CN104732085A - Satellite navigation satellite-based augmentation system availability prediction method - Google Patents

Abstract

The invention provides a satellite navigation satellite-based augmentation system availability prediction method which comprises the steps that the visible distance amendment of each satellite and the integrity monitoring station number are computed; the number of visible ionized layer breakthrough points of each ionization mesh point is computed; according to visible distance amendment, the integrity monitoring station number and the number of the visible ionized layer breakthrough points, the protection level of a satellite-based augmentation system is computed; and according to the protection level of the satellite-based augmentation system, the availability of the satellite-based augmentation system is judged. According to the satellite navigation satellite-based augmentation system availability prediction method, the availability of a satellite navigation satellite-based augmentation system can be predicted quickly, and the locating accuracy of a satellite navigation system is improved.

Description

Satellite navigation satellite-based augmentation system availability predictions method

Technical field

The present invention relates to field of satellite navigation, particularly relate to a kind of satellite navigation satellite-based augmentation system availability predictions method.

Background technology

Satellite-based augmentation system (Satellite-Based Augmentation System, be called for short SBAS), by geostationary orbit (synchronous orbit, be called for short GEO) Seeds of First Post-flight satellite navigation enhancing signal repeater, the multiple update informations such as ephemeris error, satellite clock correction, ionosphere delay can be broadcast to user, realize the improvement for original Positioning Accuracy of Satellite Navigation System.Protected level (Protect Level is called for short PL) is used for ensureing the integrity of satellite navigation satellite-based augmentation system normally and under abnormal condition.PL size needs to guarantee only to have the error of very fraction (being less than or equal to integrity risk probability) to be positioned at outside envelope.In order to ensure the availability of system, general expectation PL is very " tightly ", namely little as much as possible under guarantee integrity prerequisite.When PL is greater than threshold value (alarm limit), satellite-based augmentation system is disabled, and namely the positioning error of navigational system is excessive, has exceeded satellite-based augmentation system tolerance scope, user need carry out auxiliary positioning by other means, to meet its application demand.Also namely, by calculating PL, the availability of satellite-based augmentation system can be judged.

At present, RTCA (dio Technical Commission for Aeronautics, be called for short RTCA) define the detailed computing method of SBAS PL in GPS/Wide Area Augmentation System airborne equipment Minimum Operating Performance Standard (RTCA/DO-229D), core parameter needed for algorithm is two parameters of enhancing system real-time broadcasting: user's difference distance error (User Difference RangeError, be called for short UDRE) and graticule mesh ionosphere vertical error (Grid Ionospheric Vertical Error, be called for short GIVE), UDRE and GIVE two parameters are obtained by resolving from navigation message, and then calculate PL according to RTCA/DO-229D, and then judge the availability of satellite-based augmentation system.

But current UDRE and GIVE two parameters need to resolve from navigation message in real time, and one is cannot carry out anticipation to the availability of satellite-based augmentation system; Two is within preset time, from navigation message, continuously resolve UDRE and GIVE two parameters, and operand is large, poor in timeliness, thus cannot the availability of fast prediction satellite navigation satellite-based augmentation system, causes Positioning Accuracy of Satellite Navigation System not high.

Summary of the invention

The invention provides a kind of satellite navigation satellite-based augmentation system availability predictions method, can the availability of fast prediction satellite navigation satellite-based augmentation system, improve Positioning Accuracy of Satellite Navigation System.

Satellite navigation satellite-based augmentation system availability predictions method provided by the invention, comprising:

Calculate every visible RIMS number of satellite;

Calculate the visible IPP number of each IGP;

The PL of satellite-based augmentation system is calculated according to visible RIMS number and visible IPP number;

The availability of satellite-based augmentation system is judged according to the PL of satellite-based augmentation system.

In an embodiment of the present invention, the aforementioned PL calculating satellite-based augmentation system according to visible RIMS number and visible IPP number, comprising:

UDRE is obtained according to visible RIMS number;

GIVE is obtained according to visible IPP number;

The PL of satellite-based augmentation system is calculated according to UDRE and GIVE obtained.

In an embodiment of the present invention, the aforementioned PL calculating satellite-based augmentation system according to visible RIMS number and visible IPP number, also comprises:

Almanac according to satellite calculates satellite position;

According to the PL of UDRE, GIVE of obtaining and satellite position calculation satellite-based augmentation system.

In an embodiment of the present invention, the visible RIMS number of aforementioned calculating every satellite, comprising:

By the position in the almanac of satellite calculate every satellite a certain moment in a short time;

Travel through the RIMS that every satellite is all;

Calculate the elevation angle of each RIMS to every satellite;

The elevation angle is compared to the cutoff angle of every satellite with each RIMS, judges the observability of each RIMS;

Wherein, cutoff angle is 5 degree or 10 degree;

Add up every visible RIMS number of satellite.

