CN101089650A - Error separation method based on foundation strength system and foundation strength system - Google Patents

Abstract

An error separating method based on ground-base intensification system includes separately calculating code smooth s\pseudo-distance of ground station and code smooth pseudo-distance of client station, separately estimating ionized layer delay error of ground station and ionized layer delay error of client station, broadcasting data of ground station to client station and carrying out differential calibration on said data by client station. The ground-base intensification system applied in said method is also disclosed.

Description

Error separating method and ground enhanced system based on the ground enhanced system

Technical field

The present invention relates to a kind of GPS navigation localization method, particularly utilize the method for carrying out the difference location based on the error separating method of ground enhanced system; The invention still further relates to a kind of GPS navigation positioning system, particularly based on the navigator fix of ground enhanced system.

Background technology

GPS (Global positioning system also is satellite navigation system, hereinafter to be referred as: GPS) comprise three parts: space segment, ground segment and user segment.The positioning principle of GPS is: the user receives the navigation signal of the satellites transmits of space segment, calculates the time of signal from satellite arrival receiver user, multiply by the light velocity again, is the distance of satellite to receiver user; Come out in the position of Aerospace Satellite ephemeris computation via satellite; The user observes 3 equations of 3 satellites foundation about own three-dimensional position simultaneously, thereby calculates three-dimensional position.Because the receiver user clock can not be synchronous fully with satellite clock, so in positioning equation, also comprise the unknown number of a receiver clock correction, therefore in fact the user needs to observe simultaneously 4 satellites, sets up 4 equations, resolves user's three-dimensional position and receiver clock correction.

In the position of receiver, in fact also comprise the error that ephemeris, star clock, ionosphere and the tropospheric delay of satellite and receiver thermonoise and multipath effect cause, so this distance that calculates is called pseudorange at satellite that the user records.Concerning the user of GPS, directly pass through the nearly 12.5 meters error of positioning result of its computation of pseudoranges.There have been a lot of systems to obtain more high-precision positioning result by assisted user now, wherein there is a type systematic to be called ground enhanced system (Ground BasedAugmentation System, hereinafter to be referred as: GBAS), the user obtains more high-precision positioning result by receiving the enhancing information that is sent by land station.

GBAS is based on the correlation principle of error, think that star clock error, ephemeris error, ionosphere and tropospheric delay error are strong correlations on time or space, promptly two very near observers of distance observe same satellite simultaneously, and then their positioning error is basic identical.Therefore, in the local scope, can obtain high orientation precision by the mode of difference.The principle of work of GBAS is such, and the reference station in known exact position obtains pseudo range observed quantity, calculates the actual distance of satellite and reference station again, and the difference of calculating both obtains the difference correction value, and it is sent to receiver user; Receiver user utilizes these difference correction values to correct the pseudo range observed quantity of oneself, then can obtain the positioning result of degree of precision.

Yet, in the reality in the error of pseudo range observed quantity, ionosphere delay error in time and satellite-signal change through ionospheric path and satellite elevation angle, and the variation in ionosphere itself also causes ionosphere delay error to change with the place in time, and these variations have brought additional error to GBAS.

Usually use the carrier smoothing treatment technology to eliminate this additional error among the GBAS, use sign indicating number observed quantity and carrier phase observed quantity to carry out complementary filter by uniting, by increasing noise and the multipath error that time constant filter reduces smoothing code pseudorange after the filtering, this technology is very ripe and become the basis of GBAS.Yet because ionospheric refraction makes ionospheric time gradient can produce the residual error of smothing filtering to the inconsistency of sign indicating number observed quantity and carrier phase observed quantity influence, and its size is directly proportional with the smoothing filter time constant.Because the characteristic of above-mentioned carrier smoothing treatment technology will design noise and the multipath error of the time constant filter of a compromise in order to balance smoothing code pseudorange, and the filtering residual error that causes of ionospheric time gradient.

