CN103197326A - Multi-constellation single base station receiver clock difference estimation method - Google Patents

Abstract

The invention discloses a multi-constellation single base station receiver clock difference estimation method. When multi-constellation data are in fusion process, positions of satellites when signals are emitted cannot be accurately confirmed due to different receiver clock differences among different constellations and the effect of delaying of signal propagation, error terms which are related to the satellite speed and caused by receiver clock differences still can cause changing of errors and affect an actual positioning effect, wherein the maximum error can reach 1m. In the calculation of the positions of the satellites, the receiver clock differences are estimated, the time delaying of the signal propagation is corrected, the receiver clock differences are resolved through a Kalman filtering method, and accordingly the method is practical and can obtain accurate geometrical distance between receivers with corrected receiver clock differences and the satellites. The method can reduce the effect of the receiver clock differences which are related to the satellite speed to a submillimeter level, is suitable for a receiver with clock jumping being one millisecond, and achieves high-accuracy positioning of the multi-constellation fusion.

Description

A kind of single base station receiver clock correction method of estimation of many constellations

Technical field

The present invention relates to the satnav field, relate in particular to single base station receiver clock correction method of estimation of many constellations.

Background technology

GNSS network differential location technology is the hot technology in present satnav field, be widely used in industries such as mapping and survey of territorial resources, with virtual reference station (VirtualReferenceStation, VRS) technology is the network differential technology rise of representative, makes and sets up the recent tendency that base station network type GPS service system becomes Current GPS technology application development.The VRS technology is as the GPS real-time dynamic positioning technology under many base stations environment, be that collection Internet technology, wireless communication technique, computer networking technology and GPS technology are the network RTK location technology of one, also be wide, the most successful representative high-tech achievement of current application, the VRS technical system has represented the conventional RTK developing direction of location technology of new generation afterwards.

The basic skills of VRS technological orientation is: each reference station continuous acquisition observation data, and be real-time transmitted to data and handle database with control center, carry out network calculations; The ambiguity of carrier phase value of each individual baseline in control center's online resolving GPS reference station net; Data processing centre (DPC) utilizes the two difference composition errors on every baseline of reference station net carrier phase observation data calculating, and sets up the spatial parameter model apart from correlated error accordingly; The movement station user will locate the NMEA(NationalMarineElectronicsAssociation that obtains by single-point, American National maritime affairs Institution of Electronics) rough coordinates of form sends to control center, and a virtual reference station is created at this coordinate position by control center; Control center is according to the relative geometrical relation of reference station, user and gps satellite, obtains space correlation error between movement station and reference station by the interpolation computation model, generates the dummy observation at VRS place again according to the dummy observation computation model; Control center sends to the movement station user to dummy observation as network differential correcting information; User's movement station receives network differential information and VRS constitutes short baseline, carries out difference by conventional RTK computation model and resolves, and determines customer location, and quick realization is fixing and obtain real-time centimetre-sized bearing accuracy, sees shown in Figure 1.

In conventional two differential mode types, the receiver clock correction item relevant with the light velocity of each website asks poor mode to be eliminated between by star when making up two difference, ignored the receiver clock correction item relevant with satellite velocities to the influence of observation equation.In data handling procedure, for the more stable receiver that changes in 1 microsecond of clock, only exist less than 1 millimeter error with respect to raw observation and to ignore its influence.Yet the difference owing to the designed receiver clock of each manufacturer, the clock that the part receiver exists big receiver clock correction even some receiver 1ms to occur is jumped, the clock correction value relevant with satellite velocities understood the maximum error effect that produces near 1 meter at the geometric distance that calculates, and can not be eliminated or weaken in two differences.Therefore, need accurately to estimate each receiver clock correction, the geometric distance of revising between satellite and receiver has obtained the correct positioning result.

