CN115567872A - SSR-based virtual observation value calculation method and device and storage medium - Google Patents
SSR-based virtual observation value calculation method and device and storage medium Download PDFInfo
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Abstract
The invention discloses a virtual observed value calculation method and a virtual observed value calculation device based on SSR, wherein the method comprises the following steps: determining a master station according to an ionosphere and a troposphere and calculating pseudo range and phase deviation correction information of the master station; dividing an area to be tested into a plurality of grid points and determining the grid points where users are located and corresponding master stations; and acquiring pseudo range and phase deviation correction information of the corresponding main station, and constructing a virtual observation equation by combining SSR correction information and satellite error correction information to obtain a virtual observation value of the grid point where the user is located. The pseudo range and the phase deviation correction information of the master station are applied to the calculation of the virtual observed value, so that the positioning precision is improved; meanwhile, the area to be measured is divided into a plurality of grid points, the grid points where the area to be measured is located are determined according to the approximate positions of the users, the virtual observed values are calculated, the system performance is improved, meanwhile, the calculation load of the server can be controlled, and the problem that the calculation load of the server is uncontrollable due to the fact that the number of the users is increased is solved. The invention also discloses a storage medium.
Description
Technical Field
The invention relates to the field of space geodetic surveying, in particular to a virtual observation value calculation method and device based on SSR and a storage medium.
Background
At present, in a network RTK (Real-time kinematic carrier phase difference) Positioning technology, an SSR (State Space response, state Space domain) to OSR (Observation domain) technology is adopted to combine the network RTK technology and a PPP (precision Point position) technology to solve the problems of limited operation range, long PPP convergence time and the like of an existing CORS (GNSS Continuously running Reference station), the method firstly calculates a virtual Observation value based on an original Observation equation of a pseudo-range phase, but calculates a satellite geometric distance, an ionosphere delay correction number, a troposphere delay correction number only according to a user's approximate position and SSR correction information when calculating the virtual Observation value, and does not calculate a phase deviation correction number and a phase deviation correction number, resulting in low subsequent Positioning precision. Meanwhile, in the calculation, the virtual observation value is generated based on the approximate position of the user, and if a large number of users perform positioning at the same time, the calculation load of the server is increased, and the data processing is slow.
Disclosure of Invention
In order to overcome the defects of the prior art, one of the purposes of the present invention is to provide a virtual observed value calculation method based on SSR, which can solve the problems that the existing virtual observed value calculation will affect the positioning accuracy and the system performance.
The invention also aims to provide a virtual observation value calculation device based on SSR, which can solve the problems that the existing virtual observation value calculation influences the positioning precision and the system performance.
It is a further object of the present invention to provide a storage medium capable of solving the problems that the conventional calculation of virtual observed values affects the positioning accuracy and the system performance.
One of the purposes of the invention is realized by adopting the following technical scheme:
the SSR-based virtual observation value calculation method comprises the following steps:
and a correction number calculation step: selecting a plurality of reference stations as master stations according to the service ranges of the ionosphere and the troposphere, and calculating pseudo-range deviation correction information and phase deviation correction information of each master station;
a region dividing step: acquiring a region to be detected, dividing the region to be detected into a plurality of grid points, and determining grid points where users are located and a master station corresponding to the grid points where the users are located;
virtual value calculating step: and acquiring pseudo-range deviation correction information and phase deviation correction information of the corresponding master station, constructing a virtual observation equation by combining the SSR correction information and the satellite error correction information, and solving the virtual observation equation to obtain a virtual observation value of the grid point where the user is located.
Further, the method also comprises the following steps: a sending step: and coding the virtual observation value of the grid point where the user is located according to an RTCM coding protocol to generate differential data, and sending the differential data to the user for network RTK positioning.
Further, the step of calculating the correction number specifically includes:
the first step is as follows: obtaining a pseudo-range original observed value of each master station and calculating to obtain all satellite positions according to the pseudo-range observed value of each master station and SSR correction information;
the second step is as follows: calculating the station-satellite geometric distance, the satellite clock error, the troposphere inclination delay error and the ionosphere inclination delay error of each satellite frequency point at the position of each main station according to each satellite position and SSR correction information;
the third step: acquiring a pseudo-range original observation value and a phase original observation value of each satellite frequency point of each master station, and combining the pseudo-range virtual observation value and the phase virtual observation value to obtain pseudo-range deviation correction information and phase deviation correction information of each master station; wherein the content of the first and second substances,
correcting information for pseudorange bias, P i s Is the raw observation of the pseudorange,
for the pseudo-range virtual observations,
in order to correct the information for the phase deviation,
in order to obtain the original observed value of the phase,
is a phase virtual observation.
