The method of selection errors in satellite navigation systems

 

(57) Abstract:

The invention relates to radio engineering and is intended to improve the accuracy of navigation systems location. This is due to the fact that the method of allocation errors in satellite radionavigation system based on the reception of navigation signals from satellites to ground-based measuring stations, one of which is a reference. In the measuring points to measure the pseudorange and pseudokarst. The results of these measurements for each measurement point is passed to the processing centre, which define vector-scalar error of the expressions: Rij=DDij+ Ctnipj + DDSP, and received a scalar error average on a given interval. The received vector is a scalar error does not depend on the location of the reference measurement points. 1 Il., table 1.

The invention relates to radio engineering, in particular to radar, and can be used in navigation systems determine the location of objects, using differential correction.

The level of technology.

Known methods for isolating errors in the satellite is antilego method of navigation definitions in satellite navigation GLONASS", Radionavigation and time, RIRV, 1992, "global positioning system (GPS) or Navstar", Navigation (USA), 1978, v. 25, N 2). These methods are based on the definition of differential errors in the a priori known point in space and the distribution of their actions on adjacent region, referred to as a work area reference station. Within the working area maximum accuracy is achieved in the center and decreases toward the periphery, thereby limiting the size of the stage.

To reduce errors in large regions need to be deployed in the same region of a continuous network of reference stations and approximate the amendments from adjacent stations for smoothing errors within the working area of the region (US patent N 5621646, 1997). Since the field gradient error at an arbitrary point between stations is unknown and changes with movement of the satellite, then the approximation can only be used a simple polynomial of the first order, which does not allow to obtain a sufficient accuracy of the allocation error for differential correction is not only extended, but also for the local working area separate base station.

The essence of the invention.

To improve the accuracy of burial is accuracy. This is due to the fact that the method of allocation errors in satellite radionavigation system is to receive navigation signals from satellites i, where i = 2, 3,..., n on land measuring points, one of which is a reference. In ground-based measuring stations whose numbers j = 0, 1, 2,..., N measure the pseudorange and pseudokarst. The results of these measurements from each terrestrial measurement point is passed to the processing center, in which first define the vector of errors, and then scalar error, which is determined using the results obtained by the reference measuring point, the error is determined from the expression: RISMij= DDij+ With tj+ DDSP< / BR>
< / BR>
where DDij= [(Xi-xj)2+ (Yi-yj)2+ (Zi-zj)2]0.5,

C is the speed of light,

tj- change of the time scale of the j-th land measuring point,

xj, yj, zj- a priori coordinates of the j-th land measuring point,

DDSPVDDi- scalar error, respectively, for the pseudorange and pseudokarst,

vector valid Noah speed of the i-th satellite, presented in the form of a transposed matrix is the row,

a priori (according to epimeric) coordinates and velocity of the i-th satellite, presented in the form of a transposed matrix is the row,

vector error for the coordinates and velocities of the i-th satellite, respectively, presented in the form of a transposed matrix is the row,

the wavelength of the satellite signal,

f0ifjthe reference oscillator frequency for the i-th satellite and the j-th land measuring point, respectively,

and the resulting scalar error average on a given interval.

The drawing shows an example implementation of the method in accordance with the invention, which shows:

1 - a system of radio navigation satellites;

20- ground reference measuring point;

21-2N- ground measurement points;

3 - the communication channel;

4 - processing center.

Information confirming the possibility of carrying out the invention.