In an embodiment of the present invention, aforementioned the elevation angle to be compared to the cutoff angle of every satellite with each RIMS, judges the observability of each RIMS, comprising:

If the elevation angle is greater than cutoff angle, then RIMS is visible;

If the elevation angle is less than or equal to cutoff angle, then RIMS is invisible.

In an embodiment of the present invention, the visible IPP number of each IGP of aforementioned calculating, comprising:

By the position in the almanac of satellite calculate every satellite a certain moment in a short time, distribute in conjunction with RIMS dead reckoning IPP;

Travel through the IPP that each IGP is all;

Calculate the distance of each IPP to each IGP;

The distance of each IPP to each IGP is compared with cut-off distance, judges the availability of each IPP;

Wherein, ending distance is 600 kms;

Add up each IGP can all IPP numbers.

In an embodiment of the present invention, aforementioned by the distance of each IPP to each IGP with cut-off distance compare, judge the availability of each IPP, comprising:

If the distance of IPP to IGP is less than cut-off distance, then IPP can use;

If the distance of IPP to IGP is more than or equal to cut-off distance, then IPP is unavailable.

In an embodiment of the present invention, the aforementioned PL according to satellite-based augmentation system judges the availability of satellite-based augmentation system, comprising:

The PL of satellite-based augmentation system is compared with protected level threshold value;

If the PL of satellite-based augmentation system is less than or equal to protected level threshold value, then satellite-based augmentation system can be used;

If the PL of satellite-based augmentation system is greater than protected level threshold value, then satellite-based augmentation system is unavailable.

Satellite navigation satellite-based augmentation system availability predictions method provided by the invention, by calculating every visible RIMS number of satellite, and the visible IPP number of each IGP, the PL of satellite-based augmentation system can be calculated, and no longer need real time parsing navigation message, thus anticipation can be carried out to the availability of satellite navigation satellite-based augmentation system fast, and then improve Positioning Accuracy of Satellite Navigation System.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is the system construction drawing of EGNOS;

Satellite navigation satellite-based augmentation system availability predictions method flow diagram that Fig. 2 provides for one embodiment of the invention;

Fig. 3 is RIMS and the IGP distribution plan of EGNOS;

Satellite navigation satellite-based augmentation system availability predictions method flow diagram that Fig. 4 provides for another embodiment of the present invention;

Satellite navigation satellite-based augmentation system availability predictions method flow diagram that Fig. 5 provides for further embodiment of this invention;

Satellite navigation satellite-based augmentation system availability predictions method flow diagram that Fig. 6 provides for yet another embodiment of the invention;

Fig. 7 is the fit correlation figure of visible RIMS number and UDREI;

Fig. 8 is the fit correlation figure of visible IPP number and GIVEI;

Fig. 9 is the protected level calculation flow chart of satellite-based augmentation system.

Embodiment

For making the object of the embodiment of the present invention, technical scheme and advantage clearly, below in conjunction with the accompanying drawing in the embodiment of the present invention, technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.

Satellite-based augmentation system (Satellite-Based Augmentation System, be called for short SBAS) the main improvement realized for original Positioning Accuracy of Satellite Navigation System, at present, the whole world has established multiple SBAS system, as Wide Area Augmentation System (the Wide Area Augmentation System of the U.S., be called for short WAAS), Muscovite difference correction and monitoring system (System for Differential Corrections andMonitoring, be called for short SDCM), geostationary orbiter Navigation Overlay Service (the EuropeanGeostationary Navigation Overlay Service in Europe, be called for short EGNOS), the multisatellite of Japan strengthens system (Multi-functional Satellite Augmentation System, be called for short MSAS) and geostationary track enhanced navigation system (the GPS Aided Geo Augmented Navigation of India, be called for short GAGAN).The present invention mainly sets forth satellite navigation satellite-based augmentation system availability predictions method of the present invention for EGNOS, but satellite navigation satellite-based augmentation system availability predictions method of the present invention is applicable to various SBAS system, is not only only limitted to applicable EGNOS.

Fig. 1 is the system construction drawing of EGNOS.As shown in Figure 1, the system architecture of EGNOS comprises: space segment, ground segment and user segment.Space segment is primarily of GPS (Global PositioningSystem, be called for short GPS) satellite, GLONASS (Global Navigation Satellite System) (Global Navigation SatelliteSystem, be called for short GLONASS) satellite and geostationary orbit (synchronous orbit, be called for short GEO) satellite composition, for keeping and realizing and the distance correction on ground and integrity monitoring station (Ranging andIntegrity Monitoring Stations, be called for short RIMS) and central station (Master Control Center, be called for short MCC) between write to each other, and complete the command information being sent to user by MCC.Ground segment forms, for controlling and data processing EGNOS system comprehensively primarily of RIMS, MCC and navigation ground station (Navigation Land Earth Station is called for short NLES).User segment is made up of EGNOS reference receiver, user segment relates to the application such as aviation, navigation and traffic above-ground, the receiver that user uses needs the signal that simultaneously can receive EGNOS and GPS/GLONASS, and has the function information of EGNOS and GPS/GLONASS being positioned to aggregation of data process.

