CN104614741B - Real-time precise satellite clock error estimation method not impacted by deviation of code frequency of GLONASS - Google Patents
Real-time precise satellite clock error estimation method not impacted by deviation of code frequency of GLONASS Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
- G01S19/27—Acquisition or tracking or demodulation of signals transmitted by the system creating, predicting or correcting ephemeris or almanac data within the receiver
Abstract
The invention discloses a real-time precise satellite clock error estimation method not impacted by deviation of code frequency of GLONASS, the GPS, GLONASS real-time precise satellite clock error estimation is executed by the GNSS reference station network, a plurality of independent time-frequency error parameters are set in the function model for absorbing the deviation of code frequency of GLONASS taking part in the calculating station receiver, the time-frequency error ISFB parameter, the receiver error and the GLONASS satellite clock error can be effectively separated by selecting the reference clock and addition survey station ISFB constraint condition, the adverse effect caused by the absorption of the GLONASS satellite clock error estimated value for the different survey station code frequency can be avoided; compared with the prior art, the GLONASS real-time precise satellite clock error estimation value precision can be obviously improved while the GPS real-time satellite clock error estimation value precision is not impacted.
Description
Technical field
The present invention relates to satellite geodetic surveying and technical field of navigation and positioning, more particularly, to one kind are not subject to GLONASS code frequency
Between deviation effects real-time accurate satellite clock correction method of estimation.
Background technology
High-precision real-time satellite clock error correction is to support real-time accurate One-Point Location (Real-Time Precise
Point Positioning, RT-PPP) technology key.Because satellite atomic clock is easily subject to frequency stability, variation of ambient temperature
Etc. factor impact, the supper-fast satellite clock correction product that IGS and its analysis center provide the forecast precision in a few hours may under
It is down to several ns levels it is impossible to meet the requirement of RT-PPP.General using the whole world or local tracking station network provide non-in real time
Difference carrier phase and Pseudo-range Observations, are defended on the premise of fixing survey station position and the ultrafast ephemeris of IGS furnish a forecast track
The real-time estimation of star clock correction.Based on GPS/GLONASS combination RT-PPP need to provide simultaneously high-precision real time GPS and
GLONASS satellite clock correction product.On April 1st, 2013, the formal release of IGS can provide real-time satellite track and satellite clock correction product
RTS (Real-time Service) service；This service is currently under test phase, and is only provided that real-time GPS satellite
Clock error correction product.So far, IGS not yet provides the GLONASS Clock Bias product of official, only ESOC, IAC,
Tetra- analysis centers of GFZ and NRCan provide Clock Bias product afterwards.With the progressively recovery of GLONASS system, entirely
The net distribution of ball GLONASS tracking station dramatically increased more in the past, has possessed and provides real-time GLONASS Clock Bias product
Basis.
Different from GPS, current GLONASS system uses frequency division multiple access (frequency division multiple
Access, FDMA) distinguish the signal being derived from different satellites, thus can produce the hardware different because of channel frequence inside receiver
Delay distortion item (inter-channel bias, ICB), is also called inter-frequency deviation (inter-frequnency bias, IFB).
There are some researches show, GLONASS code inter-frequency deviation in the interchannel difference of different frequency up to several meters, and with receiver type,
The factors such as firmware version, antenna type are relevant.When joint GPS/GLONASS carries out satellite clock correction estimation, need to estimate that two connect
Receipts machine clock correction item, i.e. GPS clock correction and GLONASS receiver clock-offsets；If GPS and GLONASS satellite clock correction adopt when
Between basis reference different, then it is also contemplated that the system time deviation of the two.Prior art is typically passed through to introduce " system time difference " ginseng
Number, GLONASS receiver clock-offsets is expressed as the form of GPS clock correction and system time difference sum.For GPS code
Hardware delay, because all gps satellite signals adopt identical fixed frequency, this delay will be absorbed by GPS clock correction；For
GLONASS receiver code hardware delay, code inter-frequency deviation has differences because frequency is different, thus the system time difference introducing will only
Absorb the common portion of receiver GLONASS code hardware delay.Therefore, " the system time difference " parameter will be made up of three parts, that is,：
The system time deviation of GPS and GLONASS, GLONASS receiver code average retardation and the GPS code delay that need to deduct.
Obviously, prior art does not consider the impact of GLONASS code inter-frequency deviation in carrying out satellite clock correction estimation function modeling；
A GLONASS code inter-frequency deviation part can estimative GLONASS satellite clock correction absorb, and nubbin will be embodied in yard pseudorange and see
In measured value residual error.When carrying out satellite clock correction estimation, due to the presence of phase ambiguity parameter, high-precision carrier phase observable is only
Determine accurate change between epoch for the satellite clock correction, and Pseudo-range Observations are to provide estimated clock to the main contributions of clock correction solution
The time reference benchmark of difference.The joint real-time estimation of GPS/GLONASS Clock Bias, typically using from the whole world or region
The GNSS reference station network real-time observed data stream of distribution；For the clock correction valuation of every GLONASS satellite, between different epoch
The survey station being participated in solving may and differ.Prior art does not consider the inter-frequency deviation in GLONASS code Pseudo-range Observations
, this will lead to the different satellite clock correction basis references with reference to the determination of station yard pseudorange to be difficult to converge to stationary value.In deduction satellite
After clock constant deviations, each combined influence with reference to station yard inter-frequency deviation will make GLONASS satellite clock correction valuation larger model
The fluctuation enclosed, thus lead to the reduction of GLONASS real-time satellite clock bias estimation precision.
