning information matches with the time information of the correction information, and if so, the positioning information is corrected by using the correction information.
In specific implementation, when the ground system calculates and obtains the correction information, a timestamp can be added to the correction information, and the time corresponding to the timestamp is the time of positioning information which can be corrected by using the correction information; and the low-earth-orbit satellite adds a time stamp to the positioning information at the same time, wherein the time corresponding to the time stamp is the time appointed by the positioning information. After the low earth orbit satellite receives the correction information sent by the ground system, whether the low earth orbit satellite is matched with the ground system can be judged according to the time stamp in the correction information and the time stamp of the positioning information, and if the low earth orbit satellite is matched with the ground system, the positioning information is corrected. Wherein, the matching can be that the timestamps of the two are equal, or the time difference between the two is within a preset time range.
In a specific implementation, the IODE value of each satellite provided in the broadcast ephemeris may be used to perform numerical matching with the IODE value attached to each orbit correction number and clock error correction number, and if the IODE values are equal, the orbit calculated by the broadcast ephemeris is corrected by using the orbit correction number, and the clock error calculated by the broadcast ephemeris is corrected by using the clock error correction number.
In a possible implementation manner of the embodiment of the application, before the ground system corrects the positioning information by using the correction information, whether the received correction information is available or not may be further determined, so as to avoid that the accuracy of the orbit determination is affected by correcting the positioning information by using the unavailable correction information. Specifically, the low earth orbit satellite judges whether the correction information is available according to the integrity information acquired and transmitted by the ground system; the integrity information includes an indication of whether revision information is available. And if the correction information is available, correcting the positioning information. That is, if the integrity information includes a mark that the correction information is available, the positioning information is corrected by using the correction information; if the integrity information comprises the mark that the correction information is unavailable, the positioning information is not corrected.
For the purpose of understanding the implementation principle of the present application, refer to fig. 5, which is a low-earth satellite orbit determination framework diagram provided in the embodiment of the present application, wherein a low-earth satellite-mounted GNSS receiver acquires on-board GNSS observation data, broadcast ephemeris transmitted by navigation satellites, and orbit correction numbers and clock correction numbers transmitted by a terrestrial system. And then, calculating to obtain a corrected orbit of the navigation satellite, namely an actual orbit and a corrected clock error, namely an actual clock error, and calculating to obtain the orbit and the speed of the low-orbit satellite according to the actual orbit of the navigation satellite, the actual clock error and the GNSS observation data. And performing Kalman filtering on the orbit and the speed of the low-orbit satellite obtained by calculation, and outputting a result if the filtering is converged to indicate that the orbit determination result is reliable. If not, the result is not output. And after each filtering is finished, predicting the position and speed information of the low-orbit satellite at the next moment by using the position and speed parameters obtained by the current filtering calculation and a dynamic model, taking the position and speed information as prior values of the filtering parameters at the next moment, filtering again, and circulating in sequence.
Apparatus embodiment
Based on the above method embodiment, the present application further provides a low-earth orbit determination system, which will be described below with reference to the accompanying drawings.
Referring to fig. 6, which is a block diagram of a low earth orbit satellite positioning system provided in an embodiment of the present application, as shown in fig. 6, the system may include:
may include a terrestrial system 601, a low earth orbit satellite 602.
A surface system 601 for performing the methods of method embodiment one and method embodiment two;
and the low-orbit satellite 602 is used for executing the method described in the third method embodiment.
In specific implementation, the ground system 601 may obtain the observation data and the broadcast ephemeris of the navigation satellite in real time through the global GNSS tracking station, and then calculate and obtain the orbit correction number and the clock error correction number about the navigation satellite according to the position of the ground system, the observation data, and the broadcast ephemeris, and send the orbit correction number and the clock error correction number to the low-orbit satellite 602, so that the low-orbit satellite 602 corrects the orbit and the clock error of the navigation satellite obtained by its own calculation according to the orbit correction number and the clock error correction number, and obtains the corrected orbit and the corrected clock error of the navigation satellite. The low earth orbit satellite 602 then makes orbit determination based on the corrected orbit, the corrected clock error and the observation data.
