CN108732597B - Method and system for establishing time reference of multi-satellite navigation system - Google Patents
Method and system for establishing time reference of multi-satellite navigation system Download PDFInfo
- Publication number
- CN108732597B CN108732597B CN201810564951.XA CN201810564951A CN108732597B CN 108732597 B CN108732597 B CN 108732597B CN 201810564951 A CN201810564951 A CN 201810564951A CN 108732597 B CN108732597 B CN 108732597B
- Authority
- CN
- China
- Prior art keywords
- satellite
- clock
- navigation system
- time
- satellite navigation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/23—Testing, monitoring, correcting or calibrating of receiver elements
- G01S19/235—Calibration of receiver components
-
- 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
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/35—Constructional details or hardware or software details of the signal processing chain
- G01S19/37—Hardware or software details of the signal processing chain
Landscapes
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Signal Processing (AREA)
- Position Fixing By Use Of Radio Waves (AREA)
Abstract
The invention discloses a method and a system for establishing a time reference of a multi-satellite navigation system, wherein the method comprises the following steps: acquiring ground station GNSS observation data and satellite-borne GNSS observation data of a multi-satellite navigation system, and respectively constructing a corresponding ground station observation model and a corresponding satellite-borne GNSS observation model according to the ground station GNSS observation data and the satellite-borne GNSS observation data; performing combined precise orbit determination and time synchronization on navigation satellites and low orbit satellites in a multi-satellite navigation system according to a ground station observation model and a satellite-borne GNSS observation model to obtain clock errors of each satellite navigation system; constructing the time scale of the multi-satellite navigation system according to the clock error of each satellite navigation system; and constraining the time scale to the system time of a certain satellite navigation system, and generating a uniform time reference of each satellite in the multi-satellite navigation system. The method can realize the establishment and maintenance of the continuous and stable time reference of the multi-satellite navigation system based on the satellite-borne atomic clock of the multi-satellite navigation system.
Description
Technical Field
The invention relates to the technical field of satellite navigation, in particular to a method and a system for establishing a time reference of a multi-satellite navigation system based on a satellite-borne atomic clock of the multi-satellite navigation system.
Background
The time is one of three basic elements (time, orbit and signal) forming the satellite navigation system, plays a supporting role for the satellite navigation system, is an important guarantee for maintaining the normal operation order and the working flow of the system, and determines the functions and performances of positioning, time service and speed measurement provided by the satellite navigation system to a great extent.
The time reference of the navigation system is used as a unified time reference of the satellite navigation system, and is a time scale generated according to the comparison data of the clock-keeping group, and the navigation system needs to unify the time of each satellite-borne atomic clock to the time reference and transmit the time to a user for use. Each navigation system establishes a specific time reference (system time). Currently, the time reference of the satellite navigation system includes two defining ways:
1) a main clock: the method comprises the steps that a main clock of a main control station is defined, such as GLONASS system time GLONASS, a plurality of high-precision atomic clocks configured by a ground monitoring part are compared with GLONASS through data and are traced to Russian national standard time UTC (SU), GLONASS satellite time is kept by a satellite-borne atomic clock, a comprehensive control center compares the GLONASS satellite time with the GLONASS twice every day, and a satellite clock correction value is transmitted to a satellite; the BDT of the Beidou system is also a main clock definition mode, is established and maintained by a time-frequency system positioned in a main control station of the Beidou second-generation ground operation and control system, is traced to a national time service center UTC (NTSC) of a Chinese academy, is transmitted to each monitoring station clock by adopting a satellite two-way time transmission technology, and is transmitted to each satellite clock by using a radio two-way time comparison technology, so that the time synchronization of the system is ensured.
2) A paper surface clock: the method is a synthesized clock mode and is defined by a clock group consisting of all ground clocks and satellite clocks, and the system time scale is obtained by weighted average of all clocks. If the system time of the GPS is GPST, the ground main control station weights the combined clock of the high-precision atomic clock of the monitoring station and the satellite-borne atomic clock of the satellite together through a Kalman filtering algorithm, establishes and maintains the GPST and traces to the U.S. naval astronomical stage UTC (USNO). The Galileo time system GST is also defined by a combination clock, a ground control center receives observation data from a measuring station, UTC is obtained through a common view method, clock error correction number and average frequency are generated through filtering, and the average frequency acts on a Galileo system main clock and is used for establishing a system reference GST. And the time scale establishment of the international GNSS service organization (IGS) is also a clock synthesis way, and an internal time reference is obtained by weighted average by using a plurality of stable measuring stations and a GPS satellite clock and is restricted to the GPST, so that the final synthesized clock difference product has the same time reference.
Because different satellite navigation systems have differences in design concept, time, orbit, frequency and the like, the existing method for establishing the time reference has the following problems:
1) the system time determined by each system has time deviation, so that the finally solved satellite clock error also has time deviation;
2) the satellite-borne atomic clocks of the low-earth orbit satellites are not utilized when the time reference of each system is established and maintained, and only the satellite-borne atomic clocks of the navigation satellites are used at the satellite end, so that the system cannot be applied to a multi-satellite navigation system comprising each satellite navigation system and the low-earth orbit satellites.
Disclosure of Invention
In view of the above problems, the present invention provides a method and a system for establishing a time reference of a multi-satellite navigation system, which can achieve establishment and maintenance of a continuous and stable time reference based on a satellite-borne atomic clock of the multi-satellite navigation system.