At present in single-frequency GBAS system, because the time gradient of ionosphere delay error can't solve to the additional difference correction residual error that GBAS brings.Following GPS (Global Position System) (GlobalNavigation Satellite System, be called for short: GNSS) designed a plurality of navigation frequencys for the civilian users station, the use of many navigation frequencys observed quantity will help to estimate more accurately ionosphere delay error, and the smoothing filter of the no ionosphere of structure deviation, alleviate the influence of ionosphere delay error to the GBAS system.

Present bias free (Divergence-Free, be called for short: DFree) filtering method just is to use the double frequency observation data to improve the precision of smothing filtering, this method uses the dual-frequency carrier observed quantity to make up the carrier phase observed quantity of combination, make ionosphere delay error component wherein all identical with the size and the symbol of the ionosphere delay error component of sign indicating number in the observed quantity, before filtering, by asking this component of poor cancellation, again it is added in the smoothing code pseudorange after the filtering earlier.Like this, the DFree method has been eliminated the filtering residual error that the ionosphere delay time gradient produces.But, be two-frequency signal because the method uses, so dual-frequency carrier noise and multipath error have been introduced in the sign indicating number smoothing pseudo range.

In addition, when using the carrier smoothing treatment technology, ionospheric spatial gradient also can cause additional difference correction error at user side, and its size is generally 0.2cm/km.And the existing single-frequency of difference correction residual error that this spatial gradient brings still is that the double frequency user can't eliminate.

Summary of the invention

One aspect of the present invention is, a kind of error separating method based on the ground enhanced system is provided, and makes user's difference bearing accuracy be improved.

Another aspect of the present invention is, a kind of ground enhanced system is provided, and makes the user use this system can obtain the very high positioning result of precision.

In order to realize first aspect of the present invention, the error separating method based on the ground enhanced system of some embodiments of the present invention comprises the steps:

Calculate ground system sign indicating number smoothing pseudo range;

Estimation ground system ionosphere delay error;

Calculate user's station yard smoothing pseudo range;

Estimation subscriber station ionosphere delay error;

Described ground system sign indicating number smoothing pseudo range and described ground system ionosphere delay error are sent to subscriber station;

Subscriber station carries out difference correction to described ground system sign indicating number smoothing pseudo range, ground system ionosphere delay error and described user's station yard smoothing pseudo range, subscriber station ionosphere delay error.

By said method, some embodiments of the present invention can be eliminated the influence of the spatial gradient of ionosphere delay, and further reduce noise and multipath error in yard smoothing pseudo range.

In order to realize second aspect of the present invention, the ground enhanced system of other embodiment of the present invention comprises land station and subscriber station, and land station and subscriber station include receiver and data chainning radio station, is used for receiving and transmitting data, wherein:

Described land station comprises: first filter unit is used to calculate ground station yard smoothing pseudo range; Second filter unit is used to estimate land station's ionosphere delay error;

Described subscriber station comprises: the 3rd filter unit is used to calculate user's station yard smoothing pseudo range; The 4th filter unit is used to estimate the subscriber station ionosphere delay error; The difference processing unit is used for described land station is broadcast to the data of subscriber station and data that described subscriber station is tried to achieve are carried out difference correction, obtains the difference correction value.

In the above-mentioned ground enhanced system, after subscriber station is received the data that land station sends, carry out data processing, solve the difference positioning result, and improve bearing accuracy.

Also in conjunction with the accompanying drawings the present invention is described in further detail below by specific embodiment.

Description of drawings

Fig. 1 is the process flow diagram of error separating method of the present invention;

Fig. 2 is a ground enhanced system structural representation of the present invention;

Fig. 3 is a filter unit structural representation of the present invention.

