An Overview of the LAAS VHF Data Broadcast

Trent A. Skidmore Orville K. Nyhus Aaron A. Wilson

Abstract:	This paper provides a comprehensive overview of the VHF data broadcast (VDB) being developed for the Local Area Augmentation System (LAAS) in the United States by the FAA and RTCA, and the corresponding Ground Based Augmentation System (GBAS) being developed by the International Civil Aviation Organization (ICAO). The VDB is a critical system element used to transfer GPS (and GNSS) differential corrections, integrity, and final approach segment information from the LAAS ground facility to aircraft conducting approaches to the LAAS-serviced airport. The safe introduction of the VDB function into the aeronautical radio navigation band (108.000 - 117.975 MHz) currently utilized worldwide for the VOR system and the ILS localizer is an important factor in the timely transition to LAAS. Topics covered include a system perspective of the core elements of the VDB, including the link budget, modulation issues, transmitter and receiver properties, and spectrum planning considerations. The use of time division multiple access (TDMA) as a means of achieving efficient use of the spectrum is also discussed. Antenna and polarization characteristics of both the ground-based transmitter and airborne receiving antenna are considered. Sample results are included to illustrate properties of this important element of the emerging precision approach standard.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	671 - 680
Cite this article:	Wilson, Trent A. Skidmore Orville K. Nyhus Aaron A., "An Overview of the LAAS VHF Data Broadcast," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 671-680.
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