Scintillation Effects in the News

Potential Effects on GPS and GLONASS

GPS Spacecraft (SV3)

Two articles in the 1 December 1997 issue of Aviation Week discuss potential GPS problems with ionospheric scintillation in the context of the predicted increase in solar activity over the next four years.

Of concern to all users will be an increase in solar activity over the next four years, which will stress the GPS system and applications developed during a particularly benign time. Of specific concern for aircraft will be any disruption of the signal during precision approaches. But the impending period of "solar max" also raises the question of whether the system will be more susceptible to unintentional interference during that period, and the larger issue of its vulnerability to intentional jamming. All interference issues heighten concerns about the risk to aviation of relying on a single navigation aid.

"GPS Success Sparks New Concerns for Users," B. Nordwall, pp. 58-60

In March, 1989, one of the largest solar storms in 25 years created an unstable ionosphere with scintillations that made GPS signals untrackable for periods of time. Even surveyors using dual-frequency receivers, which should have been less susceptible, were affected in southern California.

"Solar Storms Threaten GPS Reception," B. Nordwall, pp. 61-62

Two articles in the 14 October 1996 issue of Aviation Week discuss potential GPS problems with ionospheric scintillation.

With the increased research into augmented systems has come an appreciation for factors that may be significant for D-GPS, but are not important for unagumented GPS. Irregularities in the ionosphere cause rapid variations or scintillations in the amplitude and phase of GPS signals. Though generally of negligible effect at mid-latitudes, scintillation effects can be a significant problems at low latitudes, particularly right after sunset, according to Mark Knight and Anthony Finn. Knight is a engineer and Finn a senior research scientist with the Microwave Radar Div. of the Defense Science and Technology Organization of Salisbury, South Australia.

"Optimism grows for GPS/Glonass," B. Nordwall, pp. 58-59

Based on the following paper presented at the recent Institute of Navigation GPS-96 symposium:

M. Knight and A. Finn, "The impact of ionospheric scintillations on GPS performance," presented at ION GPS-96, to be published in Proceedings of ION GPS-96, Institute of Navigation, 1996.

... it seems likely that the ionosphere will have some important impacts on GPS as solar maximum; both link outages due to scintillation, and navigation errors due to large-scale structures.

"Atmospheric/multipath concerns for D-GPS," B. Nordwall, pp. 60-61

Based on the following paper presented at the recent Institute of Navigation GPS-96 symposium:

G. Bishop, Sa. Basu, K. Groves, M. Smitham, K. Lehnis, D. Jacobs, P. Gehred, D. Howell, G. Bainum, and D. Goldizen, "Upcoming ionospheric impacts on GPS at solar max - what do we know / what do we need?," presented at ION GPS-96, to be published in Proceedings of ION GPS-96, Institute of Navigation, 1996.

See the solar-maximum predictions page for climatological scintillation conditions in the post-sunset equatorial region expected at the upcoming maximum in solar activity.

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