CN111624630B - GNSS-based satellite selection method and device, terminal and storage medium - Google Patents
GNSS-based satellite selection method and device, terminal and storage medium Download PDFInfo
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- CN111624630B CN111624630B CN201910152514.1A CN201910152514A CN111624630B CN 111624630 B CN111624630 B CN 111624630B CN 201910152514 A CN201910152514 A CN 201910152514A CN 111624630 B CN111624630 B CN 111624630B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—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
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
- G01S19/28—Satellite selection
Abstract
The invention discloses a satellite selection method, a satellite selection device, a satellite selection terminal and a storage medium based on GNSS, and belongs to the technical field of navigation. The method comprises the following steps: calculating the clock error of the receiver and the position of a user according to the navigation message and the observed quantity of the satellite in the sight distance; calculating the observation residual error of the uncertain satellite according to the clock error of the receiver and the user position; and determining the uncertain satellite and the in-line-of-sight satellite of which the observation residual meets the first threshold condition as the observation satellite. The method determines the type of the tracked satellite according to the estimated position and map information of the user, calculates the clock error of the receiver and the position of the user according to the navigation message and the observed quantity of the satellite in the sight distance, and further takes the satellite in the sight distance as the observation satellite, wherein the observation residual error value meets a first threshold condition. Because the selection is carried out according to the map information, unreliable satellites can be eliminated, the observation quality of the selected satellites is improved, more accurate positioning can be realized in the urban environment, and the method can be widely applied to handheld equipment, vehicle-mounted systems and the like.
Description
Technical Field
The invention relates to the technical field of navigation, in particular to a satellite selection method, a satellite selection device, a satellite selection terminal and a storage medium based on GNSS.
Background
When positioning is performed based on a GNSS (Global Navigation Satellite System), a process of selecting a suitable Satellite to participate in user position calculation is called Satellite selection. The satellite selection is carried out based on the GNSS, satellites with poor observation quality can be removed, error introduction is reduced, the most appropriate satellite distribution can be selected, and the influence of errors in satellite observation quantity on the position of a user is reduced.
In the related art, when satellite selection is performed based on a GNSS, the following method is mainly adopted: and acquiring the elevation angle and the satellite signal carrier-to-noise ratio of each tracked satellite, and determining the satellite as the selected observation satellite if the elevation angle of any satellite is greater than a first preset value and/or the satellite signal carrier-to-noise ratio is greater than a second preset value.
However, in urban environments, due to the existence of buildings, problems such as occlusion and multipath may occur, resulting in poor observation quality of the observation satellite selected according to the elevation angle and the carrier-to-noise ratio of the satellite signal. For example, a satellite with a higher elevation angle in the direction occluded by a building may have a poorer quality of view than a satellite with a lower elevation angle in the non-occluded direction.
Disclosure of Invention
In order to solve the problems of the related art, embodiments of the present invention provide a method, an apparatus, a terminal and a storage medium for selecting a satellite based on a GNSS. The technical scheme is as follows:
in one aspect, a GNSS-based satellite selection method is provided, and the method includes:
determining the type of a tracked satellite according to the estimated position of a user and map information, wherein the type comprises an in-sight satellite, an out-sight satellite and an uncertain satellite;
calculating the clock error of the receiver and the position of a user according to the navigation message and the observed quantity of the satellite in the sight distance;
calculating the observation residual error of the uncertain satellite according to the receiver clock error and the user position;
and determining the uncertain satellite and the in-line-of-sight satellite of which the observation residual meets the first threshold condition as the observation satellite.
In another aspect, a GNSS-based satellite selection apparatus is provided, the apparatus including:
the first determining module is used for determining the type of the tracked satellite according to the estimated position of the user and the map information, wherein the type comprises an in-sight satellite, an out-sight satellite and an uncertain satellite;
the first calculation module is used for calculating the clock error of the receiver and the position of a user according to the navigation message and the observed quantity of the satellite in the sight distance;
the second calculation module is used for calculating the observation residual error of the uncertain satellite according to the receiver clock error and the user position;
and the second determining module is used for determining the uncertain satellite and the in-line-of-sight satellite of which the observation residual meets the first threshold value condition as the observation satellite.
In another aspect, a terminal is provided that includes a processor and a memory having at least one instruction, at least one program, set of codes, or set of instructions stored therein, which is loaded and executed by the processor to implement a GNSS based satellite selection method.
In another aspect, a computer-readable storage medium having stored therein at least one instruction, at least one program, a set of codes, or a set of instructions, loaded and executed by a processor to implement a GNSS based satellite selection method is provided.
The technical scheme provided by the embodiment of the invention has the following beneficial effects:
determining the type of the tracked satellite according to the estimated position and map information of the user, calculating the clock error of the receiver and the position of the user according to the navigation message and the observed quantity of the satellite in the sight distance, and taking the satellite in the sight distance as an observation satellite when the observation residual value meets a first threshold condition. Because the selection is carried out according to the map information, unreliable satellites can be eliminated, the observation quality of the selected satellites is improved, and more accurate positioning can be realized in the urban environment.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is an architecture diagram of positioning based on a GNSS system according to an embodiment of the present invention;
fig. 2 is an application scenario diagram according to an embodiment of the present invention;
FIG. 3 is a flowchart of a GNSS-based satellite selection method according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an elevation angle of a satellite provided by an embodiment of the present invention;
FIG. 5 is a schematic diagram of determining whether a satellite is occluded based on a map plane according to an embodiment of the present invention;
FIG. 6 is a diagram illustrating a GNSS based satellite selection process according to an embodiment of the present invention;
FIG. 7 is a schematic structural diagram of a GNSS-based satellite selection apparatus according to an embodiment of the present invention;
fig. 8 is a block diagram illustrating a terminal according to an exemplary embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Before the method provided by the embodiment of the present invention is executed, the terms used in the embodiment of the present invention are explained.