Further, the virtual value calculating step includes:
a first calculation step: calculating a pseudo-range initial value, a station satellite geometric distance, a satellite position and a satellite clock error according to the coordinates of the grid point where the user is located and the SSR correction information;
an equation construction step: and constructing a virtual observation equation according to the satellite position, the satellite clock error, the station-satellite geometric distance, the satellite error correction information, the pseudo-range deviation correction information of the main station and the phase deviation correction information, and solving the virtual observation equation to obtain a virtual observation value of the grid point where the user is located.
Further, the first calculating step includes:
and a signal emission time calculating step: calculating to obtain signal emission time according to the current observation time and the signal default propagation time in the system;
satellite position and clock error calculation: calculating according to the signal transmitting time and the satellite broadcast ephemeris to obtain the satellite position and the satellite clock error;
and a pseudo-range initial value calculation step: calculating a geometric distance of a satellite to be outbound according to the satellite position, the satellite clock error and the position information of a grid point where a user is located, then calculating a signal propagation time according to the geometric distance of the satellite to be outbound, judging whether the difference value between the signal propagation time and the signal default propagation time in the system is smaller than a preset threshold value, and if so, calculating a pseudo-range initial value according to the geometric distance of the satellite to be outbound and the satellite clock error; if not, updating the default propagation time of the signal in the system according to the signal propagation time and then executing the signal transmission time calculation step;
wherein, the calculation formula of the pseudo-range initial value is as follows: p 0 ＝ρ-cdt s ；
In the formula: p 0 Is the initial value of pseudo range, rho is the geometric distance of the satellite, c is the speed of light, dt s Is the satellite clock error.
Further, the calculating of the pseudorange initial value to obtain the geometric distance of the satellite according to the pseudorange initial value, the satellite position, the satellite clock error and the position information of the grid point where the user is located in the pseudorange initial value calculating step specifically includes:
and (3) correcting: correcting the satellite position and the satellite clock error according to the calculated pseudo-range initial value and the satellite broadcast ephemeris;
a judging step: calculating according to the satellite position to obtain a satellite elevation angle, judging whether the satellite elevation angle meets a cut-off elevation angle or not, and if so, executing a satellite-standing geometric distance calculation step; if not, acquiring the next satellite, recalculating the satellite altitude angle according to the position of the next satellite, and executing a judgment step;
and (3) calculating the geometric distance of the standing satellites: and calculating the geometric distance of the satellite according to the satellite position and the satellite clock error.
Further, the dividing the region to be measured into a plurality of grid points in the region dividing step specifically includes: and dividing the area to be detected into a plurality of square grid points according to the longitude and latitude.
Further, the formula of the virtual observation equation is as follows:
in the formula:
pseudo-range virtual observations are made;
is a phase virtual observation; rho is the geometric distance of the satellite; dt s Is the satellite clock error; t is s Delay correcting information for tropospheric tilt;
delay correcting information for ionospheric tilt;
correcting information for satellite antenna PCV;
correcting information for satellite antenna phase winding;
correcting information for pseudo range deviation;
correcting information for the phase deviation; the ionospheric tilt delay correction information is obtained from ionospheric correction information in the SSR correction information; the troposphere inclination delay correction information is obtained from troposphere correction information in SSR correction information; and the PCV correction information and the phase winding correction information of the satellite antenna are obtained from satellite antenna files.
The second purpose of the invention is realized by adopting the following technical scheme:
an SSR-based virtual observation calculation device comprising a memory having stored thereon a virtual observation calculation program running on a processor, the virtual observation calculation program being a computer program, and a processor that implements the steps of an SSR-based virtual observation calculation method as employed by one of the objects of the present invention when executing the virtual observation calculation program.
The third purpose of the invention is realized by adopting the following technical scheme:
a storage medium that is a computer-readable storage medium having stored thereon a computer program that is a virtual observation calculation program that, when executed by a processor, implements the steps of an SSR-based virtual observation calculation method as employed by one of the objects of the present invention.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, the area closest to the user is divided according to the position of the user, and the service of the virtual reference station is provided for the user, so that the problem of increased calculation load of the server caused by large number of users is avoided; meanwhile, when the virtual observation deviation of the master station is calculated, the position of a user is considered, and meanwhile, the pseudo range and the phase deviation of the master station are calculated, so that the positioning accuracy of the network RTK is improved.