Embodiment

At first introduce the model of sign indicating number and carrier phase observed quantity in the gps system down:

Suppose that sign indicating number and carrier phase observed quantity under the L1 frequency of GPS are ρ ₁And φ ₁, its equation is respectively:

$\left\{\begin{array}{c}{\mathrm{\ρ}}_1=r+i_1+{\mathrm{\η}}_{\mathrm{\ρ}1}\\ {\mathrm{\φ}}_1=r-i_1+N_1+{\mathrm{\η}}_{\mathrm{\φ}1}\end{array}\right.---\left(1\right)$

Wherein: the common error sum that r is the user in the actual distance of satellite and a sign indicating number observed quantity, the carrier phase observed quantity, common error comprises that star clock, ephemeris and tropospheric error and " select availability (Selective Availability is called for short: SA) " satellite-signal disturb; i ₁Be the ionosphere delay error in following yard of L1 frequency and the carrier phase observed quantity; N ₁Integer ambiguity for the carrier phase observed quantity; η _{ρ 1}, η _{φ 1}Be respectively the noise and the multipath error sum of a yard observed quantity, carrier phase observed quantity.

Similarly, sign indicating number and the carrier phase observed quantity under the L2 frequency of GPS is ρ ₂And φ ₂, its equation is respectively:

$\left\{\begin{array}{c}{\mathrm{\&rho;}}_2=r+{\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="A20071011871600171.png"\; state="\{\{state\}\}">i</figure-callout>}}_2+{\mathrm{\&eta;}}_{\mathrm{\&rho;}2}\\ {\mathrm{\&phi;}}_2=r-i_2+{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="A20071011871600171.png"\; state="\{\{state\}\}">N</figure-callout>}}_2+{\mathrm{\&eta;}}_{\mathrm{\&phi;}2}\end{array}\right.---\left(2\right)$

Some embodiments of the present invention propose, in the data handling procedure of GBAS land station, to carry out twice carrier smoothing filtering, a filtering is used for calculating the sign indicating number smoothing pseudo range, by increasing time constant filter, weaken noise and multipath error component in yard smoothing pseudo range as much as possible, another time filtering is used for accurately estimating ionosphere delay error, and the ionosphere delay error of sign indicating number smoothing pseudo range that has weakened noise and multipath error respectively and accurately estimation is issued subscriber station respectively;

In the process that subscriber station is handled data, for the single-frequency user, the sign indicating number smoothing pseudo range that can continue to use land station to send is proofreaied and correct, and its processing mode is identical with traditional GBAS working method; For the double frequency user, owing to also can carry out twice carrier smoothing filtering, once obtain the sign indicating number pseudo range observed quantity of subscriber station, another time filtering uses the double frequency observed quantity to calculate the ionosphere delay error of subscriber station, ionosphere delay error with subscriber station deducts land station's ionosphere delay error that land station sends, just can calculate the ionosphere delay spatial gradient between subscriber station and land station, thereby eliminate the influence of this error, improve the difference bearing accuracy.

The concrete steps that ionosphere delay error is separated as shown in Figure 1, for:

Step 101, calculating ground station yard smoothing pseudo range;

Step 102, estimation land station ionosphere delay error;

Step 103, calculating user station yard smoothing pseudo range;

Step 104, estimation subscriber station ionosphere delay error;

Step 105, ground station yard smoothing pseudo range and land station's ionosphere delay error are sent to subscriber station;

Step 106, subscriber station carry out difference correction to ground station yard smoothing pseudo range, land station's ionosphere delay error and user's station yard smoothing pseudo range, subscriber station ionosphere delay error.