Satellite navigation satellite-based augmentation system availability predictions method flow diagram that Fig. 2 provides for one embodiment of the invention.As shown in Figure 2, satellite navigation satellite-based augmentation system availability predictions method that the present embodiment provides, comprising:

S101: calculate every visible RIMS number of satellite;

Wherein, based on RIMS position in satellite-based augmentation system, with from the satellite position that satellite almanac calculates, the visible RIMS number of statistical computation every satellite.

Concrete, RIMS refers to that all visible pseudorange values are measured in monitoring station, and completes the monitoring station of part integrity monitoring.It should be noted that, due to error and the delay of radio signal in ionosphere and troposphere of satellite clock, receiver clock, the actual distance measured and satellite have certain difference to the geometric distance of receiver, therefore, generally claim the distance measured to be pseudorange.

For example, at present, EGNOS has 39 RIMS.But wherein part RIMS is still in test phase, do not put into operation, part RIMS only monitors for UDRE or only for GIVE monitoring, the RIMS being actually used in UDRE monitoring has 31.Fig. 3 is RIMS and the IGP distribution plan of EGNOS, as shown in Figure 3, based on RIMS position in EGNOS system, can accurately know RIMS position.On the other hand, the position of satellite any instant in a short time can be calculated by the almanac of satellite.Thus, the geometry distribution of satellite and RIMS can be obtained according to RIMS position and satellite position, thus statistical computation can obtain every visible RIMS number of satellite.

S102: calculate the visible IPP number of each IGP;

Wherein, based on RIMS position and satellite position in satellite-based augmentation system, calculate IPP position, according to IGP and IPP position, the visible IPP number of each IGP of statistical computation.

It should be noted that, the intersection point that the line of satellite and RIMS and ionosphere sphere are formed is IPP, therefore, can calculate obtain IPP position according to RIMS position and satellite position.

For example, at present, 4 vertical graticule mesh bands (North and South direction) and 1 horizontal graticule mesh band (east-west direction) is employed in EGNOS.Wherein, vertical graticule mesh band comprises the 3rd band (55 IGP), the 4th band (85 IGP), the 5th band (78 IGP), the 6th band (21 IGP); Horizontal graticule mesh band is the 9th band (80 IGP).As shown in Figure 3, based on IGP position in EGNOS system, can accurately know IGP position.On the other hand, the position of satellite any instant in a short time can be calculated by the almanac of satellite.IPP position can be obtained according to RIMS and satellite position, according to IGP position and IPP position can obtain IGP and IPP geometry distribution, thus can statistical computation obtain each IGP can IPP number.

S103: the PL calculating satellite-based augmentation system according to visible RIMS number and visible IPP number;

Concrete, according to the visible RIMS number calculated and visible IPP number, the PL of satellite-based augmentation system directly can be calculated.

It should be noted that, the PL calculating satellite-based augmentation system according to visible RIMS number and visible IPP number in the present embodiment can be accomplished in several ways, as the PL just wherein a kind of implementation directly calculating satellite-based augmentation system according to the visible RIMS number that calculates and visible IPP number, also can by the PL of the visible RIMS number that calculates and visible IPP number indirect calculation satellite-based augmentation system, concrete PL implementation the present embodiment calculating satellite-based augmentation system according to visible RIMS number and visible IPP number does not limit at this.

S104: the availability judging satellite-based augmentation system according to the PL of satellite-based augmentation system.

Concrete, as long as calculate the PL of satellite-based augmentation system, PL is compared with the protected level threshold value (also claiming alarm to limit) of satellite-based augmentation system, the availability of satellite-based augmentation system can be judged.

It should be noted that, the protected level threshold value of satellite-based augmentation system is fixing, and what protected level threshold value was concrete can refer to RTCA/DO-229D regulation, and the present invention does not repeat them here.

In this step, optionally, according to the availability that the PL of satellite-based augmentation system judges satellite-based augmentation system, comprising:

The PL of satellite-based augmentation system is compared with protected level threshold value;

If the PL of satellite-based augmentation system is less than or equal to protected level threshold value, then satellite-based augmentation system can be used;

If the PL of satellite-based augmentation system is greater than protected level threshold value, then satellite-based augmentation system is unavailable.