In one aspect of the present invention, a method for establishing a time reference of a multi-satellite navigation system is provided, including:
acquiring ground station GNSS observation data and satellite-borne GNSS observation data of a multi-satellite navigation system, and respectively constructing a corresponding ground station observation model and a corresponding satellite-borne GNSS observation model according to the ground station GNSS observation data and the satellite-borne GNSS observation data;
according to the ground station observation model and the satellite-borne GNSS observation model, performing combined precise orbit determination and time synchronization on the navigation satellites and the low-orbit satellites in the multi-satellite navigation system to obtain clock errors of each satellite navigation system;
constructing the time scale of the multi-satellite navigation system according to the clock error of each satellite navigation system;
and constraining the time scale to the system time of a certain satellite navigation system, and generating a unified time reference of each satellite in the multi-satellite navigation system, so that each satellite navigation system adds the unified time reference to the corresponding original clock error to obtain the satellite clock error under the unified time reference.
Optionally, the performing, according to the ground station observation model and the satellite-borne GNSS observation model, combined precise orbit determination and time synchronization on the navigation satellites and the low orbit satellites in the multi-satellite navigation system to obtain the clock error of each satellite navigation system includes:
respectively carrying out linearization processing on the ground station observation model and the satellite-borne GNSS observation model according to preset parameter initial values;
calculating the ground station observation model and the satellite-borne GNSS observation model after linearization by adopting a least square method to obtain clock error parameters of each satellite navigation system;
and constraining the clock error parameters of each satellite navigation system to the corresponding navigation ephemeris.
Optionally, the constructing a time scale of a multi-satellite navigation system according to the clock difference of each satellite navigation system includes:
performing phase conversion on the clock error of each satellite navigation system to obtain a frequency observation value of each satellite navigation system;
constructing a clock state equation of each satellite clock, and constructing a clock observation equation based on the clock state equation;
combining satellite clocks corresponding to each navigation satellite and the low-orbit satellite into a clock set, and constructing a state equation of the clock set according to a clock state equation of each satellite clock;
constructing an observation equation of the clock group according to the state equation of the clock group and the frequency observation value of each satellite navigation system;
calculating the frequency sequence of each satellite clock relative to the system time of the satellite navigation system to be constrained according to the observation equation of the clock set;
and calculating the time sequence of each satellite clock relative to the system time according to the frequency sequence, and constructing the time scale according to the time sequence.
Optionally, the calculating the time sequence of each satellite clock relative to the system time according to the frequency sequence includes:
and performing integral operation on the frequency sequence to obtain a corresponding time sequence of the satellite clock time relative to the system time.
Optionally, the constraining the time scale to a system time of a certain satellite navigation system to form a unified time reference of each satellite in the multi-satellite navigation system includes:
constructing a state equation and an observation equation of a constraint algorithm;
and calculating a time sequence constrained to the system time of a certain satellite navigation system by adopting a Kalman filtering method according to the state equation and the observation equation of the constraint algorithm, and taking the time sequence as a uniform time reference of each satellite in the multi-satellite navigation system.
In another aspect of the present invention, there is provided a time reference establishing system for a multi-satellite navigation system, including:
the model construction unit is used for acquiring ground station GNSS observation data and satellite-borne GNSS observation data of the multi-satellite navigation system, and constructing a corresponding ground station observation model and a corresponding satellite-borne GNSS observation model according to the ground station GNSS observation data and the satellite-borne GNSS observation data respectively;
the clock error acquisition unit is used for performing combined precise orbit determination and time synchronization on the navigation satellite and the low-orbit satellite in the multi-satellite navigation system according to the ground station observation model and the satellite-borne GNSS observation model to acquire the clock error of each satellite navigation system;
the time scale establishing unit is used for establishing the time scale of the multi-satellite navigation system according to the clock error of each satellite navigation system;
and the time reference generating unit is used for constraining the time scale to the system time of a certain satellite navigation system, generating a unified time reference of each satellite in the multi-satellite navigation system, so that each satellite navigation system adds the unified time reference to the corresponding original clock error to obtain the satellite clock error under the unified time reference.
Optionally, the clock difference obtaining unit includes:
the linearization processing module is used for respectively carrying out linearization processing on the ground station observation model and the satellite-borne GNSS observation model according to preset parameter initial values;
the first calculation module is used for calculating the ground station observation model and the satellite-borne GNSS observation model after linearization by adopting a least square method to obtain clock error parameters of each satellite navigation system;
and the constraint processing module is used for constraining the clock error parameters of each satellite navigation system to the corresponding navigation ephemeris.
Optionally, the time scale establishing unit includes:
the phase conversion module is used for carrying out phase conversion on the clock error of each satellite navigation system to obtain a frequency observation value of each satellite navigation system;
the first model building module is used for building a clock state equation of each satellite clock and building a clock observation equation based on the clock state equation;
the second model building module is used for combining the satellite clocks corresponding to the navigation satellites and the low-orbit satellites into a clock set and building a state equation of the clock set according to the clock state equation of each satellite clock;
the third model building module is used for building the observation equation of the clock group according to the state equation of the clock group and the frequency observation value of each satellite navigation system;
the second calculation module is used for calculating the frequency sequence of each satellite clock relative to the system time of the satellite navigation system to be constrained according to the observation equation of the clock set;
and the time scale construction module is used for calculating the time sequence of each satellite clock relative to the system time according to the frequency sequence and constructing the time scale according to the time sequence.