Wherein the concrete steps of step 101 calculating ground station yard smoothing pseudo range are:

Step 1011, utilize the dual-frequency carrier observed quantity to make up combined carriers phase observations amount Φ, that is: $\mathrm{\&Phi;}={\mathrm{\&phi;}}_1-\frac{2}{\mathrm{\&alpha;}}({\mathrm{\&phi;}}_1-{\mathrm{\&phi;}}_2),$ With φ ₁, φ ₂Substitution,

Φ＝r+i ₁+N _Φ1+η _Φ1，

Wherein r is described ground system or the subscriber station pseudo-range measurements to satellite; i ₁Be the ionosphere delay error in observed quantity of L1 frequency code and the carrier phase observed quantity; N _{Φ 1}Be the integer ambiguity of combined carriers phase observations amount, $N_{\mathrm{\&Phi;}1}=N_1-\frac{2}{\mathrm{\&alpha;}}(N_1-N_2);$ η _{Φ 1}Noise and multipath error in the combined carriers phase observations amount, ${\mathrm{\&eta;}}_{\mathrm{\&Phi;}1}={\mathrm{\&eta;}}_{\mathrm{\&phi;}1}-\frac{2}{\mathrm{\&alpha;}}({\mathrm{\&eta;}}_{\mathrm{\&phi;}1}-{\mathrm{\&eta;}}_{\mathrm{\&phi;}2});$

Notice that getting ionosphere component call sign among Φ this moment changes.

Step 1012, sign indicating number observed quantity ψ=ρ ₁=r+i ₁+ η _{ρ 1}, before filtering, earlier deduct Φ with ψ, but cancellation ionosphere delay error component i wherein then ₁, obtain

χ＝η _ρ1-(N _Φ1+η _Φ1)；

Step 1013, with the χ behind the cancellation ionosphere delay error after the filtering of bias free smoothing filter, obtain

$\widehat{\mathrm{\&chi;}}=-N_{\mathrm{\&Phi;}1}+F({\mathrm{\&eta;}}_{\mathrm{\&rho;}1}-{\mathrm{\&eta;}}_{\mathrm{\&Phi;}1}),$

Wherein F is the low-pass filtering transport function;

Step 1014,

Obtain filtered sign indicating number smoothing pseudo range with combined carriers phase observations amount Φ addition again:

$\widehat{\mathrm{\&Psi;}}=r+i_1+{\mathrm{\&epsiv;}}_D,$

ε wherein _D=F η _{ρ 1}+ (1-F) η _{Φ 1}Be noise and multipath error additional in the sign indicating number smoothing pseudo range.

By the sign indicating number smoothing pseudo range that obtains as can be known, since before the filtering first cancellation ionosphere delay error, so no longer produce additional ionospheric error after the filtering, so filter time constant can long enough, in order to reduce noise and multipath error additional in yard smoothing pseudo range.

The concrete steps of step 102 estimation land station ionosphere delay error are:

The difference of step 1021, calculating L1 frequency code observed quantity and the observed quantity of L2 frequency code, that is:

ψ＝ρ ₁-ρ ₂＝(i ₁-i ₂)+η _ρ12，

Wherein, i ₂Be the ionosphere delay error in observed quantity of L2 frequency code and the carrier phase observed quantity, the noise and the difference of multipath error: the η of L1 and the following yard observed quantity of L2 frequency _{ρ 12}=η _{ρ 1}-η _{ρ 2}

The difference of step 1022, calculating L1 frequency carrier phase observations amount and L2 frequency carrier phase observations amount, that is:

φ＝-(φ ₁-φ ₂)＝(i ₁-i ₂)-N ₁₂-η _φ12，

Wherein, the difference of the integer ambiguity of L1 and L2 frequency carrier phase observations amount is N ₁₂=N ₁-N ₂, the noise in L1 and the L2 frequency carrier phase observations amount and the difference of multipath error are η _{φ 12}=η _{φ 1}-η _{φ 2}

Step 1023, deduct the difference φ of described L1 frequency carrier phase observations amount and L2 frequency carrier phase observations amount with the difference ψ of observed quantity of described L1 frequency code and the observed quantity of L2 frequency code, but cancellation ionosphere delay error component (i wherein then ₁-i ₂), obtain χ=η _{ρ 12}+ N ₁₂+ η _{φ 12}