GDOP: the Geometric Dilution Precision (Geometric Precision factor) is a very important coefficient for measuring the Positioning Precision, and represents a distance vector amplification factor between a receiver and a space satellite caused by a GPS (Global Positioning System) ranging error. The volumetric volume delineated by the unit vector from the receiver to the space satellite characterizing the participating positioning solution is inversely proportional to GDOP, and is also referred to as the geometric dilution of precision factor. In fact, the satellites are concentrated in a region in spatial distribution, and the more similar the angles from the receivers to the satellites, the larger the value of GDOP, the smaller the unit vector volume represented, and the GDOP at this time may cause the positioning accuracy to deteriorate. On the contrary, the satellites are not concentrated in one area in the spatial distribution and can be uniformly distributed in different azimuth areas, the larger the angle difference between the receiver and the spatial satellite is, the smaller the value of the GDOP is, the larger the volume of the unit vector body represented by the GDOP is, and the higher the positioning accuracy is caused by the GDOP at the moment.
Satellite signal carrier-to-noise ratio: the parameters given by the baseband part of the GNSS receiver measure the strength of each satellite signal, which is an inherent parameter in the embodiment of the present invention.
Pseudo range: in the satellite positioning process, the GNSS receiver calculates the distance between the receiver and the satellite including errors such as a receiver clock.
Receiver clock error: the difference between the clock of the receiver and the satellite standard clock.
For GNSS based implementations of positioning, GNSS receiver software is required for processing. The GNSS receiver software is divided into a baseband part and a resolving part. The baseband part is used for demodulating the received navigation message of the satellite and acquiring satellite coordinates, error correction information and the like from the navigation message; and the resolving part is responsible for solving the coordinates of the user position according to the observed quantity and the satellite coordinates. The observations include pseudorange observations, phase measurements, doppler measurements, and the like. The pseudo-range observed quantity is obtained by the product of the light speed and the difference between the signal receiving time of the navigation message and the signal sending time of the navigation message, and the measured reference of the signal receiving time of the navigation message is the clock of the receiver, the measured reference of the signal sending time of the navigation message is the atomic clock of the GNSS system, and the signal sending time of the navigation message is more accurate relative to the signal receiving time of the navigation message, so that the coordinate of the position of the user and the receiver clock difference between the clock of the receiver and the clock of the GNSS system can be used as unknowns to solve.
For each satellite, an equation may be formed that takes the coordinates of the user's position and the receiver clock error as unknowns, based on the relationship between the distance between the coordinates of the user's position and the satellite coordinates and the pseudorange observations. By solving these equations in a simultaneous manner into a system of equations, the coordinates of the receiver clock error and the user position can be obtained. When the equation set is established, the equations corresponding to which satellites are selected to form the equation set, which is actually the satellite selection process. The main objective of satellite selection is to select satellites with good observation quality and reliability as much as possible.
Currently, when satellite selection is performed based on GNSS in the related art, the following two methods can be adopted:
the first method is to select according to the satellite elevation angle and the satellite signal carrier-to-noise ratio. The elevation angle of the satellite is compared with a first preset value, the carrier-to-noise ratio of the satellite signal is compared with a second preset value, and when the elevation angle of the satellite is larger than the first preset value, for example, 10 degrees, and/or the carrier-to-noise ratio of the satellite signal is larger than the second preset value, the satellite is determined as an observation satellite.
The second method selects a satellite combination with the minimum GDOP factor according to a certain empirical strategy, and determines the satellites in the combination as observation satellites. For example, 1 satellite with the highest elevation angle and at least 3 satellites with the middle elevation angles distributed around as uniformly as possible are selected as the satellite combination with the smallest GDOP factor.
Aiming at the first, in urban environment, due to the existence of buildings, problems such as shielding, multipath and the like can be caused, and satellites with higher observation quality can not be selected only according to the elevation angle and the carrier-to-noise ratio of satellite signals.
For the second method, the more satellites that generally participate in the calculation, the smaller the GDOP, and the satellite selection strategy based on the GDOP is generally applied to the age with limited hardware resources, and it is desirable to reduce errors as much as possible under the condition of using fewer satellites (for example, 4 satellites). With the increasing processing capability of GNSS receivers, the number of satellites participating in computation is not a problem, and a situation that tens of satellites participate in computation often occurs, so that the satellite selection strategy based on the GDOP is not optimal, and the key point is to ensure the reliability of pseudo-range observed quantities of the used satellites of the satellites.
In order to solve the problems in the related art, the embodiment of the invention provides a satellite selection method based on a GNSS, which aims at the problem of positioning drift caused by unreliable observation quality of each satellite in an urban environment. The method mainly comprises the following steps:
1. according to the approximate position of the user and surrounding buildings on the map, the tracked satellite is divided into three types of in-sight distance, out-of-sight distance and uncertain according to the elevation angle and the azimuth angle of the satellite.
2. If the number of the satellites in the sight distance is not less than 4, calculating the clock error between the user position and the receiver through the navigation messages of the satellites in the sight distance, and executing the step 3; and if the number of the satellites in the visual range is less than 4, ending the process.
3. And calculating pseudo-range estimators of all uncertain satellites according to the clock error of the user position and the receiver, calculating an absolute value of a difference between the pseudo-range estimators and the pseudo-range observed quantities, taking the absolute value as an observation residual error, and taking the uncertain satellites and satellites in sight distance which meet threshold conditions of the observation residual error as observation satellites, thereby completing the satellite selection process.
Fig. 1 is an architecture diagram of positioning based on a GNSS system according to an embodiment of the present invention, referring to fig. 1, including at least one satellite and a terminal.
