Real-time PPP whole-cycle ionosphere elimination combination ambiguity fixing method and device based on PPP-B2b, terminal equipment and storage medium

Abstract

The invention discloses a real-time PPP whole-cycle ionosphere elimination combination ambiguity fixing method and device based on PPP-B2b, terminal equipment and a storage medium, and belongs to the technical field of GNSS positioning and navigation, and the method comprises the steps: obtaining original observation data of a plurality of satellites and PPP-B2b correction information; according to the original observation data and the correction information of each row, generating wide lane and narrow lane floating point ambiguity resolution; calculating wide lane and narrow lane FCB of each satellite according to the wide lane and narrow lane floating point ambiguity resolution; and according to the wide-lane floating point ambiguity resolution, the wide-lane FCB, the narrow-lane floating point ambiguity resolution and the narrow-lane FCB, generating the whole-cycle ionosphere elimination combined ambiguity. According to the method, the PPP-B2b service broadcasted in real time is used for resolving, the method does not depend on post precision products, and the real-time performance can be guaranteed. By implementing the invention, the problem that the whole-cycle ionosphere elimination combination ambiguity cannot be solved in real time in the prior art can be solved.

Description

Technical Field

[0001] The present invention relates to the field of GNSS positioning and navigation technology, and in particular to a real-time PPP whole-cycle ionospheric combination ambiguity fixing method, device, terminal equipment and storage medium based on PPP-B2b. Background Art

[0002] With the development of the Global Navigation Satellite System (GNSS), Precise Point Positioning (PPP) technology has become a research focus. This technology overcomes the drawback of differential techniques requiring a base station, enabling high-precision positioning services with a single receiver. To further improve positioning accuracy when using the PPP mode, PPP ambiguity fixation (PPP-AR) can be used to restore the whole-cycle characteristics of the carrier phase, i.e., to fix the ionospheric-free combined ambiguity. However, PPP ambiguity fixation requires the use of precise ephemeris and clock products, both of which typically have a lag, making real-time resolution of the whole-cycle ionospheric-free combined ambiguity impossible. Summary of the Invention

[0003] The present invention provides a method, apparatus, terminal device and storage medium for fixing the real-time PPP whole-cycle ionospheric elimination combined ambiguity based on PPP-B2b, which can solve the problem in the prior art that the whole-cycle ionospheric elimination combined ambiguity cannot be solved in real time.

[0004] An embodiment of the present invention provides a real-time PPP whole-cycle ionospheric combination ambiguity fixing method based on PPP-B2b, comprising:

[0005] Obtaining raw observation data of a plurality of satellites through a plurality of observation stations to obtain PPP-B2b correction information; wherein each of the satellites is a GPS satellite or a BDS satellite;

[0006] For each of the satellites, generating a widelane float ambiguity resolution and a narrowlane float ambiguity resolution of the satellite based on the original observation data of the satellite acquired by all observation stations and the PPP-B2b correction information;

[0007] Calculating a widelane FCB of each satellite based on the widelane float ambiguity resolution of all the satellites, and calculating a narrowlane FCB of each satellite based on the narrowlane float ambiguity resolution of all the satellites;

[0008] For each of the satellites, an integer ionospheric-free combined ambiguity is generated according to the widelane float deambiguation, the widelane FCB, the narrowlane float deambiguation and the narrowlane FCB of the satellite.

[0009] Furthermore, the PPP-B2b correction information includes: satellite inter-code deviation correction number;

[0010] The original observation data includes: original pseudorange observation values ​​and original carrier phase observation values;

[0011] Generating the widelane float ambiguity resolution and the narrowlane float ambiguity resolution of the satellite based on the original observation data of the satellite acquired by all observation stations and the PPP-B2b correction information includes:

[0012] Correcting the original pseudorange observation value and the original carrier phase observation value of each measuring station according to the satellite inter-code bias correction number to obtain the corrected pseudorange observation value and the corrected carrier phase observation value of each measuring station;

[0013] Calculating the ionospheric-free combined float resolution of the satellite based on the corrected pseudorange observations and corrected carrier phase observations of all stations;

[0014] Calculating a widelane floating point ambiguity resolution of the satellite based on the corrected pseudorange observations and the corrected carrier phase observations;

[0015] The narrowlane float deambiguity of the satellite is calculated according to the ionospheric-free combined float deambiguity and the widelane float deambiguity.

[0016] Furthermore, the calculating of the satellite's ionospheric-free combined float ambiguity resolution based on the corrected pseudorange observations and corrected carrier phase observations of all stations includes:

[0017] According to the corrected pseudorange observations and corrected carrier phase observations of all stations, a pseudorange-carrier observation model and an ionospheric elimination equation group are constructed.

[0018] By using a Kalman filtering method, under the constraints of the ionospheric elimination equations, the pseudorange-carrier observation model is solved to obtain the ionospheric elimination combined floating point ambiguity resolution;

[0019] The process of constructing the pseudorange-carrier observation model includes:

[0020] When the satellite is a GPS satellite, a GPS satellite pseudorange-carrier observation model is constructed based on the corrected pseudorange observation values ​​and corrected carrier phase observation values ​​of all measurement stations;

[0021] When the satellite is a BDS satellite, a BDS satellite pseudorange-carrier observation model is constructed based on the corrected pseudorange observation values ​​and corrected carrier phase observation values ​​of all measurement stations.