Summary of the invention

The inventive method is from the signal reception and launch satellite and the receiver clock correction angle that clock face causes constantly, analyzed the generation reason of various constellations different receivers clock correction, the receiver clock correction item of having derived relevant with the light velocity and satellite velocities in detail is to the error formula of raw observation influence, a kind of receiver clock correction of estimating in satellite position calculation has been proposed, the practical approach of corrected signal propagation delay, this method can effectively be estimated each constellation receiver clock correction value, and be applicable to exist big receiver clock correction to utilize this method accurate Calculation and unified each constellation satellite position coordinate, and come the comparison correction effect by checking respective satellite and receiver geometric distance variable quantity.The influence of the receiver clock correction item relevant with satellite velocities is attenuated to submillimeter level, and is applicable to the receiver that exists 1 millisecond of clock to jump, and realizes the hi-Fix that many constellations merge.

Technical scheme of the present invention is:

Many constellations clock correction is analyzed:

For receiver moment t _kReceive satellite emission signal, this moment receiver clock correction is δ _k, t during namely with respect to GPS:

t=t _k-δ _k

The station star distance of this t moment receiver and satellite

Can be expressed as

${\mathrm{\ρ}}_k^i=\mathrm{c\τ}$

$=|r_k\left(t\right)-r^i(t-\mathrm{\τ})|$

Wherein c is the light velocity, and τ is signal propagation time, r _kReceiver vector position when (t) being signal reception time t, r ⁱSatellite vector position when (t-τ) is signal x time t-τ, r ⁱ(t-τ) can be expressed as again:

$r^i(t-\mathrm{\τ})=r^i\left(t\right)-{\stackrel{\·}{r}}^i\left(t\right)\mathrm{\τ}$

Utilize above-mentioned formula, we can solve signal propagation time τ:

$(c^2-{\stackrel{\·}{r}}^i\left(t\right)\·{\stackrel{\·}{r}}^i\left(t\right)){\mathrm{\τ}}^2-2{\stackrel{\·}{r}}^i\left(t\right)(r_k\left(t\right)-r^i\left(t\right))\mathrm{\τ}$

$-(r_k\left(t\right)\·r_k\left(t\right)-2r_k\left(t\right)\·r^i\left(t\right)+r^i\left(t\right)\·r^i\left(t\right))=0$

For many constellation systems, the various constellations system the clock correction corrected value of corresponding master station inequality, the corrected value precision is to be determined by each master station clock accuracy between each system, and is separate.For the satellite of same constellation, itself and receiver clock correction can be merged estimation, and for many constellations, each constellation should have its independent receiver clock correction value and estimate its precision.So the receiver clock correction value of each constellation is actual here be:

${\mathrm{\δt}}_k=\mathrm{\δ}{\hat{t}}_k+\mathrm{\δ}{t}_{G/R/C/E}^i$

Here

Refer to the clock correction corrected value of various constellations (corresponding to GPS, GLONASS, the Big Dipper, GALILEO) master station, Corrected value for the clock of receiver own.

Kalman filtering method is estimated receiver clock correction:

1) adopts satellite pseudorange guestimate satellite-signal transmission time τ ₀=P/c; Suppose initial receiver clock correction δ t _kBe 0, utilize initial observation epoch and signal transmission time τ ₀Obtain the instantaneous coordinate (X of satellite ⁱ, Y ⁱ, Z ⁱ) and initial satellite clock correction correction δ t ⁱ ₀, since regional reference station network (move satnav service colligate system continuously, ContinuousOperational ReferenceSystem, CORS) in, base station coordinates is known, then can calculate the geometric distance of initial satellite position and receiver

, and recomputate signal transmission time

${\mathrm{\ρ}}_k^i=\sqrt{{(X^i-X_k)}^2+{(Y^i-Y_k)}^2+{(Z^i-Z_k)}^2}$

${\mathrm{\τ}}_k^i=\frac{1}{c}{\mathrm{\ρ}}_k^i$

2) make up receiver clock correction estimate equation, find the solution various constellations receiver clock correction value separately single epoch, and wherein n is the population of satellite, δ t _k(G), δ t _k(R), δ t _k(C), δ t _k(E) be respectively the corresponding receiver clock correction value of GPS, GLONASS, the Big Dipper, GALILEO, δ t ⁱExpression the initial satellite clock correction correction of corresponding satellite

BX=L

For the CORS base station, because its coordinate is known, only need estimate receiver clock correction, can estimate by list least square epoch, for its coordinate the unknown of rover station, still need make up Kalman filter and find the solution with it as unknown parameter:

X ^T=[δX,δY,δZ,δt _k(G),δt _k(R),δt _k(C),δt _k(E)]

Wherein, δ X, δ Y, δ Z are base station coordinate correction value, δ t _k(G), δ t _k(R), δ t _k(C), δ t _k(E) be respectively the corresponding receiver clock correction value of GPS, GLONASS, the Big Dipper, GALILEO, n is the population of satellite,

Be coefficient after the equation linearization.

