T
Tom Potter
Sam Wormley said:I don't know why you didn't read the ICD-GPS-200D in the first place,
Dennis Sue... and you would have noticed the sections on relativity.
Quotes from http://www.navcen.uscg.gov/gps/geninfo/IS-GPS-200D.pdf
that use the GENERIC term " "relativistic".
1. The nominal frequency of this source -- as it appears to an observer on the ground -- is 10.23 MHz.
The SV 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 ? f/f = -4.4647E-10, equivalent to a change in the
P-code chipping rate of 10.23 MHz offset by a ? f = -4.5674E-3 Hz. This is equal to 10.22999999543 MHz.
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2, The algorithms defined below (a) allow all users to correct the
code phase time received from the SV with respect to both SV code phase offset and relativistic effects, (b) permit
the "single frequency" (L1 or L2) user to compensate for the effects of SV group delay differential (the user who
utilizes both frequencies does not require this correction, since the clock parameters account for the induced
effects),
for the SV implementation characteristics of group delay bias and mean differential group delay. Since these
coefficients do not include corrections for relativistic effects, the user's equipment must determine the requisite
relativistic correction. Accordingly, the offset given below includes a term to perform this function.
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3. for the SV implementation characteristics of group delay bias and mean differential group delay. Since these
coefficients do not include corrections for relativistic effects, the user's equipment must determine the requisite
relativistic correction. Accordingly, the offset given below includes a term to perform this function.
The user shall correct the time received from the SV with the equation (in seconds)
GPS system time = message transmission time - phase time offset
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4. the relativistic correction term (seconds) which is given by
relativistic correction term = F e orbital parameter(A) sin orbital parameter(Ek.
while F is a constant whose value is
F = 2*µ^.5 / c^2 = - 4.442807633x10^-10
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5. The control segment will utilize the following alternative but equivalent expression for the relativistic effect when
estimating the NAV parameters:
equivalent expression for the relativistic effect = 2 * (instantaneous position vector of the SV) * (instantaneous velocity vector of the SV) / C^2
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1. Why call the affect of acceleration on the frequency of an oscillator
a "relativistic effect" when this was discovered over 300 years ago
by Galileo, and England sent ships all over the Earth with
standard pendulum "oscillators" over 200 years ago,
and Newton use the data to compute the shape of the Earth,
and tides all over the world?
2. Uses the term "relativistic effect" to point out where it isn't needed.
3. Calls "phase time offset" a "relativistic effect".
4. Calls a constant involving Maxwell's permeability of space,
and Maxwell's speed of Electromagnetic waves a "relativistic effect".
5. Calls geometric vectors "relativistic effects".
Note that if the use of the term "relativistic effects"
is proof that General relativity is essential to the GPS System,
then all one has to do is reference my posts,
as I, like techwriters, General Relativity Gurus and Cultists,
newspapers, movies, etc. often use the generic phrase ""relativistic effect".
As I demonstrated in another post today,
as long as a few satellites maintain stable orbits,
and a GPS receiver provided with the orbital data
of the computers can identify the satellites,
it is a simple matter to compute the location of the receiver
limited mainly by random noise and artifact.
It is a sad fact
that General Relativity has cost the world
enormous amounts of time, money and minds.
A mind is a terrible thing to waste.
--
Tom Potter
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