The satellite transmits navigation messages to a receiver of the terminal, so that the terminal is navigated.
The terminal is provided with a positioning SDK (Software Development Kit) of map data, which can be a smart phone, a vehicle, etc.
The embodiment of the invention is applied to the positioning SDK with map data, and particularly applied to the satellite selection stage during the resolving of the positioning SDK. When the positioning result is output, the algorithm library can be called to execute. Taking an android system as an example, information such as observed quantity output by an android Application Programming Interface (API) is combined with map information to screen satellites participating in resolving, so that more accurate position coordinates are provided.
With the android system opening a pseudo-range observation amount and navigation information query interface, the terminal can obtain the pseudo-range observation amount and navigation messages provided by the GNSS chip through the API, and therefore resolving can be carried out in the positioning SDK again. Referring to fig. 2, the positioning SDK obtains pseudo-range observed quantity and navigation messages from a GNSS chip through an API of an android system, and obtains layer data in a map product, so as to determine whether a satellite is blocked by combining distribution of a building vector diagram, and accurately select the satellite for resolving. Compared with the automatic solution of the GNSS chip, the method can remove unreliable satellites more accurately, thereby realizing more accurate positioning in urban environment.
The embodiment of the present invention provides a flow chart of a GNSS-based satellite selection method, which is implemented by a terminal, and referring to fig. 3, the method provided by the embodiment of the present invention includes:
301. and determining the type of the tracked satellite according to the estimated position of the user and the map information.
The user estimated position is the approximate position of the user. The user estimated position can be derived from GNSS positioning under a good observation condition before entering an urban canyon, can also be derived from other positioning systems such as WiFi fingerprint and inertial navigation, and can also be derived from a previous positioning result when the positioning is carried out by adopting the method provided by the embodiment of the invention. The map information is used for representing the position relation among the buildings, and the map information at least comprises the outline and the like of the buildings. The types of the satellites include an in-sight satellite, an out-of-sight satellite, an uncertain satellite and the like.
Specifically, when the terminal determines the type of the tracked satellite according to the estimated position and the map information of the user, the following steps may be adopted:
3011. the terminal makes a circle by taking the estimated position of the user as the center and the preset length as the radius.
The preset length can be adjusted according to the building density of the area, and can also be set to be a constant, for example, 200 m.
3012. And the terminal selects a target building vector frame with an overlapping area with the circle from the building vector frames on the map plane indicated by the map information.
When a circular area is drawn by taking the predicted position of a user as the center and taking the preset length as the radius, a target building vector frame with an overlapping area with the circular area can be selected from the building vector frames on the map plane indicated by the map information, and the target building indicated by the target building vector frame is a building involved in the star choosing process.
3013. And the terminal determines the type of the tracked satellite according to the user estimated position, the tracked satellite and the target building vector frame.
The method comprises the steps that a terminal obtains projection of a connecting line between any satellite and a user estimated position on a map plane, whether intersection points exist between the projection and a target building vector frame or not is judged, and when the intersection points do not exist between the projection and the target building vector frame, it can be determined that the satellite is not located in an occlusion area; when the projection and the target building vector frame have an intersection point, it can be determined that the satellite is in the occlusion region. According to whether the satellite is in the shielding area or not, the terminal determines the satellite which is not in the shielding area and the satellite which is in the shielding area and the elevation angle of which meets a second threshold value condition as the in-line-of-sight satellite; determining the satellite which is in the shielding area and the elevation angle of which meets a third threshold value condition as an out-of-sight satellite; and determining other satellites except the in-line-of-sight satellite and the out-of-line-of-sight satellite in the tracked satellites as uncertain satellites.
Wherein the second threshold condition and the third threshold condition are empirically determined, the second threshold condition indicating a threshold that is greater than the threshold indicated by the third threshold condition. That is, the terminal uses the satellite not located in the shielded area and the satellite located in the shielded area but having a larger elevation angle as the in-line-of-sight satellite, uses the satellite located in the shielded area and having a smaller elevation angle as the out-of-line-of-sight satellite, and uses the remaining satellites as the uncertain satellites.
The elevation angle is an included angle between a connecting line of the satellite and the user estimated position and the projection of the connecting line on the map plane. Referring to fig. 4, satellite elevation is labeled.
Referring to fig. 5, when determining the type of the tracked satellite, the terminal first obtains the user estimated position and map information, and makes a circle with the user estimated position as the center and r as the radius, and takes the building with the area overlapping the circular area as the selected target building. Then, each tracking satellite is connected with the user estimated position, and the connection line of each tracking satellite and the user estimated position is projected on the map plane, as can be seen from fig. 5, if the projection of the connection line of the satellite and the user estimated position on the map plane and the vector frame of the building 2 have an overlapping area, it can be determined that the satellite is in a shielding area, and the type of the satellite is further determined according to the elevation angle of the satellite.
302. And calculating the clock error of the receiver and the position of the user according to the navigation message and the observed quantity of the satellite in the sight distance.
Generally, the observation results of the satellites in the sight distance can be considered to be reliable, and when the number of the satellites in the sight distance meets the number requirement, calculation can be performed according to the satellites in the sight distance. Therefore, the terminal can firstly acquire the number of the satellites in the sight distance and judge whether the number requirement is met or not according to the number of the satellites in the sight distance, and when the number of the satellites in the sight distance is smaller than the preset number, the terminal exits from the scheme and the process is finished; when the number of the satellites in the sight distance is larger than the preset number, the terminal can calculate the clock error of the receiver and the position of the user based on the navigation messages of the satellites in the sight distance. The preset number may be determined empirically, and may be 4, 5, etc. The observations include pseudorange observations, phase measurements, doppler measurements, and the like.