The use experience model is determined observed reading weight and initial parameter value, if receiver does not exist clock to jump, can adopt white noise to come the variation of analog receiver clock correction, for the receiver that exists clock to jump, sets corresponding receiver clock correction dynamic noise matrix and is

, σ _t=3.0e5, unit are rice, jump by the 1ms clock and are caused the pseudorange maximum changing value.

3) the receiver clock correction value of utilizing for second step obtained is calculated corresponding

Satellite position obtains accurate receiver and the satellite geometry distance of corrected received machine clock correction constantly.

In the computation process of above-mentioned satellite position and receiver clock correction, also need consider the influence of earth rotation and relativistic effect, and the relevant atmosphere convection layer of modelling and ionosphere delay error item, to obtain correct receiver clock correction and satellite position information.

Advantage of the present invention and beneficial effect:

Many constellations reference station satellite clock correction method of estimation, from satellite and the receiver clock correction angle that signal receives and the emission clock face causes constantly, analyzed the generation reason of various constellations different receivers clock correction, the receiver clock correction item of having derived relevant with the light velocity and satellite velocities in detail is to the error formula of raw observation influence, and the difference of having compared different vendor's receiver clock, a kind of receiver clock correction of estimating in satellite position calculation has been proposed, the practical approach of corrected signal propagation delay, this method can effectively be estimated each constellation receiver clock correction value, and be applicable to exist big receiver clock correction to utilize this method accurate Calculation and unified each constellation satellite position coordinate, and come the comparison correction effect by checking respective satellite and receiver geometric distance variable quantity.By a large amount of measured data analyses, by revising accurate satellite position, correct many constellations blur level result and relevant atmosphere delay error can have been calculated.Show with the experiment of Big Dipper laboratory reference station data based on the GPS of Southeast China University: this method is attenuated to submillimeter level with the influence of the receiver clock correction item relevant with satellite velocities, and be applicable to the receiver that exists 1 millisecond of clock to jump, realize the hi-Fix that many constellations merge.

Description of drawings

Fig. 1 is VRS and reference station net graph of a relation;

Fig. 2 is each base station receiver GPS clock correction of baseline LIXI-JLHU;

Fig. 3 is each base station receiver Big Dipper clock correction of baseline LIXI-JLHU;

Fig. 4 is that baseline LIXI-JLH satellite carrier changes (G19 satellite) with the station star apart from difference;

Fig. 5 is that baseline LIXI-JLH satellite carrier changes (C06 satellite) with the station star apart from difference;

Fig. 6 is the atmosphere errors delay that the two differences of baseline LIXI-JLH satellite add the clock correction correction;

Fig. 7 is the atmosphere errors delay that the two differences of baseline LIXI-JLH satellite do not add the clock correction correction;

Fig. 8 is certain brand three system receiver receiver clock correction;

Fig. 9 is IGSHofn website receiver GPS clock correction;

Figure 10 is IGSHofn website receiver Big Dipper clock correction;

Figure 11 is that the IGSohi2 website is received machine GPS clock correction;

Figure 12 is IGSwuhn website receiver GPS clock correction.

Embodiment

Adopt one group of GPS of Southeast China University and Big Dipper laboratory reference station data, comprise Big Dipper double frequency B1, B2 carrier wave pseudorange observation data, the L1 of GPS, L2 carrier wave pseudorange observation data, laboratory reference station are selected the gift west wing LIXI of Southeast China University binary-star system (GPS and the Big Dipper) reference station and lake, Kowloon JLHU binary-star system reference station for use, and base length is 19.7km, the receiver model is and the logical U240 of core star that data sampling is spaced apart 1 second.Fig. 2 is two website receiver GPS clock correction values, Fig. 3 is two website receiver Big Dipper clock correction values, wherein the LIXI website is jumped at the 3522nd receiver clock that takes place 1 millisecond epoch, and the generation that clock is jumped is caused by receiver itself, jumps so the clock correction value of GPS and the Big Dipper produces at synchronization.

