[FOSS-GPS] High accuracy positioning with low cost GPS devices:a FOSS project

Michael Tandy m.j.tandy at warwick.ac.uk
Thu Apr 30 13:30:45 EDT 2009

> 1) LEA-4T data quality: code observations seem to have a noise that is
> correlated in time and this correlation is currently not modeled in the
> Kalman filter; phase observations show a similar correlation and, in
> addition, they present "jumps" probably due to the clock drift corrections
> implemented in the receiver. At the moment these "jumps" are treated as
> cycle slips, but a "smarter" solution is surely possible.

Something I've been wondering about is: the UBX-RXM-RAW message has a
known jitter of a few milliseconds [1] and the time-tag is only
precise to 1 millisecond, while some sources [2] suggest that time-tag
errors between receivers need to be in the microsecond range. Was the
imprecise time tag a problem for you, and if so how did you overcome


[1] http://www.u-blox.com/customersupport/faq_antaris/Rinex.html
[2] http://www.gmat.unsw.edu.au/snap/gps/gps_survey/chap6/638.htm

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