Specifically, the terminal may calculate the receiver clock offset and the user position according to the navigation message of the satellite in the line of sight, and may adopt the following steps:
3022. and the terminal acquires the satellite coordinates and the error correction information of the satellite in the line of sight from the navigation messages of the satellite in the line of sight.
3023. And the terminal corrects the satellite coordinates of the satellites in the sight distance according to the error correction information of the satellites in the sight distance to obtain the satellite correction coordinates of the satellites in the sight distance.
3024. The terminal obtains the receiver clock error and the user position by solving an equation by applying the following formula according to the pseudo-range observed quantity of the in-sight satellite, the satellite correction coordinate of the in-sight satellite and the error correction information of the in-sight satellite:
wherein, i is the i-th in-line-of-sight satellite, i is 1,2,3iAre pseudorange observations of satellites within view,
coordinates are corrected for the satellites of the satellites in the ith line of sight, (x, y, z) user position,
the ionospheric correction quantity corresponding to the satellite in the ith sight distance,
and b is a troposphere correction quantity corresponding to the satellite in the ith sight distance, b is a receiver clock error, and c is a light velocity constant.
When N is notWhen the time is less than 4, the terminal simultaneously establishes equations of the satellites in the N sight distances into an equation set, and solves the equations by adopting methods such as least square and the like, so that estimated values of the user position and the receiver clock error can be obtained. Wherein the estimate of the user's position may be expressed as
The estimate of the receiver clock error may be expressed as
303. And calculating the observation residual error of the uncertain satellite according to the receiver clock error and the user position.
Generally, if only in-line-of-sight satellites are used, the resulting GDOP values are large, resulting in inaccurate positioning. Only when the number of satellites participating in the solution is sufficiently large, the resulting GDOP value is small. Therefore, reliable satellites can be screened out from uncertain satellites by calculating the observation residual error of the uncertain satellites according to the calculated receiver clock error and the user position, so that all available satellites can be applied as far as possible. And the observation residual value is the difference value between the pseudo-range observed quantity and the pseudo-range estimation quantity.
When the terminal calculates the observation residual error of the uncertain satellite according to the receiver clock error and the user position, the following steps can be adopted:
3031. and the terminal acquires the satellite coordinates and the error correction information of the uncertain satellite from the navigation message of the uncertain satellite.
3032. And the terminal corrects the satellite coordinates of the uncertain satellite according to the error correction information of the uncertain satellite to obtain the satellite correction coordinates of the uncertain satellite.
3033. The terminal calculates the observation residual error of the uncertain satellite by applying the following formula according to the pseudo-range observed quantity of the uncertain satellite, the satellite correction coordinate of the uncertain satellite, the error correction information of the uncertain satellite, the receiver clock error and the user position:
wherein j is the j th uncertain satellite, j equals N +1, N +2, N +3jFor the observation residual, p, of the jth uncertain satellitejTo uncertain the pseudorange observations of the satellites,
the satellite correction coordinates for the jth uncertain satellite, (x, y, z) the user position,
the ionospheric correction quantity corresponding to the jth uncertain satellite,
the correction quantity of the troposphere corresponding to the jth uncertain satellite is b, the clock error of the receiver is b, and the light velocity constant is c.
304. And determining the uncertain satellite and the in-line-of-sight satellite of which the observation residual meets the first threshold condition as the observation satellite.
The threshold indicated by the first threshold condition may be an average value of the observation residual values of the satellites in each line of sight, or may also be a maximum value of the observation residual values of the satellites in each line of sight, which is not specifically limited in the embodiment of the present invention.
And the terminal compares the observation residual of each uncertain satellite with a first threshold value, and determines the uncertain satellite and the in-line-of-sight satellite of which the observation residual meets the condition of the first threshold value as the observation satellite, thereby completing the satellite selection process. For example, the threshold indicated by the first threshold condition is 50 meters, and if the observation residual of a certain satellite is less than the threshold 3, the certain satellite is classified into an in-line-of-sight satellite, otherwise, the certain satellite is classified as an out-of-line-of-sight satellite.
Based on the determined observation satellite, the terminal can adopt the observation satellite to determine the actual position of the user, the actual position is more accurate relative to the estimated position of the user and the user position calculated by adopting the in-line-of-sight satellite, and the positioning result is more reliable.
Fig. 6 is a schematic diagram of a process of selecting a satellite by using the method provided by the embodiment of the present invention, and referring to fig. 6, the method includes the following steps:
1. and acquiring the approximate position of the user, calculating the direction angle and the elevation angle of the tracking satellite according to the approximate position of the user, and acquiring the outline information of each building on the map plane.
2. Connecting each satellite with the approximate position of the user, projecting the connecting line of each satellite and the approximate position of the user on a map plane, and dividing the satellites into three types of in-sight satellites, out-of-sight satellites and uncertain satellites according to whether the projection and a building vector diagram on the plane map have an overlapping area and the direction angle and the elevation angle of the satellites.
3. And (4) judging whether the number of the satellites in the sight distance is not less than 4, if so, entering a next positioning epoch or exiting the scheme, and if so, executing the step 4.
4. And calculating the coordinate of the user position and the receiver clock error based on the navigation message and the observed quantity of the satellite in the sight distance, substituting the coordinate of the user position and the receiver clock error into an observation equation established by the uncertain satellite to obtain the pseudo-range estimation quantity of the uncertain satellite, and calculating the observation residual error of the uncertain satellite according to the pseudo-range observed quantity of the uncertain satellite.
5. And comparing the observation residual value of the uncertain satellite with a threshold value indicated by a first threshold value condition, and taking the satellite with the observation residual value smaller than the threshold value indicated by the first threshold value condition and the in-line-of-sight satellite as observation satellites to finish satellite selection.
