On Aug 29, Tom Roberts wrote:
> But the GPS satellite clocks DO display the same
> time in the ECI frame (they also all tick at the same
> rate MEASURED IN THAT FRAME).
The GPS situation needs to be analyzed with an absolute time and
absolute simultaneity. After denying the absolute frame of reference,
Tom finds the ECI frame as the substitute. Relative simultaneity just
added more mysticism that at the end of the day where you still have
to use absolute simultaneity to resolve any issues. Of course, the
self-styled physicists with a combined intelligence of not much more
than an amoeba have really, really difficult time understanding that.
They really don’t know what they are doing. <shrug>
> one must always specify in which frame the clocks are
> in sync; I did so.
You don’t if simultaneity is absolute, and this is where physics is
much simpler than relative simultaneity. All experiments show
simultaneity is absolute. Only under absolute simultaneity, the
interferometers can give experimentally repeatable, coherent
interference patterns. <shrug>
> Not true. The relativistic corrections to the GPS are absolutely required for it
> to operate within its specifications; it simply would not work without them.
That is a myth. See Koobee Wublee’s recent post on this.
http://groups.google.com/group/sci.physics.relativity/msg/5847920d8e567050
> Given the physical situation of the earth, no such positioning system would work
> without relativistic corrections. The primary correction is to the tick rate of
> the satellite clocks
It is time that has to be synchronized among the satellites.
Theoretically, each satellite can have different clock with different
tick rate than the others. Synchronizing time is practically a
software solution. After all these years, Tom still cannot understand
this simple issue. Again, time is the accumulation of clock. <shrug>
> BTW modern receivers use more than 4 satellites, in order to
> improve the accuracy of their position fix. They perform a
> multi-parameter fit, rather than simply solving 4 equations
> for 4 unknowns.
This point is irrelevant in our discussions. You need to understand
the pertinent issues here before bringing up engineering
improvements. <shrug>
> In particular, the GPS is REQUIRED to keep a single system time, and to maintain
> that time within 1 microsecond of UTC module leap seconds.
It does not have to be synchronized with the UTC time.
Synchronization with the UTC time is done through software. That
piece of information is another piece of almanac data to be downloaded
into each receiver. It plays no role in the GPS calculations.
<shrug>
> Every GPS receivers has a local clock, but one that is vastly less accurate than
> GPS time.
It sounds like Tom is still confused with what time and clock are (per
Koobee Wublee’s definitions, see the link provided above). You must
understand the two definitions before any discussions can continue.
<shrug>
On a side note, each Einstein Dingleberries tends to fabricate his own
fantasy about why GPS clock synchronization is necessary. For
example, professor Andersen from Trondheim University in Norway
claimed the correction is done for the mixers. In another words,
without the relativistic corrections, it would be impossible to
demodulate the almanac information from GPS carrier frequencies.
Amazingly, he used to work in the industry as an RF engineer. Wow!
Ahahaha...