Satellite navigation satellite-based augmentation system availability predictions method that the present embodiment provides, by calculating every visible RIMS number of satellite, and the visible IPP number of each IGP, the PL of satellite-based augmentation system can be calculated, and no longer need real time parsing navigation message, thus anticipation can be carried out to the availability of satellite navigation satellite-based augmentation system fast, and then improve Positioning Accuracy of Satellite Navigation System.

Satellite navigation satellite-based augmentation system availability predictions method flow diagram that Fig. 4 provides for another embodiment of the present invention.As shown in Figure 4, on the basis of above-mentioned S101, calculate every visible RIMS number of satellite, comprising:

S101a: by the position in the almanac of satellite calculate every satellite a certain moment in a short time;

S101b: travel through the RIMS that every satellite is all;

S101c: calculate the elevation angle of each RIMS to every satellite;

Concrete, to certain satellite inscribed time a certain, first utilize almanac to resolve its position, then travel through all RIMS, calculate the elevation angle of each RIMS to this satellite.

S101d: compared to the cutoff angle of every satellite with each RIMS at the elevation angle, judges the observability of each RIMS;

Wherein, described cutoff angle is 5 degree or 10 degree.

Concrete, the elevation angle is compared to the cutoff angle of every satellite with each RIMS, judges the observability of each RIMS, comprising:

If the elevation angle is greater than cutoff angle, then RIMS is visible;

If the elevation angle is less than or equal to cutoff angle, then RIMS is invisible.

S101e: add up every visible all RIMS number of satellite.

Satellite navigation satellite-based augmentation system availability predictions method that the present embodiment provides, on the basis of above-described embodiment, by judging the observability of each RIMS, the visible RIMS number of concrete calculating every satellite, ensure that the accuracy of the visible RIMS number of statistical computation every satellite, and then ensure that the accuracy of the PL calculating satellite-based augmentation system, thus anticipation can be carried out to the availability of satellite navigation satellite-based augmentation system fast, improve Positioning Accuracy of Satellite Navigation System.

Satellite navigation satellite-based augmentation system availability predictions method flow diagram that Fig. 5 provides for further embodiment of this invention.As shown in Figure 5, on the basis of above-mentioned S102, calculate the visible IPP number of each IGP, comprising:

S102a: by the position in the almanac of satellite calculate every satellite a certain moment in a short time, distribute in conjunction with RIMS dead reckoning IPP;

S102b: travel through the IPP that each IGP is all;

S102c: calculate the distance of each IPP to each IGP;

Concrete, first, utilize almanac to calculate satellite position, distribute in conjunction with RIMS dead reckoning IPP; Then, to certain IGP inscribed time a certain, travel through all IPP, calculate each IPP to this IGP according to distance.

S102d: the distance of each IPP to each IGP is compared with cut-off distance, judges the availability of each IPP;

Wherein, described cut-off distance is 600 kms (km).

Concrete, the distance of each IPP to each IGP is compared with cut-off distance, judges the availability of each IPP, comprising:

If the distance of IPP to IGP is less than cut-off distance, then IPP can use;

If the distance of IPP to IGP is more than or equal to cut-off distance, then IPP is unavailable.

S102e: add up each IGP can all IPP numbers.

Satellite navigation satellite-based augmentation system availability predictions method that the present embodiment provides, on the basis of above-described embodiment, by judging the availability of each IPP, the visible IPP number of each IGP of concrete calculating, ensure that the accuracy of the visible IPP number of each IGP of statistics, and then ensure that the accuracy of the PL calculating satellite-based augmentation system, thus anticipation can be carried out to the availability of satellite navigation satellite-based augmentation system fast, improve Positioning Accuracy of Satellite Navigation System.

Satellite navigation satellite-based augmentation system availability predictions method flow diagram that Fig. 6 provides for yet another embodiment of the invention.As shown in Figure 6, on the basis of above-mentioned S103, calculate the PL of satellite-based augmentation system according to visible RIMS number and visible IPP number, comprising:

S103a: obtain UDRE according to visible RIMS number;

Concrete, according to the fit correlation figure of visible RIMS number and UDREI, can UDREI be obtained by visible RIMS number, and then obtain UDRE according to the UDREI obtained.Fig. 7 is the fit correlation figure of visible RIMS number and UDREI, as shown in Figure 7, wherein, UDREI is user's difference distance error mark value (User Difference Range Error Indicator is called for short UDREI), represents and carries out stepping to UDRE value, UDREI value is from 0 to 15,0-13 represents the different stepping values of UDRE, and 14 representatives do not monitor this satellite, and 15 to represent UDRE data unavailable.

