CN114879239B - Regional three-frequency integer clock error estimation method for enhancing instantaneous PPP fixed solution - Google Patents

Regional three-frequency integer clock error estimation method for enhancing instantaneous PPP fixed solution Download PDF

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CN114879239B
CN114879239B CN202210809875.0A CN202210809875A CN114879239B CN 114879239 B CN114879239 B CN 114879239B CN 202210809875 A CN202210809875 A CN 202210809875A CN 114879239 B CN114879239 B CN 114879239B
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clock error
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CN114879239A (en
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陶钧
瞿子扬
张高舰
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Kepler Satellite Technology Wuhan Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/42—Determining position
    • G01S19/43—Determining position using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry
    • G01S19/44—Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

The invention provides a regional three-frequency integer clock error estimation method for enhancing an instantaneous PPP fixed solution, which belongs to the technical field of global satellite navigation systems, and is used for creatively classifying parameters to be estimated in the process of regional station network original observed quantity with high sampling rate, classifying the parameters such as ambiguity parameters, receiver clock error parameters, ionospheric delay and the like which need to be reduced in time, designing corresponding matrix element storage blocks, and realizing the efficient processing of blocks of different parameters to be estimated. The method creatively extracts the uncalibrated phase delay of the ultra-wide lane, the wide lane and the narrow lane and the satellite clock error in the regional network solution, improves the ambiguity fixing efficiency by utilizing a step-by-step ambiguity fixing strategy, obtains the final integer clock error under the constraint of the narrow lane integer ambiguity, and aims at introducing a large number of parameters to be estimated in the original observation equation in the dense-stage regional station network, how to introduce an efficient calculation method to overcome the calculation burden caused by the large parameters of the ionized layer, and realizes the rapid solution of the three-frequency real-time clock error.

Description

Regional three-frequency integer clock error estimation method for enhancing instantaneous PPP fixed solution
Technical Field
The invention relates to the technical field of GNSS satellite navigation positioning data processing, in particular to a regional tri-frequency integer clock error estimation method for enhancing instantaneous PPP fixed solution.
Background
By utilizing high-precision satellite orbit and clock error products, a precise point-of-sale (PPP) technology can realize global decimeter-level or even centimeter-level positioning based on a single receiver device, and the method is widely applied to the fields of seismic monitoring, global Navigation Satellite System (GNSS) water vapor remote sensing, low-orbit satellite orbit determination and the like in recent years. Due to the large delay of the international GNSS service IGS final orbit and clock error products, PPP technology has long been limited to post-processing mode. In order to further expand real-time applications, international GNSS Service (IGS) announces to develop PPP real-time service (RTS) in 2013, aiming to assist users in achieving real-time PPP by broadcasting enhancement information such as satellite orbit and clock offset in real time. The realization of PPP service requires high-quality real-time clock error and track products, the current ultra-fast track provided by IGS is updated once within 6 hours, the track forecast precision can meet the requirement of high-precision real-time application, the ultra-fast track update frequency of part of analysis centers even reaches 1 hour update, the corresponding track precision is further improved, and the research of high-precision real-time satellite clock error fast estimation becomes a research hotspot of the current real-time PPP service. The precision level of the broadcast satellite clock error is at a nanosecond level, and the requirement of a centimeter-level real-time PPP user is difficult to meet, so that the satellite clock error needs to be estimated in real time through real-time data observation of a global or regional network. In order to meet the timeliness requirement of the real-time positioning service, a large number of inactive ambiguity parameters can be eliminated through epoch difference, and the estimation efficiency of the real-time clock error is improved. However, the method simultaneously eliminates clock reference, satellite clock error estimation values in absolute sense cannot be obtained, the non-differential non-combination method has important significance for obtaining satellite clock errors with definite reference, but deviation information is kept through pseudo-range observation, and a large amount of calculation caused by a high-dimensional normal equation provides challenges for real-time services.
