XPost: sci.math   
   From: relativity@paulba.no   
      
   Den 25.11.2025 01:06, skrev Thomas 'PointedEars' Lahn:   
   > Paul B. Andersen wrote:   
   >> Den 24.11.2025 00:36, skrev Thomas 'PointedEars' Lahn:   
   >>> Paul B. Andersen wrote:   
   >>>> Den 22.11.2025 20:19, skrev Thomas 'PointedEars' Lahn:   
   >>>>> Scot Deyanov wrote:   
   >>>>>> Thomas 'PointedEars' Lahn wrote:   
   >>>>>>> A manipulated clock is not a clock.   
   >>>>>>>   
   >>>>>>> When we say that time is what is measured with a clock we mean a device   
   >>>>>>> that is not manipulated, that merely follows Nature.   
   >>>>>> no shit sherlock, once that manipulation is done, that clock is a clock   
   >>>>>> like everybody clock   
   >>>>> Which part of "_not_ manipulated" did you not understand?   
   >>>>   
   >>>> It is however common to call the manipulated clock   
   >>>> in a GPS satellite - a clock.   
   >>>   
   >>> The satellite's clock is not manipulated; never has been.   
   >>   
   >> The statement in Maciej Woźniak's idiotic post you responded   
   >> to was: "it's a matter of how we decide to adjust clocks"   
   >>   
   >> The adjustment he referred to was that the rate of   
   >> a GPS SV clock is adjusted down by (1 - 4.4647e-10) compared   
   >> to a clock which is running at the rate defined by SI.   
   >   
   > Doubtful.  I doubt that he has even understood the basics of how GPS works,   
   > given his constant clueless babbling of "t' = t".   
      
   No, certain.   
   It is this clock adjustment Maciej Woźniak has talked about in   
   umpteen posts.   
   Since this adjustment make the rate the SV-clock be equal to UTC,   
   this proves in his distorted mind that t' = t (whatever that may mean).   
      
   >   
   >> Your response was: "A manipulated clock is not a clock."   
   >>   
   >> I interpreted that to mean that you called the adjustment   
   >> of the SV clock rate a "manipulation".   
   >>   
   >> But OK, I accept that you don't call this adjustment a "manipulation":   
   >>   
   >> But what kind of manipulation of a clock makes it cease to be a clock?   
   >   
   > When it ceases to measure a (proper) time.  For example, even the modified   
   > GPS clocks still measure a (proper) time, just not the proper time where   
   > they are because that turns out to be impractical (due to GR effects); they   
   > measure something close to the proper time on the ground instead.   
   >   
   > IOW: A clock is no longer a clock if someone or something manipulates it   
   > *while it is in operation* (or when it ceases to operate properly).  (I   
   > repeat: This does NOT happen with the atomic clocks aboard GNSS satellites.)   
   >   
      
   Not quite true.   
      
   GPS clocks from Block IIR and later can be 'manipulated' while   
   they are in operation.   
   It has a Time Keeping System which was described in a paper which is   
   no more available, but here is a quote from it:   
      
   "The purpose of the GPS Block II-R TKS shown in Figure 1   
     is to tune the 10.23 MHz digitally controlled VCXO to produce   
     the GPS navigation signal with the timing accuracy of RAFS.   
     By linking the VCXO to the RAFS using a control loop controlled   
     by software, it is possible to precisely adjust the frequency   
     and phase of the TKS output, to cancel drift of the RAFS once   
     it has been characterized, and to detect any anomalous RAFS   
     frequency or phase excursions."   
      
   TKS  = Time Keeping System   
   RAFS = Rubidium Atomic Frequency Standard   
      
   Here is another paper which also mention the TKS.   
   At least you can find the Figure 1. in the quote above.   
      
     https://www.researchgate.net/publication/288747030_On-board_si   
   nal_integrity_for_GPS   
      
   I don't think this possibility is much used, though.   
   The point with the fine tuning is to make the SVs less dependent   
   on frequent upload of correctional data.   
      
   --   
   Paul   
      
   https://paulba.no/   
      
   --- SoupGate-Win32 v1.05   
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