Method and system for minimizing storage and processing of ionospheric grid point correction information
AssigneeGarmin Ltd.
InventorsClayton Barber, Cliff Pemble
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Abstract
A method and system are provided for minimizing storage and processing of ionospheric grid point corrections transmitted from WAAS satellites in a global positioning system. Based upon a current location, the system creates a boundary around the current location and collects ionospheric grid point corrections within the boundary. The collected correction points are used to correct the position initially determined by a global positioning system.
Claims31
A method in a global positioning system for minimizing storage and processing of ionospheric grid point correction data, the method comprising:
- determining a current position;
- creating a boundary based upon the current position;
- and
- obtaining grid point correction data corresponding to correction points within the boundary.
A method in a global positioning system for minimizing storage and processing of ionospheric grid point correction data, the method comprising:
- determining a current position;
- determining one or more bands and one or more blocks based upon the current position;
- and
- obtaining a set of correction points, wherein the set is derived from the grid point correction data corresponding to correction points within the one or more blocks and the one or more bands surrounding the current position.
A computer-readable medium having data stored thereon a data structure for storing ionospheric grid boundaries comprising:
- a first data field containing data representing a northernmost latitude;
- a second data field containing data representing a southernmost latitude;
- a third data field containing data representing a number of latitudes in the boundary, wherein the number of boundary latitudes is derived from the northernmost latitude and southernmost latitude;
- a table containing an entry for each of the boundary latitudes, wherein each entry contains a grid point latitude, an easternmost longitude, a westernmost longitude, a grid point correction array pointer and a number of grid point correction array entries;
- and
- a fourth data field containing data representing a total number of grid point correction entries for all latitudes within the boundary.
A computer-readable medium having data stored thereon an ionospheric grid point bands data structure, comprising:
- multiple boundary indicator data fields for each grid point band containing data representing an indication that a grid point correction message within each of the grid point bands should be processed based upon a computed grid boundary.
A computer-readable medium having data stored thereon a data structure for storing ionospheric grid point blocks comprising:
- a grid point block table containing an entry for each of a plurality of possible ionospheric grid point bands, wherein each band has a plurality of possible grid point blocks and, wherein each block within each band contains an indication to process a grid point correction message based upon a computed grid point boundary.
A computer-readable medium having data stored thereon a data structure for storing ionospheric grid point corrections received from a grid point correction message, comprising:
- a first data field containing data representing a grid point longitude;
- a second data field containing data representing a vertical delay estimate;
- a third data field containing data representing an ionospheric vertical error indicator;
- and
- a fourth data field containing data representing a reception time of the correction message,
- wherein the data fields establish a correction message for a grid point.
A method in a global positioning system for minimizing storage and processing of ionospheric grid point correction data, the method comprising:
- determining a current position;
- creating a boundary based upon the current position;
- obtaining grid point correction data corresponding to correction points within the boundary;
- and
- implementing the foregoing steps in a portable, hand-held navigation device.
Dependencies are inferred from the claim text.