6. And resolving by adopting the determined observation satellite, and outputting a positioning result.
According to the method provided by the embodiment of the invention, the type of the tracked satellite is determined according to the estimated position and map information of the user, the clock error of the receiver and the position of the user are calculated according to the navigation message and the observed quantity of the satellite in the sight distance, and the observation residual error value meets the first threshold condition and the satellite in the sight distance is used as the observation satellite. Because the selection is carried out according to the map information, unreliable satellites can be eliminated, the observation quality of the selected satellites is improved, and more accurate positioning can be realized in the urban environment.
Referring to fig. 7, an embodiment of the present invention provides a GNSS-based satellite selection apparatus, including:
the first determining module 701 is used for determining the types of the tracked satellites according to the estimated position of the user and the map information, wherein the types comprise an in-sight satellite, an out-of-sight satellite and an uncertain satellite;
a first calculation module 702, configured to calculate a receiver clock error and a user position according to a navigation message and an observed quantity of a satellite in a line of sight;
a second calculating module 703, configured to calculate an observation residual error of the uncertain satellite according to the receiver clock error and the user position;
and a second determining module 704, configured to determine the uncertain satellite and the in-line-of-sight satellite whose observation residual meets the first threshold condition as the observation satellite.
In another possible implementation manner, the first determining module 701 is configured to make a circle with the user estimated position as a center and a preset length as a radius; selecting a target building vector frame with an overlapping area with the circle from all building vector frames on a map plane indicated by the map information; and determining the type of the tracked satellite according to the user estimated position, the tracked satellite and the target building vector frame.
In another possible implementation manner, the first determining module 701 is configured to obtain a projection of a connection line between any one satellite and the estimated user position on a map plane; when the projection does not have an intersection point with the vector frame of the target building, determining that the satellite is not in the occlusion area; determining satellites which are not in the shielding area and are in the shielding area and the elevation angle of which meets a second threshold value condition as satellites in the sight distance; determining the satellite which is in the shielding area and the elevation angle of which meets a third threshold value condition as an out-of-sight satellite; and determining other satellites except the in-line-of-sight satellite and the out-of-line-of-sight satellite in the tracked satellites as uncertain satellites.
In another possible implementation manner, the first calculation module 702 is configured to obtain a satellite coordinate and error correction information of a satellite in a line of sight from a navigation message of the satellite in the line of sight; correcting the satellite coordinates of the satellites in the sight distance according to the error correction information of the satellites in the sight distance to obtain satellite correction coordinates of the satellites in the sight distance; according to the pseudo-range observed quantity of the in-line-of-sight satellite, the satellite correction coordinates of the in-line-of-sight satellite and the error correction information of the in-line-of-sight satellite, the following formulas are applied, and the receiver clock error and the user position are obtained by solving the equations:
wherein, i is the i-th in-line-of-sight satellite, i is 1,2,3iAre pseudorange observations of satellites within view,
coordinates are corrected for the satellites of the satellites in the ith line of sight, (x, y, z) user position,
the ionospheric correction quantity corresponding to the satellite in the ith sight distance,
and b is a troposphere correction quantity corresponding to the satellite in the ith sight distance, b is a receiver clock error, and c is a light velocity constant.
In another possible implementation manner, the second calculation module 703 is configured to obtain satellite coordinates and error correction information of an undetermined satellite from a navigation message of the undetermined satellite; correcting the satellite coordinates of the uncertain satellite according to the error correction information of the uncertain satellite to obtain satellite correction coordinates of the uncertain satellite; according to the pseudo-range observed quantity of the uncertain satellite, the satellite correction coordinate of the uncertain satellite, the error correction information of the uncertain satellite, the receiver clock error and the user position, the following formula is applied to calculate the observation residual error of the uncertain satellite:
wherein j is the j th uncertain satellite, j equals N +1, N +2, N +3jFor the observation residual, p, of the jth uncertain satellitejTo uncertain the pseudorange observations of the satellites,
the satellite correction coordinates for the jth uncertain satellite, (x, y, z) the user position,
the ionospheric correction quantity corresponding to the jth uncertain satellite,
the correction quantity of the troposphere corresponding to the jth uncertain satellite is b, the clock error of the receiver is b, and the light velocity constant is c.
In another possible implementation manner, the apparatus further includes:
the acquisition module is used for acquiring the number of satellites in sight distance;
a first calculating module 702, configured to calculate a receiver clock offset and a user position according to a navigation message of satellites in a line of sight when the number of satellites in the line of sight is greater than a preset number.
In another possible implementation, the apparatus further includes;
and the third determining module is used for determining the actual position of the user by adopting the observation satellite.
To sum up, the device provided by the embodiment of the present invention determines the type of the tracked satellite according to the estimated position of the user and the map information, calculates the receiver clock offset and the user position according to the navigation messages and the observed quantity of the satellites in the line of sight, and further takes the satellites in the line of sight and the satellites in the line of sight as the observation satellites, wherein the observation residual values satisfy the first threshold condition. Because the selection is carried out according to the map information, unreliable satellites can be eliminated, the observation quality of the selected satellites is improved, and more accurate positioning can be realized in the urban environment.
Fig. 8 is a block diagram illustrating a terminal 800 according to an exemplary embodiment of the present invention. The terminal 800 may be: a smart phone, a tablet computer, an MP3 player (Moving Picture Experts Group Audio Layer III, motion video Experts compression standard Audio Layer 3), an MP4 player (Moving Picture Experts Group Audio Layer IV, motion video Experts compression standard Audio Layer 4), a notebook computer, or a desktop computer. The terminal 800 may also be referred to by other names such as user equipment, portable terminal, laptop terminal, desktop terminal, etc.