In one possible implementation, the system may further include: a communications satellite. The communication satellite is positioned between the ground system and the low-orbit satellite and is used for forwarding data sent by the ground system to the low-orbit satellite.
It should be noted that in this embodiment, specific implementations of the terrestrial system and the low-earth satellite may refer to the above method embodiment, and details are not described herein again.
Apparatus embodiment one
Based on the above method embodiment, the present application further provides a low-earth orbit satellite positioning device, which will be described below with reference to the accompanying drawings.
Referring to fig. 7, which is a structural diagram of an orbit determination apparatus for a low earth orbit satellite according to an embodiment of the present application, as shown in fig. 7, the apparatus is applied to a low earth orbit satellite, and the apparatus may include:
a first obtaining unit 701, configured to obtain broadcast ephemeris and observation data of a navigation satellite;
a correcting unit 702, configured to obtain positioning information according to the broadcast ephemeris, and correct the positioning information based on correction information of the positioning information obtained and sent by a ground system;
a first calculating unit 703 is configured to determine an orbit of the low-orbit satellite by using the corrected positioning information and the observation data.
In one possible implementation, the correction information is obtained by the ground system through calculation according to the position of the ground system, the observation data of the navigation satellite and the broadcast ephemeris.
In a possible implementation manner, the positioning information includes an orbit and a clock error of a navigation satellite, and the correction information includes an orbit correction number and a clock error correction number of the navigation satellite; the corrected positioning information includes a corrected track and a corrected clock error.
In one possible implementation, the orbit correction number is obtained by the ground system according to a real-time precise orbit of a navigation satellite and an orbit of the navigation satellite;
the real-time precise orbit of the navigation satellite is obtained by the ground system according to the position of the ground system, the observation data and the broadcast ephemeris;
the orbit of the navigation satellite is obtained by the ground system according to the broadcast ephemeris;
the clock error correction number is obtained by the ground system according to the real-time precise clock error of the navigation satellite and the clock error of the navigation satellite;
the real-time precise clock error of the navigation satellite is obtained by the ground system according to the observation data and the real-time precise orbit;
the clock offset of the navigation satellite is obtained by the ground system from the broadcast ephemeris.
In one possible implementation manner, the first computing unit includes:
the first obtaining subunit is configured to perform filtering calculation according to the corrected orbit, the corrected clock error and the observation data, and obtain orbit parameters of the low-earth-orbit satellite in each preset direction;
the first calculating subunit is used for calculating the sum of variances of the orbit parameters of the low-orbit satellite in each preset direction;
the first determining subunit is configured to determine, when the sum of the variances of the orbit parameters of the low-orbit satellite in the preset directions is smaller than a preset threshold, the orbit of the low-orbit satellite according to the orbit parameters of the low-orbit satellite in the preset directions.
In one possible implementation, the apparatus further includes:
a first judgment unit configured to judge whether the time information of the positioning information and the time information of the correction information match;
the correcting unit is specifically configured to correct the positioning information by using the correction information when the determination result of the first determining unit is a match.
In one possible implementation, the apparatus further includes:
the second judgment unit is used for judging whether the correction information is available or not according to the integrity information acquired and sent by the ground system; the integrity information includes an indication of whether the revision information is available;
the correcting unit is specifically configured to correct the positioning information when the determination result of the second determining unit is that the correction information is available.
It should be noted that, in this embodiment, implementation of each unit may refer to the above method example, and details of this embodiment are not described herein again.
Device embodiment II
Referring to fig. 8, there is shown a block diagram of another low earth orbit determination device for use in a ground system, the device comprising:
a second acquisition unit 801 configured to acquire observation data and broadcast ephemeris of the navigation satellite;
a second calculating unit 802, configured to obtain correction information of the navigation satellite according to the position of the ground system, the observation data, and the broadcast ephemeris; the correction information is used for correcting the positioning information by the low-orbit satellite to obtain corrected positioning information; and the corrected positioning information and the observation data of the navigation satellite obtained by the low-orbit satellite are used for the low-orbit satellite to carry out real-time orbit determination.
In one possible implementation, the correction information includes an orbit correction number and a clock correction number of the navigation satellite; the positioning information comprises an orbit and a clock error of a navigation satellite, and the corrected positioning information comprises a corrected orbit and a corrected clock error.