On the other hand, the convergence rate and precision of satellite clock error estimation can be further improved by fixing the non-differential ambiguity, and the method is favorable for quick high-precision positioning of a real-time user. For ambiguity fixing, it can be generally achieved by the fractional phase bias FCB method and the integer clock (IRC) method, which are theoretically equivalent. With the provision of observation signals of multiple frequency points by new navigation satellite systems such as Beidou and Galileo, the redundancy of observed quantities in user positioning can be improved by the multi-frequency signals, and the convergence speed and reliability of positioning can be improved.
Therefore, the method has important significance for enhancing the rapid convergence of the real-time PPP, improving the robustness of the real-time PPP and solving the estimation problem of the multi-frequency real-time integer satellite clock error.
Disclosure of Invention
In view of the above, the present invention provides a method for estimating a regional three-frequency integer clock difference for enhancing an instantaneous PPP fixation solution, which does not need to input observation data without an ionosphere into an estimator, but uses non-combination observation to effectively utilize multiple frequency signals.
The technical scheme of the invention is realized as follows: a regional three-frequency integer clock error estimation method for enhancing an instantaneous PPP fixed solution is characterized by comprising the following steps: classifying ambiguity parameters needing to be reduced in time, receiver clock error parameters, ionospheric delay and other parameters, designing corresponding matrix element storage blocks, and realizing efficient block processing of different parameters to be estimated; in the area network resolving, the uncalibrated phase delays of the ultra-wide lane, the wide lane and the narrow lane and the satellite clock error are extracted together, and the fixing efficiency of the ambiguity is improved by utilizing a step-by-step ambiguity fixing strategy to obtain the final integer clock error under the constraint of the whole ambiguity of the narrow lane.
On the basis of the technical scheme, preferably, on the basis of establishing a regional tracking station network, the ground station provides observation data and broadcast ephemeris of multiple GNSS to the operation system in real time and simultaneously acquires a GNSS real-time orbit product;
based on the original observation data, establishing a GNSS observation equation:
Figure 270304DEST_PATH_IMAGE001
on the basis of the above technical solution, preferably, a design matrix formed by the GNSS observation equation is subjected to parameter recombination by using an S-transform method, and after an accurate satellite orbit and ground station coordinate true value is brought into the GNSS observation equation, a non-combined geometric model after parameter recombination is expressed as:
Figure 105405DEST_PATH_IMAGE002
the variables may be expressed as:
Figure 849370DEST_PATH_IMAGE003
based on the above technical solution, the preferred re-parameterized satellite clock error and the clock error provided by the international GNSS service organization
Figure 492841DEST_PATH_IMAGE004
Compatibility of the product without the ionized layer is consistent, wherein
Figure 687062DEST_PATH_IMAGE005
And
Figure 353667DEST_PATH_IMAGE006
to absorb the remaining time-invariant and time-variant portions of the hardware bias,
Figure 291536DEST_PATH_IMAGE007
linearly related to the degree of ambiguity.
On the basis of the technical scheme, preferably, the amplitude of a GPS constellation is corrected by using inter-frequency clock bias, the time-invariant part at the satellite end is pre-calibrated through a specific observed value bias product, and the residual estimation parameters of a three-frequency clock difference model are
Figure 789513DEST_PATH_IMAGE008
。
On the basis of the technical scheme, preferably, the ultra-wide lane ambiguity is formed by utilizing the original ambiguity
Figure 30002DEST_PATH_IMAGE009
And wide lane ambiguity
Figure 308536DEST_PATH_IMAGE010
Mitigation of geometric and ionospheric effects:
Figure 456621DEST_PATH_IMAGE011
the ambiguity is no longer of an integer nature, since hardware deviations are absorbed. To correctly apply the ambiguity integer constraints, the ambiguity floating point solution is expressed as follows:
Figure 277946DEST_PATH_IMAGE012
on the basis of the above technical solution, preferably, the estimated uncalibrated phase delay product is used to sequentially restore the integer attribute of each ambiguity, and an ambiguity fixed probability test method is introduced, and the calculation formula is as follows:
Figure 545461DEST_PATH_IMAGE013
wherein x is
Figure 452237DEST_PATH_IMAGE014
Is rounded off when
Figure 731909DEST_PATH_IMAGE015
The corresponding ambiguity candidate is selected as a reliable integer solution.