In general, the terminal 800 includes: a processor 801 and a memory 802.
The processor 801 may include one or more processing cores, such as a 4-core processor, an 8-core processor, and so forth. The processor 801 may be implemented in at least one hardware form of a DSP (Digital Signal Processing), an FPGA (Field-Programmable Gate Array), and a PLA (Programmable Logic Array). The processor 801 may also include a main processor and a coprocessor, where the main processor is a processor for Processing data in an awake state, and is also called a Central Processing Unit (CPU); a coprocessor is a low power processor for processing data in a standby state. In some embodiments, the processor 801 may be integrated with a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content required to be displayed on the display screen. In some embodiments, the processor 801 may further include an AI (Artificial Intelligence) processor for processing computing operations related to machine learning.
In some embodiments, the terminal 800 may further include: a peripheral interface 803 and at least one peripheral. The processor 801, memory 802 and peripheral interface 803 may be connected by bus or signal lines. Various peripheral devices may be connected to peripheral interface 803 by a bus, signal line, or circuit board. Specifically, the peripheral device includes: at least one of a radio frequency circuit 804, a touch screen display 805, a camera 806, an audio circuit 807, a positioning component 808, and a power supply 809.
The peripheral interface 803 may be used to connect at least one peripheral related to I/O (Input/Output) to the processor 801 and the memory 802. In some embodiments, the processor 801, memory 802, and peripheral interface 803 are integrated on the same chip or circuit board; in some other embodiments, any one or two of the processor 801, the memory 802, and the peripheral interface 803 may be implemented on separate chips or circuit boards, which are not limited by this embodiment.
The Radio Frequency circuit 804 is used for receiving and transmitting RF (Radio Frequency) signals, also called electromagnetic signals. The radio frequency circuitry 804 communicates with communication networks and other communication devices via electromagnetic signals. The rf circuit 804 converts an electrical signal into an electromagnetic signal to be transmitted, or converts a received electromagnetic signal into an electrical signal. Optionally, the radio frequency circuit 804 includes: an antenna system, an RF transceiver, one or more amplifiers, a tuner, an oscillator, a digital signal processor, a codec chipset, a subscriber identity module card, and so forth. The radio frequency circuit 804 may communicate with other terminals via at least one wireless communication protocol. The wireless communication protocols include, but are not limited to: metropolitan area networks, various generation mobile communication networks (2G, 3G, 4G, and 5G), Wireless local area networks, and/or WiFi (Wireless Fidelity) networks. In some embodiments, the radio frequency circuit 804 may further include NFC (Near Field Communication) related circuits, which are not limited in this application.
The display screen 805 is used to display a UI (User Interface). The UI may include graphics, text, icons, video, and any combination thereof. When the display 805 is a touch display, the display 805 also has the ability to capture touch signals on or above the surface of the display 805. The touch signal may be input to the processor 801 as a control signal for processing. At this point, the display 805 may also be used to provide virtual buttons and/or a virtual keyboard, also referred to as soft buttons and/or a soft keyboard. In some embodiments, the display 805 may be one, providing the front panel of the terminal 800; in other embodiments, the display 805 may be at least two, respectively disposed on different surfaces of the terminal 800 or in a folded design; in still other embodiments, the display 805 may be a flexible display disposed on a curved surface or a folded surface of the terminal 800. Even further, the display 805 may be arranged in a non-rectangular irregular pattern, i.e., a shaped screen. The Display 805 can be made of LCD (Liquid Crystal Display), OLED (Organic Light-Emitting Diode), and other materials.
The camera assembly 806 is used to capture images or video. Optionally, camera assembly 806 includes a front camera and a rear camera. Generally, a front camera is disposed at a front panel of the terminal, and a rear camera is disposed at a rear surface of the terminal. In some embodiments, the number of the rear cameras is at least two, and each rear camera is any one of a main camera, a depth-of-field camera, a wide-angle camera and a telephoto camera, so that the main camera and the depth-of-field camera are fused to realize a background blurring function, and the main camera and the wide-angle camera are fused to realize panoramic shooting and VR (Virtual Reality) shooting functions or other fusion shooting functions. In some embodiments, camera assembly 806 may also include a flash. The flash lamp can be a monochrome temperature flash lamp or a bicolor temperature flash lamp. The double-color-temperature flash lamp is a combination of a warm-light flash lamp and a cold-light flash lamp, and can be used for light compensation at different color temperatures.
The audio circuit 807 may include a microphone and a speaker. The microphone is used for collecting sound waves of a user and the environment, converting the sound waves into electric signals, and inputting the electric signals to the processor 801 for processing or inputting the electric signals to the radio frequency circuit 804 to realize voice communication. For the purpose of stereo sound collection or noise reduction, a plurality of microphones may be provided at different portions of the terminal 800. The microphone may also be an array microphone or an omni-directional pick-up microphone. The speaker is used to convert electrical signals from the processor 801 or the radio frequency circuit 804 into sound waves. The loudspeaker can be a traditional film loudspeaker or a piezoelectric ceramic loudspeaker. When the speaker is a piezoelectric ceramic speaker, the speaker can be used for purposes such as converting an electric signal into a sound wave audible to a human being, or converting an electric signal into a sound wave inaudible to a human being to measure a distance. In some embodiments, the audio circuitry 807 may also include a headphone jack.
The positioning component 808 is used to locate the current geographic position of the terminal 800 for navigation or LBS (Location Based Service). The Positioning component 808 may be a Positioning component based on the GPS (Global Positioning System) in the united states, the beidou System in china, the graves System in russia, or the galileo System in the european union.