The proposed method is illustrated by a specific example. Navigation signals emitted by the system 1 radionavigation satellites, accepted by all land measuring points 20-2N(NIP). In measuring the s from each measurement point, located in the area 1 radionavigation satellites transmit on the communication channel 3 to the processing centre 4. In the center of the handle 4 on the adopted results determine the first vector error of the expressions:

RISMij= DDij+ C tnip+ DDSP< / BR>
< / BR>
where DDij=[(Xi-xj)2+ (Yi+ yj)2+ (Zi-zj)2]0.5< / BR>
C is the speed of light,

tnip- change of the time scale of the j-th land measuring point,

xj, yj, zj- a priori coordinates of the j-th land measuring point,

DDSPVDDi- scalar error, respectively, for the pseudorange and pseudokarst,

the vector of the actual coordinates of the i-th satellite, presented in the form of a transposed matrix is the row,

the actual speed vector of the i-th satellite, presented in the form of a transposed matrix is the row,

a priori (according to epimeric) coordinates and velocity of the i-th satellite, presented in the form of a transposed matrix is the row,

vector error for the coordinates and velocities of the i-th satellite, respectively, presented in the form of a transposed matrix is the row,

bottom measuring point, respectively.

Equation (1) can be written in the form:

< / BR>
< / BR>
where F1and F2mean functional (1)

To define the pattern of errors is solved backward navigation task: for selecting a reference point space point of location of land measuring points (NIP) 20- 2Nspecified in the system of equations (1) vectors:

< / BR>
< / BR>
define the vector of the actual current position of each visible satellite. Vector errors are obtained as the difference between the actual and the a priori (ephemeris) vectors of the satellite.

Limited network NIP 20- 2Nconsists of several independent, dual-frequency, geodesic bound receivers placed at the greatest possible distance that conduct Autonomous measurements of pseudorange and pseudokarst with respect to its own standard of time and frequency (AVC). NIP 20in the network is selected as the reference and measuring relatively EVC system of radio navigation satellites. No synchronization and reconciliation of scales between the paragraphs not required.

First, the results of the measurements based system of nonlinear equations relative to following the tion of the velocity vector satellites:

< / BR>
- scalar errors for distances and speeds:

DDSPVDDi< / BR>
offsets of time scales tNIPjand frequency fijreference oscillator (not shown) of each NIP 2:

tNIPjfij= (f0i- fj),

where j = 0,1,2,...,N, i=2,3,...,n

The total number of unknowns in the system is determined by the number (N) NIP 2 in the network and the number (n) of the processed satellites (SP.). The minimum number of satellites nmin= 2. The number of equations in the system must satisfy the inequality:

nN 4n+N,

whence it follows that the ratio between the number of NPCs in the network and the number of observed satellites, as shown in the table below. Also there are and the dimension of the matrix system of equations.

The system of nonlinear equations for the coordinates can be written in the following form:

< / BR>
A similar system is written for speed:

< / BR>
As can be seen, the system (2) and (3) - equation of the second order in General. Numerical solution of such equations can be found by using widely used in satellite navigation systems (SNS) of the least squares method (OLS). To obtain a rapid convergence of solutions of system (2) and (3) must be given to vijnanam: taking the first difference for each satellite between measurements NIP 2jwhere j = 1,2,3...N, and NIP 20and then the second difference by satellites, will provide the desired type of system. For example, when n = 2 satellites and N = 8 NIP 2, the system of differential equations for the coordinates will be written in the form:

< / BR>
System (4) of 8 equations with 6 unknowns has a standard for navigation tasks GPSr view and is solved in a known manner (OLS) relative to the actual coordinates of the satellites

< / BR>
Similarly, by taking the first and second differences as well transform (3) into a system of differential equations, which after substitution has already been found above the actual coordinates decide on the actual speeds of the satellites:

< / BR>
Found the full vector of the actual position of the satellite (i.e., the vector of its coordinates and speed) allows us now to compute the desired vector of error to their ephemeris values:

< / BR>
< / BR>
Then move on to a second stage of processing - definition of scalar errors.

To obtain a scalar errors of the method of measurement of radio navigation options regarding AVC satellite IR when taken with vector errors. For their calculation is based on measurements obtained on the abutment NIP 20. Ur the statutory timeline for NIP 20,

ErrtInaErrfIna- synchronization error in time and frequency NIP 20.