In one possible implementation manner, the second computing unit includes:
the second calculation subunit is used for obtaining the real-time precise orbit of the navigation satellite according to the position of a ground system, the observation data and the broadcast ephemeris;
a third computing subunit, configured to obtain the orbit of the navigation satellite according to the broadcast ephemeris;
the fourth calculation subunit is configured to obtain an orbit correction number of the navigation satellite according to the real-time precise orbit and the orbit of the navigation satellite;
the fifth calculating subunit is configured to obtain a real-time precision clock error of the navigation satellite according to the observation data and the real-time precision orbit;
a sixth calculating subunit, configured to obtain a clock offset of the navigation satellite according to the broadcast ephemeris;
and the seventh calculating subunit is used for obtaining the clock correction number of the navigation satellite according to the real-time precise clock correction and the clock correction of the navigation satellite.
In one possible implementation manner, the second computing subunit includes:
the second determining subunit is used for obtaining the orbit of the navigation satellite according to the broadcast ephemeris to determine the orbit as an initial value of the navigation satellite orbit;
and the third determining subunit is configured to modify the initial value of the navigation satellite orbit according to the position of the ground system and the observation data, and determine the modified navigation satellite orbit as the real-time precise orbit of the navigation satellite.
In one possible implementation, the positioning information is obtained by the low-earth satellite according to the acquired broadcast ephemeris of the navigation satellite. In one possible implementation, the apparatus further includes:
a third obtaining unit, configured to obtain integrity information according to the correction information, where the integrity information includes a flag indicating whether the correction information is available.
It should be noted that, implementation of each unit in this embodiment may refer to the above method embodiment, and this embodiment is not described herein again.
It should be noted that, in the present specification, the embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other. For the system or the device disclosed by the embodiment, the description is simple because the system or the device corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
It should be understood that in the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" for describing an association relationship of associated objects, indicating that there may be three relationships, e.g., "a and/or B" may indicate: only A, only B and both A and B are present, wherein A and B may be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single item(s) or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.
It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (27)

1. A low-orbit satellite orbit determination method is applied to the low-orbit satellite, and comprises the following steps:
acquiring broadcast ephemeris and observation data of a navigation satellite;
obtaining positioning information according to the broadcast ephemeris, and correcting the positioning information based on correction information of the positioning information, which is obtained and sent by a ground system, wherein the positioning information comprises an orbit and a clock error of a navigation satellite, and the correction information comprises an orbit correction number and a clock error correction number of the navigation satellite;
and adopting the corrected positioning information and the observation data to fix the orbit of the low-orbit satellite.
2. The method of claim 1, wherein the correction information is calculated by the terrestrial system based on a position of the terrestrial system, observations of navigation satellites, and broadcast ephemeris.
3. The method of claim 1, wherein the modified positioning information comprises a modified orbit and a modified clock error.
4. The method of claim 1, wherein the orbit correction numbers are obtained by the ground system from real-time precise orbits of navigation satellites and orbits of navigation satellites;
the real-time precise orbit of the navigation satellite is obtained by the ground system according to the position of the ground system, the observation data and the broadcast ephemeris;
the orbit of the navigation satellite is obtained by the ground system according to the broadcast ephemeris;
the clock error correction number is obtained by the ground system according to the real-time precise clock error of the navigation satellite and the clock error of the navigation satellite;
the real-time precise clock error of the navigation satellite is obtained by the ground system according to the observation data and the real-time precise orbit;
the clock offset of the navigation satellite is obtained by the ground system from the broadcast ephemeris.
5. The method of claim 3, wherein said using said modified orbit and said modified clock error and said observation data to orbit said low earth orbiting satellite comprises:
carrying out filtering calculation according to the corrected orbit, the corrected clock error and the observation data to obtain orbit parameters of the low-orbit satellite in each preset direction;
calculating the sum of variances of the orbit parameters of the low-orbit satellite in each preset direction;
and when the sum of the variances of the orbit parameters of the low-orbit satellite in the preset directions is smaller than a preset threshold value, determining the orbit of the low-orbit satellite according to the orbit parameters of the low-orbit satellite in the preset directions.