On the basis of the technical scheme, preferably, the narrow lane integer value is back-substituted into the three-frequency integer clock difference estimation model, and the satellite clock difference and the receiver clock difference absorb corresponding clock differences
Figure 204478DEST_PATH_IMAGE016
And
Figure 786769DEST_PATH_IMAGE017
the corresponding three-frequency integer clock difference estimation model can be expressed as:
Figure 39896DEST_PATH_IMAGE018
the newly introduced variables for each term in equation (8) can be expressed as:
Figure 529783DEST_PATH_IMAGE019
on the basis of the technical scheme, preferably, the communication link is used for broadcasting the resolved three-frequency integer clock error product and the precise orbit by adopting the following observation equation:
Figure 325701DEST_PATH_IMAGE020
Figure 672369DEST_PATH_IMAGE021
the sum of the line-of-sight vectors representing a unit length,
Figure 553737DEST_PATH_IMAGE022
is a delta value relative to an a priori position,
Figure 847315DEST_PATH_IMAGE023
the pseudorange observation equations are ignored.
On the basis of the technical scheme, preferably, a method of least square ambiguity reduction correlation adjustment method with partial ambiguity solution is used for obtaining the optimal integer solution; finally, after the narrow lane ambiguity is resolved, the fast convergent PPP solution can be realized.
Compared with the prior art, the regional three-frequency integer clock error estimation method for enhancing the instantaneous PPP fixed solution has the following beneficial effects:
the invention has proposed a three-frequency integer clock error estimation method and operation system based on regional station network, the invention does not need to input the observation data without ionosphere into the estimator, but use the non-combination observation to utilize a plurality of frequency signals effectively, to the large amount of waiting to estimate parameters introduced in the original observation equation in the dense-level regional station network, introduce the high-efficient computational method to overcome the calculation burden that the big parameter of ionosphere causes, realize the fast resolving of three-frequency real-time clock error;
and determining a ambiguity fixing strategy aiming at ultra-wide lane, wide lane and narrow lane observation values formed by multi-frequency signals, and improving the ambiguity fixing efficiency as much as possible.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart illustrating a method for estimating a local three-frequency integer clock offset for enhancing an instantaneous PPP fixation solution according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
As shown in fig. 1, a method for estimating a local three-frequency integer clock offset for enhancing an instantaneous PPP fixation solution includes the following steps:
step 1: on the basis of establishing a regional tracking station network, a ground station provides observation data and broadcast ephemeris of multiple GNSS to an operation system in real time, and meanwhile, a GNSS real-time orbit product is obtained;
step 2: based on the raw observation data, a GNSS observation equation is established.
Figure 622373DEST_PATH_IMAGE001
（1）
In formula (1):
Figure 280887DEST_PATH_IMAGE024
is the expected value;
Figure 180710DEST_PATH_IMAGE025
and
Figure 340296DEST_PATH_IMAGE026
means for representing pseudoranges and carrier phase measurements between a satellite s and a station r of a constellation g at a frequency i, i =1,2, 3;
Figure 110806DEST_PATH_IMAGE027
is the geometric distance between the satellite r and the station s;
Figure 64856DEST_PATH_IMAGE028
and
Figure 451975DEST_PATH_IMAGE029
respectively representing the receiver clock error and the satellite clock error by taking meters as units;
Figure 290618DEST_PATH_IMAGE030
is the ionospheric delay at a first frequency and is mapped to other frequencies by a scaling factor
Figure 774689DEST_PATH_IMAGE031
；
Figure 837323DEST_PATH_IMAGE032
Representing zenith tropospheric delay by its mapping function
Figure 915000DEST_PATH_IMAGE033
；
Figure 153739DEST_PATH_IMAGE034
Are of corresponding wavelength
Figure 633262DEST_PATH_IMAGE035
The degree of ambiguity of;
Figure 866797DEST_PATH_IMAGE036
and
Figure 290825DEST_PATH_IMAGE037
a constant part representing hardware delays of the receiver and satellite pseudoranges;
Figure 268008DEST_PATH_IMAGE038
and
Figure 602038DEST_PATH_IMAGE039
indicating phaseA constant part of the hardware delay of (a); the varying portions of the phase hardware delays of the receiver and satellite are further represented as
Figure 68791DEST_PATH_IMAGE040
And
Figure 917799DEST_PATH_IMAGE041
。
and 3, step 3: and solving a three-frequency ambiguity floating solution. Since the design matrix formed by equation (1) has rank deficiency, and not all parameters in the equation can be estimated, the present invention uses S-transform for parameter reorganization. After the formula (1) is substituted into the true values of the precise satellite orbit and ground station coordinates, the non-combined geometric model after parameter recombination can be further expressed as:
Figure 901935DEST_PATH_IMAGE002
（2）
the variables in equation (2) can be expressed as:
Figure 215105DEST_PATH_IMAGE042
Figure 728126DEST_PATH_IMAGE043
and
Figure 64429DEST_PATH_IMAGE044
is the observation, which is the pseudo-range and phase observation between the satellite s of the constellation identifier g and the station r at frequency i, i =1,2,3, minus the calculation, which is solved according to the precise orbital and ground true coordinates of the satellite.