Drawings
FIG. 1 is a flow chart of a method for calculating a virtual observation value based on SSR provided by the present invention;
FIG. 2 is a flowchart of step S1 in FIG. 1;
FIG. 3 is a flowchart of step S3 in FIG. 1;
fig. 4 is a flowchart of step S31 in fig. 3.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and the detailed description, and it should be noted that any combination of the embodiments or technical features described below can be used to form a new embodiment without conflict.
Example one
As shown in fig. 1, the invention provides a virtual observed value calculation method based on SSR, which includes two parts, that is, calculating a pseudo-range phase correction of a master station, dividing a measurement area, determining the master station according to a user location, and calculating a corresponding virtual observed value according to the pseudo-range phase correction of the master station, so as to perform subsequent network RTK positioning. Specifically, the method comprises the following steps:
s1, selecting a plurality of reference stations as the master stations according to the service ranges of the ionosphere and the troposphere, and calculating a pseudo-range deviation correction number and a phase deviation correction number of each master station.
The master station is a reference station capable of providing phase deviation correction information and pseudo-range deviation correction information, and is a region to be measured.
And adding the pseudo-range deviation correction information and the phase deviation correction information of the master station into the calculation of the virtual observed value so as to improve the positioning accuracy.
And S2, acquiring a region to be detected, dividing the region to be detected into a plurality of grid points, and determining the grid point where the user is located and a corresponding main station of the grid point where the user is located.
The invention can reduce the complexity of data processing by dividing the grid points of the region to be detected. Specifically, the area to be measured is divided into a plurality of square grid points according to the longitude and latitude. Each grid point corresponds to a serving master station.
In addition, when the grid point is determined, the grid point is also determined according to the approximate position of the user, wherein the approximate position of the user refers to an approximate rough position and can be estimated.
Each grid point also has coordinate information, that is, position information of the grid point, which indicates a coordinate range of the square region corresponding to the grid point. Specifically, the coordinate range of each grid point can be defined by representing the coordinate values of four points of the square area.
When the master station is selected, the master station closest to the lattice point is selected, and meanwhile, the problem that the calculation load of the server is increased due to the fact that the number of users is increased in the prior art can be solved through the area measurement division.
And S3, acquiring pseudo-range deviation correction information and phase deviation correction information of a main station corresponding to the grid point where the user is located, constructing a virtual observation equation by combining the SSR correction information and the satellite error correction information, and solving the virtual observation equation to obtain a virtual observation value of the grid point where the user is located.
And S4, sending the calculated virtual observation value of the grid point where the user is located to the user for network RTK positioning.
Specifically, the virtual observation value of the grid point where the user is located is encoded according to an RTCM (Radio Technical Commission for landmark services) encoding protocol to generate differential data, and then the differential data is sent to the user for network RTK positioning. Further, as shown in fig. 2, the step S1 includes the steps of:
and S11, obtaining the pseudo-range original observed value of each main station and calculating to obtain all satellite positions according to the pseudo-range original observed value of the corresponding main station and SSR correction information.
The SSR correction information comprises satellite orbit correction information, satellite clock error correction information, ionosphere correction information and troposphere correction information, and can be obtained according to service areas capable of providing ionosphere and convection processes for the main station. Specifically, the data can be calculated according to the observation data of the base station and then broadcasted through a corresponding algorithm.
And S12, calculating the station-satellite geometric distance, the satellite clock error, the troposphere inclination delay error and the ionosphere inclination delay error of each satellite frequency point at the position of each main station according to the position of each satellite and the SSR correction information. For a GPS, there are three frequency points, L1, L2, and L5, which may specifically refer to a RINEX data format or an interface file of a corresponding system.
And S13, obtaining a pseudo-range original observation value and a phase original observation value of each satellite frequency point of each master station, and calculating pseudo-range deviation correction information and phase deviation correction information of the master station according to the pseudo-range virtual observation value and the phase virtual observation value.
The pseudo-range original observation value and the phase original observation value are obtained through detection of a GNSS receiver of the master station.
The pseudo-range virtual observation value and the phase virtual observation value refer to parameters of the pseudo-range observation value and the phase observation value which are not modeled, for example, for the pseudo-range, the pseudo-range virtual observation value and the phase virtual observation value include a receiver clock error, a receiver-side hardware delay and a satellite-side hardware delay, and the phase includes an ambiguity parameter.