[0022] Furthermore, the calculating the widelane float ambiguity resolution of the satellite based on the corrected pseudorange observation value and the corrected carrier phase observation value includes:

[0023] The wide-lane floating-point ambiguity resolution of the satellite is calculated based on the corrected pseudorange observation value and the corrected carrier phase observation value through the MW combined observation model.

[0024] Furthermore, the calculating of the widelane FCB of each satellite based on the widelane float ambiguity resolution of all the satellites, and the calculating of the narrowlane FCB of each satellite based on the narrowlane float ambiguity resolution of all the satellites, comprises:

[0025] The ambiguity error equation is constructed with the floating point ambiguity solution, the integer part of the ambiguity, the phase bias of the station receiver system, the FCB at the station receiver side, and the FCB at the satellite side as parameters.

[0026] Substituting the widelane float ambiguity solutions of all the satellites into the ambiguity error equation, solving the ambiguity error equation, and obtaining the widelane FCB of each satellite;

[0027] Substituting the narrowlane float ambiguity solutions of all the satellites into the ambiguity error equation, solving the ambiguity error equation, and obtaining the narrowlane FCB of each satellite.

[0028] Furthermore, generating an integer ionospheric-free combined ambiguity based on the widelane float ambiguity resolution, the widelane FCB, the narrowlane float ambiguity resolution, and the narrowlane FCB of the satellite includes:

[0029] Correcting the widelane floating point ambiguity according to the widelane FCB to obtain a corrected widelane floating point ambiguity; correcting the narrowlane floating point ambiguity according to the narrowlane FCB to obtain a corrected narrowlane floating point ambiguity;

[0030] Fixing the corrected widelane floating point ambiguity and the corrected narrowlane floating point ambiguity respectively by using an ambiguity reduction correlation method to obtain an integer widelane ambiguity and an integer narrowlane ambiguity;

[0031] The integer-cycle ionospheric-free combined ambiguity is calculated according to the integer-cycle wide-lane ambiguity and the integer-cycle narrow-lane ambiguity.

[0032] Furthermore, after respectively fixing the corrected widelane floating point ambiguity resolution and the corrected narrowlane floating point ambiguity resolution by using the ambiguity reduction correlation method to obtain the integer widelane ambiguity and the integer narrowlane ambiguity, the method further includes:

[0033] Calculate the first bootstrapping success rate and the first ratio index of the fixed wide-lane floating-point deambiguation, and calculate the second bootstrapping success rate and the second ratio index of the fixed narrow-lane floating-point deambiguation;

[0034] If the first bootstrapping success rate is not less than a preset bootstrapping success rate threshold and the first ratio index is not less than a preset ratio index threshold, the widelane floating point deambiguity is fixed successfully; otherwise, the widelane floating point deambiguity is fixed failed;

[0035] If the second bootstrapping success rate is not less than the bootstrapping success rate threshold and the second ratio index is not less than the ratio index threshold, the narrow lane floating point deambiguity is fixed successfully; otherwise, the narrow lane floating point deambiguity is fixed failed;

[0036] If both the wide-lane float ambiguity resolution and the narrow-lane ambiguity resolution are fixed successfully, the subsequent operation of calculating the whole-cycle ionospheric-free combined ambiguity resolution will be continued. Otherwise, the subsequent operation of calculating the whole-cycle ionospheric-free combined ambiguity resolution will not be performed.

[0037] Another embodiment of the present invention further provides a real-time PPP whole-cycle ionospheric de-ambiguity fixing device based on PPP-B2b, comprising: a data acquisition module, a floating-point de-ambiguity calculation module, an FCB calculation module, and an ambiguity fixing module;

[0038] The data acquisition module is used to acquire raw observation data of a plurality of satellites through a plurality of observation stations and obtain PPP-B2b correction information; wherein each of the satellites is a GPS satellite or a BDS satellite;

[0039] The floating point ambiguity resolution calculation module is configured to generate, for each satellite, a wide lane floating point ambiguity resolution and a narrow lane floating point ambiguity resolution of the satellite based on the original observation data of the satellite acquired by all observation stations and the PPP-B2b correction information;

[0040] The FCB calculation module is configured to calculate the widelane FCB of each satellite based on the widelane float ambiguity resolution of all the satellites, and calculate the narrowlane FCB of each satellite based on the narrowlane float ambiguity resolution of all the satellites;

[0041] The ambiguity fixing module is configured to generate, for each satellite, an integer ionospheric-free combined ambiguity based on the widelane float deambiguation, the widelane FCB, the narrowlane float deambiguation and the narrowlane FCB of the satellite.

[0042] Another embodiment of the present invention also provides a terminal device, including: a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the steps of the real-time PPP whole-week ionospheric combination ambiguity fixation method based on PPP-B2b of the present invention.

[0043] Another embodiment of the present invention also provides a computer-readable storage medium item, including: a stored computer program, which, when the computer program is running, controls the device where the computer-readable storage medium is located to perform the steps of the real-time PPP whole-week ionospheric combination ambiguity fixation method based on PPP-B2b of the present invention.

