SX BLUE GPS iSXblue II+ GNSSTM, Руководство пользователя

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SXblue Series User Manual 94
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GPS satellite timing errors
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GPS satellite orbit errors
Figures B-1 and B-2 show the ground segments of the WAAS and EGNOS
systems, respectively. In 2007, a total of 13 monitoring stations have been added
to the existing WAAS network, increasing the ionospheric coverage for this SBAS
constellation. The location is shown in red in Figure B-1: 4 in Alaska, 4 in Canada
and 5 in Mexico.
Figure B-1 WAAS Ground Segment (end of 2007)
Provided that a GPS satellite is available to the SBAS reference station network
for tracking purposes, orbit and timing error corrections will be available for that
satellite. Ionospheric corrections for that satellite are only available if the signal
passes through the ionospheric map provided by SBAS (ex. the WAAS ionospheric
map covers the entire Central and North American region). As an example, if a
satellite is South of your current location at a low elevation angle, the pierce point
of the ionosphere will be considerably South of your location since the ionosphere
is at an altitude of approximately 60 km. There must be sufficient ionospheric map
coverage beyond your location in order to have ionospheric correctors for all
satellites.