Aviation Use of RNSS in the 1215-1300 MHz Band

Kristine P. Maine and Thomas A. Stansell Jr.

Abstract:	The Federal Aviation Administration (FAA) has defined a new GPS signal called L5, which will be included on Block IIF and subsequent satellites. A key reason for L5 is to permit dual-frequency navigation, which is required to eliminate ionospheric refraction error, with both frequencies being in an aeronautical radionavigation service (ARNS) band, as are L1 today and L5 in the future. The first IIF is scheduled for launch in 2005, but a complete constellation of satellites with L5 is not expected before 2015. In the meantime, another new civil signal, called L2C, has been developed and will be included on all Block IIR﷓M and subsequent satellites. Although L2C is not specifically in an ARNS band, it is in a band which is internationally protected for satellite navigation. The L2C signal is more robust than the present L1 C/A signal, the first launch will be in 2003, and it will be fully available at least four years before L5. Many present-day, high-precision civil applications require dual-frequency measurements. Therefore, civil equipment has been developed with “semi-codeless” access to L2. This technique is more expensive and far more vulnerable to interference than future equipment will be when L2C becomes available. Even so, there are about 50,000 users worldwide, including centimeter level aircraft navigation for photogrammetry. Users with modern versions of these receivers are reporting no L2 interference problems. Therefore, we expect L2C to be as interference free as L1 C/A is today for aviation use. (A full description of L2C is posted on the U.S. Coast Guard web site: www.navcen.uscg.gov.) This paper suggests that aviation users should not have to wait an additional four or five years for the important advantages of signal redundancy and dual-frequency accuracy. (Many believe WAAS will not be able to provide Cat-I performance until dual-frequency user equipment becomes available.) This paper recommends that L2C be designed into aviation equipment as soon as possible. Although not necessary, it also would be desirable for the L2 frequency to be designated an ARNS band. Technical, operational, and spectrum regulatory issues must be addressed. This paper identifies these issues and presents potential solutions which would allow aviation to experience the benefits of a second signal much sooner than waiting exclusively for L5.
Published in:	Proceedings of the 58th Annual Meeting of The Institute of Navigation and CIGTF 21st Guidance Test Symposium (2002) June 24 - 26, 2002 Hyatt Regency Hotel Albuquerque, NM
Pages:	569 - 580
Cite this article:	Maine, Kristine P., Stansell, Thomas A., Jr., "Aviation Use of RNSS in the 1215-1300 MHz Band," Proceedings of the 58th Annual Meeting of The Institute of Navigation and CIGTF 21st Guidance Test Symposium (2002), Albuquerque, NM, June 2002, pp. 569-580.
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