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Ranging and Pioneer



 
 
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  #1  
Old August 14th 06, 12:39 PM posted to sci.astro.research
Oh No
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Posts: 433
Default Ranging and Pioneer

Thus spake "
Oh No wrote:
Thus spake "
Oh No wrote:
The signal from Pioneer uses an effective Doppler frequency of 1MHz,
equivalent to a distance scale of 300m.

... the MDA is
capable of measuring phase to 1/256 of a
cycle or about 0.5mm in range. ...


This might be true if everything were perfect, but it is not. To
interpolate higher frequencies than the 1MHz effective Doppler frequency
one has to assume no such thing as cycle slip, for example. In fact even
GPS systems are plagued with cycle slip.


Surely the quantum effects are only
affected by the equipment, not assumptions,
but no matter, this was just FYI. Cycle slips
were sufficiently infrequent that many were
corrected by hand by the analysts going
over the data. I believe Anderson et al may
have excluded any measurement with a cycle
slip from subsequent processing but I'm not
sure on that without rechecking the paper.


I don't think Anderson actually says how frequent cycle slips were, just
that some were examined by an analyst. They did exclude the data.
Anderson says:

"If a blunder point is observed, the count is stopped and
a Doppler point is generated by summing the preceding
points. Otherwise the count is continued until a specified
maximum duration is reached. Cases where this
procedure detected the need for cycle corrections were
flagged in the database and often individually examined
by an analyst. Sometimes the data was corrected, but
nominally the blunder point was just eliminated. This
ensures that the data is consistent over a pass. However,
it does not guarantee that the pass is good, because other
errors can affect the whole pass and remain".


I am not sure that that
is what they are saying because I had been given to believe that the
measurements of Mars are the most accurate within the Solar system.


Perhaps in percentage terms, ranging using
the corner refectors on the Moon achieves cm
accuracy.


Sorry, I overlook the obvious.


... The conventional
linear Hubble law if applied to Pioneer 10
predicts an apparent acceleration some
15000 times smaller than the anomaly given
by the equation a_H = 2 H v. I don't understand
why you think your analysis produces a result
four orders of magnitude larger than the normal
Hubble Law under either of the regimes you
explain above.

Sorry if I'm being a bit slow but it is this factor
of 15000 increase that I cannot fathom.


I am not quite sure where the 15000 increase is, or what the equation
a_H = 2 Hv refers to.


Take the Hubble constant H as 71km/s per MPc.
A parsec is 3.09e16 m and an AU is 1.5e11 m
so changing units H = 3.44e-7 m/s per AU.

In Jan 1987 the craft was at 40 AU so the signal
had to travel 80 AU giving a redshift due to the
Hubble constant equivalent to a speed of
2.75e-5 m/s. Similarly in Dec 1994 at the end
of the period analysed for Pioneer 10, the range
was 60 AU and the round trip 120 AU which
gives an apparent speed from the Hubble Law of
4.13e-5 m/s.

That's a change of 1.38e-5 m/s in a time of 2921
days or 2.51e8 s giving an apparent acceleration
of 5.50e-14 m/s^2. Compare that with the anomaly
of 8.74e-10 m/s^2.

The equation that summarises that is a = 2 H v
where H is the Hubble constant, v is the radial
speed of the craft, a is the resulting apparent
acceleration and the factor of 2 is due to the
double trip.

I have it that quantum coordinates introduce an
acceleration in time which can be shown by a coordinate transformation
equivalent to an acceleration Hc.


If it is an effect in time, that could be quite different
to the ranging analysis and might explain why the
numbers differ so much. Of the phenomenological
time models considered by Anderson et al, do any
of their equations (60) through (65) match? See
page 46 of gr-qc/0104064 for details.

Equation 60 is the probably the best match, though I am not sure how
different it is from 61 or 62. I used cosmic time, but in the quantum
domain an "accelerating" time coordinate is used, proportional to the
expansion parameter. This will affect Doppler, but not ranging which is
based on cosmic time.




Regards

--
Charles Francis
substitute charles for NotI to email
  #2  
Old August 14th 06, 03:47 PM posted to sci.astro.research
[email protected]
external usenet poster
 
Posts: 96
Default Ranging and Pioneer

Oh No wrote:
Thus spake "
Oh No wrote:
Thus spake "

.....
I don't think Anderson actually says how frequent cycle slips were, just
that some were examined by an analyst. They did exclude the data.


The samples are generally once per minute and
few are missing in the small sample of days I
have examined. That may give you an upper
limit of a few per hour at most, possibly much
lower, that you could compare with your predicted
rate.

I am not quite sure where the 15000 increase is, or what the equation
a_H = 2 Hv refers to.


snip derivations

... giving an apparent acceleration
of 5.50e-14 m/s^2. Compare that with the anomaly
of 8.74e-10 m/s^2.


Did that clarify my comment and show how the
speed of the craft comes into the equation?

Can you now explain why your result is so much
higher for Pioneer yet that doesn't translate to
extra-galactic redshift measurements?

I have it that quantum coordinates introduce an
acceleration in time which can be shown by a coordinate transformation
equivalent to an acceleration Hc.


What puzzles me here is that your anomalous
acceleration is independent of the craft speed.
If the craft were sitting at a fixed location with
neither radial nor tangential velocity (e.g. station
keeping with a solar sail), this implies you would
still get a downlink frequency shift which increased
linearly with time for a constant uplink frequency
and it would also be independent of distance (as
is observed) hence should apply to short range
measurements over some spread of distance
resolution.

... Of the phenomenological
time models considered by Anderson et al, do any
of their equations (60) through (65) match? ...

Equation 60 is the probably the best match, though I am not sure how
different it is from 61 or 62.


I need to refresh my memory on the details.

I used cosmic time, but in the quantum
domain an "accelerating" time coordinate is used, proportional to the
expansion parameter. This will affect Doppler, but not ranging which is
based on cosmic time.


Interesting, that might offer you another test as
an inconsistency with other means of measuring
the solar plasma. From page 10 of gr-qc/0104064:

"Thus, the ranging data are independent of the Doppler
data, which represents a frequency shift of the radio carrier
wave without modulation. For example, solar plasma
introduces a group delay in the ranging data but a phase
advance in the Doppler data.

Ranging data can also be used to distinguish an actual
range change from a fictitious range change seen in
Doppler data that is caused by a frequency error [39].
The Doppler frequency integrated over time (the accumulated
phase) should equal the range change except for
the difference introduced by charged particles."

George
  #3  
Old August 14th 06, 11:25 PM posted to sci.astro.research
Jonathan Silverlight[_5_]
external usenet poster
 
Posts: 41
Default Ranging and Pioneer

In message , Oh No
writes
Thus spake "
Oh No wrote:

I am not sure that that
is what they are saying because I had been given to believe that the
measurements of Mars are the most accurate within the Solar system.


Perhaps in percentage terms, ranging using
the corner refectors on the Moon achieves cm
accuracy.


Sorry, I overlook the obvious.


Apache Point hopes to get millimeter accuracy but doesn't seem to have
done so at the last update (June 2006)
http://physics.ucsd.edu/~tmurphy/apollo/apollo.html
 




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