S103b: obtain GIVE according to visible IPP number;

Concrete, according to the fit correlation figure of visible IPP number and GIVEI, can GIVEI be obtained by visible IPP number, and then obtain GIVE according to the GIVEI obtained.Fig. 8 is the fit correlation figure of visible IPP number and GIVEI, as shown in Figure 8, wherein, GIVEI is that mark value (Grid Ionospheric Vertical Error Indicator is vertically missed in graticule mesh ionosphere, be called for short GIVEI), represent and GIVE value stepping is exported.GIVEI value represents the different stepping values of GIVE from 0 to 15,0-14, and 15 represent this grid points is not monitored to.

S103c: the PL calculating satellite-based augmentation system according to UDRE and GIVE obtained.

Wherein, according to UDRE and GIVE obtained, the calculating of the PL of satellite-based augmentation system provides the computing formula of PL according to RTCA/DO-229D:

$\mathrm{HP}{L}_{\mathrm{SBAS}}=\left\{\begin{array}{c}{K}_{H,\mathrm{NPA}}\·d_{\mathrm{major}}\\ K_{H,\mathrm{PA}}\·d_{\mathrm{major}}\end{array}\right\}---\left(1\right)$

VPL _SBAS＝K _v·d _U(2)

In above formula, $d_{\mathrm{major}}=\sqrt{\frac{d_{\mathrm{est}}^2+d_{\mathrm{north}}^2}{2}+\sqrt{\frac{{(d_{\mathrm{est}}^2-d_{\mathrm{north}}^2)}^2}{2}+d_{\mathrm{EN}}^2}},d_U^2=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{S}_U^2,{\mathrm{\σ}}_i^2,$ $d_{\mathrm{est}}^2=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{S}_{\mathrm{east},i}^2{\mathrm{\σ}}_i^2,d_{\mathrm{north}}^2=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{S}_{\mathrm{north}}^2,{\mathrm{\σ}}_i^2,d_{\mathrm{EN}}=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{S}_{\mathrm{east},i}{S}_{\mathrm{north},i}{\mathrm{\σ}}_i^2,S=\left[\begin{array}{cccc}{S}_{\mathrm{east},1}& S_{\mathrm{east},2}& ...& S_{\mathrm{east},N}\\ S_{\mathrm{north},1}& S_{\mathrm{north},2}& ...& S_{\mathrm{north},N}\\ S_{U,1}& S_{U,2}& ...& S_{U,N}\\ S_{t,1}& S_{t,2}& ...& S_{t,N}\end{array}\right],$ ${\mathrm{\σ}}_i^2={\mathrm{\σ}}_{i,\mathrm{flt}}^2+{\mathrm{\σ}}_{i,\mathrm{UIRE}}^2+{\mathrm{\σ}}_{i,\mathrm{air}}^2+{\mathrm{\σ}}_{i,\mathrm{tropo}}^2.$

Wherein, HPL _sBASfor satellite-based augmentation system horizon location error protected level, VPL _sBASfor satellite-based augmentation system perpendicular positioning error protection level, K _{h, NPA}for calculating the scale-up factor of HPL in non-precision approach (Non-Precision Approach is called for short NPA) situation, K _{h, PA}for calculating the scale-up factor of HPL in precision approach (PrecisionApproach is called for short PA) situation, K _vfor calculating the scale-up factor of VPL, d _majorfor the error uncertainty in the semi-major axis direction of error ellipse, d _u, d _east, d _northbe respectively the distributed model of envelope true error distribution in sky, east, north standard deviation upwards, d _eNfor distributed model in the Orient to north covariance upwards, S is the local derviation matrix of positioning error to pseudorange error, σ _ifor pseudorange standard deviation, σ _{i, flt}for pseudo range difference correction standard deviation, σ _{i, UIRE}for ionospheric error standard deviation, σ _{i, air}for airboarne receiver error to standard deviation, σ _{i, tropo}for tropospheric error standard deviation.

Optionally, calculate the PL of satellite-based augmentation system according to visible RIMS number and visible IPP number, also comprise:

Almanac according to satellite calculates satellite position;

According to the PL of UDRE, GIVE of obtaining and satellite position calculation satellite-based augmentation system.

Concrete, Fig. 9 is the protected level calculation flow chart of satellite-based augmentation system, and as shown in Figure 9, the protected level PL detailed process calculating satellite-based augmentation system can be:

First, calculate UDRE according to RIMS number, calculate GIVE according to IPP number, calculate satellite position according to satellite almanac;

Secondly, σ is calculated according to UDRE _{i, flt}, calculate σ according to GIVE _{i, UIRE}, according to satellite position calculation observing matrix G;

Then, according to σ _{i, flt}and σ _{i, UIRE}calculate σ _i, calculate local derviation matrix S according to observing matrix G;

Again, according to σ _id is calculated with S _est, d _north, d _eN, d _major, d _u;

Finally, according to d _est, d _north, d _eN, d _major, d _ucalculate VPL _sBASand VPL _sBAS.