Optionally, the time scale building module is specifically configured to perform an integration operation on the frequency sequence to obtain a time sequence of the satellite clock time relative to the system time.
Optionally, the time reference generating unit includes:
the fourth model building module is used for building a state equation and an observation equation of the constraint algorithm;
and the third calculation module is used for calculating a time sequence constrained to the system time of a certain satellite navigation system by adopting a Kalman filtering method according to the state equation and the observation equation of the constraint algorithm, and taking the time sequence as a uniform time reference of each satellite in the multi-satellite navigation system.
According to the method and the system for establishing the time reference of the multi-satellite navigation system, when the time reference is established by utilizing the observation data of the ground station network GNSS and the satellite-borne GNSS covering all systems, the stability and the reliability of the result are ensured; in the process of establishing the time reference, all satellite-borne atomic clocks are utilized to form an atomic clock group, and the atomic clock group is maintained through weighting, so that higher stability and precision of a short period term of the time reference are ensured; the time reference is finally constrained to the time of a certain satellite navigation system, so that the stability of the long-period term of the time reference is ensured, the finally obtained clock error of each satellite has a uniform time reference, and the fusion processing and the application of the data of the multi-satellite navigation system are facilitated.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 is a flow chart of a method for establishing a time reference for a multi-satellite navigation system according to an embodiment of the present invention;
FIG. 2 is a flowchart illustrating a step S12 of the method for establishing a time reference for a multi-satellite navigation system according to an embodiment of the present invention;
FIG. 3 is a flowchart illustrating a step S13 of the method for establishing a time reference for a multi-satellite navigation system according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a time reference establishing system of a multi-satellite navigation system according to an embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Fig. 1 schematically shows a flow chart of a method for time reference establishment for a multi-satellite navigation system according to an embodiment of the invention. Referring to fig. 1, the method for establishing a time reference of a multi-satellite navigation system according to an embodiment of the present invention specifically includes the following steps:
s11, acquiring ground station GNSS observation data and satellite-borne GNSS observation data of the multi-satellite navigation system, and respectively constructing a corresponding ground station observation model and a corresponding satellite-borne GNSS observation model according to the ground station GNSS observation data and the satellite-borne GNSS observation data.
The GNSS observation equation of the ground station is:
the satellite-borne GNSS observation equation is as follows:
wherein, f is the frequency,
is a carrier phase observation (in distance), s represents a navigation satellite, k represents a survey station or low earth orbit satellite,
is a pseudo-range observation that is,
in order to be a degree of ambiguity,
for the geometric distance, dt, between ground station or low-orbit satellite and navigation satellitekTo measureClock error of the satellite at station or low orbit,. dtsIn order to navigate the clock offset of the satellite,
to account for the ionospheric effects on phase and pseudorange,
in order to delay the tropospheric delay,
the effects on phase and pseudorange are corrected for various other corrections, including multipath, antenna phase center, earth solid tide, ocean load tide, relativistic effects, etc.
And S12, performing combined precise orbit determination and time synchronization on the navigation satellite and the low orbit satellite in the multi-satellite navigation system according to the ground station observation model and the satellite-borne GNSS observation model, and acquiring the clock error of each satellite navigation system.
And S13, constructing the time scale of the multi-satellite navigation system according to the clock error of each satellite navigation system.
And S14, constraining the time scale to the system time of a certain satellite navigation system, and generating a unified time reference of each satellite in the multi-satellite navigation system, so that each satellite navigation system adds the unified time reference to the corresponding original clock error to obtain the satellite clock error of each satellite under the unified time reference, thereby realizing the satellite clock error of the unified time reference of the multi-satellite navigation system.
According to the time reference establishing method for the multi-satellite navigation system, when the time reference is established by using the observation data of the ground station network GNSS and the satellite-borne GNSS covering all systems, the stability and the reliability of the result are ensured; in the process of establishing the time reference, all satellite-borne atomic clocks are utilized to form an atomic clock group, and the atomic clock group is maintained through weighting, so that higher stability and precision of a short period term of the time reference are ensured; the time reference is finally constrained to the time of a certain satellite navigation system, so that the stability of the long-period term of the time reference is ensured, the finally obtained clock error of each satellite has a uniform time reference, and the fusion processing and the application of the data of the multi-satellite navigation system are facilitated.