Step 1024, with the χ behind the cancellation ionosphere delay error after smoothing filter filtering, obtain: $\widehat{\mathrm{\&chi;}}={\mathrm{<figure-callout\; id="12"\; label="N"\; filenames="A20071011871600171.png"\; state="\{\{state\}\}">N</figure-callout>}}_{12}+F{\mathrm{\&eta;}}_{\mathrm{\&rho;}12}+F{\mathrm{\&eta;}}_{\mathrm{\&phi;}12},$ Wherein F is the low-pass filtering transport function;

Step 1025, described

Difference φ addition with described L1 frequency carrier phase observations amount and L2 frequency carrier phase observations amount obtains filtered ionosphere delay error again:

$\widehat{\mathrm{\&psi;}}=(i_1-i_2)+{\mathrm{\&epsiv;}}_1,$

ε wherein ₁=F η _{ρ 12}+ (F-1) η _{φ 12}Be noise and multipath error additional in the ionosphere delay error;

Step 1026, with ionosphere delay error $\widehat{\mathrm{\&psi;}}=(i_1-i_2)+{\mathrm{\&epsiv;}}_1$ Obtain the estimated value of L1 frequency ionosphere delay error through convergent-divergent: ${\hat{i}}_1=i_1+\frac{1}{\mathrm{\&alpha;}}{\mathrm{\&epsiv;}}_1.$

By the process of the above-mentioned estimated value of asking L1 frequency ionosphere delay error as can be known, since before the filtering also cancellation in advance ionosphere delay error, so can not produce additional ionospheric error after the filtering, therefore equally can be by increasing the time constant of filtering, reduce noise and multipath error additional in the estimated value of ionosphere delay error, make the ionosphere delay error of estimation more accurate.

With the user's station yard smoothing pseudo range in the solution procedure calculation procedure 103 identical with step 1021～1026 with above-mentioned steps 1011～1014 With the subscriber station ionosphere delay error in the step 104 Sign indicating number smoothing pseudo range and ionosphere delay error that land station is obtained send to subscriber station simultaneously, and the data that data that land station sent by subscriber station and user oneself try to achieve are handled.

Wherein the sign indicating number smoothing pseudo range and the ionosphere delay error of land station are respectively:

${\widehat{\mathrm{\&Psi;}}}^B=r^B+i_1^B+{\mathrm{\&epsiv;}}_D^B,$

${\hat{i}}_1^B=i_1^B+\frac{1}{\mathrm{\&alpha;}}{\mathrm{\&epsiv;}}_1^B;$

The sign indicating number smoothing pseudo range and the ionosphere delay error of subscriber station are respectively:

${\widehat{\mathrm{\&Psi;}}}^A=r^A+i_1^A+{\mathrm{\&epsiv;}}_D^A,$

${\hat{i}}_1^A=i_1^A+\frac{1}{\mathrm{\&alpha;}}{\mathrm{\&epsiv;}}_1^A.$

Obviously, for the user, It is ratio

More accurate estimation to local ionosphere delay error,

With Difference be the ionosphere delay error that the ionosphere spatial gradient causes.Now, the user only needs to deduct the ionosphere delay error of estimation from the sign indicating number smoothing pseudo range, remainder is carried out Difference Calculation, that is:

Right

Carry out difference correction, can obtain the very high difference correction value of precision

$\mathrm{\&Delta;\&Psi;}=({\widehat{\mathrm{\&Psi;}}}^A-{\hat{i}}_1^A)-({\widehat{\mathrm{\&Psi;}}}^B-{\hat{i}}_1^B).$

Above-mentioned based on the GBAS system, utilize error separating to ask the method for difference correction value, ask the method for difference correction value to compare with traditional single-frequency user, error separating method has been eliminated the influence owing to the ionosphere spatial gradient, the difference correction error of adding in subscriber station; But, but sign indicating number and carrier phase noise and multipath error under the L2 frequency of land station are introduced aerial user, this defective can be by being reduced the growth of filtering time.Therefore, as long as filtering time long enough, the global error of GBAS system has still reduced, and user's difference bearing accuracy is improved.