It should be noted that, positioning error is calculated by observing matrix G (depending on the geometry of satellite) the local derviation matrix S of pseudorange error, uDREI and GIVEI broadcast by satellite calculates, concrete, the PL calculating satellite-based augmentation system according to UDRE with GIVE obtained with existing in provide the computing method of the computing formula of PL according to RTCA/DO-229D and computation process consistent, do not repeat them here.

Satellite navigation satellite-based augmentation system availability predictions method that the present embodiment provides, on the basis of above-described embodiment, by calculating every visible RIMS number of satellite, and the visible IPP number of each IGP, UDRE obtains according to every satellite visible RIMS number infers and forecast, and GIVE obtains according to each IGP visible IPP number infers and forecast, UDRE, GIVE no longer needs real time parsing navigation message to obtain, the PL of satellite-based augmentation system can be calculated, thus anticipation can be carried out to the availability of satellite navigation satellite-based augmentation system fast, and then improve Positioning Accuracy of Satellite Navigation System.

It should be noted that, in the above-described embodiments, UDRE is relevant to satellite visible RIMS number, and the visible IPP number of GIVEI and IGP is correlated with, by with under type computational analysis:

Carry out computational analysis to UDRE is relevant to satellite visible RIMS number, concrete computational analysis step is as follows:

(1) the multi-frequency observation pseudorange that monitoring station is measured sends to central station after pretreatment in monitoring station, completes the satellite clock solution to each monitoring station receiver at central station.Correct through monitoring station receiver clock-offsets, the observed range obtained is with R _mrepresent, at this moment R _min only comprise satellite clock correction.

(2) calculate distance by monitoring station known coordinate and through correction co-ordinates of satellite calculate, and with receive clock correction become soon and slowly become correction correct, calculating distance represent with R.Calculate the error comprised in distance R and have satellite ephemeris residual error and satellite clock correction.

(3) to R _mget difference with R, its difference dR is: dR=R _m-R (3)

Wherein, satellite ephemeris residual error and the star clock residual error of this satellite is only comprised in dR.

(4) all difference dRs of central station to the different monitoring stations of monitoring same satellite add up, and can obtain the UDRE value of respective satellite, namely $\mathrm{UDRE}=\stackrel{\‾}{\mathrm{dR}}+\mathrm{\κ}\left(\mathrm{Pr}\right){\mathrm{\σ}}_{\mathrm{dR}}---\left(4\right)$

Wherein, for mean value, σ _dRfor the standard deviation of correspondence, κ (Pr) is the fractile of corresponding degree of confidence 99.9%.

As can be seen from UDRE and the analysis of satellite visible RIMS number correlation computations, for same satellite, its UDRE value is relevant to its visible RIMS number, visible RIMS number is more, dR is more, can find from formula (4), the reaction of UDRE now to Satellite clock/ephemeris error is also more accurate.

Carry out computational analysis to the visible IPP number of GIVE and IGP is relevant, concrete computational analysis step is as follows:

(1) monitoring station observation data obtains the ionosphere sight line delay valuation of i-th breakthrough point IPP in t by pre-service, and this value is converted to ionosphere vertical delay valuation by inclination factor .Meanwhile, the ionosphere vertical delay of i-th IPP in t is gone out by last update cycle interpolation then the ionospheric vertical delay error of this IPP is calculated

$e_{\mathrm{IP}{P}_I}\left(t\right)=I_{{\mathrm{IPP}}_i}\left(t\right)-{\hat{I}}_{I{\mathrm{PP}}_i}\left(t\right)---\left(5\right)$

(2) suppose that the turnover rate that in satellite-based augmentation system, observation data is transmitted to central station in monitoring station is 10 seconds (s), and central station is 3 minutes (min) to the turnover rate of user's radio network lattice point vertical delay and GIVE, so, can obtain by 18 e for each IPP _{i PP}t () is the error sequence of the ionosphere vertical delay of a group, wherein e _{i PP}t () is the error sequence of the ionosphere vertical delay of a group.

(3) central station judges the error sequence number around a jth net point IGP in adjacent four unit.

If wherein have 3 grid cells at least, at least containing 1 vertical error sequence in each unit, the GIVE value of this IGP point just can be calculated; Otherwise the GIVE that marks this IGP is " unavailable " in next 3min.