In the embodiment of the present invention, as shown in fig. 2, the step S12, according to the ground station observation model and the satellite-borne GNSS observation model, performs combined precise orbit determination and time synchronization on the navigation satellites and the low orbit satellites in the multi-satellite navigation system to obtain the clock error of each satellite navigation system, and specifically includes the following steps:
and S121, respectively carrying out linearization processing on the ground station observation model and the satellite-borne GNSS observation model according to preset parameter initial values. The method specifically comprises the following steps: respectively generating observation distances O from the medium and high orbit GNSS satellite to the low orbit satellite and the ground station according to the preprocessed ground tracking data of the medium and high orbit GNSS satellite and the GNSS satellite observation data of the low orbit satellite; calculating the geometric distance from the medium-high orbit GNSS satellite to the low orbit satellite and the ground station according to a preset parameter initial value; correcting the calculated geometric distance to obtain a calculated distance C from the medium and high orbit GNSS satellite to the low orbit satellite and the ground station; carrying out difference operation on an observed distance O from a medium and high orbit GNSS satellite to a ground station and a calculated distance C to generate a prior residual error of an observation model of the ground station, and carrying out difference operation on the observed distance O from the medium and high orbit GNSS satellite to a low orbit satellite and the calculated distance C to generate a prior residual error of a satellite-borne GNSS observation model; calculating partial derivatives of the corresponding parameter vectors by using the observation models according to the approximate values of the parameter vectors in each observation model to obtain a first information matrix of the ground station observation model and a second information matrix of the satellite-borne GNSS observation model; and constructing a linearized observation equation corresponding to the first observation model according to the prior residual of the ground station observation model and the first information matrix, and constructing a linearized observation equation corresponding to the second observation model according to the prior residual of the satellite-borne GNSS observation model and the second information matrix.
And S122, calculating the ground station observation model and the satellite-borne GNSS observation model after linearization by adopting a least square method to obtain clock error parameters of each satellite navigation system.
And S123, constraining the clock error parameters of the satellite navigation systems to the corresponding navigation ephemeris.
Simplified dynamics orbit determination is adopted in multi-GNSS navigation satellite and low orbit satellite fusion precise orbit determination and time synchronization, state vectors such as orbit parameters and force model parameters of each satellite, ground station, low orbit satellite-borne clock error parameters, navigation satellite clock error parameters and the like are obtained through estimation, and clock error parameters of each navigation satellite are constrained to respective navigation ephemeris, namely the clock error parameters of each navigation satellite are constrained to the respective navigation ephemeris
In the formula (I), the compound is shown in the specification,
the satellite clock error parameter represents the satellite clock error parameter of the j-th satellite of a certain satellite navigation system, and n represents the number of the satellites of the system.
In the embodiment of the present invention, as shown in fig. 3, the step S13 of constructing the time scale of the multi-satellite navigation system according to the clock error of each satellite navigation system specifically includes the following steps:
s131, performing phase conversion on the clock difference of each satellite navigation system to obtain a frequency observation value of each satellite navigation system.
In specific application, a frequency observation value is formed by changing the phase of clock differences of different navigation satellites, and the clock difference of a satellite j is set to be equal to that of a certain time system (taking ORIT as an example)
According to
Observed values of component frequencies under ORIT
S132, constructing a clock state equation of each satellite clock, and constructing a clock observation equation based on the clock state equation.
The state equation for a single satellite clock can be written as follows:
wherein
In the formula (I), the compound is shown in the specification,
respectively representing a frequency offset and a frequency drift,
white noise representing frequency and random walk-around noise of frequency.
The Allan variance of the clock is
The variance of white noise and random walk noise of frequency can be obtained by an Allan variance inversion method
Namely:
drive noise
The covariance q of (a) is:
the observation equation for a single satellite clock can be written as follows:
where n represents measurement noise, typically white noise, and its variance r is:
in the formula (I), the compound is shown in the specification,
representing the median error of the satellite j clock difference.
S133, combining the satellite clocks corresponding to the navigation satellites and the low orbit satellites into a clock set, and constructing a state equation of the clock set according to the clock state equation of each satellite clock.
The N satellite clocks of all systems (including each navigation system and low orbit satellite) form a clock set, and then the state equation of the clock set is as follows:
for equation of state, state variables of clock group
Transition matrix Φ, drive noise
The covariance Q of (a) is:
wherein
Representing the state vector of the ith clock, q(1)Represents the covariance of the driving noise of the ith clock.
Allan variance at τ per clock
Weighting to obtain time scale after weighted average
The weight is calculated by the formula:
and S134, constructing an observation equation of the clock set according to the state equation of the clock set and the frequency observation value of each satellite navigation system.
Is provided with
The observation equation for the clock set is:
observation of a clock group for an observation equation
The observation matrix H and the covariance matrix R of the clock error observation noise are respectively as follows:
and S135, calculating the frequency sequence of each satellite clock relative to the system time of the satellite navigation system to be constrained according to the observation equation of the clock set.
S136, calculating the time sequence of each satellite clock relative to the system time according to the frequency sequence, and calculating the time sequence of each satellite clock relative to the system time according to the time sequenceThe time series constructs the time scale. Further, said calculating a time series of respective satellite clocks with respect to the system time from the frequency series comprises: performing integral operation on the frequency sequence to obtain a corresponding time sequence of satellite clock time relative to the system time
Where GPST is the satellite clock time of a certain navigation satellite system and NEWT is the system time.
In one embodiment, Kalman filtering is used to calculate the clock speed and drift of the clock at the new scale, and a new frequency scale sequence, denoted ORIT, relative to the system time
Namely:
then integrating the above frequency sequence to obtain the corresponding time sequence, and recording as
In the embodiment of the present invention, constraining the time scale to the system time of a certain satellite navigation system in step S14 to form a unified time reference for each satellite in the multi-satellite navigation system specifically includes the following steps:
constructing a state equation and an observation equation of a constraint algorithm;
and calculating a time sequence constrained to the system time of a certain satellite navigation system by adopting a Kalman filtering method according to the state equation and the observation equation of the constraint algorithm, and taking the time sequence as a uniform time reference of each satellite in the multi-satellite navigation system.