Content of the invention
The technical problem to be solved is for involved defect in background technology, provides one kind not to be subject to
The real-time accurate satellite clock correction method of estimation of GLONASS code inter-frequency deviation impact.
The present invention is to solve above-mentioned technical problem to employ the following technical solutions:
A kind of real-time accurate satellite clock correction method of estimation not affected by GLONASS code inter-frequency deviation, comprises the following steps：
Step 1), obtain the real time GPS from GNSS reference station network, GLONASS observes data；
Step 2), real-time Detection of Cycle-slip is carried out to GPS, GLONASS observation data obtaining in step 1, and all to occurring
The epoch jumped is marked；
Step 3), to step 1) in obtain each GNSS reference station GPS, GLONASS observation data, separately constitute and disappear
Ionospheric combination observation；
Wherein, the computing formula for survey station r, gps satellite i composition iono-free combination observation is：
In formula, G represents GPS system；It is respectively gps satellite i corresponding code pseudorange and carrier phase electric eliminating
Absciss layer combination observation；f1、f2Represent L respectively1And L2The frequency of carrier wave；P1 G、With Φ1 G、It is respectively survey station r respective tones
The GPS code pseudorange of rate and carrier phase raw observation；
For survey station r, GLONASS satellite j form iono-free combination observation computing formula be：
In formula, R represents GLONASS system,It is respectively GLONASS satellite j corresponding code pseudorange and carrier wave
Phase place iono-free combination observation；K represents the GLONASS frequency channel number corresponding to satellite j；fK,1、fK,2Represent respectively and defend
The L of the GLONASS frequency channel K corresponding to star j1And L2Carrier frequency；P1 R、With Φ1 R、It is respectively survey station r corresponding frequencies
GLONASS code pseudorange and carrier phase raw observation；
Step 4), to step 1) in obtain each GNSS reference station GPS, GLONASS observation data, set up respectively
GLONASS receiver code inter-frequency deviation parameter is wherein closed by GPS, GLONASS satellite observational equation with system time-difference parameter
And, it is that the GLONASS satellite of every observation is respectively provided with an independent time-frequency straggling parameter；
Wherein, for survey station r, gps satellite i, its observational equation is expressed as：
In formula,Defend distance for GPS；GPS clock correction respectively to be estimated and satellite clock correction；
For gps satellite i corresponding electric eliminating absciss layer phase ambiguity；Tiltedly postpone for the corresponding troposphere of gps satellite i；δtideFor tide
Nighttide effect correction；δrelCorrect for relativistic effect；δphwIt is wound around for antenna phase and correct；Be respectively GPS code pseudorange and
The corresponding observation noise of carrier phase；C is the light velocity in vacuum, λGWavelength corresponding to GPS electric eliminating absciss layer carrier phase observable；
For survey station r, GLONASS satellite j, its observational equation is expressed as：
In formula,Defend distance for GLONASS；For GLONASS satellite clock correction to be estimated；For GLONASS satellite j
Corresponding electric eliminating absciss layer phase ambiguity；Tiltedly postpone for the corresponding troposphere of GLONASS satellite j；Defend for GLONASS
Wavelength corresponding to star j electric eliminating absciss layer carrier phase observable；βj,rFor the time-frequency straggling parameter of GLONASS satellite j to be estimated, specifically
It is expressed as：
In formula, dtSYSFor system time deviation；For GLONASS receiver code average retardation deviation；For GPS receiver
Machine code delay deviation；N is in-orbit GLONASS satellite quantity；For GLONASS receiver code inter-frequency deviation, it is embodied as：
In formula,It is respectively between GLONASS original P1 and P2 Pseudo-range Observations corresponding receiver code frequency partially
Difference；
Step 5), extract each GNSS reference station position coordinateses from the SINEX file of the up-to-date announcement of IGS；From the ultrafast star of IGS
The prediction orbit going through offer extracts the coordinate of the satellite position of Current observation epoch；Every error source in observational equation is built
Mould corrects；Select one and be equipped with the GNSS reference station stablizing frequency marking, using its receiver clock as Reference clock；
Step 6), participate in resolving the GPS/GLONASS moonscope equation linearisation of GNSS reference station by all, and represent
Become matrix form；
Step 7), introduce additional constraint condition, that is, suppose that each survey station is needed to be estimated " time-frequency deviation " sum is 0；
Step 8), parameter estimation is carried out using EKF method；Wherein, to be labeled as occur cycle slip go through
Unit, is extended Kalman Filter Estimation after fuzziness parameter is reset again；
Step 9), export real-time satellite clock correction result.