Preferably, the calculation formula of the pseudo-range deviation correction information and the phase deviation correction information is as follows:
in the formula:
correcting information for pseudorange bias, P i s Is the raw observation of the pseudorange,
for the pseudo-range virtual observations of the pseudo-range,
in order to correct the information for the phase deviation,
in order to obtain the original observed value of the phase,
is a phase virtual observation.
That is, the pseudo-range deviation correction information and the phase deviation correction information of the master station can be obtained by calculating the master station, and meanwhile, data such as the geometric distance of the satellite, the clock error of the satellite, the inclination delay error of the troposphere, the inclination delay error of the ionosphere and the like can also be obtained.
Preferably, as shown in fig. 3, step S3 specifically includes:
and S31, calculating to obtain a pseudo-range initial value, a station satellite geometric distance, a satellite position and a satellite clock error according to the coordinates of the grid point where the user is located and the SSR correction information.
And S32, constructing a virtual observation equation according to the satellite position, the satellite clock error, the station-satellite geometric distance, the satellite error correction information and the pseudo-range phase deviation correction number of the master station, and solving the virtual observation equation to obtain a virtual observation value of the grid point where the user is located.
The satellite error correction information includes satellite antenna phase wrapping correction information, satellite antenna PCV correction information, troposphere tilt delay correction information, and ionosphere tilt delay correction information. Wherein the ionospheric tilt delay correction information is obtained from ionospheric correction information in the SSR correction information; tropospheric tilt delay correction information is derived from tropospheric correction information in the SSR correction information; the PCV correction information and the phase winding correction information of the satellite antenna are obtained from satellite antenna files.
The pseudo range refers to an approximate distance between a ground receiver and a satellite in a satellite positioning process, so that a pseudo range initial value is calculated according to SSR correction information and position information of a lattice point where a user is located.
Preferably, the present invention further provides a method for calculating an initial value of a pseudorange, as shown in fig. 4, where step S31 includes:
and step S311, calculating the signal emission time according to the current observation time and the signal default propagation time in the system.
Preferably, the initial value of the signal default propagation time may be preset, for example, set to 0.08s.
And step S312, calculating the satellite position and the satellite clock error according to the signal transmitting time and the satellite broadcast ephemeris.
And step S313, calculating the geometric distance of the satellite to be stopped according to the satellite position, the satellite clock error and the position information of the grid point where the user is located, and then calculating the signal propagation time according to the geometric distance of the satellite to be stopped.
Step S314, judging whether the difference value between the signal propagation time and the signal default propagation time in the system is smaller than a preset threshold value, if so, executing step S315; if not, the default propagation time of the signal in the system is updated according to the signal propagation time, and then step S311 is executed.
And step S315, calculating a pseudo-range initial value according to the station satellite geometric distance and the satellite clock error.
Wherein, the calculation formula of the pseudo-range initial value is as follows: p 0 ＝ρ-cdt s 。
In the formula: p 0 Is the initial value of pseudo range, rho is the geometric distance of the satellite, c is the speed of light, dt s Is the satellite clock error.
Wherein, the step S313 of calculating the geometric distance of the satellite specifically includes: firstly, correcting the satellite position and the satellite clock error according to the calculated pseudo-range initial value and the satellite broadcast ephemeris, then calculating the satellite altitude angle according to the satellite position, judging whether the satellite altitude angle meets a cut-off altitude angle, and if so, calculating the geometric distance of a satellite according to the satellite position and the satellite clock error; if not, acquiring the next satellite, recalculating the satellite altitude according to the position of the next satellite, and then judging until the condition is met.
The altitude angle refers to an included angle between a connecting line of the satellite and the receiver and a horizontal plane, and the value range is [0,90 ]. And the cut-off altitude angle is a threshold value, and when the altitude angle of the satellite is lower than the threshold value, the satellite does not participate in data processing, and is rejected. Because the altitude angle of the satellite is low when the satellite just enters or leaves the visual field, the data is noisy, and the satellite is not suitable for satellite navigation positioning, and the satellite needs to be eliminated, the satellite with the altitude angle which does not meet the requirement needs to be eliminated when the satellite geometric distance is calculated.
Further, the invention also provides a virtual observation equation, such as formula (2):
wherein the content of the first and second substances,
pseudo-range virtual observations;
a phase virtual observation value; rho is the geometric distance of the satellite; dt s Is the satellite clock error; t is s Delay correcting information for tropospheric tilt;
delay correcting information for ionospheric tilt;
correcting information for satellite antenna PCV;
correcting information for satellite antenna phase winding; d s Correcting information for pseudo range deviation; b s Is phase deviation correction information.
