On Fri, Sep 30, 2011 at 2:59 AM, mike cook <michael.c...@sfr.fr> wrote: >> Both GPS and VLBI require knowledge of UTC and UT1 for implementation. How >> does the GPS pick up the UT1 corrections? VLBI, at least when I was >> involved with it many years ago, depends on the IERS circular. >> > GPS doesn't transmit DUT1 as far as I can see. It just tells you how to get > from GPS time to UTC .
? The GPS navigation message includes a complete set of earth orientation parameters (as determined by USNO, who also publishes IERS Bulletin A). The receiver needs the earth orientation to be able to translate from XYZ (earth-centered inertial) coordinates (which is how the satellite ephemerides are specified) to earth-centered, earth-fixed coordinates and then to WGS84 latitude and longitude. DUT1 gets 31 bits, including the sign, and is in units of 2^(-24) second. They also give a rate of change so it can be approximated to first order by the receiver. -Keith _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