(4) poor to each the IPP error sequence instrument error limit meeting above condition in 3min

$E_{\mathrm{IP}{P}_I}\left(t\right)=\left|\stackrel{\‾}{e_{\mathrm{IP}{P}_I}\left(y\right)}\right|+\mathrm{\κ}\left(\mathrm{Pr}\right)\·S_t---\left(6\right)$

In above formula, $\stackrel{\‾}{e_{\mathrm{IP}{P}_I}\left(t\right)}=\frac{1}{m}\underset{k=1}{\overset{m}{\mathrm{\Σ}}}{e}_{\mathrm{IP}{P}_k}\left(t_k\right),S_i=\sqrt{\frac{1}{m-1}\underset{k=1}{\overset{m}{\mathrm{\Σ}}}{(e_{\mathrm{IP}{P}_I}\left(t_k\right)-\stackrel{\‾}{e_{\mathrm{IP}{P}_I}\left(t\right)})}^2}.$

Wherein, for the average of vertical delay error, S _ifor the standard deviation of vertical delay error, m is error sequence number, and now m=18, κ (Pr) are the fractile of corresponding degree of confidence 99.9%.

(5) by central station computing grid point absolute upright error:

$\widehat{e_{\mathrm{IGP}\left(j\right)}}=\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\left(\frac{\sin \left({\mathrm{\θ}}_i\right)}{d_{\mathrm{ij}}}\right)\·\left|e_{\mathrm{IP}{P}_I}\left(t\right)\right|}{\underset{k=1}{\overset{n}{\mathrm{\Σ}}}\frac{\sin \left({\mathrm{\θ}}_k\right)}{d_{\mathrm{kj}}}}---\left(7\right)$

Wherein, θ _ithe elevation angle of survey station to satellite, d _ijit is the distance between i-th IPP to a jth IGP.N is the breakthrough point number of contiguous grid.

(6) GIVE at computing grid point IGP point place:

$\mathrm{GIV}{E}_j=\max \left(E_{\mathrm{IPP},j}\right)+{\hat{e}}_{\mathrm{iGP}\left(j\right)}+q/2---\left(8\right)$

Wherein, max (E _{iPP, j}) be the maximal value of all breakthrough point error limits, for the absolute error of net point ionosphere delay, q/2 is max quantization error.

As can be seen from the analysis of GIVE and IGP visible IPP number correlation computations, for a certain IGP determined, the GIVE value of its correspondence and available around it (consider that EGNOS graticule mesh size is 5 degree, " available " refers to and is less than 600km to IGP distance) IPP is relevant, IP available P number is more, and it is more accurate to the estimation of ionosphere delay error.

It should be noted that, in the above-described embodiments, the fit correlation figure between the visible IPP number of the fit correlation figure between UDREI and the visible RIMS number of satellite, GIVEI and IGP, by obtaining with under type analysis:

The present invention is in order to obtain the fit correlation figure between UDREI and the visible RIMS number of satellite, and the fit correlation figure between the visible IPP number of GIVEI and IGP, the enhancing data in January are reached by statistical treatment EGNOS system, establish the model being calculated UDREI by RIMS number, calculated the model of GIVEI by IPP number.

Set up the model being calculated UDREI by RIMS number, detailed process is as follows:

(1) every visible RIMS number of satellite is calculated

Concrete, concrete calculating every satellite visible RIMS number is the same with the Method and Process calculating every satellite visible RIMS number in above-described embodiment, above-described embodiment specifically illustrates the Method and Process calculating every visible RIMS number of satellite in detail, does not repeat them here.

It should be noted that, in order to avoid the accidental error that single test is brought, need enlarged sample capacity, and simulation time is taken as January, just can fully add up different satellite diverse geographic location, not in the same time under visible RIMS number.

(2) the UDREI value of every satellite is resolved

Concrete, resolve the navigation message that EGNOS system GEO satellite is broadcast, the enhancing information such as star clock/ephemeris corrections can be obtained, just containing the UDREI value that every gps satellite is real-time in its data.

(3) model being predicted UDREI by RIMS number is set up

With RIMS number for independent variable, UDREI is dependent variable, both matchings funtcional relationship.

Set up the model being calculated GIVEI by IPP number, detailed process is as follows:

(1) calculate each IGP can IPP number

Concrete, concrete each IGP can IPP number with calculate in above-described embodiment each IGP can the Method and Process of IPP number the same, above-described embodiment specifically illustrate in detail each IGP can the Method and Process of IPP number, do not repeat them here.

It should be noted that, in order to avoid the accidental error that single test is brought, need enlarged sample capacity, and simulation time is taken as January, just fully can add up IGP at diverse geographic location, do not descend IP available P number in the same time.

(2) the GIVEI value of each IGP is resolved

Concrete, resolve the navigation message that EGNOS system GEO satellite is broadcast, can the enhancing information such as ionosphere corrections be obtained, just containing the GIVEI value that each IGP is real-time in its data.

(3) model being predicted GIVEI by IPP number is set up

With visible IPP number for independent variable, GIVEI is dependent variable, both matchings funtcional relationship.

Last it is noted that above each embodiment is only in order to illustrate technical scheme of the present invention, be not intended to limit; Although with reference to foregoing embodiments to invention has been detailed description, those of ordinary skill in the art is to be understood that: it still can be modified to the technical scheme described in foregoing embodiments, or carries out equivalent replacement to wherein some or all of technical characteristic; And these amendments or replacement, do not make the essence of corresponding technical scheme depart from the scope of various embodiments of the present invention technical scheme.

