Calculation method for network-specific factors in a network of reference stations for a satellite-based positioning system

• US 7,948,433 B2
• Filed: 05/30/2007
• Issued: 05/24/2011
• Est. Priority Date: 06/13/2006
• Status: Active Grant

• Current Assignee: Leica Geosystems AG (Hexagon AB)
• Original Assignee: Leica Geosystems AG (Hexagon AB)
• Inventors: Zebhauser, Benedikt, Alves, Paul, Euler, Hans-Jurgen, Takac, Frank, Seatovic, Dejan
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): LIU, HARRY K
• Application Number:
  US12/304,264
• Publication Number:
  US 20100001903A1
• Time in Patent Office: 1,455 Days
• Field of Search: 342/357.24, 342/357.52
• US Class Current: 342/357.52
• 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.

Claims

1. A correction calculation method performed by a computer processor 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.

2. A correction calculation method according to claim 1, wherein the minimum spanning tree is derived from the graph according to the Prim or Kruskal algorithm.

3. A correction calculation method according to claim 1, wherein an edge connecting two nodes is generated only if the distance between the nodes does not exceed a specified distance threshold.

4. A correction calculation method according to claim 3, wherein all edges which do not exceed the distance threshold are generated in the graph.

5. A correction calculation method according to either of claims 3, 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.

6. A correction calculation method according to claim 1, wherein an edge connecting two nodes is generated only if the eclidean distance between the nodes does not exceed a specified distance threshold.

7. A correction calculation method according to claim 1, 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.

8. A correction calculation method according to claim 1, wherein, as a cardinality condition, the number of permissible nodes is in the range of 4 to 8.

9. A correction calculation method according to claim 1, wherein the cardinality condition is chosen so that:

10. A correction calculation method according to claim 1, wherein, during partition, at least one reference station is assigned to at least two groups.

11. A correction calculation method according to claim 1, wherein at least some of the receiving units of the network are mobile receiving units.

12. A computer program product as a record on a data medium having code sequences for carrying out the correction calculation method according to claim 1.