Method and system for post-processing differential global positioning system satellite positional data
First Claim
1. For use with a differential global positioning system (GPS) that includes:
- a plurality of GPS satellites that transmit to earth navigational signals including at least satellite orbital position data, GPS time data, and satellite identification data;
at least one earth-based reference station that receives said navigational signals and computes at least pseudo-range correction data; and
an earth-based user receiver, at a user location, able to receive said navigational signals and compute a user position;
a method for recovering accurate post-processed information as to said user position even if said pseudo-range correction data are not received in real-time, the method comprising the following steps;
(a) computing and storing stand-alone position of said user receiver at at least one time, using said navigational signals;
(b) storing time at which said navigational signals were used to compute said stand-alone position;
(c) storing identity of each of said GPS satellites whose navigational signals were used to compute said stand-alone position;
(d) using pre-stored almanac data for each of said GPS satellites whose navigational signals were used in step (a) and using information stored at step (a), step (b) and step (c) to compute a direction cosine from said user receiver to each of said GPS satellites whose navigational signals were used to compute said stand-alone position (hereinafter, said used GPS satellites);
wherein at least one said reference station computed and transmitted pseudo-range correction data for each of said used GPS satellites; and
(e) using direction cosine data computed at step (d) to map each of said pseudo-range correction data corresponding to each of said used GPS satellites and for each time at which said stand-alone position was computed to obtain corrections to said user position.
2 Assignments
0 Petitions
Accused Products
Abstract
In a DGPS, accurate post-processed corrections to user receiver locations are made while minimizing the amount of data required to be stored at reference station and user receiver positions. Further, such corrections are available even if reference station corrections cannot be received by the user in real-time. The user receiver acquires in-view GPS satellites, computes, and stores user stand-alone position, time of computation, and acquired satellite identification. Reference stations generate correction data for the same satellites at the same time period, which correction data are broadcast but need not be received by the user in real-time. Almanac information for the relevant satellites is also made available to at least the user receiver. Stand-alone user receiver positional data and the almanac data for the same acquired satellites are used by a CPU, located at a remote site able to receive reference station transmissions and/or in the user receiver, to compute corrections to user receiver positions.
-
Citations
20 Claims
-
1. For use with a differential global positioning system (GPS) that includes:
-
a plurality of GPS satellites that transmit to earth navigational signals including at least satellite orbital position data, GPS time data, and satellite identification data; at least one earth-based reference station that receives said navigational signals and computes at least pseudo-range correction data; and an earth-based user receiver, at a user location, able to receive said navigational signals and compute a user position; a method for recovering accurate post-processed information as to said user position even if said pseudo-range correction data are not received in real-time, the method comprising the following steps; (a) computing and storing stand-alone position of said user receiver at at least one time, using said navigational signals; (b) storing time at which said navigational signals were used to compute said stand-alone position; (c) storing identity of each of said GPS satellites whose navigational signals were used to compute said stand-alone position; (d) using pre-stored almanac data for each of said GPS satellites whose navigational signals were used in step (a) and using information stored at step (a), step (b) and step (c) to compute a direction cosine from said user receiver to each of said GPS satellites whose navigational signals were used to compute said stand-alone position (hereinafter, said used GPS satellites); wherein at least one said reference station computed and transmitted pseudo-range correction data for each of said used GPS satellites; and (e) using direction cosine data computed at step (d) to map each of said pseudo-range correction data corresponding to each of said used GPS satellites and for each time at which said stand-alone position was computed to obtain corrections to said user position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. For use with a differential global positioning system (GPS) that includes at least:
-
a plurality of GPS satellites that transmit navigational signals to earth including at least satellite orbital position data, GPS time data, and satellite identification data; at least one earth-based reference station that includes a central processor unit coupled to a memory, and receives said navigational signals and computes and transmits at least pseudo-range correction data; a system that recovers accurate post-processed information as to a user position even if said pseudo-range correction data are not available in real-time, the system including; an earth-based user receiver that includes at least a central processor unit (CPU) coupled to a memory, said user receiver disposed at a user location and able to receive said navigational signals and, whether in real-time or subsequently, able to receive said pseudo-range correction data; a software routine, loadable into said memory for execution by said CPU to carry out the following steps; (a) storing in said memory a correction data file that is formed by (i) computing stand-alone position of said user receiver using said navigational signals, (ii) storing time at which said navigational signals were used to compute said stand-alone position, and (iii) storing identity of each of said GPS satellites whose navigational signals were used to compute said stand-alone position (said used GPS satellites); wherein at least one said reference station tracks each of said used GPS satellites; (b) loading into said memory pre-stored almanac data for each of said used GPS satellites; (c) using the stored said correction data file and the loaded said almanac data to compute a direction cosine from said user receiver to each said used GPS satellite; and (d) using direction cosine data computed at step (c) to map each of said pseudo-range correction data corresponding to each of said used GPS satellites and for each time at which said stand-alone position was computed to obtain corrections to said user position. - View Dependent Claims (19, 20)
-
Specification