For two poor observed readings, the carrier wave of two differences and station star distance

Difference reflects be fixing blur level and two difference tropospheric delay and two difference ionospheric delay values, wherein the less variation of length of delay in short baseline of back two atmosphere errors is slow, can ignore that it is right Influence.

$\mathrm{\Δ}\▿(\mathrm{\λ\φ}-\mathrm{\ρ})=\mathrm{\Δ}\▿N+\mathrm{\Δ}\▿T-\mathrm{\Δ}\▿I$

Utilize said method, relatively the carrier wave of the two differences of this baseline and station star distance Difference change, the analysis receiver clock is jumped the influence to two poor observed readings.The results are shown in Figure 4,5.Fig. 4 is that the two differences of GPS19 satellite change, and Fig. 5 is that the two differences of Big Dipper C06 satellite change.

Among the last figure, the satellite altitude angle is more little, the station star that its product of being jumped by radial velocity and receiver clock causes is more big apart from the error hop value, simultaneously, utilize the method for correction mentioned in this article station star distance, can solve the error that receiver clock correction causes station star distance effectively, to obtain the correct blur level result of baseline.

In network RTK (Real-TimeKinematic, real-time dynamic positioning), utilize the exact position of website to generate two differences troposphere, the ionosphere delays of each baseline in real time.After the two difference of the fixed base blur level, adopt and do not have models estimation ionospheric delay values how much, relevant clock with satellite velocities is jumped the saltus step that can not cause ionosphere delay, and for two poor tropospheric delay value, adopt the combination of no ionosphere to obtain accurately two difference tropospheric delay value, this moment, the receiver clock correction error relevant with satellite velocities can influence the generation of atmosphere errors to the saltus step that causes tropospheric delay value, shown in Fig. 6,7.

Among Fig. 6,7, do not consider that the receiver clock correction relevant with satellite velocities can obtain wrong tropospheric delay value and jump the saltus step that causes tropospheric delay value constantly at clock, ionospheric delay values adopts how much models of nothing to calculate, used herein is that correct blur level result calculates the ionospheric delay values on L1, the L2, of particular note, do not consider the correction of receiver clock correction, clock is jumped and can be caused satellite ambiguity resolution result incorrect and influence the correct generation of ionospheric delay values constantly.

Receiver clock jumping meeting is to producing the error (relevant with the satellite altitude angle) near 1 meter on the geometric distance between satellite and receiver, this part error can not be eliminated in two differences, and influence the fixing and difference bearing accuracy of blur level.Method of estimation to many constellations satellite clock correction in this paper, can determine the geometric distance between satellite orbital position and estimation satellite and receiver effectively, solve the receiver clock and jump the influence that data are handled, the time reference of each constellation in unified many constellations data anastomosing algorithm has engineering significance simultaneously.

The above only is preferred implementation of the present invention; be noted that for those skilled in the art; under the prerequisite that does not break away from the principle of the invention, can also make the some improvements and modifications that can expect, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (2)

1. the base station of constellation list more than kind receiver clock correction method of estimation is characterized in that:

Use satellite pseudorange observed reading to divide exactly the light velocity to obtain the rough satellite-signal transmission time, calculate instantaneous position and the satellite clock correction correction of satellite according to the described rough satellite-signal transmission time;

Utilize continuously the base station known coordinate in the operation satnav service colligate CORS of the system net, calculate the accurate distance of satellite distance base station, to determine the accurate satellite-signal travel-time;

Make up receiver clock correction estimate equation according to various constellations, receiver clock correction value is found the solution in filtering;

At many constellation systems, the various constellations system the clock correction corrected value of corresponding master station inequality, the corrected value precision is to be determined by each master station clock accuracy between each system, and separate; For the satellite of same constellation, itself and receiver clock correction can be merged estimation, and for many constellations, each constellation should have its independent receiver clock correction value and estimate its precision, the receiver clock correction value of each constellation is actual here is:

${\mathrm{\δt}}_k=\mathrm{\δ}{\hat{t}}_k+\mathrm{\δ}{t}_{G/R/C/E}^i$

Here

Refer to the clock correction corrected value of various constellations master station, described various constellations corresponds to GPS, GLONASS, the Big Dipper, GALILEO,

For the corrected value of the clock of receiver own, for various constellations, should have independent receiver clock correction δ t separately _kEstimate to analyze;

Utilize receiver clock correction value to calculate accurate receiver and the satellite geometry distance of corrected received machine clock correction;

Carry out carrier wave ambiguity resolution and the difference location of virtual reference station VRS according to above result.

2. the base station of constellation list more than kind receiver clock correction method of estimation may further comprise the steps:

(1), each base station continuous acquisition observation data, and be real-time transmitted to central server to receive each base station moonscope data, described each base station moonscope data comprise satellite L1, L2 carrier phase observation data and P1, P2 pseudorange observation information, and carry out the real time data pre-service, described pre-service comprises rough error and cycle slip detection;

(2), the satellite pseudorange guestimate satellite-signal transmission time τ that adopts receiver observation to obtain ₀=P/c; Suppose initial receiver clock correction δ t _kBe 0, utilize initial observation epoch and signal transmission time τ ₀Obtain the instantaneous coordinate (X of satellite ⁱ, Y ⁱ, Z ⁱ) and the initial satellite clock correction correction δ t that utilizes the ephemeris file to obtain ⁱ ₀, because in regional reference station network, base station coordinates is known, then can calculate the geometric distance of initial satellite position and receiver

, and recomputate signal transmission time

, wherein P is actual measurement pseudorange observed reading, c is light velocity value,

${\mathrm{\ρ}}_k^i=\sqrt{{(X^i-X_k)}^2+{(Y^i-Y_k)}^2+{(Z^i-Z_k)}^2}$

${\mathrm{\τ}}_k^i=\frac{1}{c}{\mathrm{\ρ}}_k^i$

(3), make up receiver clock correction estimate equation, find the solution various constellations receiver clock correction value separately single epoch, wherein n is the population of satellite, δ t _k(G), δ t _k(R), δ t _k(C), δ t _k(E) be respectively the corresponding receiver clock correction value of GPS, GLONASS, the Big Dipper, GALILEO, δ t ⁱThe initial satellite clock correction correction of the corresponding satellite of expression institute, ε be for comprising tropospheric delay, ionosphere delay and be correlated with not modeled residual error item, noise item,

BX=L

For the continuous operation satnav service colligate CORS of system base station, because its coordinate is known, only need estimate receiver clock correction, can estimate by list least square epoch, for its coordinate the unknown of rover station, still need make up Kalman filter and find the solution with it as unknown parameter:

X ^T=[δX,δY,δZ,δt _k(G),δt _k(R),δt _k(C),δt _k(E)]

Wherein, δ X, δ Y, δ Z are base station coordinate correction value, δ t _k(G), δ t _k(R), δ t _k(C), δ t _k(E) be respectively the corresponding receiver clock correction value of GPS, GLONASS, the Big Dipper, GALILEO, n is the population of satellite,

Be coefficient after the equation linearization;

The use experience model is determined observed reading weight and initial parameter value, if receiver does not exist clock to jump, can adopt white noise to come the variation of analog receiver clock correction, for the receiver that exists clock to jump, sets corresponding receiver clock correction dynamic noise matrix and is

, σ _t=3.0e5, unit are rice, jump by the 1ms clock and are caused the pseudorange maximum changing value;

(4), the receiver clock correction value of utilizing for second step obtained is calculated corresponding

Moment satellite position, obtain accurate receiver and the satellite geometry distance of corrected received machine clock correction, in the computation process of above-mentioned satellite position and receiver clock correction, also need consider the influence of earth rotation and relativistic effect, and the relevant atmosphere convection layer of modelling and ionosphere delay error item, finally obtain correct receiver clock correction and satellite position information.

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