Constraint to a certain system time can utilize the long term of the system time reference to make the short period term of the new reference more stable, and also taking constraint to ORIT as an example, the state equation and observation equation of the constraint algorithm can be expressed as:
in the formula
Is a matrix vector of 2 × 1 dimensions, the two parts are the difference of clock skew and clock speed under GPST and NEWT respectively,
and ξ, which represent the process noise of the state equation and the random noise of the observation equation, respectively, u is the random model error used to constrain the change in frequency observation value and satisfies the loss function minimum.
Computing a time series constrained to an original degree using Kalman filtering
A new time reference, NEWT, is obtained as a unified time reference for the multi-satellite navigation system.
After the uniform time reference of the multi-satellite navigation system is obtained, each satellite navigation system adds the uniform time reference to the original clock error to obtain the satellite clock error with the same time reference, so that the satellite clock error with the uniform time-space reference of the multi-system is realized;
reduce the original clock difference to NEWT, i.e.
The satellite clock error with the uniform time reference can be obtained.
The multi-satellite navigation system time reference established by the embodiment of the invention also ensures the stability and reliability of the long and short period items of the time reference through real-time calculation and updating.
For simplicity of explanation, the method embodiments are described as a series of acts or combinations, but those skilled in the art will appreciate that the embodiments are not limited by the order of acts described, as some steps may occur in other orders or concurrently with other steps in accordance with the embodiments of the invention. Further, those skilled in the art will appreciate that the embodiments described in the specification are presently preferred and that no particular act is required to implement the invention.
Fig. 4 is a schematic structural diagram of a time reference establishing system of a multi-satellite navigation system according to an embodiment of the present invention. Referring to fig. 4, the time reference establishing system of the multi-satellite navigation system according to the embodiment of the present invention specifically includes a model constructing unit 401, a clock offset obtaining unit 402, a time scale establishing unit 403, and a time reference generating unit 404, where:
the model building unit 401 is configured to obtain ground station GNSS observation data and satellite-borne GNSS observation data of a multi-satellite navigation system, and build a corresponding ground station observation model and a corresponding satellite-borne GNSS observation model according to the ground station GNSS observation data and the satellite-borne GNSS observation data, respectively;
a clock error obtaining unit 402, configured to perform joint precise orbit determination and time synchronization on a navigation satellite and a low-orbit satellite in the multi-satellite navigation system according to the ground station observation model and the satellite-borne GNSS observation model, and obtain a clock error of each satellite navigation system;
a time scale establishing unit 403, configured to establish a time scale of a multi-satellite navigation system according to the clock error of each satellite navigation system;
a time reference generating unit 404, configured to constrain the time scale to a system time of a certain satellite navigation system, and generate a unified time reference for each satellite in the multiple satellite navigation systems, so that each satellite navigation system adds the unified time reference to a respective original clock offset, so as to obtain a satellite clock offset under the unified time reference.
In an optional embodiment of the present invention, the clock difference obtaining unit 402 includes a linearization processing module, a first calculation module, and a constraint processing module, where:
the linearization processing module is used for respectively carrying out linearization processing on the ground station observation model and the satellite-borne GNSS observation model according to preset parameter initial values;
the first calculation module is used for calculating the ground station observation model and the satellite-borne GNSS observation model after linearization by adopting a least square method to obtain clock error parameters of each satellite navigation system;
and the constraint processing module is used for constraining the clock error parameters of each satellite navigation system to the corresponding navigation ephemeris.
In an optional embodiment of the present invention, the time scale establishing unit 403 includes a phase transformation module, a first model constructing module, a second model constructing module, a third model constructing module, a second calculating module, and a time scale constructing module, where:
the phase conversion module is used for carrying out phase conversion on the clock error of each satellite navigation system to obtain a frequency observation value of each satellite navigation system;
the first model building module is used for building a clock state equation of each satellite clock and building a clock observation equation based on the clock state equation;
the second model building module is used for combining the satellite clocks corresponding to the navigation satellites and the low-orbit satellites into a clock set and building a state equation of the clock set according to the clock state equation of each satellite clock;
the third model building module is used for building the observation equation of the clock group according to the state equation of the clock group and the frequency observation value of each satellite navigation system;
the second calculation module is used for calculating the frequency sequence of each satellite clock relative to the system time of the satellite navigation system to be constrained according to the observation equation of the clock set;
and the time scale construction module is used for calculating the time sequence of each satellite clock relative to the system time according to the frequency sequence and constructing the time scale according to the time sequence.
Further, the time scale construction module is specifically configured to perform an integration operation on the frequency sequence to obtain a time sequence of the corresponding satellite clock time relative to the system time.
In an optional embodiment of the present invention, the time reference generating unit 404 comprises a fourth model building module and a third calculating module, wherein:
the fourth model building module is used for building a state equation and an observation equation of the constraint algorithm;
and the third calculation module is used for calculating a time sequence constrained to the system time of a certain satellite navigation system by adopting a Kalman filtering method according to the state equation and the observation equation of the constraint algorithm, and taking the time sequence as a uniform time reference of each satellite in the multi-satellite navigation system.
For the system embodiment, since it is basically similar to the method embodiment, the description is simple, and for the relevant points, refer to the partial description of the method embodiment.