6. The method according to claim 1, wherein before the correction of the positioning information based on the correction information of the positioning information acquired and transmitted by the ground system, the method further comprises:
judging whether the time information of the positioning information and the correction information is matched or not;
and if the positioning information is matched with the positioning information, correcting the positioning information.
7. The method according to any of claims 1-6, wherein prior to the correcting the positioning information, the method further comprises:
judging whether the correction information is available or not according to the integrity information acquired and transmitted by the ground system; the integrity information includes an indication of whether the revision information is available;
and if so, correcting the positioning information.
8. A low-orbit satellite orbit determination method is applied to a ground system, and comprises the following steps:
acquiring observation data and broadcast ephemeris of a navigation satellite;
acquiring correction information of a navigation satellite according to the position of the ground system, the observation data and the broadcast ephemeris; the correction information is used for correcting the positioning information by the low-orbit satellite to obtain corrected positioning information, wherein the correction information comprises an orbit correction number and a clock error correction number of the navigation satellite, and the positioning information comprises an orbit and a clock error of the navigation satellite; and the corrected positioning information and the observation data of the navigation satellite obtained by the low-orbit satellite are used for the low-orbit satellite to carry out real-time orbit determination.
9. The method of claim 8, wherein the modified positioning information comprises a modified orbit and a modified clock error.
10. The method of claim 8, wherein obtaining the correction information for the navigation satellites based on the position of the ground system, the observation data, and the broadcast ephemeris comprises:
acquiring a real-time precise orbit of the navigation satellite according to the position of a ground system, the observation data and the broadcast ephemeris;
acquiring the orbit of the navigation satellite according to the broadcast ephemeris;
acquiring the orbit correction number of the navigation satellite according to the real-time precise orbit and the orbit of the navigation satellite;
acquiring real-time precision clock error of the navigation satellite according to the observation data and the real-time precision orbit;
acquiring clock error of the navigation satellite according to the broadcast ephemeris;
and acquiring the clock error correction number of the navigation satellite according to the real-time precise clock error and the clock error of the navigation satellite.
11. The method of claim 10, wherein obtaining the real-time precise orbit of the navigation satellite based on the position of the ground system, the observation data, and the broadcast ephemeris comprises:
acquiring the orbit of the navigation satellite according to the broadcast ephemeris to determine the orbit as an initial value of the navigation satellite;
and correcting the initial value of the navigation satellite orbit according to the position of the ground system and the observation data, and determining the corrected navigation satellite orbit as the real-time precise orbit of the navigation satellite.
12. The method of claim 8, wherein the positioning information is obtained by the low-earth satellite from acquired broadcast ephemeris of the navigation satellite.
13. The method according to any one of claims 8-12, further comprising:
obtaining integrity information from the revision information, the integrity information including an indication of whether the revision information is available.
14. A low earth orbit satellite tracking system, the system comprising: ground system, low earth orbit satellite;
the surface system for performing the method of any one of claims 8-13;
the low earth orbit satellite configured to perform the method of any of claims 1-7.
15. An orbit determination device for a low-orbit satellite, wherein the device is applied to the low-orbit satellite, and the device comprises:
a first acquisition unit for acquiring broadcast ephemeris and observation data of a navigation satellite;
a correction unit, configured to obtain positioning information according to the broadcast ephemeris, and correct the positioning information based on correction information of the positioning information obtained and sent by a ground system, where the positioning information includes an orbit and a clock error of a navigation satellite, and the correction information includes an orbit correction number and a clock error correction number of the navigation satellite;
and the first calculation unit is used for performing orbit determination on the low-orbit satellite by adopting the corrected positioning information and the observation data.
16. The apparatus of claim 15, wherein the correction information is calculated by the terrestrial system based on a position of the terrestrial system, observations of navigation satellites, and broadcast ephemeris.
17. The apparatus of claim 15, wherein the modified positioning information comprises a modified orbit and a modified clock error.
