Acceptance of Real-Time Kinematic by the Professional Surveyor

Timo Allison, Peter Griffioen, and Nicholas Talbot

Abstract:	Over the past few years, Real-time Kinematic (RTK) surveying has become recognized as a major advance in the science of GPS positioning. Substantial increases in field productivity can be associated with the elimination of time consuming post-processing of satellite data - a requirement of traditional Kinematic and Static GPS surveying. In addition, the availability of Quality Assurance indicators in real-time guarantees results before vacating the site. The inability to post-process Kinematic data due to cycle-slips is no longer a concern. Blunders in field procedures can also be detected and costly re-surveys prevented. Although RTK systems, such as the Site SurveyorTM product, requiring static initialization (integer ambiguity resolution) have been commercially available for over a year, the maximum benefits of RTK are realized when this initialization process is fully automatic and transparent to the surveyor, either when static or moving. Many researchers have presented RTK results from controlled experiments. However, considerable innovation was required to transition from engineering prototype to a reliable and fully integrated commercial survey system. The following paper highlights the challenges that were overcome to produce the GPS Total Stationm product. This is the first RTK system offering automatic initialization to be accepted by the professional surveyor. The system is based on proven 4000SSE dual-frequency GPS receiver technology, and TrimTaIkTW inter-station communication links. Similar functionality to the Survey Total Station (optical theodolite integrated with electronic distance measurement) is provided with numerous advantages such as increased range, no inter- station visibility constraint, operability under all weather conditions, and rugged design without fragile optics. The performance of RTK systems can be judged by the initialization reliability and the time to initialize (which are closely tied). The latter is equivalent to the time taken to start providing centimeter-level survey accuracy after, for example, a complete loss of lock on all satellites. Test results are given when 5 or more satellites are visible, which rely on highly efficient integer search strategies. It is assumed throughout that the policies of both Selective Availability (SA), and Anti-Spoofing (encryption of the P&e signal, AS) will not be amended in the near term, and that operation of commercial RTK systems under these conditions must be considered as standard procedure.
Published in:	Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994) September 20 - 23, 1994 Salt Palace Convention Center Salt Lake City, UT
Pages:	329 - 337
Cite this article:	Allison, Timo, Griffioen, Peter, Talbot, Nicholas, "Acceptance of Real-Time Kinematic by the Professional Surveyor," Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994), Salt Lake City, UT, September 1994, pp. 329-337.
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