Centre county Pennsylvania, USA | Great clarifications, particularly the explanation of WAAS DGPS receiver behavior during periods where ionosphere delays exceed 45 meters. That explains (in clear text) why WAAS is (more) problematic during periods of very high ionosphere activity.
More questions on ionosphere corrections for DGPS. How can ionosphere delay corrections broadcast by any DGPS correction service provider be as accurate (to the user) as ionosphere corrections that are derived from ionosphere delay measurements made by the user's high quality dual frequency receiver ?
I believe (not certain) that ionosphere delay corrections broadcast by any DGPS correction service are guesses (interpolated from dual frequency measurements of ionosphere delay at each correction service ground station). Ionosphere delay corrections from the user's high quality dual frequency receiver are ionosphere delay measurements for the actual path between each GPS satellite and the user's receiving antenna, not guesses. If that's true, then ionosphere delay corrections broadcast by DGPS service providers should have additional (guess) error at the user's location, Can that additional error be significant if ionosphere delay de-correlation distances are less than distances between (most) DGPS correction service ground reference stations ?
Thanks much, clear explanation of complex stuff is greatly appreciated.
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correction on an earlier post about WAAS