18. The apparatus of claim 15, wherein the orbit correction numbers are obtained by the ground system from real-time precise orbits of navigation satellites and orbits of navigation satellites;
the real-time precise orbit of the navigation satellite is obtained by the ground system according to the position of the ground system, the observation data and the broadcast ephemeris;
the orbit of the navigation satellite is obtained by the ground system according to the broadcast ephemeris;
the clock error correction number is obtained by the ground system according to the real-time precise clock error of the navigation satellite and the clock error of the navigation satellite;
the real-time precise clock error of the navigation satellite is obtained by the ground system according to the observation data and the real-time precise orbit;
the clock offset of the navigation satellite is obtained by the ground system from the broadcast ephemeris.
19. The apparatus of claim 17, wherein the first computing unit comprises:
the first obtaining subunit is configured to perform filtering calculation according to the corrected orbit, the corrected clock error and the observation data, and obtain orbit parameters of the low-earth-orbit satellite in each preset direction;
the first calculating subunit is used for calculating the sum of variances of the orbit parameters of the low-orbit satellite in each preset direction;
the first determining subunit is configured to determine, when the sum of the variances of the orbit parameters of the low-orbit satellite in the preset directions is smaller than a preset threshold, the orbit of the low-orbit satellite according to the orbit parameters of the low-orbit satellite in the preset directions.
20. The apparatus of claim 15, further comprising:
a first judgment unit configured to judge whether the time information of the positioning information and the time information of the correction information match;
the correcting unit is specifically configured to correct the positioning information by using the correction information when the determination result of the first determining unit is a match.
21. The apparatus of any one of claims 15-20, further comprising:
the second judgment unit is used for judging whether the correction information is available or not according to the integrity information acquired and sent by the ground system; the integrity information includes an indication of whether the revision information is available;
the correcting unit is specifically configured to correct the positioning information when the determination result of the second determining unit is that the correction information is available.
22. An orbit determination device for a low-orbit satellite, wherein the device is applied to a ground system, and the device comprises:
the second acquisition unit is used for acquiring the observation data and the broadcast ephemeris of the navigation satellite;
the second calculation unit is used for obtaining the correction information of the navigation satellite according to the position of the ground system, the observation data and the broadcast ephemeris; the correction information is used for correcting the positioning information by the low-orbit satellite to obtain corrected positioning information, wherein the correction information comprises an orbit correction number and a clock error correction number of the navigation satellite, and the positioning information comprises an orbit and a clock error of the navigation satellite; and the corrected positioning information and the observation data of the navigation satellite obtained by the low-orbit satellite are used for the low-orbit satellite to carry out real-time orbit determination.
23. The apparatus of claim 22, wherein the modified positioning information comprises a modified orbit and a modified clock error.
24. The apparatus of claim 22, wherein the second computing unit comprises:
the second calculation subunit is used for obtaining the real-time precise orbit of the navigation satellite according to the position of a ground system, the observation data and the broadcast ephemeris;
a third computing subunit, configured to obtain the orbit of the navigation satellite according to the broadcast ephemeris;
the fourth calculation subunit is configured to obtain an orbit correction number of the navigation satellite according to the real-time precise orbit and the orbit of the navigation satellite;
the fifth calculating subunit is configured to obtain a real-time precision clock error of the navigation satellite according to the observation data and the real-time precision orbit;
a sixth calculating subunit, configured to obtain a clock offset of the navigation satellite according to the broadcast ephemeris;
and the seventh calculating subunit is used for obtaining the clock correction number of the navigation satellite according to the real-time precise clock correction and the clock correction of the navigation satellite.
25. The apparatus of claim 24, wherein the second computing subunit comprises:
the second determining subunit is used for obtaining the orbit of the navigation satellite according to the broadcast ephemeris to determine the orbit as an initial value of the navigation satellite orbit;
and the third determining subunit is configured to modify the initial value of the navigation satellite orbit according to the position of the ground system and the observation data, and determine the modified navigation satellite orbit as the real-time precise orbit of the navigation satellite.
26. The apparatus of claim 22, wherein the positioning information is obtained by the low-earth satellite from acquired broadcast ephemeris of the navigation satellite.
27. The apparatus of any one of claims 22-26, further comprising:
a third obtaining unit, configured to obtain integrity information according to the correction information, where the integrity information includes a flag indicating whether the correction information is available.
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