[0044] The following beneficial effects are achieved by implementing the present invention:

[0045] The present invention obtains raw observation data from multiple satellites through multiple observation stations and obtains PPP-B2b correction information. Each satellite is a GPS satellite or a BDS satellite. For each satellite, a widelane float ambiguity resolution and a narrowlane float ambiguity resolution are generated based on the raw observation data and PPP-B2b correction information obtained by all observation stations. A widelane float ambiguity block (FCB) for each satellite is calculated based on the widelane float ambiguity resolutions of all satellites, and a narrowlane float ambiguity block (FCB) for each satellite is calculated based on the narrowlane float ambiguity resolutions of all satellites. For each satellite, an integer ionospheric-free combined ambiguity is generated based on the widelane float ambiguity resolution, the widelane FCB, the narrowlane float ambiguity resolution, and the narrowlane FCB. The present invention uses the real-time broadcast PPP-B2b service to resolve the integer ionospheric-free combined ambiguity, without relying on post-precision products. This ensures real-time performance and enables real-time resolution of the integer ionospheric-free combined ambiguity. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0047] Figure 1 1 is a flow chart of a method for fixing PPP whole-cycle ionospheric combination ambiguity based on PPP-B2b provided by one embodiment of the present invention;

[0048] Figure 2 It is a structural diagram of a real-time PPP whole-cycle ionospheric combination ambiguity fixing device based on PPP-B2b provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0049] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions in this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the term "include" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0051] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0052] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0053] In the description of the embodiments of the present application, the term "several" refers to more than two (including two).

[0054] See also Figure 1 To solve the problem in the prior art that the whole-cycle ionospheric elimination combined ambiguity cannot be resolved in real time, an embodiment of the present invention provides a real-time PPP whole-cycle ionospheric elimination combined ambiguity fixing method based on PPP-B2b, comprising:

[0055] S1. Obtaining raw observation data of a plurality of satellites through a plurality of observation stations and obtaining PPP-B2b correction information; wherein each of the satellites is a GPS satellite or a BDS satellite.

[0056] It should be noted that currently, international GNSS services are able to provide real-time orbital clock corrections via the Internet. my country's BeiDou-3 satellite positioning system has also released the PPP-B2b service, which carries real-time orbital clock corrections and satellite code bias information on the B2b signal. Users receive these corrections through GNSS receivers, restore the broadcast ephemeris to a precise product, and perform precise point positioning. Therefore, a method for real-time PPP ambiguity fixation based on PPP-B2b is theoretically feasible, but there is currently little research in this area. Therefore, the present invention innovatively provides a real-time PPP whole-week ionospheric elimination combined ambiguity fixation method based on PPP-B2b to solve the problem that traditional PPP ambiguity fixation technology cannot resolve whole-week ionospheric elimination combined ambiguity in real time.

[0057] In step S1, the present invention involves several observation stations and several satellites. Some of these satellites are GPS satellites, some are BDS satellites, or all of them can be GPS satellites or all of them can be BDS satellites. Each observation station obtains raw observation data from all satellites through a receiver. In addition, it also needs to obtain PPP-B2b correction information, which mainly includes correction parameters.

[0058] S2. For each satellite, generate a widelane float ambiguity resolution and a narrowlane float ambiguity resolution of the satellite based on the original observation data of the satellite acquired by all observation stations and the PPP-B2b correction information.

[0059] The main steps in step S2 are: using the PPP-B2b correction information to correct the original observation data, and then generating the wide-lane float ambiguity resolution and narrow-lane float ambiguity resolution of the satellite based on the corrected observation data.

[0060] In a preferred embodiment, the PPP-B2b correction information includes: satellite inter-symbol bias correction number;

[0061] The original observation data includes: original pseudorange observation values ​​and original carrier phase observation values;

[0062] Generating the widelane float ambiguity resolution and the narrowlane float ambiguity resolution of the satellite based on the original observation data of the satellite acquired by all observation stations and the PPP-B2b correction information includes:

[0063] Correcting the original pseudorange observation value and the original carrier phase observation value of each measuring station according to the satellite inter-code bias correction number to obtain the corrected pseudorange observation value and the corrected carrier phase observation value of each measuring station;

[0064] Calculating the ionospheric-free combined float resolution of the satellite based on the corrected pseudorange observations and corrected carrier phase observations of all stations;

[0065] Calculating a widelane floating point ambiguity resolution of the satellite based on the corrected pseudorange observations and the corrected carrier phase observations;

[0066] The narrowlane float deambiguity of the satellite is calculated according to the ionospheric-free combined float deambiguity and the widelane float deambiguity.

[0067] In this embodiment, the raw pseudorange and carrier phase observations are corrected using satellite intersymbol bias corrections to obtain corrected pseudorange and carrier phase observations, respectively. The ionospheric-free combined float resolution and widelane float resolution are then calculated based on these corrected pseudorange and carrier phase observations. Furthermore, the narrowlane float resolution is calculated.

[0068] The correction formula for pseudorange observations is:

[0069]

[0070] Where, represents the corrected pseudorange observation value at the frq frequency; l frq Represents the original pseudorange observation value at frq frequency; DCB frq Indicates the satellite inter-code bias correction number at the frq frequency;

[0071] The correction formula for the carrier phase observation value is:

[0072]

[0073] Where, Represents the corrected carrier phase observation value at the frq frequency; represents the original carrier phase observation value at the frq frequency; λ represents the wavelength of the carrier.

[0074] In a preferred embodiment, the calculating of the satellite's ionospheric-free combined float ambiguity resolution based on the corrected pseudorange observations and corrected carrier phase observations of all stations comprises:

[0075] According to the corrected pseudorange observations and corrected carrier phase observations of all stations, a pseudorange-carrier observation model and an ionospheric elimination equation group are constructed.