The re-parameterized satellite clock error is compared with that provided by the international GNSS service organization according to equation (2)
Figure 711311DEST_PATH_IMAGE004
The compatibility of the product without the ionized layer is consistent. Additional parameters
Figure 754353DEST_PATH_IMAGE005
And
Figure 828489DEST_PATH_IMAGE006
to absorb the remaining time-invariant and time-variant portions of the hardware bias,
Figure 652088DEST_PATH_IMAGE007
and the ambiguity is linearly related, wherein the amplitude of a GPS constellation is the largest and ranges from 0 to 25 cm, and the inter-frequency clock deviation can be used for correction. In order to further reduce the dimension of the normal equation matrix, the time-invariant part of the satellite side is pre-calibrated by a specific observation deviation product. Therefore, the residual estimation parameter of the three-frequency clock difference model is
Figure 712448DEST_PATH_IMAGE008
。
And 4, step 4: the uncalibrated phase delays are solved. The key problem of obtaining the three-frequency integer clock is to restore the ambiguity before estimating the satellite clock, and the accuracy of the original ambiguity extracted by directly utilizing the uncalibrated phase delay is lower in consideration of the high correlation between the original ambiguity and the ionosphere parameters. Aiming at the fixation of the three-frequency ambiguity, the invention adopts a cascade mode to gradually solve the fixation problem of the wide lane ambiguity and the narrow lane ambiguity so as to improve the success rate of the ambiguity fixation. The invention fully utilizes the original ambiguity to form the ultra-wide lane
Figure 734631DEST_PATH_IMAGE009
Ambiguities and wide lane ambiguities
Figure 917350DEST_PATH_IMAGE010
Mitigation of geometric and ionospheric effects:
Figure 165929DEST_PATH_IMAGE011
（3）
since hardware bias is absorbed, the ambiguity is no longer integer in nature, and in order to correctly apply the ambiguity integer constraint, the ambiguity floating solution is expressed as follows:
Figure 889035DEST_PATH_IMAGE012
（4）
in formula (4):
Figure 968986DEST_PATH_IMAGE045
and
Figure 260290DEST_PATH_IMAGE046
fractional parts of hardware delay from the receiver and satellite side, respectively;
Figure 875727DEST_PATH_IMAGE047
is the integer ambiguity;
Figure 340207DEST_PATH_IMAGE048
the estimation was performed using the following equation:
Figure 477927DEST_PATH_IMAGE049
（5）
in formula (5):
Figure 64766DEST_PATH_IMAGE050
is the product of kronecker;
Figure 22358DEST_PATH_IMAGE051
and
Figure 352845DEST_PATH_IMAGE052
is an identity matrix having dimensions r and s;
Figure 141809DEST_PATH_IMAGE053
and
Figure 40495DEST_PATH_IMAGE054
are respectively dimension of
Figure 875596DEST_PATH_IMAGE055
And
Figure 353982DEST_PATH_IMAGE056
the vector of (a);
fractional part
Figure 590928DEST_PATH_IMAGE057
Consisting of satellite hardware delay and receiver hardware delay, can be expressed as follows:
Figure 191674DEST_PATH_IMAGE058
（6）
in formula (6)
Figure 123858DEST_PATH_IMAGE059
Is the rounded symbol, returns the nearest integer value,
Figure 796148DEST_PATH_IMAGE060
and
Figure 559704DEST_PATH_IMAGE061
linear correlation, in order to solve the rank deficiency problem in data processing, a satellite with the largest altitude angle of the formula satellite clock is selected as a reference.
