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Sunnyvale, CA | since the sunspots affect the GPS signal that passes through the ionosphere, the beacon and Omnistar signals will be affected, however to a lesser degree because of the method of DGPS correction generation for these services. The WAAS ionosphere correction has a time constant of 6 hours (according to the WAAS technical documents) which makes WAAS unable to respond to a short term change in the ionoshpere, like at sunrise. Beacon corrections are in real-time, and Beacon correcitons can track the fast ionosphere changes. It is not all good for Beacon correcitons, however. Because of increased ionosphere activity results in patches of differences in ionosphere electron density, Beacon DGPS corrections deterioriate in accuracy more rapidly with distance when the sunspot counts are high compared to beacon DGPS corrections during times of a quiet sun. This phenomena is sometimes called geographic decorrelation.
Omnistar XP/HP corrections are affected to a lesser degree than WAAS because this higher performing system use dual frequency user receivers receivers which are able to perform their own ionosphere corrections. | |
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Ez-guidie 500