[0076] By using a Kalman filtering method, under the constraints of the ionospheric elimination equations, the pseudorange-carrier observation model is solved to obtain the ionospheric elimination combined floating point ambiguity resolution;

[0077] The process of constructing the pseudorange-carrier observation model includes:

[0078] When the satellite is a GPS satellite, a GPS satellite pseudorange-carrier observation model is constructed based on the corrected pseudorange observation values ​​and corrected carrier phase observation values ​​of all measurement stations;

[0079] When the satellite is a BDS satellite, a BDS satellite pseudorange-carrier observation model is constructed based on the corrected pseudorange observation values ​​and corrected carrier phase observation values ​​of all measurement stations.

[0080] In this embodiment, assuming that high-order ionospheric delays are ignored, antenna phase center offset and variance, phase wrapping, solid-state tides, Earth rotation, and relativistic effects are corrected in advance. Based on the corrected pseudorange observations and corrected carrier phase observations from all stations, a pseudorange-carrier observation model and ionospheric-eliminating equations are constructed. Taking into account the influence of inter-system bias, the pseudorange-carrier phase observation model is as follows:

[0081] (1) GPS satellite pseudorange-carrier observation model:

[0082]

[0083] Where, The frequency of the r-th station is f i The corrected pseudorange observation value corresponding to the GPS satellite, where i=1,2; represents the satellite-to-ground distance of the GPS satellite at the rth station; c represents the speed of light; δt r represents the receiver clock error of the rth station; δt s,G Indicates the satellite clock error corresponding to the GPS satellite; represents the oblique tropospheric delay corresponding to the GPS satellite at the r-th station; represents the ionospheric delay corresponding to the GPS satellite at the rth station; represents the pseudorange observation noise corresponding to the GPS satellite; represents the floating point ambiguity resolution corresponding to the GPS satellite; represents the carrier phase observation noise corresponding to the GPS satellite;

[0084] (2) BDS satellite pseudorange-carrier observation model:

[0085]

[0086] Where, The frequency of the r-th station is f i The corrected pseudorange observation value corresponding to the BDS satellite, where i = 1, 2; δt represents the satellite-to-ground distance corresponding to the BDS satellite at the rth station; s,C Indicates the satellite clock error corresponding to the BDS satellite; represents the oblique tropospheric delay corresponding to the BDS satellite at the r-th station; represents the ionospheric delay corresponding to the BDS satellite at the r-th station; represents the pseudorange observation noise corresponding to the BDS satellite; represents the floating point ambiguity resolution corresponding to the BDS satellite; ISB represents the carrier phase observation noise corresponding to the BDS satellite; GC Indicates the inter-system deviation of the receiver clock;

[0087] Note that the ionospheric delay has different effects on the signals of the two frequencies in the pseudorange and carrier phase observations. The ionospheric elimination equations constructed are:

[0088]

[0089] Where i = 1, j = 2, f i represents the frequency of the i-th frequency point signal, P represents the ionospheric-free combined pseudorange observation value of satellite s observed by station r, i represents the pseudorange observation value of the i-th frequency point. Similarly, L represents the ionospheric composite carrier phase observation value of satellite s observed by station r, i Represents the carrier phase observation value of the i-th frequency point.

[0090] It should be noted that the observations after ionospheric elimination can be considered to have eliminated the influence of ionospheric delay and reduced the number of parameters to be estimated.

[0091] In the above formula, pseudorange observations, carrier phase observations, satellite position, and satellite clock errors are known parameters. Receiver position, receiver clock error, receiver clock system bias, slant tropospheric delay, ionospheric delay, and floating point resolution are unknown parameters (i.e., parameters to be estimated). Of the known parameters, satellite position and satellite clock errors are calculated using broadcast ephemeris and then recovered into precise orbit and clock products using PPP-B2b corrections.

[0092] The method for recovering the precise track is:

[0093] X B2b =X brdc -δX B2b ;

[0094] Where, X B2b Indicates the corrected precise satellite position, X brdcrepresents the satellite position calculated from the broadcast ephemeris, δX B2b Indicates the satellite position correction number. Since the satellite orbit correction number provided by PPP-B2b is the radial, tangential, and normal correction number of a single satellite orbit, it needs to be converted into the satellite position correction number, that is:

[0095]

[0096] Where r = X brdc represents the satellite position calculated from the broadcast ephemeris, represents the satellite velocity calculated from the broadcast ephemeris, × represents the matrix cross multiplication operation, δO radial ,δO along ,δO cross Indicates the raw orbit correction provided by PPP-B2b.

[0097] The method for recovering the precise satellite clock error is:

[0098]

[0099] Where, t sat represents the corrected satellite clock error; t brdc represents the satellite clock error calculated from the broadcast ephemeris; C0 represents the clock correction number; and c represents the speed of light.

[0100] The Kalman filter approach uses a pseudorange-carrier phase observation model for calculation. The Kalman filter method can be divided into two steps: state update and observation update. The state update models the noise term and the trend and variance of the estimated parameter, giving a predicted value. The measurement update process uses the observation equation to calculate the estimated parameter based on the given predicted value. With each observation update, the estimated parameter value becomes closer to the true value. All estimated parameters are calculated simultaneously.

