SCAT-l VHF Data Link: Developments and Testing

Trent Skidmore

Abstract:	The development of the VHF air-to-ground data link for the Special Category I (SCAT-l) DGNSS Instrument Approach System (as defined in the RTCA DO-217) has been a key area of debate over the past year. The primary focus of attention has been on two issues: transmission band and modulation format. The FAA’s decision to assign the DGNSS broadcast information to a protected aeronautical radionavigation band resulted in the selection of the upper Very High Frequency Omnirange (VOR) band (112 MHz - 117.950 MHz) as the means of delivering the information to the approaching aircraft. The ability of the VHF modulation format specified in Appendix F of DO- 217 to meet both early implementation and potential future growth needs was brought into question and a data link subgroup of RTCA Special Committee- 159, Working Group 4 was formed. This group was essentially tasked with evaluating the ovrerall suitability of the 2400 baud ACARS-like signal specified in Appendix F to meet the needs of the users. The subgroup determined that the aviation community might best be served by adapting a data link based on the emerging physical layer of the ICAO SARPS for the VHF Data link. The procedure for establishing the interference criteria for integrating the SCAT-I VHF transmissions into the upper VOR band are described. Preliminary test results of this integration are shown.
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:	1279 - 1284
Cite this article:	Skidmore, Trent, "SCAT-l VHF Data Link: Developments and Testing," 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. 1279-1284.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In