The virtual observation value of the grid point where the user is located can be obtained by solving the formula (2), and the pseudo-range phase deviation correction information of the master station is taken into account when the virtual observation value of the grid point is calculated, so that the accuracy of subsequent positioning can be improved. Meanwhile, the area to be measured is divided into a plurality of square grid points according to the longitude and latitude, then the grid point where the user is located and the corresponding master station are determined, the pseudo-range phase deviation correction information of the master station is combined to realize the virtual observation value of the grid point where the user is located, and the problem that the server load is increased due to the existence of a large number of users can be avoided through area division. That is, after the area is divided, the maximum computation load of the server is inevitably determined, so that the maximum computation load of the server is controllable, and the server is not overloaded. Meanwhile, the invention also adds the step of matching the corresponding master station according to the position of the user to realize the calculation of the pseudo range deviation and the phase deviation of the master station, thereby avoiding the problem of non-uniform reference caused by the locality of the pseudo range and the phase deviation, and improving the positioning precision of the user in the network RTK positioning.
Example two
An SSR-based virtual observation calculation device comprising a memory and a processor, the memory having stored thereon a virtual observation calculation program running on the processor, the virtual observation calculation program being a computer program, the processor implementing the following steps when executing the virtual observation calculation program:
and a correction number calculation step: selecting a plurality of reference stations as master stations according to the service ranges of the ionosphere and the troposphere, and calculating pseudo-range deviation correction information and phase deviation correction information of each master station;
a region dividing step: obtaining a region to be detected, dividing the region to be detected into a plurality of grid points, and determining grid points where users are located and a main station corresponding to the grid points where the users are located;
virtual value calculating step: and acquiring pseudo-range deviation correction information and phase deviation correction information of the corresponding master station, constructing a virtual observation equation by combining the SSR correction information and the satellite error correction information, and solving the virtual observation equation to obtain a virtual observation value of the grid point where the user is located.
Further, still include: a sending step: and coding the virtual observation value of the grid point where the user is located according to an RTCM coding protocol to generate differential data, and sending the differential data to the user for network RTK positioning.
Further, the correction number calculating step specifically includes:
the first step is as follows: obtaining a pseudo-range original observed value of each master station and calculating to obtain all satellite positions according to the pseudo-range observed value of each master station and SSR correction information;
the second step is as follows: calculating the station-satellite geometric distance, the satellite clock error, the troposphere inclination delay error and the ionosphere inclination delay error of each satellite frequency point at the position of each main station according to each satellite position and SSR correction information;
the third step: acquiring a pseudo-range original observation value and a phase original observation value of each satellite frequency point of each master station, and combining the pseudo-range virtual observation value and the phase virtual observation value to obtain pseudo-range deviation correction information and phase deviation correction information of each master station; wherein the content of the first and second substances,
correcting information for pseudorange bias, P i s Is the raw observation of the pseudorange,
for the pseudo-range virtual observations,
in order to correct the information for the phase deviation,
in order to obtain the original observed value of the phase,
is a phase virtual observation.
Further, the virtual value calculating step includes:
a first calculation step: calculating a pseudo-range initial value, a station satellite geometric distance, a satellite position and a satellite clock error according to the coordinates of the grid point where the user is located and the SSR correction information;
an equation construction step: and constructing a virtual observation equation according to the satellite position, the satellite clock error, the station-satellite geometric distance, the satellite error correction information, the pseudo-range deviation correction information of the main station and the phase deviation correction information, and solving the virtual observation equation to obtain a virtual observation value of the grid point where the user is located.
Further, the first calculating step includes:
and a signal emission time calculation step: calculating to obtain signal emission time according to the current observation time and the signal default propagation time in the system;
satellite position and clock error calculation: calculating according to the signal transmitting time and the satellite broadcast ephemeris to obtain the satellite position and the satellite clock error;
and a pseudo-range initial value calculation step: calculating a geometric distance of a satellite to be outbound according to the satellite position, the satellite clock error and the position information of a grid point where a user is located, then calculating a signal propagation time according to the geometric distance of the satellite to be outbound, judging whether the difference value between the signal propagation time and the signal default propagation time in the system is smaller than a preset threshold value, and if so, calculating a pseudo-range initial value according to the geometric distance of the satellite to be outbound and the satellite clock error; if not, updating the default propagation time of the signal in the system according to the signal propagation time and then executing the signal transmission time calculation step;
wherein, the calculation formula of the pseudo-range initial value is as follows: p 0 ＝ρ-cdt s ；
In the formula: p is 0 Is the initial value of pseudo range, rho is the geometric distance of the satellite, c is the speed of light, dt s Is the satellite clock error.
Further, the calculating of the pseudorange initial value to obtain the geometric distance of the satellite according to the pseudorange initial value, the satellite position, the satellite clock error and the position information of the grid point where the user is located in the pseudorange initial value calculating step specifically includes:
and a correction step: correcting the satellite position and the satellite clock error according to the calculated pseudo-range initial value and the satellite broadcast ephemeris;
a judging step: calculating according to the satellite position to obtain a satellite elevation angle, judging whether the satellite elevation angle meets a cut-off elevation angle or not, and if so, executing a satellite-standing geometric distance calculation step; if not, acquiring the next satellite, recalculating the satellite altitude according to the position of the next satellite, and then executing a judgment step;
and (3) calculating the geometric distance of the standing satellites: and calculating the geometric distance of the satellite according to the satellite position and the satellite clock error.
Further, the dividing the region to be measured into a plurality of grid points in the region dividing step specifically includes: and dividing the area to be measured into a plurality of square grid points according to the longitude and latitude.
Further, the formula of the virtual observation equation is as follows:
in the formula:
pseudo-range virtual observations;
is a phase virtual observation; rho is the geometric distance of the satellite; dt s Is the satellite clock error; t is s Delay correcting information for tropospheric tilt;
delay correcting information for ionospheric tilt;
correcting information for satellite antenna PCV;
correcting information for satellite antenna phase winding;
correcting information for pseudo range deviation;
correcting information for the phase deviation; the ionospheric tilt delay correction information is obtained from ionospheric correction information in the SSR correction information; the troposphere inclination delay correction information is obtained from troposphere correction information in SSR correction information; and the PCV correction information and the phase winding correction information of the satellite antenna are obtained from satellite antenna files.
EXAMPLE III
A storage medium that is a computer-readable storage medium having stored thereon a computer program that is a virtual observation calculation program that, when executed by a processor, implements the steps of:
and a correction number calculation step: selecting a plurality of reference stations as master stations according to the service ranges of the ionosphere and the troposphere, and calculating pseudo-range deviation correction information and phase deviation correction information of each master station;
a region dividing step: acquiring a region to be detected, dividing the region to be detected into a plurality of grid points, and determining grid points where users are located and a master station corresponding to the grid points where the users are located;
virtual value calculating step: and acquiring pseudo-range deviation correction information and phase deviation correction information of the corresponding master station, constructing a virtual observation equation by combining the SSR correction information and the satellite error correction information, and solving the virtual observation equation to obtain a virtual observation value of the grid point where the user is located.
Further, still include: a sending step: and coding the virtual observation value of the grid point where the user is located according to an RTCM coding protocol to generate differential data, and sending the differential data to the user for network RTK positioning.
Further, the correction number calculating step specifically includes:
the first step is as follows: obtaining a pseudo-range original observed value of each master station and calculating to obtain all satellite positions according to the pseudo-range observed value of each master station and SSR correction information;
the second step is as follows: calculating the station-satellite geometric distance, the satellite clock error, the troposphere inclination delay error and the ionosphere inclination delay error of each satellite frequency point at the position of each master station according to the position of each satellite and the SSR correction information;
the third step: acquiring a pseudo-range original observation value and a phase original observation value of each satellite frequency point of each master station, and combining the pseudo-range virtual observation value and the phase virtual observation value to obtain pseudo-range deviation correction information and phase deviation correction information of each master station; wherein the content of the first and second substances,
correcting information for pseudorange bias, P i s Is the original observed value of the pseudo range,
for the pseudo-range virtual observations of the pseudo-range,
in order to correct the information for the phase deviation,
in order to obtain the original observed value of the phase,
is a phase virtual observation.
Further, the virtual value calculating step includes:
a first calculation step: calculating a pseudo-range initial value, a station satellite geometric distance, a satellite position and a satellite clock error according to the coordinates of the grid point where the user is located and the SSR correction information;
an equation construction step: and constructing a virtual observation equation according to the satellite position, the satellite clock error, the station-satellite geometric distance, the satellite error correction information, the pseudo-range deviation correction information of the main station and the phase deviation correction information, and solving the virtual observation equation to obtain a virtual observation value of the grid point where the user is located.