[0101] In a preferred embodiment, the calculating the widelane float ambiguity resolution of the satellite based on the corrected pseudorange observations and the corrected carrier phase observations comprises:

[0102] The wide-lane floating-point ambiguity resolution of the satellite is calculated based on the corrected pseudorange observation value and the corrected carrier phase observation value through the MW combined observation model.

[0103] In this embodiment, the wide-lane floating-point ambiguity resolution of the satellite is calculated based on the corrected pseudorange observations and the corrected carrier phase observations using the MW combined observation model. The formula is:

[0104]

[0105] Where MW(i,j) represents the MW combination operation on the observation values ​​of the i-th and j-th frequency points; N WL represents the wide-lane floating-point deambiguation; λ i Represents the wavelength of the observation value at the i-th frequency point, that is

[0106] The calculation formula for the narrow lane floating point ambiguity resolution is:

[0107]

[0108] Where N NL represents the floating-point solution of narrow lane ambiguity; λ IF The wavelength of the deionospheric observations; λ NL represents the wavelength of the narrow lane combination; Represents the ionospheric deambiguation float.

[0109] S3. Calculate the widelane FCB of each satellite based on the widelane float ambiguity resolution of all the satellites, and calculate the narrowlane FCB of each satellite based on the narrowlane float ambiguity resolution of all the satellites.

[0110] In a preferred embodiment, the calculating of the widelane FCB of each satellite based on the widelane float ambiguity resolution of all the satellites, and the calculating of the narrowlane FCB of each satellite based on the narrowlane float ambiguity resolution of all the satellites, comprises:

[0111] The ambiguity error equation is constructed with the floating point ambiguity solution, the integer part of the ambiguity, the phase bias of the station receiver system, the FCB at the station receiver side, and the FCB at the satellite side as parameters.

[0112] Substituting the widelane float ambiguity solutions of all the satellites into the ambiguity error equation, solving the ambiguity error equation, and obtaining the widelane FCB of each satellite;

[0113] Substituting the narrowlane float ambiguity solutions of all the satellites into the ambiguity error equation, solving the ambiguity error equation, and obtaining the narrowlane FCB of each satellite.

[0114] In this embodiment, after obtaining the floating-point ambiguity resolution, the variance of the wide-lane ambiguity and narrow-lane ambiguity floating-point solutions can be obtained using the covariance propagation law. Since it is impossible to obtain the FCB at the satellite end and the receiver end through a single receiver, M measurement stations in the area are selected to calculate the FCB product for ambiguity fixation.

[0115] The expression of the ambiguity error equation is:

[0116]

[0117] Where p is the number of GPS floating ambiguities; q is the number of floating ambiguity satellites; m is the number of stations containing GPS observations; n is the number of stations containing BDS observations; j is the number of GPS satellites; k is the number of BDS satellites. represents the floating point resolution of the ipth GPS satellite, ip = 1, ..., p; Indicates the integer part of the ambiguity of the ipth GPS satellite, which is obtained by rounding the floating-point ambiguity resolution to the nearest integer; represents the floating point ambiguity resolution of the iqth BDS satellite, iq = 1,...,q; The integer part of the ambiguity of the iqth BDS satellite is obtained by rounding the floating point ambiguity resolution to the nearest integer; R i represents a matrix whose i-th column element is -1 and other column elements are 0; S i Indicates that each row has a matrix with an element of 1, corresponding to a certain satellite, and the other elements are matrices of 0. The purpose of distinguishing G, GC, and C here is to indicate that the position and operation objects of each matrix are different; represents the FCB at the receiver end of the im-th station, im=1,...,m;

[0118] represents the inter-system phase deviation of the in-th receiver; Indicates the satellite-side FCB of the ij-th GPS satellite; R represents the satellite-side FCB of the ikth BDS satellite; ε(·) represents the noise term. i The i-th column of S is -1, and the rest of the positions are 0; i Each row of has one element that is 1, corresponding to a satellite, and the other elements are 0.

[0119] Since the fractional phase deviations of the receiver and the satellite are linearly related, the satellite with the highest GPS and BDS elevation angles is initially selected as the reference. A constraint equation is added, that is, the FCB of the reference satellite is set to 0 to ensure that the differential observation equations are solvable.

[0120] Widelane and narrowlane ambiguities are resolved using the least squares ambiguity decorrelation method. Calculating FCB corrections using the least squares method requires an initial value. The floating-point ambiguity solutions of different satellites in the same time period are single-differenced with the floating-point ambiguity solutions of the reference satellite. All single-differences from the same satellite are averaged to reduce the impact of the receiver FCB. The initial satellite FCB value is obtained by subtracting the integer portion from this average. When calculating the initial satellite FCB value, single-differences with absolute values ​​exceeding 0.5 cycles are discarded. The satellite with the largest number of single-differences is used as a backup reference satellite. The initial satellite FCB value is used to correct the floating-point ambiguity solutions. The satellite decimal deviations from the same time period are averaged to obtain a stable initial receiver FCB value. The solution is iterated using weighted residuals until the change in the FCB stabilizes.

[0121] S4. For each satellite, generate an integer ionospheric-free combined ambiguity based on the widelane float deambiguation, the widelane FCB, the narrowlane float deambiguation, and the narrowlane FCB of the satellite.

