| There are a variety of large-scale applications that desire centimetre to decimetre level positioning and navigation accuracy. Some of these applications include surveying, agriculture fertilisation and yield monitoring, aircraft precision landings, intelligent transportation systems, and harbour/river navigation and docking. The Global Positioning System is one of the few, and perhaps the only, service that can meet the requirements of these projects.; Centimetre to decimetre level positioning accuracy requires the use of carrier-phase GPS measurements. The system must be operated in a double differential mode in which a nearby reference station is used to calibrate for errors in the satellite differential measurements. For large-scale applications, a network of multiple differential reference stations is necessary.; While Carrier-Phase Network Differential GPS (CP-NDGPS) is theoretically possible, its implementation is complex and has not been fully developed. This dissertation describes one method of implementing CP-NDGPS using Partial Derivative Algorithms. Partial derivative algorithms are implemented by the network service provider, and are used to estimate signal errors that cannot be measured by a single GPS reference station.; The information sent to the user by the network service provider is communicated through a data link. The amount of information communicated defines the data link bandwidth. A PDA is an efficient method of filtering the information and reducing the data link bandwidth, which is often limited to transfer speeds of 9600 bits per second (bps). |