Further, the first calculating step includes:
and a signal emission time calculation step: calculating to obtain signal emission time according to the current observation time and the signal default propagation time in the system;
satellite position and clock error calculation: calculating according to the signal transmitting time and the satellite broadcast ephemeris to obtain a satellite position and a satellite clock error;
and a pseudo-range initial value calculation step: calculating a geometric distance of a satellite to be outbound according to the satellite position, the satellite clock error and the position information of a grid point where a user is located, then calculating a signal propagation time according to the geometric distance of the satellite to be outbound, judging whether the difference value between the signal propagation time and the signal default propagation time in the system is smaller than a preset threshold value, and if so, calculating a pseudo-range initial value according to the geometric distance of the satellite to be outbound and the satellite clock error; if not, updating the default propagation time of the signal in the system according to the signal propagation time and then executing the signal transmission time calculation step;
wherein, the calculation formula of the pseudo-range initial value is as follows: p 0 ＝ρ-cdt s ；
In the formula: p 0 As initial value of pseudo range, rho is geometric distance of satellite, c is speed of light，dt s Is the satellite clock error.
Further, the calculating of the pseudorange initial value to obtain the geometric distance of the satellite according to the pseudorange initial value, the satellite position, the satellite clock error and the position information of the grid point where the user is located in the pseudorange initial value calculating step specifically includes:
and (3) correcting: correcting the satellite position and the satellite clock error according to the calculated pseudo-range initial value and the satellite broadcast ephemeris;
a judging step: calculating according to the satellite position to obtain a satellite elevation angle, judging whether the satellite elevation angle meets a cut-off elevation angle or not, and if so, executing a satellite-standing geometric distance calculation step; if not, acquiring the next satellite, recalculating the satellite altitude according to the position of the next satellite, and then executing a judgment step;
and a step of calculating the geometric distance between the standing satellites: and calculating the geometric distance of the satellite according to the satellite position and the satellite clock error.
Further, the dividing the region to be measured into a plurality of grid points in the region dividing step specifically includes: and dividing the area to be detected into a plurality of square grid points according to the longitude and latitude.
Further, the formula of the virtual observation equation is:
in the formula:
pseudo-range virtual observations;
is a phase virtual observation; rho is the geometric distance of the satellite; dt s Is the satellite clock error; t is s Delay correcting information for tropospheric tilt;
delay correcting information for ionospheric tilt;
correcting information for satellite antenna PCV;
correcting information for satellite antenna phase winding;
correcting information for pseudo range deviation;
correcting information for the phase deviation; the ionospheric tilt delay correction information is obtained from ionospheric correction information in the SSR correction information; the troposphere inclination delay correction information is obtained from troposphere correction information in SSR correction information; and the PCV correction information and the phase winding correction information of the satellite antenna are obtained from satellite antenna files.
The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are within the protection scope of the present invention.
Claims (10)
1. The SSR-based virtual observation value calculation method is characterized by comprising the following steps:
and a correction number calculation step: selecting a plurality of reference stations as master stations according to the service ranges of the ionosphere and the troposphere, and calculating pseudo-range deviation correction information and phase deviation correction information of each master station;
a region dividing step: obtaining a region to be detected, dividing the region to be detected into a plurality of grid points, and determining grid points where users are located and a main station corresponding to the grid points where the users are located;
virtual value calculating step: and acquiring pseudo-range deviation correction information and phase deviation correction information of the corresponding master station, constructing a virtual observation equation by combining the SSR correction information and the satellite error correction information, and solving the virtual observation equation to obtain a virtual observation value of the grid point where the user is located.
2. A method of calculating a virtual SSR-based observation according to claim 1 further comprising: a sending step: and coding the virtual observation value of the grid point where the user is located according to an RTCM coding protocol to generate differential data, and sending the differential data to the user for network RTK positioning.
3. An SSR-based virtual observation calculation method according to claim 1, characterized in that said correction number calculation step specifically comprises:
the first step is as follows: acquiring a pseudo-range original observed value of each master station, and calculating to obtain all satellite positions according to the pseudo-range observed value and SSR correction information of each master station;
the second step is as follows: calculating the station-satellite geometric distance, the satellite clock error, the troposphere inclination delay error and the ionosphere inclination delay error of each satellite frequency point at the position of each main station according to each satellite position and SSR correction information;
the third step: acquiring a pseudo-range original observation value and a phase original observation value of each satellite frequency point of each master station, and combining the pseudo-range virtual observation value and the phase virtual observation value to obtain pseudo-range deviation correction information and phase deviation correction information of each master station; wherein the content of the first and second substances,
correcting information for pseudorange bias, P i s Is the raw observation of the pseudorange,
for the pseudo-range virtual observations,
in order to correct the information for the phase deviation,
in order to obtain the original observed value of the phase,
is a phase virtual observation.