[0122] In a preferred embodiment, generating the integer ionospheric-free combined ambiguity based on the widelane float ambiguity resolution, the widelane FCB, the narrowlane float ambiguity resolution, and the narrowlane FCB of the satellite includes:

[0123] Correcting the widelane floating point ambiguity according to the widelane FCB to obtain a corrected widelane floating point ambiguity; correcting the narrowlane floating point ambiguity according to the narrowlane FCB to obtain a corrected narrowlane floating point ambiguity;

[0124] Fixing the corrected widelane floating point ambiguity and the corrected narrowlane floating point ambiguity respectively by using an ambiguity reduction correlation method to obtain an integer widelane ambiguity and an integer narrowlane ambiguity;

[0125] The integer-cycle ionospheric-free combined ambiguity is calculated according to the integer-cycle wide-lane ambiguity and the integer-cycle narrow-lane ambiguity.

[0126] It should be noted that when correcting the floating point resolution of the BDS satellite, the ISPB, that is, the inter-system phase bias of the receiver, is also required.

[0127] The input of the ambiguity reduction correlation method is a series of floating-point ambiguity vectors after FCB correction, and the corresponding integer ambiguity can be found according to the least squares method.

[0128] The ambiguity reduction correlation method is mainly divided into two steps: reduction correlation transformation and optimal integer search.

[0129] First, perform a Z transform on the ambiguity float solution vector:

[0130]

[0131] Where, represents the transformed ambiguity vector; Z T represents the Z transformation matrix; represents the ambiguity vector; is the variance-covariance matrix of the transformed ambiguity vector; represents the variance-covariance matrix of the ambiguity vector; L T DL is the result after Cholesky decomposition;

[0132] After the transformation, the correlation of the floating-point solution vector is reduced, and the objective equation can be expressed as:

[0133]

[0134] Where Q z represents the variance-covariance matrix of the ambiguity vector z to be determined.

[0135] By searching the ambiguity subset vector and achieving the target equation, the optimal ambiguity vector can be obtained. After obtaining the optimal solution, the integer ambiguity vector can be restored according to the following formula:

[0136]

[0137] Where, represents the transformed ambiguity vector that satisfies the objective equation, represents the ambiguity vector recovered from the transformed ambiguity vector that achieves the target equation.

[0138] In a preferred embodiment, after respectively fixing the corrected widelane float deambiguity and the corrected narrowlane float deambiguity by using the ambiguity reduction correlation method to obtain the integer widelane ambiguity and the integer narrowlane ambiguity, the method further includes:

[0139] Calculate the first bootstrapping success rate and the first ratio index of the fixed wide-lane floating-point deambiguation, and calculate the second bootstrapping success rate and the second ratio index of the fixed narrow-lane floating-point deambiguation;

[0140] If the first bootstrapping success rate is not less than a preset bootstrapping success rate threshold and the first ratio index is not less than a preset ratio index threshold, the widelane floating point deambiguity is fixed successfully; otherwise, the widelane floating point deambiguity is fixed failed;

[0141] If the second bootstrapping success rate is not less than the bootstrapping success rate threshold and the second ratio index is not less than the ratio index threshold, the narrow lane floating point deambiguity is fixed successfully; otherwise, the narrow lane floating point deambiguity is fixed failed;

[0142] If both the wide-lane float ambiguity resolution and the narrow-lane ambiguity resolution are fixed successfully, the subsequent operation of calculating the whole-cycle ionospheric-free combined ambiguity resolution will be continued. Otherwise, the subsequent operation of calculating the whole-cycle ionospheric-free combined ambiguity resolution will not be performed.

[0143] In this embodiment, the bootstrapping success rate can be expressed as:

[0144]

[0145] where Φ(x) is the probability density function of the standard normal distribution and n is the number of integer ambiguities.

[0146] The ratio index can be expressed as:

[0147]

[0148] Where, represents the inverse matrix of the variance-covariance matrix of the ambiguity vector, represents the optimal integer ambiguity vector, represents the suboptimal integer ambiguity vector.

[0149] Since PPP-B2b only has precise orbit corrections from the GPS / BDS systems, the thresholds are appropriately increased here: the bootstrapping success rate threshold is set to 0.999, and the ratio index threshold is set to 10.0.

[0150] The present invention uses the real-time broadcast PPP-B2b service to resolve the whole-week ionospheric-free combined ambiguity, does not rely on subsequent precise products, can ensure real-time performance, and realizes the real-time resolution of the whole-week ionospheric-free combined ambiguity.

[0151] In addition, even if precise orbit clock products from different institutions are used, different solution strategies are adopted, and the accuracy differences need to be considered. If a unified precise orbit clock product is not used when solving decimal deviations, the solution error will be too large, resulting in the inability to fix the whole-cycle ambiguity. The present invention restores a unified precise orbit clock product based on the PPP-B2b service. Since the PPP-B2b service provides orbit clock corrections for both the GPS and BDS systems, the present invention does not need to introduce precise orbit clock products issued by other institutions. The product solution strategy remains unified, avoiding the problem of excessive solution errors causing the inability to fix the whole-cycle ambiguity.

[0152] After calculating the whole-cycle ionospheric-free combined ambiguity, GNSS positioning can be performed in real time based on the whole-cycle ionospheric-free combined ambiguity obtained in real time.