According to the method and the system for establishing the time reference of the multi-satellite navigation system, when the time reference is established by utilizing the observation data of the ground station network GNSS and the satellite-borne GNSS covering all systems, the stability and the reliability of the result are ensured; in the process of establishing the time reference, all satellite-borne atomic clocks are utilized to form an atomic clock group, and the atomic clock group is maintained through weighting, so that higher stability and precision of a short period term of the time reference are ensured; the time reference is finally constrained to the time of a certain satellite navigation system, so that the stability of the long-period term of the time reference is ensured, the finally obtained clock error of each satellite has a uniform time reference, and the fusion processing and the application of the data of the multi-satellite navigation system are facilitated.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Furthermore, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A method for establishing a time reference for a multi-satellite navigation system, comprising:
acquiring ground station GNSS observation data and satellite-borne GNSS observation data of a multi-satellite navigation system, and respectively constructing a corresponding ground station observation model and a corresponding satellite-borne GNSS observation model according to the ground station GNSS observation data and the satellite-borne GNSS observation data;
according to the ground station observation model and the satellite-borne GNSS observation model, performing combined precise orbit determination and time synchronization on the navigation satellites and the low-orbit satellites in the multi-satellite navigation system to obtain clock errors of each satellite navigation system;
constructing the time scale of the multi-satellite navigation system according to the clock error of each satellite navigation system;
constraining the time scale to the system time of a certain satellite navigation system, and generating a unified time reference of each satellite in the multi-satellite navigation system, so that each satellite navigation system adds the unified time reference to the corresponding original clock error to obtain the satellite clock error under the unified time reference;
wherein, the constructing the time scale of the multi-satellite navigation system according to the clock error of each satellite navigation system comprises:
performing phase conversion on the clock error of each satellite navigation system to obtain a frequency observation value of each satellite navigation system;
constructing a clock state equation of each satellite clock, and constructing a clock observation equation based on the clock state equation;
combining satellite clocks corresponding to each navigation satellite and the low-orbit satellite into a clock set, and constructing a state equation of the clock set according to a clock state equation of each satellite clock;
constructing an observation equation of the clock group according to the state equation of the clock group and the frequency observation value of each satellite navigation system;
calculating the frequency sequence of each satellite clock relative to the system time of the satellite navigation system to be constrained according to the observation equation of the clock set;
and calculating the time sequence of each satellite clock relative to the system time according to the frequency sequence, and constructing the time scale according to the time sequence.
2. The method of claim 1, wherein the performing combined precise orbit determination and time synchronization on the navigation satellites and the low-earth orbit satellites in the multi-satellite navigation system according to the ground station observation model and the satellite-borne GNSS observation model to obtain the clock error of each satellite navigation system comprises:
respectively carrying out linearization processing on the ground station observation model and the satellite-borne GNSS observation model according to preset parameter initial values;
calculating the ground station observation model and the satellite-borne GNSS observation model after linearization by adopting a least square method to obtain clock error parameters of each satellite navigation system;
and constraining the clock error parameters of each satellite navigation system to the corresponding navigation ephemeris.
3. The method of claim 1, wherein said calculating a time series of respective satellite clocks relative to the system time from the frequency series comprises:
and performing integral operation on the frequency sequence to obtain a corresponding time sequence of the satellite clock time relative to the system time.
4. The method of claim 1, wherein constraining the time scale to a system time of a satellite navigation system to form a unified time reference for each satellite in the multi-satellite navigation system comprises:
constructing a state equation and an observation equation of a constraint algorithm;
and calculating a time sequence constrained to the system time of a certain satellite navigation system by adopting a Kalman filtering method according to the state equation and the observation equation of the constraint algorithm, and taking the time sequence as a uniform time reference of each satellite in the multi-satellite navigation system.
5. A time reference establishment system for a multi-satellite navigation system, comprising:
the model construction unit is used for acquiring ground station GNSS observation data and satellite-borne GNSS observation data of the multi-satellite navigation system, and constructing a corresponding ground station observation model and a corresponding satellite-borne GNSS observation model according to the ground station GNSS observation data and the satellite-borne GNSS observation data respectively;
the clock error acquisition unit is used for performing combined precise orbit determination and time synchronization on the navigation satellite and the low-orbit satellite in the multi-satellite navigation system according to the ground station observation model and the satellite-borne GNSS observation model to acquire the clock error of each satellite navigation system;
the time scale establishing unit is used for establishing the time scale of the multi-satellite navigation system according to the clock error of each satellite navigation system;
a time reference generating unit, configured to constrain the time scale to a system time of a certain satellite navigation system, and generate a unified time reference for each satellite in the multiple satellite navigation systems, so that each satellite navigation system adds the unified time reference to a corresponding original clock offset, so as to obtain a satellite clock offset under the unified time reference;
the time scale establishing unit comprises:
the phase conversion module is used for carrying out phase conversion on the clock error of each satellite navigation system to obtain a frequency observation value of each satellite navigation system;
the first model building module is used for building a clock state equation of each satellite clock and building a clock observation equation based on the clock state equation;
the second model building module is used for combining the satellite clocks corresponding to the navigation satellites and the low-orbit satellites into a clock set and building a state equation of the clock set according to the clock state equation of each satellite clock;
the third model building module is used for building the observation equation of the clock group according to the state equation of the clock group and the frequency observation value of each satellite navigation system;
the second calculation module is used for calculating the frequency sequence of each satellite clock relative to the system time of the satellite navigation system to be constrained according to the observation equation of the clock set;
and the time scale construction module is used for calculating the time sequence of each satellite clock relative to the system time according to the frequency sequence and constructing the time scale according to the time sequence.
