Observed GPS and WAAS Signal-to-Noise Degradation Due to Solar Radio Bursts

A. Cerruti

Abstract:	The first direct observations of Global Positioning System (GPS) L1 (1.57542 GHz) signal-to-noise ratio degradation due to a solar radio burst are presented for an event that occurred on 7 September 2005. Signal-to-noise ratio data from three identical, collocated receivers at Arecibo Observatory and also from several Federal Aviation Administration (FAA) ide-Area Augmentation System (WAAS), were available at the time of the solar radio burst. These receivers were all in the sun-lit hemisphere and all were affected similarly. The maximum solar radio burst power associated with the 7 September 2005 flare had a peak intensity of about 8,700 solar flux units (1 SFU = 10-22 W/m2-Hz) RHCP at 1,600 MHz, which caused a corresponding decrease in the signal-to-noise ratio of about 2.3 dB across all visible satellites. Only the right-hand, circularly polarized (RHCP) emissions affected the GPS signals. To confirm the effect, the solar radio burst associated with the 28 October 2003 flare was also investigated. Although polarization data were not available for this event, the maximum degradation at GPS L1 was about 3.0 dB, and a degradation of 10 dB was observed on the semi-codeless L2 signal for a solar radio burst of 13,600 SFU. Since solar radio bursts affect all satellites in view of a receiver, all receivers in the sun-lit hemisphere, the new Galileo navigation system, and all space-based augmentation systems such as WAAS and EGNOS, they are a potential threat to life-critical systems.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	1369 - 1376
Cite this article:	Cerruti, A., "Observed GPS and WAAS Signal-to-Noise Degradation Due to Solar Radio Bursts," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 1369-1376.
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