And 5: the degree of ambiguity is fixed. The estimated UPD product is utilized to sequentially restore the integer attributes of each ambiguity, and a detection method of ambiguity fixed probability is introduced, wherein the calculation formula is as follows:
Figure 534613DEST_PATH_IMAGE013
（7）
wherein x is
Figure 78727DEST_PATH_IMAGE014
Is rounded off when
Figure 226812DEST_PATH_IMAGE015
The corresponding ambiguity candidate is selected as a reliable integer solution. And a virtual observation value formed by a fixed ultra-wide lane and a wide lane is used as a constraint, so that a narrow lane ambiguity estimation value with a higher fixed rate can be obtained.
And 6: and solving the integer clock error by using a three-frequency integer clock error estimation model. The estimation products of the three-frequency integer clock difference are obtained by back substitution of the narrow-lane integer value, in this case, the satellite clock difference and the receiver clock difference absorb the corresponding clock differences
Figure 782558DEST_PATH_IMAGE016
And
Figure 990686DEST_PATH_IMAGE017
the corresponding three-frequency integer clock difference estimation model can be expressed as:
Figure 22096DEST_PATH_IMAGE018
（8）
the newly introduced variables for each term in equation (8) can be expressed as:
Figure 645975DEST_PATH_IMAGE019
（9）
equation (8) indicates that the integer clock error product contains an ambiguity reference instead of a pseudorange reference, while an additional term is introduced to the common clock error parameter in the observation equation
Figure 384124DEST_PATH_IMAGE023
In general, considering that the weight of the pseudorange observations is small, such additional terms are negligible and eventually absorbed by the pseudorange residuals. But the ambiguity for frequency i (i > 1) will suffer
Figure 93978DEST_PATH_IMAGE016
And
Figure 222471DEST_PATH_IMAGE017
and influence, in order to solve the problem that the estimated ultra-wide lane, wide lane and uncalibrated phase delay products are not compatible with the three-frequency integer clock error estimation model, re-extracting the uncalibrated phase delay products after the integer narrow lane constraint is added.
In a normal equation formed by an observation equation, the ambiguity parameters are set to the end, the calculation burden during parameter updating is reduced, and ionospheric parameters introduced in non-differential non-combination are dynamically increased or decreased or eliminated, so that the past bulkiness of a normal equation matrix is prevented, and the calculation amount is increased.
And 7: and broadcasting and applying the three-frequency integer clock difference. The communication link is used for broadcasting the three-frequency integer clock error product and the precise track resolved by the invention to users, and for the users, the PPP users adopt the following observation equation:
Figure 40255DEST_PATH_IMAGE020
（10）
in formula (10):
Figure 367331DEST_PATH_IMAGE021
the sum of the line-of-sight vectors representing a unit length,
Figure 854944DEST_PATH_IMAGE022
is a delta value with respect to a priori position, similar to a server
Figure 533050DEST_PATH_IMAGE023
Medium pseudorange observation equations are also ignored. The integer property of the narrow lane ambiguity is recovered by a three-frequency integer clock difference estimation product. However, direct fixation typically results in a lower success rate due to the high correlation between ionospheric parameters and narrow lane ambiguity. The user side adopts the same step-by-step ambiguity fixing strategy, and in each step, the optimal integer solution is obtained by using a least square ambiguity reduction correlation adjustment method with partial ambiguity solution. Finally, the ambiguity of the narrow lane is resolvedAfter that, the fast convergent PPP solution can be realized.