Enter one as a kind of real-time accurate satellite clock correction method of estimation not affected by GLONASS code inter-frequency deviation of the present invention
The prioritization scheme of step, step 6) in write as matrix form after observational equation linearisation and be expressed as：
In formula, m, n are respectively in-orbit GPS, GLONASS satellite quantity, and k participates in resolving the quantity of survey station, p, q for epoch t
For all survey station GPS, GLONASS visible satellite numbers,For observation vector；For
GPS clock correction parameter vector to be estimated, δzwdFor tropospheric zenith wet stack emission parameter vector to be estimated, δ tG/s、δtR/sIt is respectively
GPS and GLONASS satellite clock correction parameter vector to be estimated,It is respectively GPS and GLONASS phase ambiguity ginseng to be estimated
Number vector, δ tISFBFor time-frequency deviation parameter vector to be estimated；It is respectively GPS receiver in GPS and GLONASS observational equation
Machine clock correction parameter corresponding design battle array,It is respectively tropospheric zenith wet stack emission parameter in GPS and GLONASS equation
Corresponding design battle array,It is respectively gps satellite clock correction parameter and GPS phase ambiguity parameter pair in GPS observational equation
The design battle array answered,For GLONASS satellite clock correction parameter and GLONASS phase ambiguity in GLONASS observational equation
Parameter corresponding design battle array；AISFBFor time-frequency straggling parameter corresponding design battle array, whereinHISFB=[1
1]T, IqTie up unit matrix for q,Represent Kronecker product；
O represents null matrix；εG、εRFor measurement noise vector, obey the overall distribution of zero-mean, its corresponding covariance square
Battle array ΩG、ΩRIt is diagonal matrix, be calculated as follows the diagonal entry of matrix：
In formula, σ is error in observation priori；E is the elevation of satellite at survey station；σ0Elder generation for zenith direction observation
Test middle error.
Enter one as a kind of real-time accurate satellite clock correction method of estimation not affected by GLONASS code inter-frequency deviation of the present invention
The prioritization scheme of step, step 7) in suppose that each survey station is needed to be estimated the formula that " time-frequency deviation " sum is 0 and is：
Additional constraint condition is considered as virtual observation equation, its matrix form is expressed as：
In formula,For survey station r corresponding time-frequency deviation ISFB parameter vector；AcFor corresponding design battle array, whereinekIt is 1 k dimensional vector, I for each elementuFor unit battle array, subscript u represents that the visible GLONASS of this survey station defends
Star number；OISFBFor null matrix.
Enter one as a kind of real-time accurate satellite clock correction method of estimation not affected by GLONASS code inter-frequency deviation of the present invention
The prioritization scheme of step, step 8) described in the state equation of EKF be expressed as follows：
X (t)=Ψt,t-1X(t-1)+wt-1,wt-1～(0, Ωw)
In formula, X (t), X (t-1) are the system mode vector of adjacent epoch；Ψt,t-1For state-transition matrix；wt-1For shape
State noise vector, and obey average be 0, covariance matrix be ΩwNormal distribution.
State-transition matrix Ψt,t-1It is expressed as：
In formula, O represents null matrix；I represents unit matrix；
Covariance matrix ΩwIt is expressed as：
In formula, Δ t is the time interval of adjacent epoch,qβRepresent GPS clock correction to be asked, right respectively
Fluid layer Zenith wet delay timely frequency straggling parameter.
Enter one as a kind of real-time accurate satellite clock correction method of estimation not affected by GLONASS code inter-frequency deviation of the present invention
The prioritization scheme of step, described step 4) GLONASS observational equation in phase in receiver clock-offsets parameter and GPS observational equation
With, and the time-frequency straggling parameter introducing by the system time deviation of GPS and GLONASS, GLONASS receiver code average retardation,
The GPS code delay that need to deduct and GLONASS receiver code inter-frequency deviation four part composition.