Other embodiment of the present invention propose, in the GBAS system, land station will use two carrier smoothing wave filters, a noise and a multipath error component that is used for weakening filtered sign indicating number smoothing pseudo range, another is used to estimate ionosphere delay error, and the data that obtain behind two carrier smoothing wave filters are broadcast to aerial user simultaneously.

Like this, for the single-frequency subscriber station, can continue to use the sign indicating number smoothing pseudo range to proofread and correct, its processing mode is identical with traditional GBAS.For the double frequency subscriber station, owing to wherein also comprise two carrier smoothing wave filters, can use the double frequency observed quantity to calculate subscriber station ionosphere delay error estimated value, deduct land station's ionosphere delay error that land station sends, just can calculate the ionosphere delay spatial gradient between user and land station, thereby eliminate the influence of this error, improve the difference bearing accuracy.

This GBAS system as shown in Figure 2, the B of land station comprises: receiver 6, by antenna 8 receiving satellite signals; First filter unit 1 is used to calculate ground station yard smoothing pseudo range; Second filter unit 2 is used to estimate land station's ionosphere delay error; Subscriber station is given by the data broadcasting that antenna 8 is calculated land station's first and second filter units in data chainning radio station 7.Subscriber station A comprises: receiver 6, by antenna 8 receiving satellite signals; The 3rd filter unit 3 is used to calculate user's station yard smoothing pseudo range; The 4th filter unit 4 is used to estimate the subscriber station ionosphere delay error; Difference processing unit 5 is used for land station is broadcast to the data of subscriber station and data that described subscriber station is tried to achieve are carried out difference correction, obtains the difference correction value.

Utilize sign indicating number observed quantity ρ and carrier phase observed quantity φ under L1 frequency and the L2 frequency to finish the calculating to sign indicating number smoothing pseudo range and ionospheric error of above-mentioned filter unit by the computing method of the foregoing description.First to fourth filter unit mainly comprises again and asks poor unit 9 as shown in Figure 3, is used for additive operation is carried out in sign indicating number observed quantity and carrier phase observed quantity, eliminates ionosphere delay error wherein; Wave filter 10 is used for the result who asks poor unit to obtain is carried out computing; Sum unit 11 is used for sum operation is carried out in the result and the carrier phase observed quantity of trying to achieve through wave filter, draws last filtering result.

After the difference correction value that difference unit calculates is our last needed locating information.This difference correction value has not had the influence of the spatial gradient of ionosphere delay, so precision is improved owing to obtain by having separated ionosphere delay error; And owing in filtering, also eliminated the influence of ionosphere time gradient, so can reduce noise and multipath error in yard smoothing pseudo range by increasing time constant filter as much as possible, thereby further improve the precision of difference fiducial value, obtain accurate difference positioning information.

It should be noted that at last: above embodiment only in order to technical scheme of the present invention to be described, is not intended to limit; Although with reference to previous embodiment the present invention is had been described in detail, those of ordinary skill in the art is to be understood that: it still can be made amendment to the technical scheme that aforementioned each embodiment put down in writing, and perhaps part technical characterictic wherein is equal to replacement; And these modifications or replacement do not make the essence of appropriate technical solution break away from the spirit and scope of various embodiments of the present invention technical scheme.

Claims (10)

1, a kind of method based on ground enhanced system error separating is characterized in that, step is:

Calculate ground station yard smoothing pseudo range;

Estimation land station ionosphere delay error;

Calculate user's station yard smoothing pseudo range;

Estimation subscriber station ionosphere delay error;

Described ground station yard smoothing pseudo range and described land station ionosphere delay error are sent to subscriber station;

Subscriber station carries out difference correction to described ground station yard smoothing pseudo range, land station's ionosphere delay error and described user's station yard smoothing pseudo range, subscriber station ionosphere delay error.