Substituting in (5) current measurements, found above the actual coordinates and velocities of the satellite and a priori known offset time scales and frequency of the reference oscillator to NIP 20calculate the current value of a scalar errors. The final values of scalar errors obtained after averaging them:

< / BR>
< / BR>
where m is the sample size dimensions.

The averaging interval is selected based on the ratio of the noise error of the used receiver and the permissible error of measurement of scalar errors.

Because synchronization error standard of time and frequency NIP 20includes all scalar error to the end user on the accuracy of its positioning, they will not be affected.

So, in the proposed method, for each satellite instead of one differential error is determined by the extended array of the following scalar-vector of errors:

< / BR>
not related to the location of the reference station and the amount of offset error NCR anywhere in the zone p is proposed scalar-vector of errors may be different. It can be:

1. transmission errors in the control center basic NCR for the correction of operational information satellites

2. the conversion in the usual differential error with the center of the working area, chosen at the discretion of users. As such a center can be selected as the coordinates of the center of the desired area precision navigation facilities and the location of the individual consumer. Since the correlation interval of the differential error is measured in tens of kilometers, the error of the a priori coordinates of the center can reach several kilometers. This avoids the need of additional metaproterenol at the selected point center;

3. the input scalar-vector of errors directly to the equipment user for direct correction of the measurement results (if this mode is supported by the mathematical software hardware).

To do this:

a) for the correction of operational information from each component of the array of errors:

< / BR>
added to the current value of the corresponding parameter transmitted by the satellite operational information vectors of the current coordinates and velocity of the satellite, as well as with the its reference oscillator. After that, the consumer will get ephemeris already removed errors and no additional correction for him to pursue is not required;

b) in terms of scalar - vector of errors in the differential with elected local centre of the working area at the point of use of the formula:

Diffcoordi= |KSP|cos(1)+DDSP< / BR>
Diffspeedyi= |VSP|cos(2)+VDDi,

where 1 and 2 are the angles between the corresponding vectors of errors and the line of sight of the satellite of points for which the calculated ordinary differential error.

C) with the direct input scalar - vector of errors in the equipment of the consumer first adjusted a priori (ephemeridae) parameters of the satellite

< / BR>
< / BR>
and then the usual procedure solved the navigation problem (1).

For specialists in this field and other fields when reading the present description will be clear other possible modifications of the present invention. Such modifications may include other known prior art signs. The above-described embodiment of the system does not exhaust all their variety, which can be done in selnau part, because she's like this more clearly reflects the essence of the invention.

The method for determining the errors of satellite navigation systems, namely, that receive navigation signals from satellites i, where i= 2,3,...,n, on land measuring points, numbers that j=0,1,2,..., N, is measured on land measuring points corresponding pseudorange Rijand pseudokarst VRijthe results of the measurements from each terrestrial measurement point is passed over the communication channel in the processing center, wherein the at least one terrestrial measurement points is the reference, as adopted in the Central processing measurement results for the pseudorange Rijand pseudokarst VRijdefine scalar and vector error of the expressions

Rij=DDij+Ctj+DDSP,

< / BR>
where DDij=[(Xi-xj)2+(Yi-yj)2+ (Zi-zj)2]0.5;

C is the speed of light,

tj- shift time scale j-ro land measuring point;

xj, yj, Zj- a priori coordinates j-ro land measuring point;

the valid vector is Inoi speed i-ro satellite, presented in the form of a transposed matrix - row;

a priori, according to epimeric, coordinates and velocity of the i-th satellite, presented in the form of a transposed matrix - row;

vector error for the coordinates and velocities of the i-ro satellite, respectively, presented in the form of a transposed matrix - row;

the wavelength of the satellite signal;

f0ifnjthe reference oscillator frequency for the i-th satellite and the j-th land measuring point, respectively,

DDSPVDDi- scalar error, respectively, for the pseudorange Rijand pseudokarst VRijdetermined using measurements taken at ground reference measuring points, with the final values of scalar errors obtained after averaging them at a specified time interval.

 

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