4. A method of virtual SSR-based observation computation according to claim 1 wherein said virtual value computation step comprises:
a first calculation step: calculating a pseudo-range initial value, a station satellite geometric distance, a satellite position and a satellite clock error according to the coordinates of the grid point where the user is located and the SSR correction information;
an equation construction step: and constructing a virtual observation equation according to the satellite position, the satellite clock error, the station-satellite geometric distance, the satellite error correction information, the pseudo-range deviation correction information of the main station and the phase deviation correction information, and solving the virtual observation equation to obtain a virtual observation value of the grid point where the user is located.
5. A method of calculating a virtual SSR-based observation according to claim 4 wherein said first calculating step comprises:
and a signal emission time calculation step: calculating to obtain signal transmitting time according to the current observation time and the signal default propagation time in the system;
satellite position and clock error calculation: calculating according to the signal transmitting time and the satellite broadcast ephemeris to obtain a satellite position and a satellite clock error;
and a pseudo-range initial value calculation step: calculating a geometric distance of a satellite to be outbound according to the satellite position, the satellite clock error and the position information of a grid point where a user is located, then calculating a signal propagation time according to the geometric distance of the satellite to be outbound, judging whether the difference value between the signal propagation time and the signal default propagation time in the system is smaller than a preset threshold value, and if so, calculating a pseudo-range initial value according to the geometric distance of the satellite to be outbound and the satellite clock error; if not, updating the default propagation time of the signal in the system according to the signal propagation time, and then executing a signal transmission time calculation step;
wherein, the calculation formula of the pseudo-range initial value is as follows: p 0 ＝ρ-cdt s ；
In the formula: p 0 Is the initial value of pseudo range, rho is the geometric distance of the satellite, c is the speed of light, dt s Is the satellite clock error.
6. An SSR-based virtual observation calculation method according to claim 5, wherein the pseudo-range initial value calculation step of calculating the geometric distance of the satellite according to the pseudo-range initial value, the satellite position, the satellite clock error and the position information of the grid point where the user is located specifically comprises:
and (3) correcting: correcting the satellite position and the satellite clock error according to the calculated pseudo-range initial value and the satellite broadcast ephemeris;
a judging step: calculating according to the satellite position to obtain a satellite elevation angle, judging whether the satellite elevation angle meets a cut-off elevation angle or not, and if so, executing a satellite-standing geometric distance calculation step; if not, acquiring the next satellite, recalculating the satellite altitude according to the position of the next satellite, and then executing a judgment step;
and (3) calculating the geometric distance of the standing satellites: and calculating the geometric distance of the satellite according to the satellite position and the satellite clock error.
7. An SSR-based virtual observation calculation method according to claim 1, wherein said dividing the area to be measured into a plurality of grid points in said area dividing step specifically comprises: and dividing the area to be detected into a plurality of square grid points according to the longitude and latitude.
8. A method of calculating a virtual observation based on an SSR according to claim 1 wherein the formula of the virtual observation equation is:
in the formula:
pseudo-range virtual observations;
is a phase virtual observation; rho is the geometric distance of the satellite; dt s Is the satellite clock error; t is a unit of s Delay correcting information for tropospheric tilt;
delay correcting information for ionospheric tilt;
correcting information for satellite antenna PCV;
correcting information for satellite antenna phase winding;
correcting information for pseudo range deviation;
correcting information for the phase deviation; the ionospheric tilt delay correction information is obtained from ionospheric correction information in the SSR correction information; the troposphere inclination delay correction information is obtained from troposphere correction information in SSR correction information; and the PCV correction information and the phase winding correction information of the satellite antenna are obtained from satellite antenna files.
9. An SSR-based virtual observation computation apparatus comprising a memory and a processor, the memory having stored thereon a virtual observation computation program running on the processor, the virtual observation computation program being a computer program, characterized in that the processor, when executing the virtual observation computation program, implements the steps of the SSR-based virtual observation computation method according to any one of claims 1-8.
10. A storage medium being a computer readable storage medium having stored thereon a computer program being a virtual observations calculation program, wherein the virtual observations calculation program when executed by a processor implements the steps of a SSR-based virtual observations calculation method according to any one of claims 1-8.
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