2, the method based on ground enhanced system error separating according to claim 1 is characterized in that: described calculating ground station yard smoothing pseudo range and the utilization of user's station yard smoothing pseudo range be bias free smothing filtering technology, concrete steps are:

Utilize the dual-frequency carrier observed quantity to make up combined carriers phase observations amount, described combined carriers phase observations amount Φ=r+i ₁+ N _{Φ 1}+ η _{Φ 1}, wherein r is described ground system or the subscriber station pseudo-range measurements to satellite, i ₁Be the ionosphere delay error in observed quantity of L1 frequency code and the carrier phase observed quantity, N _{Φ 1}Be the integer ambiguity of combined carriers phase observations amount, η _{Φ 1}Be noise and the multipath error in the combined carriers phase observations amount;

With sign indicating number observed quantity ρ ₁=r+i ₁+ η _{ρ 1}Deduct described combined carriers phase observations amount Φ, but cancellation ionosphere delay error component i wherein then ₁, obtain χ=η _{ρ 1}-(N _{Φ 1}+ η _{Φ 1}), η wherein _{ρ 1}Noise and multipath error for the observed quantity of L1 frequency code;

χ behind the cancellation ionosphere delay error after the filtering of bias free smoothing filter, is obtained: $\widehat{\mathrm{\&chi;}}=-N_{\mathrm{\&Phi;}1}+F({\mathrm{\&eta;}}_{\mathrm{\&rho;}1}-{\mathrm{\&eta;}}_{\mathrm{\&Phi;}1}),$ Wherein F is the low-pass filtering transport function;

Described

Obtain filtered sign indicating number smoothing pseudo range with described combined carriers phase observations amount Φ addition again: $\widehat{\mathrm{\&Psi;}}=r+i_1+{\mathrm{\&epsiv;}}_D,$ ε wherein _D=F η _{ρ 1}+ (1-F) η _{Φ 1}Be noise and multipath error additional in the sign indicating number smoothing pseudo range.

3, the method based on ground enhanced system error separating according to claim 1 is characterized in that: the step of described estimation ground system ionosphere delay error and subscriber station ionosphere delay error is specially:

Calculate the difference ψ of L1 frequency code observed quantity and the observed quantity of L2 frequency code;

Make up the difference φ of L1 frequency carrier phase observations amount and L2 frequency carrier phase observations amount, make that the ionosphere delay error difference among the φ equates with size and symbol among the ψ;

Obtain the difference of ψ and φ, removed the ionosphere delay error difference in the described difference, promptly χ=ψ-φ carries out filtering with χ through smoothing filter and obtains

φ is added back to again

Obtain

Utilize again

Ionospheric error is accurately estimated.

4, the method based on ground enhanced system error separating according to claim 3 is characterized in that: the concrete solution procedure of described difference ψ and difference φ is:

Calculate L1 frequency code observed quantity ρ ₁=r+i ₁+ η _{ρ 1}Calculate L2 frequency code observed quantity ρ ₂=r+i ₂+ η _{ρ 2}

Calculate L1 frequency carrier phase observations amount φ ₁=r-i ₁+ N ₁+ η _{φ 1}Calculate L2 frequency carrier phase observations amount φ ₂=r-i ₂+ N ₂+ η _{φ 2}

Deduct the observed quantity of L2 frequency code, that is: ψ=ρ with the observed quantity of L1 frequency code ₁-ρ ₂=(i ₁-i ₂)+η _{ρ 12}, wherein, i ₂Be the ionosphere delay error in observed quantity of L2 frequency code and the carrier phase observed quantity, η _{ρ 12}Be L1 and the noise of L2 frequency code observed quantity and the difference of multipath error;

Make up the difference φ of L1 frequency carrier phase observations amount and L2 frequency carrier phase observations amount, that is: φ=-(φ ₁-φ ₂)=(i ₁-i ₂)-N ₁₂-η _{φ 12}, wherein, N ₁₂Be the difference of the integer ambiguity of L1 and L2 frequency carrier phase observations amount, η _{φ 12}Be the noise in L1 and the L2 frequency carrier phase observations amount and the difference of multipath error.