Further as a kind of real-time accurate satellite clock correction method of estimation not affected by GLONASS code inter-frequency deviation of the present invention
Prioritization scheme, by time-frequency straggling parameter change be considered as random walk process process, error value in its priori
The present invention adopts above technical scheme compared with prior art, has following technique effect：
Carry out in real-time accurate satellite clock correction estimation procedure in joint GPS/GLONASS, traditional method is in function modelling
Do not consider the inter-frequency deviation item in GLONASS code Pseudo-range Observations, estimated GLONASS satellite clock correction will absorb from difference
The part GLONASS receiver code inter-frequency deviation of GNSS reference station.The survey station being participated in solving between different epoch may be not
Identical, each combined influence with reference to station yard inter-frequency deviation will make GLONASS satellite clock correction valuation large range of fluctuation,
Thus causing the reduction of GLONASS real-time satellite clock bias estimation precision.The present invention passes through to participate in solution for each in function model
Calculate survey station setting multiple independences " time-frequency deviation " parameter, absorb the GLONASS code inter-frequency deviation of this survey station receiver, and by choosing
Select Reference clock and additional survey station ISFB constraints, realize time-frequency deviation ISFB parameter and receiver clock-offsets, GLONASS satellite clock
Difference the efficiently separating of clock correction, it is to avoid different survey station code inter-frequency deviations are absorbed by GLONASS satellite clock correction valuation and to be brought not
Profit impact；Compared with prior art, in the case of not affecting GPS real-time satellite clock correction estimation accuracy, can significantly improve
The precision of GLONASS real-time satellite clock correction valuation.
Brief description
Fig. 1 is the flow chart of the inventive method；
Fig. 2 is the gps satellite clock correction real-time estimation result error figure that the inventive method obtains；
Fig. 3 is the GLONASS satellite clock correction real-time estimation result error figure that traditional method obtains；
Fig. 4 is the GLONASS satellite clock correction real-time estimation result error figure that the inventive method obtains；
Fig. 5 be two methods obtain GPS, GLONASS satellite clock correction real-time estimation result accuracy comparison figure；
Fig. 6 is to carry out real-time accurate One-Point Location using GPS, GLONASS real-time satellite clock correction that the inventive method obtains
Result error RMS value cartogram.
Specific embodiment
Below in conjunction with the accompanying drawings technical scheme is described in further detail, but protection scope of the present invention
It is not limited to described embodiment.
As shown in figure 1, a kind of real-time accurate satellite clock correction not affected by GLONASS code inter-frequency deviation that the present invention provides
Method of estimation, comprises the following steps that：
Step 1：Obtain the real time GPS from GNSS reference station network, GLONASS observes data；For checking institute of the present invention
The effectiveness of offer method, chooses the equally distributed 30 GPS/GLONASS tracking stations in the whole world and is used for estimating in real time of satellite clock correction
Meter, survey station distribution is as shown in Figure 1；Selected by downloading from IGS, observation data RINEX file in survey station 30s interval is used for simulating and counts in real time
According to stream, observation time is year in 2014 day of year (Day of Year, DOY) 41；By GPS/GLONASS satellite clock correction real-time estimation
The product of Clock Bias afterwards that result and European Space Agency (European Space Agency, ESA) provide is compared
Relatively, for assessing the inventive method for precision that GPS/GLONASS satellite clock correction real-time estimation can reach；
Step 2：Detection of Cycle-slip is carried out to GPS, GLONASS real-time observed data stream obtaining in step 1, and all to occurring
The epoch jumped is marked；
Step 3：GPS, GLONASS observation data to each GNSS reference station that step 1 obtains, separately constitutes deionization
Layer combination observation, is calculated by below equation：
For survey station r, gps satellite i：
In formula,It is respectively gps satellite i corresponding code pseudorange and the observation of carrier phase iono-free combination
Value；f1、f2Represent L respectively1And L2The frequency of carrier wave；P1 G、With Φ1 G、It is respectively the GPS code pseudorange of survey station r corresponding frequencies
With carrier phase raw observation；
For survey station r, GLONASS satellite j：
In formula, it is meant that identical with GPS computing formula symbol identical parameter, represents GLONASS with subscript R herein
System, subscript K represents the GLONASS frequency channel number corresponding to satellite j；
Step 4：To step 1 obtain each GNSS reference station GPS, GLONASS observation data, set up respectively GPS,
GLONASS receiver code " inter-frequency deviation " is wherein merged by GLONASS satellite observational equation with " the system time difference " parameter,
GLONASS satellite for every observation is respectively provided with an independence " time-frequency deviation " (Inter-System and Inter-
Frequency Bias, ISFB) parameter, specifically it is expressed as follows：
For survey station r, gps satellite i, its observational equation is expressed as：
In formula,Defend distance for GPS；GPS clock correction respectively to be estimated and satellite clock correction；
For gps satellite i corresponding electric eliminating absciss layer phase ambiguity；Tiltedly postpone for the corresponding troposphere of gps satellite i；δtideFor tide
Nighttide effect correction；δrelCorrect for relativistic effect；δphwIt is wound around for antenna phase and correct；Be respectively GPS code pseudorange and
The corresponding observation noise of carrier phase；C is the light velocity in vacuum, λGWavelength corresponding to GPS electric eliminating absciss layer carrier phase observable；
For survey station r, GLONASS satellite j, its observational equation is expressed as：
In formula, it is meant that identical with GPS observational equation symbol identical parameter, represents GLONASS with subscript R herein
System；Tiltedly postpone for the corresponding troposphere of GLONASS satellite j；βj,rTime-frequency deviation for GLONASS satellite j to be estimated
ISFB parameter, is embodied as：
In formula, dtSYSFor system time deviation；For GLONASS receiver code average retardation deviation；For GPS receiver
Machine code delay deviation；The GLONASS satellite sum that n observes for survey station r current epoch；For between GLONASS receiver code frequency
Deviation, is embodied as：
In formula,It is respectively the corresponding receiver code inter-frequency deviation of GLONASS original P1 and P2 Pseudo-range Observations,
fK,1、fK,2For corresponding signal frequency, corresponding GLONASS frequency channel number is K；
Note receiver clock-offsets parameter and identical, the GPS in GPS observational equation in GLONASS observational equation in this step
And GLONASS code inter-frequency deviation poor with GLONASS system time is absorbed by time-frequency deviation (ISFB) parameter, and as ginseng to be estimated
Number is estimated.
