Error analysis for the Global Positioning System: Difference between revisions

Revision as of 17:09, 29 December 2012

Revision as of 17:10, 29 December 2012

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Since GPS signals at terrestrial receivers tend to be relatively weak, natural radio signals or scattering of the GPS signals can [[Desensitization (telecommunications)|desensitize]] the receiver, making acquiring and tracking the satellite signals difficult or impossible.

[[Space weather]] degrades GPS operation in two ways, direct interference by solar radio burst noise in the same frequency band<ref>Cerruti, A., P. M. Kintner, D. E. Gary, A. J. Mannucci, R. F. Meyer, P. H. Doherty, and A. J. Coster (2008), Effect of intense December 2006 solar radio bursts on GPS receivers, Space Weather, {{doi|10.1029/2007SW000375}}, October 19, 2008</ref> or by scattering of the GPS radio signal in ionospheric irregularities referred to as scintillation.<ref>{{cite journal | author=Aarons, Jules and Basu, Santimay | title=Ionospheric amplitude and phase fluctuations at the GPS frequencies | work=Proceedings of ION GPS | volume=2 | year=1994 | pages=1569–1578}}</ref> Both forms of degradation follow the 11 year [[solar cycle]] and are a maximum at sunspot maximum although they can occur at anytime. Solar radio bursts are associated with [[solar flares]] and [[coronal mass ejectionsejection]]s (CMEs)<ref>S. Mancuso and J. C. Raymond, "Coronal transients and metric type II radio bursts. I. Effects of geometry, 2004, Astronomy and Astrophysics, v.413, p.363-371'</ref> and their impact can affect reception over the half of the Earth facing the sun. Scintillation occurs most frequently at tropical latitudes where it is a night time phenomenon. It occurs less frequently at high latitudes or mid-latitudes where magnetic storms can lead to scintillation.<ref>{{cite journal | author=Ledvina, B. M., J. J. Makela, and P. M. Kintner | year=2002 | title=First observations of intense GPS L1 amplitude scintillations at midlatitude | journal=Geophysical Research Letters | work=Geophys. Res. Lett. | volume=29 | page=1659 | doi=10.1029/2002GL014770 | issue=14 | bibcode=2002GeoRL..29n...4L}}</ref> In addition to producing scintillation, magnetic storms can produce strong ionospheric gradients that degrade the accuracy of SBAS systems.<ref>Tom Diehl, [http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/library/satNav/media/SATNAV_0604.PDF Solar Flares Hit the Earth- WAAS Bends but Does Not Break], SatNav News, volume 23, June 2004</ref>

== Artificial sources of interference ==