6. The system of claim 5, wherein the clock difference obtaining unit comprises:
the linearization processing module is used for respectively carrying out linearization processing on the ground station observation model and the satellite-borne GNSS observation model according to preset parameter initial values;
the first calculation module is used for calculating the ground station observation model and the satellite-borne GNSS observation model after linearization by adopting a least square method to obtain clock error parameters of each satellite navigation system;
and the constraint processing module is used for constraining the clock error parameters of each satellite navigation system to the corresponding navigation ephemeris.
7. The system according to claim 5, wherein the time scale construction module is configured to integrate the frequency sequence to obtain a time sequence of the corresponding satellite clock time relative to the system time.
8. The system of claim 5, wherein the time reference generation unit comprises:
the fourth model building module is used for building a state equation and an observation equation of the constraint algorithm;
and the third calculation module is used for calculating a time sequence constrained to the system time of a certain satellite navigation system by adopting a Kalman filtering method according to the state equation and the observation equation of the constraint algorithm, and taking the time sequence as a uniform time reference of each satellite in the multi-satellite navigation system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810564951.XA CN108732597B (en) | 2018-06-04 | 2018-06-04 | Method and system for establishing time reference of multi-satellite navigation system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810564951.XA CN108732597B (en) | 2018-06-04 | 2018-06-04 | Method and system for establishing time reference of multi-satellite navigation system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108732597A CN108732597A (en) | 2018-11-02 |
| CN108732597B true CN108732597B (en) | 2020-10-02 |
Family
ID=63931903
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810564951.XA Active CN108732597B (en) | 2018-06-04 | 2018-06-04 | Method and system for establishing time reference of multi-satellite navigation system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108732597B (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109520512A (en) * | 2018-12-28 | 2019-03-26 | 上海海积信息科技股份有限公司 | A kind of precision orbit determination method and device |
| CN109870898B (en) * | 2019-02-27 | 2020-11-17 | 武汉大学 | GNSS time service receiver clock combination regulation and control method and system based on PPP |
| CN110045395B (en) * | 2019-05-17 | 2021-10-08 | 北京和协航电信息科技有限公司 | Target detection method, system and equipment based on navigation satellite signals |
| CN111948686B (en) * | 2020-08-05 | 2024-04-26 | 航天恒星科技有限公司 | Time synchronization method and device |
| CN112325879A (en) * | 2020-11-03 | 2021-02-05 | 中国电子科技集团公司信息科学研究院 | Bionic composite navigation time service microsystem based on multi-source sensor integration |
| CN112445120B (en) * | 2020-11-27 | 2022-04-22 | 西安空间无线电技术研究所 | Distributed center-free space-based time reference establishing and maintaining system |
| CN113253311B (en) * | 2021-04-06 | 2024-02-06 | 探索数据科技(深圳)有限公司 | Combined satellite navigation method, system, electronic equipment and storage medium |
| CN113253314B (en) * | 2021-05-11 | 2023-06-23 | 中国科学院国家授时中心 | Time synchronization method and system between low-orbit satellites |
| CN113341685A (en) * | 2021-06-30 | 2021-09-03 | 北京微纳星空科技有限公司 | Satellite time management method, electronic device and medium |
| CN113608427B (en) * | 2021-07-09 | 2022-07-05 | 中国科学院国家授时中心 | Centralized space-based time reference establishing method |
| CN113640838B (en) * | 2021-08-19 | 2024-06-18 | 中国电力科学研究院有限公司 | Multi-system combined satellite navigation positioning time service device and method |
| CN115639743B (en) * | 2022-10-19 | 2023-05-30 | 中国科学院国家授时中心 | Method and system for establishing space-base time reference based on whole network time comparison |
| CN116299617B (en) * | 2023-02-16 | 2023-10-31 | 北京航空航天大学 | Method for establishing GNSS satellite-ground atomic clock real-time dynamic model |
| CN117377057B (en) * | 2023-12-08 | 2024-02-13 | 中国科学院国家授时中心 | Satellite-ground time synchronization method and system for low-orbit satellite and ground station |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5963167A (en) * | 1996-03-13 | 1999-10-05 | California Institute Of Technology | Analyzing system for global positioning system and general satellite tracking |
| CN102937710A (en) * | 2012-11-13 | 2013-02-20 | 北京空间飞行器总体设计部 | Method for determining user range errors caused by non-ideal characteristics of atomic clocks |
| CN103235321A (en) * | 2013-03-29 | 2013-08-07 | 东南大学 | GPS (global positioning system) pseudo-range positioning precision timing method |
| CN105158780A (en) * | 2015-07-24 | 2015-12-16 | 北京跟踪与通信技术研究所 | Navigation positioning method based on interchangeability of multiple navigation satellites |
