On Sun, 02 Mar 2008 22:25:26 +0100, "Paul B. Andersen"
wrote:
Dr. Henri Wilson skrev:
On Fri, 29 Feb 2008 10:49:44 +0100, "Paul B. Andersen"
wrote:
It is not a 'correction' as such.
It is merely a determination of the clock's drift wrt the GCs...so at any GC
time the OC's reading is predictable.
So no corrections as such is made of the rate of clocks after launch.
Why should they be..... their actual rate is of no importance.
Any oscillator anywhere, whether it run an 1000000000000 or
23984985984986948694899hz can be easily software synched with a UTC clock.
OK, I accept the retraction of your claim:
"Of course the bloody rate is changed after launch."
Your figures are merely departures from the expected readings.
Departures from the _correct_ readings, yes.
The approximate freefall correction is pre-set in order to reduce the above
drift and minimise the error, as I explained before.
Come again?
To "reduce the above drift"? :-)
So are you saying that what you call "The approximate freefall correction",
namely THIS correction:
1. All the clocks are built equal. They are all manufactured according
to the specification which says that they shall run slow by
delta_f/f = -4.4647E-10 relative to the SI-definition of a second.
The "Interface Control Document":
http://www.navcen.uscg.gov/pubs/gps/...d200cw1234.pdf
From section 3.3.1.1:
"The SV [space vehicle] carrier frequency and clock rates --
as they would appear to an observer located in the SV --
are offset to compensate for relativistic effects. The clock
rates are offset by delta_f/f = -4.4647E-10, equivalent to
a change in the P-code chipping rate of 10.23 MHz offset by
a delta_f = -4.5674E-3 Hz. This is equal to 10.22999999543 MHz."
Is to reduce the drift of the clocks shown below?
2. Actual measurements of the clocks in orbit show that their
30 days average rate errors (compared to GPS-time) we
PRN Rate error
x10-12
1 -2.51
2 -3.05
3 -5.31
4 -17.15
5 -14.99
8 1.53
9 -1.81
10 11.40
11 0.02
12 0.79
13 -2.17
14 -3.29
15 2.49
16 -0.15
17 0.67
18 -3.00
19 -1.47
20 0.76
21 0.76
22 -0.53
23 -2.85
24 -3.02
25 -5.04
26 -10.15
27 -2.61
28 0.54
29 -6.11
30 -1.49
31 1.42
You _are_ confused, are you not? :-)
Or rather - you are saying stupidities because you don't know what else to say.
But you have finally accepted that no correction
of the rate of the clocks are made after launch.
Whether or not the synching of the secondary clock is carried out on board is
irrelevant.
Preferably it would be..... but the clock reading can easily be software
corrected at the receiver, using its own signal that includes the accumulated
drift.
So we can sum it up:
1. Prior to launch, the clocks are adjusted by -4.4647E-10 as predicted by GR.
that is done simply to appease the relativists. Nobody is game enough to argue
..........for the same reason that muslims don't criticise mahommed.
(You are free to call this adjustment with a precision equivalent to
14 significant digits "the approximate free fall adjustment" if you like.
A silly name, of course, but the name doesn't change the reality.)
2. No individual correction of the rate of the SV-clocks is made after launch.
3. Actual measurements of the rate of clocks in orbit show that the errors
in the rate is as can be expected by the precision of the clocks,
which is less than 1% of the GR-correction.
The inevitable conclusion is:
The GR-prediction of the rate of clocks in GPS-orbit is proven to
be correct within the precision of the clocks.
Never proven..... and nobody gives a stuff anyway...
the principle requirement is that all orbiting clocks are in synch with each
other.
Henri Wilson. ASTC,BSc,DSc(T)
www.users.bigpond.com/hewn/index.htm
Einstein's Relativity is easy to understand if one has the IQ of a parrot and a gullibility index 0.95.