5, the method based on ground enhanced system error separating according to claim 3, it is characterized in that: the concrete steps of described filtering are:

Deduct described φ with described ψ, but cancellation ionosphere delay error component (i wherein then ₁-i ₂), obtain χ=η _{ρ 12}+ N ₁₂+ η _{φ 12}

χ after the cancellation ionosphere delay error difference through smoothing filter filtering, is obtained:

$\widehat{\mathrm{\&chi;}}=N_{12}+F{\mathrm{\&eta;}}_{\mathrm{\&rho;}12}+F{\mathrm{\&eta;}}_{\mathrm{\&phi;}12},$ Wherein F is the low-pass filtering transport function;

Described

Obtain filtered ionosphere delay error with described φ addition again: $\widehat{\mathrm{\&psi;}}=(i_1-i_2)+{\mathrm{\&epsiv;}}_1,$ ε wherein ₁=F η _{ρ 12}+ (F-1) η _{φ 12}Be noise and multipath error additional in the ionosphere delay error.

6, the method based on ground enhanced system error separating according to claim 5 is characterized in that: described ionosphere delay error can obtain the estimated value of L1 frequency ionosphere delay error behind convergent-divergent:

${\hat{i}}_1=i_1+\frac{1}{\mathrm{\&alpha;}}{\mathrm{\&epsiv;}}_1.$

7, the method based on ground enhanced system error separating according to claim 6 is characterized in that: the noise and the multipath error ε that add in the described ionosphere delay error ₁Can reduce gradually with the increase of bias free smothing filtering time.

8, the method based on ground enhanced system error separating according to claim 1 is characterized in that: described subscriber station is specially the step that described ground station yard smoothing pseudo range, land station's ionosphere delay error and described user's station yard smoothing pseudo range, subscriber station ionosphere delay error carry out difference correction:

Described user's station yard smoothing pseudo range deducts described subscriber station ionosphere delay error, that is:

Wherein

Be user's station yard smoothing pseudo range,

Be the subscriber station ionosphere delay error;

Described ground station yard smoothing pseudo range deducts described land station ionosphere delay error, that is:

Wherein

Be ground station yard smoothing pseudo range,

Be land station's ionosphere delay error;

Again the difference of the above-mentioned land station that obtains is deducted the difference of the subscriber station of obtaining, obtain the difference fiducial value.

9, a kind of ground enhanced system comprises land station and subscriber station, and land station and subscriber station include receiver and data chainning radio station, is used for receiving and transmitting data, it is characterized in that:

Described land station comprises: first filter unit is used to calculate ground station yard smoothing pseudo range; Second filter unit is used to estimate land station's ionosphere delay error;

Described subscriber station comprises: the 3rd filter unit is used to calculate user's station yard smoothing pseudo range; The 4th filter unit is used to estimate the subscriber station ionosphere delay error; The difference processing unit is used for described land station is broadcast to the data of subscriber station and data that described subscriber station is tried to achieve are carried out difference correction, obtains the difference correction value.

10, ground enhanced system according to claim 9 is characterized in that: described filter unit concrete structure comprises:

Ask poor unit, be used for additive operation is carried out in sign indicating number observed quantity and carrier phase observed quantity, eliminate ionosphere delay error wherein;

Wave filter is used for the result who asks poor unit to obtain is carried out computing;

Sum unit, sum operation is carried out in the result and the carrier phase observed quantity that are used for transfer unit is tried to achieve, draws last filtering result.

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