| CN105867108A (en) * | 2016-06-20 | 2016-08-17 | 中国科学院国家授时中心 | National standard time remote recurrence method |
| CN106443739A (en) * | 2016-09-09 | 2017-02-22 | 清华大学 | Assisted enhancement navigation method and device |
| CN107153209A (en) * | 2017-07-06 | 2017-09-12 | 武汉大学 | A kind of low rail aeronautical satellite real-time accurate orbit determination method of short arc segments |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101287999B (en) * | 2005-10-03 | 2011-11-02 | 天宝导航有限公司 | Multiple-gnss and fdma high precision carrier-phase based positioning |
| US20150212211A1 (en) * | 2014-01-24 | 2015-07-30 | Qualcomm Incorporated | Methods and systems for multi-gnss operation |
-
2018
- 2018-06-04 CN CN201810564951.XA patent/CN108732597B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5963167A (en) * | 1996-03-13 | 1999-10-05 | California Institute Of Technology | Analyzing system for global positioning system and general satellite tracking |
| CN102937710A (en) * | 2012-11-13 | 2013-02-20 | 北京空间飞行器总体设计部 | Method for determining user range errors caused by non-ideal characteristics of atomic clocks |
| CN103235321A (en) * | 2013-03-29 | 2013-08-07 | 东南大学 | GPS (global positioning system) pseudo-range positioning precision timing method |
| CN105158780A (en) * | 2015-07-24 | 2015-12-16 | 北京跟踪与通信技术研究所 | Navigation positioning method based on interchangeability of multiple navigation satellites |
| CN105867108A (en) * | 2016-06-20 | 2016-08-17 | 中国科学院国家授时中心 | National standard time remote recurrence method |
| CN106443739A (en) * | 2016-09-09 | 2017-02-22 | 清华大学 | Assisted enhancement navigation method and device |
| CN107153209A (en) * | 2017-07-06 | 2017-09-12 | 武汉大学 | A kind of low rail aeronautical satellite real-time accurate orbit determination method of short arc segments |
Non-Patent Citations (6)
| Title |
|---|
| A control theory approach to clock steering techniques;Marcello Farina等;《IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control》;20101231;第57卷(第10期);全文 * |
| Local representations of UTC in national laboratories;Peter B Whibberley等;《Metrologia》;20111231;第48卷(第4期);全文 * |
| 伍贻威等.原子钟两级驾驭算法及在建立GNSS基准中的应用.《电子学报》.2016,第44卷(第7期), * |
| 伽利略系统GSTB-V1的时间尺度算法与实现;郑子扬等;《舰船电子工程》;20081231;第28卷(第10期);全文 * |
| 原子钟两级驾驭算法及在建立GNSS基准中的应用;伍贻威等;《电子学报》;20160731;第44卷(第7期);第1节引言 * |
| 原子钟时间尺度与Kalman滤波器;卫国;《陕西天文台台刊》;19901231;全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108732597A (en) | 2018-11-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108732597B (en) | Method and system for establishing time reference of multi-satellite navigation system | |
| CN111045034B (en) | GNSS multi-system real-time precise time transfer method and system based on broadcast ephemeris | |
| Strasser et al. | Processing of GNSS constellations and ground station networks using the raw observation approach | |
| Haines et al. | One-centimeter orbit determination for Jason-1: new GPS-based strategies | |
| CN103221839B (en) | GNSS signal processing with regional augmentation message | |
| CN102498414B (en) | Gnss signal processing to estimate orbits | |
| Wilson et al. | New and improved-the broadcast interfrequency biases | |
| US8120530B2 (en) | Method and device for using GNSS satellite trajectory extension data in mobile apparatus | |
| CN117388881B (en) | Method and system for tracing satellite-borne atomic clock of low-orbit satellite to UTC (k) | |
| EP3430432A1 (en) | Navigation satellite orbit and low latency clock determination with wide-lane and narrow-lane bias corrections | |
| CN113204042B (en) | Multi-constellation combined train positioning method based on precise single-point positioning | |
| CN109154670A (en) | The wide lane deviation of navigation satellite determines system and method | |
| Hwang et al. | GPS‐Based Orbit Determination for KOMPSAT‐5 Satellite | |
| Li et al. | Precise orbit determination for the FY-3C satellite using onboard BDS and GPS observations from 2013, 2015, and 2017 | |
| CN109212562A (en) | A method of generating carrier wave pseudo range observed quantity | |
| JP2007529010A (en) | A method of performing short-term backup two-frequency navigation when measurement data is not available at one of the two frequencies | |
| CN116299586B (en) | Precise single-point positioning method, receiver, equipment and medium based on broadcast ephemeris | |
| Kuang et al. | Real-time GPS satellite orbit and clock estimation based on OpenMP | |
| Gong et al. | Precise real-time navigation of the small TJU-1 satellite using GPS, GLONASS and BDS | |
| CN117890936B (en) | Low-orbit satellite in-orbit real-time inter-satellite time transfer method and system | |
| Li et al. | Real-time marine PPP-B2b/SINS integrated navigation based on BDS-3 | |
| Fernández et al. | Copernicus POD service operations—Orbital accuracy of Sentinel-1A and Sentinel-2A | |
| Fernández et al. | The Copernicus POD Service | |
| WO2020231641A1 (en) | Methods and enhancing non-global navigation satellite system location and timing pseudorange positioning calculations and systems thereof | |
| CN118033690A (en) | PPP ambiguity fixing method and system based on factor graph optimization solution |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |