Szczepan Bialek wrote:
"Jim Lux" napisal w wiadomosci
...
Szczepan Bialek wrote:
Uzytkownik "Jim Lux" napisal w wiadomosci
...
Speed of light in space is known thanks Roemer.s method. Now are radio
transmitters on the Mars and is possibility to use the Roemer's method
for radio waves. NASA know the results. Are thy pulished?

Of course, they're published. Widely. I would check Journal of
Geophysical Research or similar publications.

As a practical matter, precise measurements of the time of flight
to/from a spacecraft is used to figure out where the spacecraft is and
its radial velocity.

Typical range accuracy is on the order of a few meters, velocities good
to a few cm/s, for something at the orbit of Neptune or Uranus.

Precise doppler measurements are used for radio science experiments,
e.g. to determine the internal structure of a planet or moon by
precisely measuring the orbit of a satellite. A typical performance for
such a measurement is 1 part in 1E15 over 1000 seconds at 32 GHz or
8GHz.
Roemer's method is the one way measurement. See:
http://www.mathpages.com/home/kmath203/kmath203.htm

We know where Jovian is so the one way measurement is possible. With
spacecraft it is impossible.
not true. We do one way measurements from spacecraft all the time. A high
quality oscillator (aka USO)is used to generate a set of phase coherent
signals at different frequencies.

Look at PN ranging or Sequential Ranging.

But the Mars is the best. Are available data for the Mars?

I don't know why Mars would be the best..

But you might start with googling "ranging Mars radiometric" or
something like that.
Or the usual tracking down the papers thing starting with one that talks
about it, and will have references.
http://seismo.berkeley.edu/~manga/folkner.pdf might give a start.
One of the footnotes mentions Viking data at S-band.

Journal of Geophysical Research (aka JGR) is where a lot of this seems
to show up.

You could search for works by authors who do this kind of thing, too.
Folkner, Asmar, Oudrhiri, Iess, Armstrong are all worth searching for.
I'd do a search for the author name AND "ranging"



For more "raw data" try the NASA Planetary Data System archive
http://pds.nasa.gov/

You're going to be on your own to find the relevant data files. Try
"radio science" as a search term.

"Jim Lux" napisal w wiadomosci
...
Szczepan Bialek wrote:
"Jim Lux" napisal w wiadomosci

Speed of light in space is known thanks Roemer.s method. Now are
radio transmitters on the Mars and is possibility to use the Roemer's
method for radio waves. NASA know the results. Are they published?

Of course, they're published. Widely. I would check Journal of
Geophysical Research or similar publications.

As a practical matter, precise measurements of the time of flight
to/from a spacecraft is used to figure out where the spacecraft is and
its radial velocity.

Typical range accuracy is on the order of a few meters, velocities
good to a few cm/s, for something at the orbit of Neptune or Uranus.

Precise doppler measurements are used for radio science experiments,
e.g. to determine the internal structure of a planet or moon by
precisely measuring the orbit of a satellite. A typical performance
for such a measurement is 1 part in 1E15 over 1000 seconds at 32 GHz
or 8GHz.
Roemer's method is the one way measurement. See:
http://www.mathpages.com/home/kmath203/kmath203.htm

We know where Jovian is so the one way measurement is possible. With
spacecraft it is impossible.

not true. We do one way measurements from spacecraft all the time. A
high quality oscillator (aka USO)is used to generate a set of phase
coherent signals at different frequencies.

Look at PN ranging or Sequential Ranging.

But the Mars is the best. Are available data for the Mars?

I don't know why Mars would be the best..

Probably is possible to measure the optic signal from the Mars satellite. If
yes, we have the direct comparison light - radio waves.
Radio transmitter can be installed only on the Mars.

But you might start with googling "ranging Mars radiometric" or something
like that.
Or the usual tracking down the papers thing starting with one that talks
about it, and will have references.
http://seismo.berkeley.edu/~manga/folkner.pdf might give a start.
One of the footnotes mentions Viking data at S-band.

Journal of Geophysical Research (aka JGR) is where a lot of this seems to
show up.

You could search for works by authors who do this kind of thing, too.
Folkner, Asmar, Oudrhiri, Iess, Armstrong are all worth searching for. I'd
do a search for the author name AND "ranging"


For more "raw data" try the NASA Planetary Data System archive
http://pds.nasa.gov/

You're going to be on your own to find the relevant data files. Try "radio
science" as a search term.

For me will be enough your steatment if speed of light and radio waves were
measured in different regions of the Solar System.
Katz: http://ipnpr.jpl.nasa.gov/progress_report/42-65/65I.PDF
wrote that the electron temperatures are from 10^4 to 10^6. Look at Fig 2.
Place the Mars instead a spacecraft. Between (a) and (c) should be some
differences.

You wrote: " NASA knows the results. Are they published? Of course, they're
published. Widely."

What the conclusion are?
I do not need the quantitative data.
S*

Szczepan Bialek wrote:

But the Mars is the best. Are available data for the Mars?
I don't know why Mars would be the best..

Probably is possible to measure the optic signal from the Mars satellite. If
yes, we have the direct comparison light - radio waves.

I don't think that there is any way to "see" a satellite at Mars.
Perhaps if one did some sort of Moon/mars occultation?

Radio transmitter can be installed only on the Mars.

There are precision transmitters suitable for this kind of measurement
at many places in the Solar System.
You're going to be on your own to find the relevant data files. Try "radio
science" as a search term.


For me will be enough your steatment if speed of light and radio waves were
measured in different regions of the Solar System.
Katz: http://ipnpr.jpl.nasa.gov/progress_report/42-65/65I.PDF
wrote that the electron temperatures are from 10^4 to 10^6. Look at Fig 2.
Place the Mars instead a spacecraft. Between (a) and (c) should be some
differences.

You wrote: " NASA knows the results. Are they published? Of course, they're
published. Widely."

What the conclusion are?
I do not need the quantitative data.

I'll assert that propagation through interplanetary space is moderately
well understood and matches all modern models of electromagnetic behavior.

Jim Lux wrote:
Szczepan Bialek wrote:

But the Mars is the best. Are available data for the Mars?
I don't know why Mars would be the best..

Probably is possible to measure the optic signal from the Mars
satellite. If yes, we have the direct comparison light - radio waves.

I don't think that there is any way to "see" a satellite at Mars.
Perhaps if one did some sort of Moon/mars occultation?

Radio transmitter can be installed only on the Mars.

There are precision transmitters suitable for this kind of measurement
at many places in the Solar System.
You're going to be on your own to find the relevant data files. Try
"radio science" as a search term.


For me will be enough your steatment if speed of light and radio waves
were measured in different regions of the Solar System.
Katz: http://ipnpr.jpl.nasa.gov/progress_report/42-65/65I.PDF
wrote that the electron temperatures are from 10^4 to 10^6. Look at
Fig 2. Place the Mars instead a spacecraft. Between (a) and (c) should
be some differences.


Are you asking if the calculations in Katz's paper for the two paths
have been experimentally verified? I don't know..
Certainly he predicts that the temporal dispersion is going to be 0.1ps
for near IR, which is, shall we say, challenging to measure.

You wrote: " NASA knows the results. Are they published? Of course,
they're published. Widely."

What the conclusion are?
I do not need the quantitative data.

I'll assert that propagation through interplanetary space is moderately
well understood and matches all modern models of electromagnetic behavior.

On Thu, 17 Mar 2011 12:52:28 -0700, Jim Lux
wrote:

Certainly he predicts that the temporal dispersion is going to be 0.1ps
for near IR, which is, shall we say, challenging to measure.

Why?

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On Thu, 17 Mar 2011 12:52:28 -0700, Jim Lux
wrote:

Certainly he predicts that the temporal dispersion is going to be 0.1ps
for near IR, which is, shall we say, challenging to measure.

Why?


measuring things to tenths of a picosecond, repeatably, can be tricky..
That's like measuring the phase difference between two 10 GHz signals
to 0.3 degrees. Or, another way to look at it is 1 picolightsecond is
about a third of a millimeter.

You're looking at
a) figuring out how to generate two signals at near IR that has a
frequency offset that can be accurately controlled. Probably some sort
of heterodyne mixing scheme would be easiest.
b) sending those two signals over the optical path through
interplanetary space.
c) recovering the signals, measuring the propagation time variation
(say, by looking at the phase difference between the modulation
signals), and then removing atmospheric effects.
d) it's probably going to be a pretty weak signal, so you'll need to
average. That means your measurement system has to be picosecond stable
over the averaging interval.

None of those steps are particularly simple or easy.

I've worked on systems to measure the (microwave) distance to Jupiter
and back with an accuracy of around 1 part in 1E15 at 32 GHz,
integrating over 1000 seconds. That's tenths of a picosecond out of 1000
seconds. It's challenging.

http://en.wikipedia.org/wiki/Juno_%28spacecraft%29
http://juno.wisc.edu/spacecraft_instruments_GSE.html

On Thu, 17 Mar 2011 17:19:09 -0700, Jim Lux
wrote:

Certainly he predicts that the temporal dispersion is going to be 0.1ps
for near IR, which is, shall we say, challenging to measure.

Why?

measuring things to tenths of a picosecond, repeatably, can be tricky..
That's like measuring the phase difference between two 10 GHz signals
to 0.3 degrees. Or, another way to look at it is 1 picolightsecond is
about a third of a millimeter.

A third of a millimeter is no big deal and for an optical (or
sub-optical) signal - trivial. Perhaps, when stated in terms of two
10 GHz signals, "near IR" is being vastly over stated.

You're looking at
a) figuring out how to generate two signals at near IR that has a
frequency offset that can be accurately controlled.

Controlled? This is dreaming in technicolor (or near IR color) if the
source is celestial.

I thought the discussion was about dispersion, the characteristic of
the medium, not sources.

Probably some sort
of heterodyne mixing scheme would be easiest.

Heterodyning is extremely commonplace and accurate - why would it be
pondered as an alternative method?

b) sending those two signals over the optical path through
interplanetary space.

This blurs my understanding of celestial where two signals is a
poverty of what is available from ANY celestial source.

c) recovering the signals,

If there is a problem of recovery, it seems it is more a practical
matter of source selection. Given the billions of celestial sources
available, I don't understand the problem.

measuring the propagation time variation
(say, by looking at the phase difference between the modulation
signals), and then removing atmospheric effects.

Why worry about the atmosphere when you can get above it?

d) it's probably going to be a pretty weak signal, so you'll need to
average. That means your measurement system has to be picosecond stable
over the averaging interval.

OK, so I am lost. This laundry list of difficulties seems to be
prepared to anticipate failure.

Name the near IR source and defend its choice in light (no pun) of
these intractable difficulties.

None of those steps are particularly simple or easy.

I've worked on systems to measure the (microwave) distance to Jupiter
and back with an accuracy of around 1 part in 1E15 at 32 GHz,

32 GHz is what photonics would call far-far IR at roughly 3 to 4
orders of magnitude distant from "near IR."

integrating over 1000 seconds. That's tenths of a picosecond out of 1000
seconds. It's challenging.

No doubt - like trying to push a peanut up Pike's Peak with your nose.
That too has been done with challenge in mind.

How did this slip from "near IR" to 32 GHz?

73's
Richard Clark, KB7QHC

"Jim Lux" napisal w wiadomosci
...
Szczepan Bialek wrote:


For me will be enough your steatment if speed of light and radio waves
were measured in different regions of the Solar System.
Katz: http://ipnpr.jpl.nasa.gov/progress_report/42-65/65I.PDF
wrote that the electron temperatures are from 10^4 to 10^6. Look at Fig
2. Place the Mars instead a spacecraft. Between (a) and (c) should be
some differences.


Are you asking if the calculations in Katz's paper for the two paths have
been experimentally verified? I don't know..

They were verified because there is a radio transmitter on the Mars. We do
not know the results.
S*