[0153] like Figure 2 As shown, based on the above method embodiment, a corresponding device embodiment is provided;

[0154] An embodiment of the present invention provides a real-time PPP whole-cycle ionospheric de-ambiguity combination fixing device based on PPP-B2b, comprising: a data acquisition module, a floating-point de-ambiguity calculation module, an FCB calculation module, and an ambiguity fixing module;

[0155] The data acquisition module is used to acquire raw observation data of a plurality of satellites through a plurality of observation stations and obtain PPP-B2b correction information; wherein each of the satellites is a GPS satellite or a BDS satellite;

[0156] The floating point ambiguity resolution calculation module is configured to generate, for each satellite, a wide lane floating point ambiguity resolution and a narrow lane floating point ambiguity resolution of the satellite based on the original observation data of the satellite acquired by all observation stations and the PPP-B2b correction information;

[0157] The FCB calculation module is configured to calculate the widelane FCB of each satellite based on the widelane float ambiguity resolution of all the satellites, and calculate the narrowlane FCB of each satellite based on the narrowlane float ambiguity resolution of all the satellites;

[0158] The ambiguity fixing module is configured to generate, for each satellite, an integer ionospheric-free combined ambiguity based on the widelane float deambiguation, the widelane FCB, the narrowlane float deambiguation and the narrowlane FCB of the satellite.

[0159] It can be understood that the above-mentioned device embodiment corresponds to the method embodiment of the present invention, which can implement the real-time PPP whole-week ionospheric combination ambiguity fixation method based on PPP-B2b provided by any one of the above-mentioned method embodiments of the present invention.

[0160] It should be noted that the device embodiments described above are merely illustrative, and some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. Furthermore, in the drawings of the device embodiments provided by the present invention, the connection relationship between modules indicates that they have a communication connection, which may be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement the present invention without inventive effort.

[0161] Based on the above-mentioned method embodiment, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the real-time PPP whole-cycle ionospheric combination ambiguity fixation method based on PPP-B2b of any embodiment of the present invention.

[0162] For example, in this embodiment, the computer program may be divided into one or more modules, which are stored in the memory and executed by the processor to implement the present invention. The one or more module elements may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program in the terminal device.

[0163] The terminal device may be a computing device such as a desktop computer, a notebook computer, a PDA, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0164] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the terminal device, connecting various parts of the entire terminal device using various interfaces and lines.

[0165] Based on the above-mentioned method embodiments, another embodiment of the present invention provides a computer-readable storage medium, including a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the real-time PPP whole-cycle ionospheric elimination combined ambiguity fixation method based on PPP-B2b as described in any one of the above-mentioned method embodiments of the present invention.

[0166] Wherein, the module / unit integrated in the device / terminal equipment, if implemented in the form of a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the process in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and when the computer program is executed by the processor, it can implement the steps of the above-mentioned various method embodiments. Wherein, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0167] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A real-time PPP whole-cycle ionospheric combination ambiguity fixation method based on PPP-B2b, characterized in that: include: Obtaining raw observation data of a plurality of satellites through a plurality of observation stations to obtain PPP-B2b correction information; wherein each of the satellites is a GPS satellite or a BDS satellite; For each of the satellites, generating a widelane float ambiguity resolution and a narrowlane float ambiguity resolution of the satellite based on the original observation data of the satellite acquired by all observation stations and the PPP-B2b correction information; Calculating a widelane FCB of each satellite based on the widelane float ambiguity resolution of all the satellites, and calculating a narrowlane FCB of each satellite based on the narrowlane float ambiguity resolution of all the satellites; For each of the satellites, an integer ionospheric-free combined ambiguity is generated according to the widelane float deambiguation, the widelane FCB, the narrowlane float deambiguation and the narrowlane FCB of the satellite.

2. The method for fixing the real-time PPP whole-cycle ionospheric combination ambiguity based on PPP-B2b according to claim 1, wherein: The PPP-B2b correction information includes: satellite inter-code deviation correction number; The original observation data includes: original pseudorange observation values ​​and original carrier phase observation values; Generating the widelane float ambiguity resolution and the narrowlane float ambiguity resolution of the satellite based on the original observation data of the satellite acquired by all observation stations and the PPP-B2b correction information includes: Correcting the original pseudorange observation value and the original carrier phase observation value of each measuring station according to the satellite inter-code bias correction number to obtain the corrected pseudorange observation value and the corrected carrier phase observation value of each measuring station; Calculating the ionospheric-free combined float resolution of the satellite based on the corrected pseudorange observations and corrected carrier phase observations of all stations; Calculating a widelane floating point ambiguity resolution of the satellite based on the corrected pseudorange observations and the corrected carrier phase observations; The narrowlane float deambiguity of the satellite is calculated according to the ionospheric-free combined float deambiguity and the widelane float deambiguity.

3. The real-time PPP whole-cycle ionospheric combination ambiguity fixing method based on PPP-B2b as claimed in claim 2, characterized in that: The calculating the ionospheric-free combined floating-point ambiguity resolution of the satellite based on the corrected pseudorange observation values ​​and the corrected carrier phase observation values ​​of all stations includes: According to the corrected pseudorange observations and corrected carrier phase observations of all stations, a pseudorange-carrier observation model and an ionospheric elimination equation group are constructed. By using a Kalman filtering method, under the constraints of the ionospheric elimination equations, the pseudorange-carrier observation model is solved to obtain the ionospheric elimination combined floating point ambiguity resolution; The process of constructing the pseudorange-carrier observation model includes: When the satellite is a GPS satellite, a GPS satellite pseudorange-carrier observation model is constructed based on the corrected pseudorange observation values ​​and corrected carrier phase observation values ​​of all measurement stations; When the satellite is a BDS satellite, a BDS satellite pseudorange-carrier observation model is constructed based on the corrected pseudorange observation values ​​and corrected carrier phase observation values ​​of all measurement stations.