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 (8)

1. A regional three-frequency integer clock error estimation method for enhancing instantaneous PPP fixed solution is characterized in that: in the original observation of the regional station network with high sampling rate, classifying parameters to be estimated, classifying ambiguity parameters, receiver clock error parameters and ionospheric delay parameters which need to be reduced in time, designing corresponding matrix element storage blocks, and realizing the efficient processing of blocks of different parameters to be estimated; in the area network resolving, extracting uncalibrated phase delays of an ultra-wide lane, a wide lane and a narrow lane and satellite clock errors together, and improving the fixing efficiency of ambiguity by using a step-by-step ambiguity fixing strategy to obtain the final integer clock error under the constraint of the whole ambiguity of the narrow lane; on the basis of establishing a regional tracking station network, a ground station provides observation data and broadcast ephemeris of multiple GNSS to an operation system in real time, and meanwhile, a GNSS real-time orbit product is obtained; based on the original observation data, establishing a GNSS observation equation:
Figure DEST_PATH_IMAGE002
（1）
in formula (1):
Figure DEST_PATH_IMAGE003
is the expected value;
Figure DEST_PATH_IMAGE004
and
Figure DEST_PATH_IMAGE005
one of the satellites s and the station r representing a frequency i, i =1,2,3, constellation gPseudorange and carrier phase measurements between;
Figure DEST_PATH_IMAGE006
is the geometric distance between the satellite r and the station s;
Figure DEST_PATH_IMAGE007
and
Figure DEST_PATH_IMAGE008
respectively representing the receiver clock error and the satellite clock error by taking meters as units;
Figure DEST_PATH_IMAGE009
is the ionospheric delay at a first frequency and is mapped to other frequencies by a scaling factor;
Figure DEST_PATH_IMAGE010
representing zenith tropospheric delay by its mapping function
Figure DEST_PATH_IMAGE011
；
Figure DEST_PATH_IMAGE012
Are of corresponding wavelength
Figure DEST_PATH_IMAGE013
The degree of ambiguity of;
Figure DEST_PATH_IMAGE014
and
Figure DEST_PATH_IMAGE015
a constant part representing hardware delays of the receiver and satellite pseudoranges;
Figure DEST_PATH_IMAGE016
and
Figure DEST_PATH_IMAGE017
a constant portion of hardware delay representing phase; the varying portions of the phase hardware delays of the receiver and satellite are further represented as
Figure DEST_PATH_IMAGE018
And
Figure DEST_PATH_IMAGE019
；
the amplitude of a GPS constellation is corrected by using the clock offset between frequencies, the time-invariant part at the satellite end is pre-calibrated by a specific observation value offset product, and the residual estimation parameter of a three-frequency clock offset model is
Figure DEST_PATH_IMAGE020
。
2. The method as claimed in claim 1, wherein the method for estimating the local three-frequency integer clock error of the enhanced instantaneous PPP fixation solution comprises: and (2) performing parameter recombination on a design matrix formed by the GNSS observation equation by using an S-transformation method, and after accurate satellite orbit and ground station coordinate true values are brought into the GNSS observation equation, expressing a non-combined geometric model after parameter recombination as follows:
Figure DEST_PATH_IMAGE021
（2）
the variables in formula (2) are represented as:
Figure DEST_PATH_IMAGE023
。
3. as claimed inSolving 2 the regional three-frequency integer clock error estimation method for enhancing the instantaneous PPP fixed solution, which is characterized in that: the re-parameterized satellite clock error and the GNSS service organization provide
Figure DEST_PATH_IMAGE024
Compatibility of the product without the ionized layer is consistent, wherein
Figure DEST_PATH_IMAGE025
And
Figure DEST_PATH_IMAGE026
to absorb the remaining time-invariant and time-variant portions of the hardware bias,
Figure DEST_PATH_IMAGE027
linearly related to the ambiguity.