Step 5：Each GNSS reference station position coordinateses are extracted from the SINEX file of the up-to-date announcement of IGS；From the ultrafast star of ESA
The prediction orbit going through offer extracts the coordinate of the satellite position of Current observation epoch；The receiver clock selecting survey station MATE is as reference
Clock；Every error source in observational equation is modeled correct, specific strategy is as shown in table 1；
Table 1：Real-time satellite clock bias estimation observation model and error source correct strategy
Step 6：Participate in resolving the GPS/GLONASS moonscope equation linearisation of GNSS reference station by all, and represent
Become matrix form；Assume that in-orbit GPS, GLONASS satellite are respectively m, n, have k survey station in epoch t and participate in resolving, own
Survey station GPS, GLONASS visible satellite number is respectively p, q, is write as matrix form and be expressed as after observational equation linearisation：
In formula,For observation vector；For GPS clock correction parameter to be estimated
Vector, δzwdFor tropospheric zenith wet stack emission parameter vector to be estimated, δ tG/s、δtR/sIt is respectively GPS and GLONASS satellite clock correction is treated
Estimate parameter vector,It is respectively GPS and GLONASS phase ambiguity parameter vector to be estimated, δ tISFBFor time-frequency deviation
Parameter vector to be estimated；It is respectively the corresponding design of GPS clock correction parameter in GPS and GLONASS observational equation
Battle array,It is respectively the corresponding design battle array of tropospheric zenith wet stack emission parameter in GPS and GLONASS equation,
It is respectively gps satellite clock correction parameter and GPS phase ambiguity parameter corresponding design battle array in GPS observational equation,For
GLONASS satellite clock correction parameter and GLONASS phase ambiguity parameter corresponding design battle array in GLONASS observational equation；AISFB
For time-frequency straggling parameter corresponding design battle array, whereinHISFB=[1 1]T, IqTie up unit matrix for q,Table
Show Kronecker product；O represents null matrix；εG、εRFor measurement noise vector, obey the overall distribution of zero-mean, its corresponding association side
Difference matrix ΩG、ΩRIt is diagonal matrix, be calculated as follows the diagonal entry of matrix：
In formula, σ is error in observation priori；E is the elevation of satellite at survey station；σ0Elder generation for zenith direction observation
Test middle error；
Step 7：Introduce additional constraint condition, that is, suppose that each survey station is needed to be estimated " time-frequency deviation " sum is 0, that is,：
Additional constraint condition is considered as virtual observation equation, its matrix form is expressed as：
In formula,For survey station r corresponding time-frequency deviation ISFB parameter vector；AcFor corresponding design battle array, whereinekIt is 1 k dimensional vector, I for each elementuFor unit battle array, subscript u represents that the visible GLONASS of this survey station defends
Star number；OISFBFor null matrix.
Step 8：Parameter estimation is carried out using EKF (Extended Kalman Filter, EKF) method,
Wherein the fuzziness parameter being labeled as generation cycle slip epoch is reset.EKF state equation is expressed as follows：
X (t)=Ψt,t-1X(t-1)+wt-1,wt-1～(0, Ωw) (11)
In formula, X (t), X (t-1) are the system mode vector of adjacent epoch；Ψt,t-1For state-transition matrix；wt-1For shape
State noise vector, and obey average be 0, covariance matrix be ΩwNormal distribution.
State-transition matrix Ψt,t-1It is expressed as：
In formula, O represents null matrix；I represents unit matrix；
Covariance matrix ΩwIt is expressed as：
In formula, Δ t is the time interval of adjacent epoch, and q represents the spectral density matrix of each state parameter.In stochastic model
In, GPS clock correction is considered as white noise sonication, in its priori, error is set to 102m；Zenith tropospheric wet stack emission is considered as
Random walk process is processed, and in its priori, error is set toBecause adjacent epoch interval of delta t is generally less,
It is considered that ISFB Parameters variation is stable within this short period, thus equally it is regarded as random walk process and processes,
In its priori, error is set toGPS and GLONASS fuzziness parameter are accordingly to be regarded as time-independent amount.