In some embodiments, terminal 800 also includes one or more sensors 810. The one or more sensors 810 include, but are not limited to: acceleration sensor 811, gyro sensor 812, pressure sensor 813, fingerprint sensor 814, optical sensor 815 and proximity sensor 816.
The acceleration sensor 811 may detect the magnitude of acceleration in three coordinate axes of the coordinate system established with the terminal 800. For example, the acceleration sensor 811 may be used to detect the components of the gravitational acceleration in three coordinate axes. The processor 801 may control the touch screen 805 to display the user interface in a landscape view or a portrait view according to the gravitational acceleration signal collected by the acceleration sensor 811. The acceleration sensor 811 may also be used for acquisition of motion data of a game or a user.
The gyro sensor 812 may detect a body direction and a rotation angle of the terminal 800, and the gyro sensor 812 may cooperate with the acceleration sensor 811 to acquire a 3D motion of the user with respect to the terminal 800. From the data collected by the gyro sensor 812, the processor 801 may implement the following functions: motion sensing (such as changing the UI according to a user's tilting operation), image stabilization at the time of photographing, game control, and inertial navigation.
Pressure sensors 813 may be disposed on the side bezel of terminal 800 and/or underneath touch display 805. When the pressure sensor 813 is disposed on the side frame of the terminal 800, the holding signal of the user to the terminal 800 can be detected, and the processor 801 performs left-right hand recognition or shortcut operation according to the holding signal collected by the pressure sensor 813. When the pressure sensor 813 is disposed at a lower layer of the touch display screen 805, the processor 801 controls the operability control on the UI interface according to the pressure operation of the user on the touch display screen 805. The operability control comprises at least one of a button control, a scroll bar control, an icon control and a menu control.
The fingerprint sensor 814 is used for collecting a fingerprint of the user, and the processor 801 identifies the identity of the user according to the fingerprint collected by the fingerprint sensor 814, or the fingerprint sensor 814 identifies the identity of the user according to the collected fingerprint. Upon identifying that the user's identity is a trusted identity, the processor 801 authorizes the user to perform relevant sensitive operations including unlocking a screen, viewing encrypted information, downloading software, paying for and changing settings, etc. Fingerprint sensor 814 may be disposed on the front, back, or side of terminal 800. When a physical button or a vendor Logo is provided on the terminal 800, the fingerprint sensor 814 may be integrated with the physical button or the vendor Logo.
The optical sensor 815 is used to collect the ambient light intensity. In one embodiment, the processor 801 may control the display brightness of the touch screen 805 based on the ambient light intensity collected by the optical sensor 815. Specifically, when the ambient light intensity is high, the display brightness of the touch display screen 805 is increased; when the ambient light intensity is low, the display brightness of the touch display 805 is turned down. In another embodiment, the processor 801 may also dynamically adjust the shooting parameters of the camera assembly 806 based on the ambient light intensity collected by the optical sensor 815.
A proximity sensor 816, also known as a distance sensor, is typically provided on the front panel of the terminal 800. The proximity sensor 816 is used to collect the distance between the user and the front surface of the terminal 800. In one embodiment, when the proximity sensor 816 detects that the distance between the user and the front surface of the terminal 800 gradually decreases, the processor 801 controls the touch display 805 to switch from the bright screen state to the dark screen state; when the proximity sensor 816 detects that the distance between the user and the front surface of the terminal 800 becomes gradually larger, the processor 801 controls the touch display 805 to switch from the screen-on state to the screen-on state.
Those skilled in the art will appreciate that the configuration shown in fig. 8 is not intended to be limiting of terminal 800 and may include more or fewer components than those shown, or some components may be combined, or a different arrangement of components may be used.
The terminal provided by the embodiment of the invention determines the type of the tracked satellite according to the estimated position and the map information of the user, calculates the clock error of the receiver and the position of the user according to the navigation message and the observed quantity of the satellite in the sight distance, and further takes the satellite in the sight distance as the observation satellite, wherein the observation residual error value meets the first threshold condition. Because the selection is carried out according to the map information, unreliable satellites can be eliminated, the observation quality of the selected satellites is improved, and more accurate positioning can be realized in the urban environment.
An embodiment of the present invention provides a computer-readable storage medium, where at least one instruction, at least one program, a code set, or a set of instructions is stored in the storage medium, and the at least one instruction, the at least one program, the code set, or the set of instructions is loaded and executed by a processor to implement the GNSS based satellite selection method shown in fig. 3.
The computer-readable storage medium provided by the embodiment of the invention determines the type of the tracked satellite according to the estimated position and map information of the user, calculates the clock error of the receiver and the position of the user according to the navigation message and the observed quantity of the satellite in the line of sight, and further takes the satellite in the line of sight and the satellite with the observation residual error value meeting the first threshold value condition as the observation satellite. Because the selection is carried out according to the map information, unreliable satellites can be eliminated, the observation quality of the selected satellites is improved, and more accurate positioning can be realized in the urban environment.
It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, where the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (9)
1. A satellite selection method based on GNSS is characterized in that the method comprises the following steps:
determining the type of a tracked satellite according to the estimated position of a user and map information, wherein the type comprises an in-sight satellite, an out-sight satellite and an uncertain satellite;
calculating the clock error of the receiver and the position of a user according to the navigation message and the observed quantity of the satellite in the sight distance;
calculating the observation residual error of the uncertain satellite according to the receiver clock error and the user position;
determining an uncertain satellite and an in-line-of-sight satellite of which the observation residual meets a first threshold condition as an observation satellite;
the calculating of the observation residual error of the uncertain satellite according to the receiver clock error and the user position comprises:
acquiring satellite coordinates and error correction information of the uncertain satellite from the navigation message of the uncertain satellite;
correcting the satellite coordinates of the uncertain satellite according to the error correction information of the uncertain satellite to obtain satellite correction coordinates of the uncertain satellite;
according to the pseudo-range observed quantity of the uncertain satellite, the satellite correction coordinate of the uncertain satellite, the error correction information of the uncertain satellite, the receiver clock error and the user position, the following formula is applied to calculate the observation residual error of the uncertain satellite:
wherein j is the j th uncertain satellite, j equals N +1, N +2, N +3jFor the observation residual, p, of the jth uncertain satellitejFor the pseudorange observations of the uncertain satellite,
(ii) satellite correction coordinates for the jth uncertain satellite, (x, y, z) being the user position,
the ionospheric correction quantity corresponding to the jth uncertain satellite,
and b is the troposphere correction quantity corresponding to the jth uncertain satellite, b is the receiver clock error, and c is the light velocity constant.