4. The method for fixing the real-time PPP whole-cycle ionospheric combination ambiguity based on PPP-B2b according to claim 2, wherein: Calculating the widelane float ambiguity resolution of the satellite based on the corrected pseudorange observation value and the corrected carrier phase observation value includes: The wide-lane floating-point ambiguity resolution of the satellite is calculated based on the corrected pseudorange observation value and the corrected carrier phase observation value through the MW combined observation model.

5. The method for fixing the real-time PPP whole-cycle ionospheric combination ambiguity based on PPP-B2b according to claim 1, wherein: The calculating of the widelane FCB of each satellite based on the widelane float ambiguity resolution of all the satellites, and the calculating of the narrowlane FCB of each satellite based on the narrowlane float ambiguity resolution of all the satellites, comprises: The ambiguity error equation is constructed with the floating point ambiguity solution, the integer part of the ambiguity, the phase bias of the station receiver system, the FCB at the station receiver side, and the FCB at the satellite side as parameters. Substituting the widelane float ambiguity solutions of all the satellites into the ambiguity error equation, solving the ambiguity error equation, and obtaining the widelane FCB of each satellite; Substituting the narrowlane float ambiguity solutions of all the satellites into the ambiguity error equation, solving the ambiguity error equation, and obtaining the narrowlane FCB of each satellite.

6. The method for fixing the real-time PPP whole-cycle ionospheric combination ambiguity based on PPP-B2b according to claim 1, wherein: Generating an integer ionospheric-free combined ambiguity according to the widelane float ambiguity resolution, the widelane FCB, the narrowlane float ambiguity resolution, and the narrowlane FCB of the satellite includes: Correcting the widelane floating point ambiguity according to the widelane FCB to obtain a corrected widelane floating point ambiguity; correcting the narrowlane floating point ambiguity according to the narrowlane FCB to obtain a corrected narrowlane floating point ambiguity; Fixing the corrected widelane floating point ambiguity and the corrected narrowlane floating point ambiguity respectively by using an ambiguity reduction correlation method to obtain an integer widelane ambiguity and an integer narrowlane ambiguity; The integer-cycle ionospheric-free combined ambiguity is calculated according to the integer-cycle wide-lane ambiguity and the integer-cycle narrow-lane ambiguity.

7. The method for fixing the real-time PPP whole-cycle ionospheric combination ambiguity based on PPP-B2b according to claim 6, wherein: After respectively fixing the corrected widelane floating point ambiguity and the corrected narrowlane floating point ambiguity by using the ambiguity reduction correlation method to obtain the integer widelane ambiguity and the integer narrowlane ambiguity, the method further includes: Calculate the first bootstrapping success rate and the first ratio index of the fixed wide-lane floating-point deambiguation, and calculate the second bootstrapping success rate and the second ratio index of the fixed narrow-lane floating-point deambiguation; If the first bootstrapping success rate is not less than a preset bootstrapping success rate threshold and the first ratio index is not less than a preset ratio index threshold, the widelane floating point deambiguity is fixed successfully; otherwise, the widelane floating point deambiguity is fixed failed; If the second bootstrapping success rate is not less than the bootstrapping success rate threshold and the second ratio index is not less than the ratio index threshold, the narrow lane floating point deambiguity is fixed successfully; otherwise, the narrow lane floating point deambiguity is fixed failed; If both the wide-lane float ambiguity resolution and the narrow-lane ambiguity resolution are fixed successfully, the subsequent operation of calculating the whole-cycle ionospheric-free combined ambiguity resolution will be continued. Otherwise, the subsequent operation of calculating the whole-cycle ionospheric-free combined ambiguity resolution will not be performed.

8. A real-time PPP whole-cycle ionospheric combination ambiguity fixing device based on PPP-B2b, characterized in that: include: Data acquisition module, floating point deambiguation calculation module, FCB calculation module and ambiguity fixing module; The data acquisition module is used to acquire raw observation data of a plurality of satellites through a plurality of observation stations and obtain PPP-B2b correction information; wherein each of the satellites is a GPS satellite or a BDS satellite; The floating point ambiguity resolution calculation module is configured to generate, for each satellite, a wide lane floating point ambiguity resolution and a narrow lane floating point ambiguity resolution of the satellite based on the original observation data of the satellite acquired by all observation stations and the PPP-B2b correction information; The FCB calculation module is configured to calculate the widelane FCB of each satellite based on the widelane float ambiguity resolution of all the satellites, and calculate the narrowlane FCB of each satellite based on the narrowlane float ambiguity resolution of all the satellites; The ambiguity fixing module is configured to generate, for each satellite, an integer ionospheric-free combined ambiguity based on the widelane float deambiguation, the widelane FCB, the narrowlane float deambiguation and the narrowlane FCB of the satellite.

9. A terminal device, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, the method implements the real-time PPP whole-cycle ionospheric combination ambiguity fixation method based on PPP-B2b according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that include: A stored computer program, wherein when the computer program is run, the device where the computer-readable storage medium is located is controlled to perform the real-time PPP whole-week ionospheric combined ambiguity fixation method based on PPP-B2b according to any one of claims 1 to 7.

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