For analyzing the effect of the method provided by the present invention, it is utilized respectively traditional method and the inventive method and experimental data is carried out
Calculate.Traditional method：" the system time difference " parameter estimated by each survey station, does not consider between GLONASS code frequency partially in function model
Difference；The inventive method：Every observation GLONASS satellite of each survey station all estimates " time-frequency deviation " parameter, in function model
Consider the GLONASS code inter-frequency deviation of each survey station.Both the above situation parameter difference only to be estimated, its observation model and parameter estimation
Strategy is all set to identical, and specifying information is as shown in table 1, table 2.
Table 2：Real-time satellite clock bias estimation parameter estimation strategy
Note：x0、σ0, σ be respectively initial parameter values, error and middle error in priori；Try to achieve for pseudorange One-Point Location
GPS and GLONASS receiver clock-offsets；Forecast clock correction for the ultrafast GPS of ESA with GLONASS satellite；For selected
The GPS clock correction of reference station.
For the sake of for convenience of explanation, gps satellite clock presses constellation and one satellite of frequency marking type of optional, and GLONASS satellite clock is pressed
Signal frequency selects a satellite, the present invention is sent out the result of satellite clock correction estimated by method and contrast traditional method is contrasted；
Related satellite information is as shown in table 3.
Table 3：Satellite clock information for clock bias estimation interpretation of result
Because GLONASS code inter-frequency deviation affects little, the GPS clock correction that two methods obtain to gps satellite clock bias estimation
Result RMS value difference very little (less than ± 0.01ns), here only provides the GPS real-time clock (RTC) taking yard inter-frequency deviation processing scheme into account
Difference estimated result；The gps satellite clock correction real-time estimation result error of DOY 41 whole day in 2014 is as shown in Figure 2.Can from Fig. 2
Go out, estimate the starting stage in satellite clock correction, due to being affected by pseudorange error, the convergence of the initial clock deviation of each satellite needs longer
Time, gps satellite clock correction result fluctuation range is larger；After restraining through 5～6h, each satellite clock correction valuation deviation all can be steady
It is scheduled in the range of ± 0.1m.
Fig. 3, Fig. 4 sets forth using traditional method and the inventive method obtained by GLONASS real-time satellite clock correction
Result.Fig. 2, Fig. 3 are it is found that the GLONASS satellite clock correction valuation deviation that traditional method obtains will be significantly greater than this for contrast
Bright method, still fluctuates after a few hours convergence in the range of ± 0.2m；And adopt the inventive method, most satellite clock correction valuations
Fluctuate in the range of ± 0.1m.
After the convergence of GPS/GLONASS real-time satellite clock bias estimation, the satellite clock correction calculating DOY 41 whole day in 2014 is estimated
The RMS value of value and ESA precise clock correction product mutual deviation afterwards, as shown in Figure 5.Can it is further seen that, obtained by two methods
Gps satellite clock correction precision statisticses value more meets, and average RMS value is respectively less than 0.2ns；For GLONASS satellite clock correction, tradition
The RMS value of method valuation deviation will be significantly greater than the inventive method, and minority satellite RMS value is close to 1ns, and the inventive method is most
Satellite RMS value is less than 0.3ns.
Fig. 6 is to estimate that the GPS/GLONASS satellite clock correction obtaining carries out real-time accurate One-Point Location using the inventive method
The 3D deviation RMS statistical result of (Real-Time Precise Point Positioning, RT-PPP).Number for test
According to 10 IGS reference stations from Europe Region, observation time is DOY 41～68 in 2014, on time segment length 2h, 6h, 12h,
24h is divided, and forecast satellite orbit is obtained by the ultrafast ephemeris that ESA issues, respectively in GLONASS single system, GPS single system
And carry out static RT-PPP under 3 kinds of patterns of GPS/GLONASS combined system, and calculate itself and IGS announcement survey station coordinate mutual deviation RMS
Value.From fig. 5, it can be seen that as a length of 2h of observation period, it is mono- that the positioning precision of GPS/GLONASS combined system is better than GPS
System, all survey station deviation RMS value are respectively less than 10cm, and GLONASS single system 3D positioning precision about 15cm about；Work as observation
When segment length more than 6h after, GPS single system is substantially suitable with the positioning precision of GPS/GLONASS combined system；The real-time list for 24h
Its solution, carries out RT-PPP and all can obtain the three-dimensional localization precision better than 5cm under Three models.
The explanation being not directed in the specific embodiment of the present invention belongs to technology well known in the art, refers to known technology
It is carried out.
