HR: 17:05h
AN: SA44A-05    [Abstracts]
TI: Performance of the GLOBALink/HF Network during the Halloween Storm Period of 2003
AU: * Goodman, J M
EM: jm(underscore)good@cox.net
AF: Radio Propagation Services, 8310 Lilac Lane, Alexandria, VA 22308 United States
AU: Patterson, J D
EM: jpatters@arinc.com
AF: ARINC, 2551 Riva Road, Annapolis, MD 21401 United States
AB: The GLOBALink/HF system, developed and managed by ARINC, is a global high frequency data link communications network providing service to commercial aviation worldwide. It consists of 14 ground stations located around the globe, and a network control center located in Annapolis. The system was designed to provide reliable aircraft communications through the use of multi-station accessibility, quasi-dynamic frequency management, and a robust time-diversity modem with equalization. Although HF (i.e., 3-30 MHz) signaling has a poor reputation when considering individual circuits, it has been shown that near-real time channel evaluation and/or adaptive frequency management can improve performance considerably. Moreover, multi-station network operation provides an additional form of diversity, which is probably the most valuable design strategy. Our paper briefly describes the system, but the major discussion will be about performance metrics derived during super storms. The Halloween storm period of October-November 2003 was a period of significant ionospheric effects. Large geomagnetic storms were evidenced. We have examined the impact on HFDL of the various phenomena observed during this period. We have found some impact on HFDL performance for the October 29-31 period, but it is minimal in amplitude. While HFDL is based upon HF propagation, a medium known for its vulnerability to ionospheric variability, the system performance metric does not reflect this vulnerability to a significant degree. This is thought to be the result of the substantial amount of diversity built into the system, especially the adaptive frequency management system, Dynacastr, a system developed by RPSI. The adaptive frequency management system involves the use of active frequency tables (or AFTs) that are based upon space weather observables. During the stormy weeks of October and November, ARINC issued over seven changes to the AFTs used by every HFDL station. These changes helped the HFDL network to maintain a delivered message success rate of 97%. The paper outlines how this was accomplished.
DE: 2435 Ionospheric disturbances
DE: 2447 Modeling and forecasting
DE: 2788 Storms and substorms
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting