From: relativity@paulba.no   
      
   Den 25.11.2025 00:55, skrev Thomas 'PointedEars' Lahn:   
   > J. J. Lodder wrote:   
   >> Thomas 'PointedEars' Lahn  wrote:   
   >>>   
   >>> The satellite's clock is not manipulated; never has been.   
   >>   
   >> FYI, Satellite GPS clocks are steered to remain in sync   
   >> with the master GPS clock at USNO.   
   >   
   > No, they are NOT "steered"; they never were.  The beat frequency is not even   
   > adjusted by a frequency synthesizer anymore (as it was with the NAVSTAR   
   > NTS-1 test satellite in 1977), but the *beat* frequency (how many cycles are   
   > counted as 1 second) is adjusted *once* (it is reduced according to GR)   
   > *before* the clock is placed in orbit.  In addition, a correction value to   
   > account for orbital variations is in included in the signal payload, as well   
   > as ephemerides updates.   
      
   Yes.   
      
   But what Lodder probably meant was that the GPS system time at   
   message transmission is 'steered',   
      
   As you probably know:   
   The SV-clock may be several μs off sync, but the SV will send   
   the correction polynomial so the time can be corrected in the receiver.   
   The correction polynomial is uploaded to the SV typically once a day,   
   so the corrected time is 'steered' to be in sync with GPS-time.   
      
   See:   
   https://paulba.no/GPS/GPS clock correction.pdf   
      
   or the Interface Control Document:   
   https://www.gps.gov/sites/default/files/2025-07/IS-GPS-200N.pdf   
      
      
      
   --   
   Paul   
      
   https://paulba.no/   
      
   --- SoupGate-Win32 v1.05   
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