Claims (6)
1. a kind of real-time accurate satellite clock correction method of estimation not affected by GLONASS code inter-frequency deviation is it is characterised in that include
Following steps：
Step 1), obtain the real time GPS from GNSS reference station network, GLONASS observes data；
Step 2), real-time Detection of Cycle-slip is carried out to GPS, GLONASS observation data obtaining in step 1, and to generation cycle slip
Epoch is marked；
Step 3), to step 1) in obtain each GNSS reference station GPS, GLONASS observation data, separately constitute deionization
Layer combination observation；
Wherein, the computing formula for survey station r, gps satellite i composition iono-free combination observation is：
In formula, G represents GPS system；It is respectively gps satellite i corresponding code pseudorange and carrier phase electric eliminating absciss layer
Combination observation；f1、f2Represent L respectively1And L2The frequency of carrier wave；P1 G、With Φ1 G、It is respectively survey station r corresponding frequencies
GPS code pseudorange and carrier phase raw observation；
For survey station r, GLONASS satellite j form iono-free combination observation computing formula be：
In formula, R represents GLONASS system,It is respectively GLONASS satellite j corresponding code pseudorange and carrier phase
Iono-free combination observation；K represents the GLONASS frequency channel number corresponding to satellite j；fK,1、fK,2Represent satellite j institute respectively
The L of corresponding GLONASS frequency channel K1And L2Carrier frequency；P1 R、With Φ1 R、It is respectively survey station r corresponding frequencies
GLONASS code pseudorange and carrier phase raw observation；
Step 4), to step 1) in obtain each GNSS reference station GPS, GLONASS observation data, set up respectively GPS,
GLONASS receiver code inter-frequency deviation parameter is wherein merged by GLONASS satellite observational equation with system time-difference parameter,
GLONASS satellite for every observation is respectively provided with an independent time-frequency straggling parameter；
Wherein, for survey station r, gps satellite i, its observational equation is expressed as：
In formula,Defend distance for GPS；GPS clock correction respectively to be estimated and satellite clock correction；For GPS
Satellite i corresponding electric eliminating absciss layer phase ambiguity；Tiltedly postpone for the corresponding troposphere of gps satellite i；δtideFor tidal effect
Correct；δrelCorrect for relativistic effect；δphwIt is wound around for antenna phase and correct；It is respectively GPS code pseudorange and carrier wave phase
The corresponding observation noise in position；C is the light velocity in vacuum, λGWavelength corresponding to GPS electric eliminating absciss layer carrier phase observable；
For survey station r, GLONASS satellite j, its observational equation is expressed as：
In formula,Defend distance for GLONASS；For GLONASS satellite clock correction to be estimated；Correspond to for GLONASS satellite j
Electric eliminating absciss layer phase ambiguity；Tiltedly postpone for the corresponding troposphere of GLONASS satellite j；Disappear for GLONASS satellite j
Wavelength corresponding to the carrier phase observable of ionosphere；βj,rFor the time-frequency straggling parameter of GLONASS satellite j to be estimated, concrete expression
For：
In formula, dtSYSFor system time deviation；For GLONASS receiver code average retardation deviation；For GPS code
Delay distortion；N is in-orbit GLONASS satellite quantity；For GLONASS receiver code inter-frequency deviation, it is embodied as：
In formula,It is respectively the corresponding receiver code inter-frequency deviation of GLONASS original P1 and P2 Pseudo-range Observations；
Step 5), extract each GNSS reference station position coordinateses from the SINEX file of the up-to-date announcement of IGS；Carry from the ultrafast ephemeris of IGS
For prediction orbit extract Current observation epoch coordinate of the satellite position；Every error source in observational equation is modeled changing
Just；Select one and be equipped with the GNSS reference station stablizing frequency marking, using its receiver clock as Reference clock；
Step 6), participate in resolving the GPS/GLONASS moonscope equation linearisation of GNSS reference station by all, and be expressed as square
Formation formula；
Step 7), introduce additional constraint condition, that is, suppose that each survey station is needed to be estimated " time-frequency deviation " sum is 0；
Step 8), parameter estimation is carried out using EKF method；Wherein, to the epoch being labeled as generation cycle slip, will
Fuzziness parameter is extended Kalman Filter Estimation after resetting again；
Step 9), export real-time satellite clock correction result.
2. the real-time accurate satellite clock correction method of estimation not affected by GLONASS code inter-frequency deviation according to claim 1,
It is characterized in that, step 6) in write as matrix form after observational equation linearisation and be expressed as：
In formula, m, n are respectively in-orbit GPS, GLONASS satellite quantity, and k participates in resolving the quantity of survey station for epoch t, and p, q are institute
There is survey station GPS, GLONASS visible satellite number,For observation vector；For GPS
Receiver clock-offsets parameter vector to be estimated, δzwdFor tropospheric zenith wet stack emission parameter vector to be estimated, δ tG/s、δtR/sBe respectively GPS and
GLONASS satellite clock correction parameter vector to be estimated,It is respectively GPS and GLONASS phase ambiguity parameter vector to be estimated,
δtISFBFor time-frequency deviation parameter vector to be estimated；It is respectively GPS clock correction in GPS and GLONASS observational equation
Parameter corresponding design battle array,It is respectively tropospheric zenith wet stack emission parameter in GPS and GLONASS equation corresponding
Design battle array,It is respectively in GPS observational equation gps satellite clock correction parameter and GPS phase ambiguity parameter is corresponding sets
Meter battle array,Corresponding with GLONASS phase ambiguity parameter for GLONASS satellite clock correction parameter in GLONASS observational equation
Design battle array；AISFBFor time-frequency straggling parameter corresponding design battle array, whereinHISFB=[1 1]T, IqFor q
Dimension unit matrix,Represent Kronecker product；
O represents null matrix；εG、εRFor measurement noise vector, obey the overall distribution of zero-mean, its corresponding covariance matrix
ΩG、ΩRIt is diagonal matrix, be calculated as follows the diagonal entry of matrix：
In formula, σ is error in observation priori；E is the elevation of satellite at survey station；σ0In priori for zenith direction observation
Error.