2. The method of claim 1, wherein determining the type of tracked satellite based on the user estimated location and map information comprises:
making a circle by taking the estimated position of the user as a center and a preset length as a radius;
selecting a target building vector frame with an overlapping area with the circle from all building vector frames on a map plane indicated by the map information;
and determining the type of the tracked satellite according to the user estimated position, the tracked satellite and the target building vector frame.
3. The method of claim 2, wherein determining the type of the tracked satellite based on the user estimated location, the tracked satellite, and the target building vector box comprises:
acquiring the projection of a connecting line between any satellite and the user estimated position on the map plane;
when the projection and the target building vector frame do not have an intersection point, determining that the satellite is not located in an occlusion area;
determining satellites which are not in the shielding area and are in the shielding area and the elevation angle of which meets a second threshold value condition as satellites in the sight distance;
determining the satellite which is in the shielding area and the elevation angle of which meets a third threshold value condition as an out-of-sight satellite;
and determining other satellites of the tracked satellites except the in-line-of-sight satellite and the out-of-line-of-sight satellite as uncertain satellites.
4. The method of claim 1, wherein calculating the receiver clock offset and the user position from the navigation messages and observations of the satellites in view comprises:
acquiring satellite coordinates and error correction information of the satellites in the sight distance from navigation messages of the satellites in the sight distance;
correcting the satellite coordinates of the in-line-of-sight satellite according to the error correction information of the in-line-of-sight satellite to obtain satellite correction coordinates of the in-line-of-sight satellite;
according to the pseudo-range observed quantity of the in-line-of-sight satellite, the satellite correction coordinates of the in-line-of-sight satellite and the error correction information of the in-line-of-sight satellite, applying the following formulas, and solving equations to obtain the receiver clock error and the user position:
wherein, i is the i-th in-line-of-sight satellite, i is 1,2,3iFor pseudorange observations of the in-line-of-sight satellites,
(ii) correcting coordinates for the satellites of the satellites in the ith line of sight, (x, y, z) the user position,
the ionospheric correction quantity corresponding to the satellite in the ith sight distance,
and b is the troposphere correction quantity corresponding to the satellite in the ith sight distance, b is the receiver clock error, and c is the light velocity constant.
5. The method of any of claims 1 to 4, wherein prior to calculating a receiver clock offset and a user position from navigation messages for in-line-of-sight satellites, further comprising:
acquiring the number of satellites in the sight distance;
and when the number of the satellites in the sight distance is larger than the preset number, the step of calculating the clock error of the receiver and the position of the user according to the navigation messages of the satellites in the sight distance is executed.
6. The method according to any one of claims 1 to 4, wherein the determining the uncertain satellite and the in-line-of-sight satellite whose observation residuals satisfy the first threshold condition as the observation satellites further comprises:
and determining the actual position of the user by adopting the observation satellite.
7. A GNSS-based satellite selection apparatus, comprising:
the first determining module is used for determining the type of the tracked satellite according to the estimated position of the user and the map information, wherein the type comprises an in-sight satellite, an out-sight satellite and an uncertain satellite;
the first calculation module is used for calculating the clock error of the receiver and the position of a user according to the navigation message and the observed quantity of the satellite in the sight distance;
the second calculation module is used for calculating the observation residual error of the uncertain satellite according to the receiver clock error and the user position;
the second determination module is used for determining the uncertain satellite and the in-line-of-sight satellite of which the observation residual meets the first threshold value condition as the observation satellite;
wherein the second computing module is further for
Acquiring satellite coordinates and error correction information of the uncertain satellite from the navigation message of the uncertain satellite;
correcting the satellite coordinates of the uncertain satellite according to the error correction information of the uncertain satellite to obtain satellite correction coordinates of the uncertain satellite;
according to the pseudo-range observed quantity of the uncertain satellite, the satellite correction coordinate of the uncertain satellite, the error correction information of the uncertain satellite, the receiver clock error and the user position, the following formula is applied to calculate the observation residual error of the uncertain satellite:
wherein j is the j th uncertain satellite, j equals N +1, N +2, N +3jFor the observation residual, p, of the jth uncertain satellitejFor the pseudorange observations of the uncertain satellite,
(ii) satellite correction coordinates for the jth uncertain satellite, (x, y, z) being the user position,
the ionospheric correction quantity corresponding to the jth uncertain satellite,
and b is the troposphere correction quantity corresponding to the jth uncertain satellite, b is the receiver clock error, and c is the light velocity constant.
8. A terminal, characterized in that it comprises a processor and a memory, in which at least one instruction, at least one program, a set of codes or a set of instructions is stored, which is loaded and executed by the processor to implement a GNSS based satellite selection method according to any of claims 1 to 6.
9. A computer readable storage medium having stored therein at least one instruction, at least one program, a set of codes, or a set of instructions, which is loaded and executed by a processor to implement the GNSS based satellite selection method according to any of claims 1 to 6.
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