Claims (8)

1. satellite navigation satellite-based augmentation system availability predictions method, is characterized in that, comprising:

Calculate every visible distance correction of satellite and integrity monitoring station RIMS number;

Calculate each ionization grid site IGP visible ionosphere pierce point IPP number;

The protected level PL of satellite-based augmentation system is calculated according to described visible RIMS number and described visible IPP number;

The availability of described satellite-based augmentation system is judged according to the protected level PL of described satellite-based augmentation system.

2. satellite navigation satellite-based augmentation system availability predictions method according to claim 1, is characterized in that, the described protected level PL calculating satellite-based augmentation system according to described visible RIMS number and described visible IPP number, comprising:

User's difference distance error UDRE is obtained according to described visible RIMS number;

Graticule mesh ionosphere vertical error GIVE is obtained according to described visible IPP number;

The protected level PL of satellite-based augmentation system is calculated according to the described UDRE obtained and described GIVE.

3. satellite navigation satellite-based augmentation system availability predictions method according to claim 2, is characterized in that, the described protected level PL calculating satellite-based augmentation system according to described visible RIMS number and described visible IPP number, also comprises:

Almanac according to satellite calculates satellite position;

According to the protected level PL of the described UDRE obtained, described GIVE and described satellite position calculation satellite-based augmentation system.

4. the satellite navigation satellite-based augmentation system availability predictions method according to any one of claims 1 to 3, is characterized in that, the visible distance correction of described calculating every satellite and integrity monitoring station RIMS number, comprising:

By the position in the almanac of satellite calculate every satellite a certain moment in a short time;

Travel through all distance corrections of every satellite and integrity monitoring station RIMS;

Calculate each distance correction and the integrity monitoring station RIMS elevation angle to every satellite;

The described elevation angle and each distance correction and integrity monitoring station RIMS are compared to the cutoff angle of every satellite, judges the observability of each distance correction and integrity monitoring station RIMS;

Wherein, described cutoff angle is 5 degree or 10 degree;

Add up every visible all distance correction of satellite and integrity monitoring station RIMS number.

5. satellite navigation satellite-based augmentation system availability predictions method according to claim 4, it is characterized in that, described the described elevation angle and each distance correction and integrity monitoring station RIMS to be compared to the cutoff angle of every satellite, judge the observability of each distance correction and integrity monitoring station RIMS, comprising:

If the described elevation angle is greater than described cutoff angle, then described distance correction and integrity monitoring station RIMS visible;

If the described elevation angle is less than or equal to described cutoff angle, then described distance correction and integrity monitoring station RIMS invisible.

6. the satellite navigation satellite-based augmentation system availability predictions method according to any one of claims 1 to 3, is characterized in that, described calculating each ionization grid site IGP visible ionosphere pierce point IPP number, comprising:

By the position in the almanac of satellite calculate every satellite a certain moment in a short time, distribute in conjunction with described distance correction and integrity monitoring station RIMS dead reckoning ionosphere pierce point IPP;

Travel through the ionosphere pierce point IPP that each ionization grid site IGP is all;

Calculate the distance of each ionosphere pierce point IPP to each ionization grid site IGP;

The distance of described each ionosphere pierce point IPP to each ionization grid site IGP is compared with cut-off distance, judges the availability of each ionosphere pierce point IPP;

Wherein, described cut-off distance is 600 kms;

Add up each ionization grid site IGP can all ionosphere pierce point IPP numbers.

7. satellite navigation satellite-based augmentation system availability predictions method according to claim 6, it is characterized in that, described by the distance of described each ionosphere pierce point IPP to each ionization grid site IGP with cut-off distance compare, judge the availability of each ionosphere pierce point IPP, comprising:

If described ionosphere pierce point IPP is less than described cut-off distance to the distance of ionization grid site IGP, then described ionosphere pierce point IPP can use;

If described ionosphere pierce point IPP is more than or equal to described cut-off distance to the distance of ionization grid site IGP, then described ionosphere pierce point IPP is unavailable.

8. the satellite navigation satellite-based augmentation system availability predictions method according to any one of claims 1 to 3, it is characterized in that, the described protected level PL according to described satellite-based augmentation system judges the availability of described satellite-based augmentation system, comprising:

The protected level PL of described satellite-based augmentation system is compared with protected level threshold value;

If the protected level PL of described satellite-based augmentation system is less than or equal to described protected level threshold value, then described satellite-based augmentation system can be used;

If the protected level PL of described satellite-based augmentation system is greater than described protected level threshold value, then described satellite-based augmentation system is unavailable.