CALCULATION METHOD FOR NETWORK-SPECIFIC FACTORS IN A NETWORK OF REFERENCE STATIONS FOR A SATELLITE-BASED POSITIONING SYSTEM

• US 20100001903A1
• Filed: 05/30/2007
• Published: 01/07/2010
• Est. Priority Date: 06/13/2006
• Status: Active Grant

• Current Assignee: Leica Geosystems AG (Hexagon AB)
• Original Assignee: Leica Geosystems AG (Hexagon AB)
• Inventors: Takac, Frank, Zebhauser, Benedikt, Alves, Paul, Euler, Hans-Jurgen, Seatovic, Dejan
• Granted Patent: US 7,948,433 B2
• Time in Patent Office: Days
• US Class Current: 342/357.09
• CPC Class Codes: G01C 15/00 Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
• CPC Class Codes: G01S 19/073 involving a network of fixed stations

Abstract

A correction calculation method for a satellite based positioning system with a network of receiving units as reference stations comprises a partitioning of the network into groups of reference stations, calculation of group-specific correction factors, amalgamation of the group-specific correction factors and subsequently, derivation of network-specific correction parameters. In this partitioning, the reference stations are represented by nodes in a connected, edge-weighted graph, in the generation of which an edge respectively connecting two nodes is only generated if it satisfies a distance-dependent connectivity condition, whereby the distance between the nodes connected by this edge is input into the weighting function of this edge. From the graph a minimum spanning tree is derived and subsequently partitioned for establishing the groups, by eliminating the edge with the highest weight for each tree, the elimination of which leads to partial trees which in each case either satisfy a cardinality condition for the number of the nodes in the two resulting partial trees, or consist of a number of nodes greater than the cardinality condition.

Claims

1-10. -10. (canceled)

11. A correction calculation method for a satellite-based positioning system including a network of receiving units as reference stations, the method comprising:

partitioning the network into groups of reference stations;

calculating group-specific correction variables;

combining the group-specific correction variables; and

deriving network-specific correction parameters, wherein during partitioning;

the reference stations are represented by nodes in a cohesive, edge-weighted graph, in the generation of which the removal of the nodes connected by this edge being input into the weighting function;

a minimum spanning tree is derived from the graph; and

the minimum spanning tree is partitioned for establishing the groups by eliminating from a tree in each case the edge which has the highest weight and the elimination of which leads to partial trees which in each case either;

satisfy a cardinality condition for the number of nodes having a lower limit n_min and an upper limit n_max in both the resulting partial trees;

or

have a number of nodes which is greater than the cardinality condition.

12. A correction calculation method according to claim 11, wherein the minimum spanning tree is derived from the graph according to the Prim or Kruskal algorithm.

13. A correction calculation method according to claim 11, wherein an edge connecting two nodes is generated only if the distance between the nodes does not exceed a specified distance threshold.

14. A correction calculation method according to claim 13, wherein all edges which do not exceed the distance threshold are generated in the graph.

15. A correction calculation method according to either of claim 13, wherein the distance threshold is determined automatically as a function of an availability of observation data and/or of network data products to be generated.

16. A correction calculation method according to claim 11, wherein an edge connecting two nodes is generated only if the eclidean distance between the nodes does not exceed a specified distance threshold.

17. A correction calculation method according to claim 11, wherein parameters of the reference stations, parameters derived from observation data of the reference stations, topography-specific parameters, and/or atmospheric parameters are input into the weighting function.

18. A correction calculation method according to claim 11, wherein, as a cardinality condition, the number of permissible nodes is in the range of 4 to 8.

19. A correction calculation method according to claim 11, wherein the cardinality condition is chosen so that:

$\frac{n_{\max }}{2}\ge <br><br>n_{\min }.$

20. A correction calculation method according to claim 11, wherein, during partition, at least one reference station is assigned to at least two groups.

21. A correction calculation method according to claim 11, wherein at least some of the receiving units of the network are mobile receiving units.

22. A computer program product as a record on a data medium having code sequences for carrying out the correction calculation method according to claim 11.