4. A method for estimating a local three-frequency integer clock error for enhancing an instantaneous PPP fixation solution, as claimed in claim 3, wherein: forming ultra wide lane ambiguities using original ambiguities
Figure DEST_PATH_IMAGE028
And wide lane ambiguity
Figure DEST_PATH_IMAGE029
Mitigation of geometric and ionospheric effects:
Figure DEST_PATH_IMAGE030
（3）
since hardware bias is absorbed, the ambiguity is no longer integer in nature, and in order to correctly apply the ambiguity integer constraint, the ambiguity floating solution is expressed as follows:
Figure DEST_PATH_IMAGE031
（4）
in formula (4):
Figure DEST_PATH_IMAGE032
and
Figure DEST_PATH_IMAGE033
fractional parts of hardware delay from the receiver and satellite side, respectively;
Figure DEST_PATH_IMAGE034
is the integer ambiguity;
Figure DEST_PATH_IMAGE035
the estimation was performed using the following equation:
Figure DEST_PATH_IMAGE036
（5）
in formula (5):
Figure DEST_PATH_IMAGE037
is the product of kronecker;
Figure DEST_PATH_IMAGE038
and
Figure DEST_PATH_IMAGE039
is an identity matrix having dimensions r and s;
Figure DEST_PATH_IMAGE040
and
Figure DEST_PATH_IMAGE041
are respectively dimension of
Figure DEST_PATH_IMAGE042
And
Figure DEST_PATH_IMAGE043
the vector of (a);
fractional part
Figure DEST_PATH_IMAGE044
Consists of satellite hardware delay and receiver hardware delay, and is expressed as follows:
Figure DEST_PATH_IMAGE045
（6）
in the formula (6)
Figure DEST_PATH_IMAGE046
Is a rounded symbol, returns the nearest integer value,
Figure DEST_PATH_IMAGE047
and with
Figure DEST_PATH_IMAGE048
Linear correlation, in order to solve the problem of rank deficiency in data processing, a satellite with the largest altitude angle of the satellite clock is selected as a reference.
5. The method of claim 4, wherein the method for estimating the local three-frequency integer clock error for enhancing the instantaneous PPP fixed solution comprises: by utilizing an estimated uncalibrated phase delay product, the integer attributes of all the ambiguities are sequentially restored, and a method for testing the ambiguity fixed probability is introduced, wherein the calculation formula is as follows:
Figure DEST_PATH_IMAGE049
（7）
wherein x is
Figure DEST_PATH_IMAGE050
Is rounded off when
Figure DEST_PATH_IMAGE051
The corresponding ambiguity candidate is selected as a reliable integer solution.
6. The method of claim 5, wherein the method for estimating the local three-frequency integer clock error for enhancing the instantaneous PPP fixed solution comprises: substituting the narrow lane integer value back into the three-frequency integer clock error estimation model, and absorbing the corresponding satellite clock error and the receiver clock error
Figure DEST_PATH_IMAGE052
And
Figure DEST_PATH_IMAGE053
the corresponding three-frequency integer clock difference estimation model is expressed as:
Figure DEST_PATH_IMAGE054
（8）
the newly introduced variables for each term in equation (8) are represented as:
Figure DEST_PATH_IMAGE055
（9）
equation (8) indicates that the integer clock error product contains an ambiguity reference instead of a pseudorange reference, while an additional term is introduced to the common clock error parameter in the observation equation
Figure DEST_PATH_IMAGE056
The pseudorange observations are ignored because they are weighted very little and are eventually absorbed by the pseudorange residuals.
7. The method as claimed in claim 6, wherein the method for estimating the local three-frequency integer clock error of the enhanced instantaneous PPP fixation solution comprises: the communication link is used for broadcasting the resolved three-frequency integer clock error product and the precise track by adopting the following observation equation:
Figure DEST_PATH_IMAGE057
（10）
in formula (10):
Figure DEST_PATH_IMAGE058
the sum of the line-of-sight vectors representing a unit length,
Figure DEST_PATH_IMAGE059
is a delta value relative to an a priori position,
Figure 320217DEST_PATH_IMAGE056
the pseudorange observation equation is ignored.
8. The method as claimed in claim 7, wherein the method for estimating the local three-frequency integer clock error of the enhanced instantaneous PPP fixation solution comprises: obtaining an optimal integer solution by using a least square ambiguity reduction correlation adjustment method with a partial ambiguity solution; finally, after the narrow lane ambiguity is resolved, the fast convergent PPP solution can be realized.
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