3. the real-time accurate satellite clock correction method of estimation not affected by GLONASS code inter-frequency deviation according to claim 2,
It is characterized in that, step 7) in suppose that each survey station is needed to be estimated the formula that " time-frequency deviation " sum is 0 and is：
Additional constraint condition is considered as virtual observation equation, its matrix form is expressed as：
In formula,For survey station r corresponding time-frequency deviation ISFB parameter vector；AcFor corresponding design battle array, whereinekIt is 1 k dimensional vector, I for each elementuFor unit battle array, subscript u represents that the visible GLONASS of this survey station defends
Star number；OISFBFor null matrix.
4. the real-time accurate satellite clock correction method of estimation not affected by GLONASS code inter-frequency deviation according to claim 3,
It is characterized in that, step 8) described in the state equation of EKF be expressed as follows：
X (t)=Ψt,t-1X(t-1)+wt-1,wt-1～(0, Ωw)
In formula, X (t), X (t-1) are the system mode vector of adjacent epoch；Ψt,t-1For state-transition matrix；wt-1Make an uproar for state
Sound vector, and obey average be 0, covariance matrix be ΩwNormal distribution;
State-transition matrix Ψt,t-1It is expressed as：
In formula, O represents null matrix；I represents unit matrix；Covariance matrix ΩwIt is expressed as：
In formula, Δ t is the time interval of adjacent epoch,qβRepresent GPS clock correction to be asked, convection current respectively
The spectral density matrix of layer Zenith wet delay timely frequency straggling parameter.
5. the real-time accurate satellite clock correction method of estimation not affected by GLONASS code inter-frequency deviation according to claim 1,
It is characterized in that, described step 4) GLONASS observational equation in receiver clock-offsets parameter with identical in GPS observational equation,
And the time-frequency straggling parameter introducing by the system time deviation of GPS and GLONASS, GLONASS receiver code average retardation, need to detain
The GPS code delay removing and GLONASS receiver code inter-frequency deviation four part composition.
6. the real-time accurate satellite clock correction method of estimation not affected by GLONASS code inter-frequency deviation according to claim 3, its
It is characterised by, the change of time-frequency straggling parameter is considered as random walk process and processes, error value in its priori
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| CN105738926A (en) * | 2016-03-30 | 2016-07-06 | 武汉大学 | Method for calibrating phase inter-frequency bias between GLONASS system receiving machines |
| CN105929430B (en) * | 2016-07-14 | 2018-09-21 | 天津市勘察院 | The quick fixing means of fuzziness between a kind of GNSS zero base lines reference station |
| CN107942356B (en) * | 2017-11-09 | 2019-09-10 | 武汉大学 | A kind of multi-frequency multi-mode GNSS broad sense absolute code bias estimation method |
| CN108254773B (en) * | 2017-11-24 | 2019-12-06 | 中国测绘科学研究院 | Real-time clock error resolving method of multiple GNSS |
| CN108196279B (en) * | 2017-12-23 | 2021-10-15 | 航天恒星科技有限公司 | Satellite clock error calculating and forecasting method based on real-time data flow |
| CN108229746B (en) * | 2018-01-08 | 2021-10-19 | 唐山学院 | Optimal correction method of polynomial forecasting model of satellite clock error data |
| CN107966722B (en) * | 2018-01-20 | 2021-07-13 | 中国人民解放军61540部队 | GNSS clock error resolving method |
| CN108919317A (en) * | 2018-04-24 | 2018-11-30 | 东南大学 | A kind of Differential positioning method for taking GLONASS pseudorange inter-frequency deviation into account |
| CN108845336B (en) * | 2018-06-21 | 2020-11-10 | 中国人民解放军国防科技大学 | GNSS time difference monitoring method considering GLONASS inter-frequency deviation |
| CN114002712B (en) * | 2021-10-08 | 2022-11-04 | 中国科学院国家授时中心 | GNSS real-time satellite clock error determination system and method based on data adaptive selection |
| CN114966760B (en) * | 2022-06-15 | 2023-08-22 | 中国科学院精密测量科学与技术创新研究院 | Ionosphere weighted non-differential non-combination PPP-RTK technology implementation method |
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