John Deere's StarFire System: WADGPS for Precision Agriculture

Tenny Sharpe, Ron Hatch and Fred Nelson

Abstract:	NavCom Technology Inc., a wholly owned subsidiary of John Deere & Co., together with the Precision Farming Group of John Deere, have designed and implemented a Wide Area Differential GPS (WADGPS) system which provides a new level of accuracy across continental distances. The system is designed for dual frequency operation and is based on several key technical developments: low-cost, high-quality, dual frequency GPS receivers were developed for use as both reference receivers and mobile receivers; special dual frequency extended smoothing techniques were developed which allow the use of refraction corrected measurements for both the reference and mobile receivers which are free of the two largest error sources in a WADGPS system ionosphere and multipath; a new L-band satellite communication receiver was developed which uses a single, multi-function antenna designed to receive both of the GPS frequencies (L1 and L2) and the Inmarsat L-band communication frequencies (1525-1565MHz); WADGPS correction algorithms were developed which exploit the dual-frequency architecture of the system to generate a single set of corrections uniformly accurate across the continental U.S. resulting in lower bandwidth requirements and more centralized processing; redundant subsystems and monitoring equipment are utilized to provide a high degree of system reliability, availability and service integrity. The paper describes the system architecture including ground infrastructure, processing techniques and user equipment. Navigation results are presented which show a new level of accuracy for WADGPS. Future directions for improvement of the system are indicated. Finally, several agricultural applications of the system are discussed as well as potential applications in other areas.
Published in:	Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000) September 19 - 22, 2000 Salt Palace Convention Center Salt Lake City, UT
Pages:	2269 - 2277
Cite this article:	Sharpe, Tenny, Hatch, Ron, Nelson, Fred, "John Deere's StarFire System: WADGPS for Precision Agriculture," Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000), Salt Lake City, UT, September 2000, pp. 2269-2277.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In