GPS satellite Clock Error Explanation

[aetherwizard]

I'm struggling to follow what you are saying. Receivers do not make any corrections to the signals received. The metadata and modelling required would be over the top compared to the gain in accuracy received. Receivers just make multilateral calculations based on the 6 or 7 signals received. The only relativity adjustment ever considered in the GPS system was the one-off frequency clock changes of the atomic clocks, pre-launch, which I had already pointed out are pointless.

I am not defending the mainstream approach to GPS signals. I'm simply explaining how they explain it. There is more than one relativity adjustment. Yes, there is the relativity adjustment to the clock rate after launch. But there are also other adjustments due the eccentricity of the satellite's orbit (if any) and to compensate for various environmental factors, such as the difference in gravitational field over the surface of the Earth. The adjustments can be made either at the satellite or in the receiver. Again, I am not saying that I think these adjustments are necessary, I'm just saying that the relativists use these arguments to support relativity.

Like you, I also pointed out the pointless nature of the relativity measurements in light of two facts, one the ionospheric disturbance greatly exceeds the relativity adjustment, and two, the satellites are not even dependent upon the onboard clocks as much as they are on the targeting points on the ground and the stars. The real clock of the GPS system is therefore the satellite's orbit, not the clock inside the satellite. The clock inside the satellite functions more like a metronome than an actual time reference. The real time reference is the time it takes for the GPS constellation to return to a place over specific ground targets relative to the star positions.

There are many errors associated with the signals including the ionospheric errors which I agree can be large. But the standard modelling cannot account for short term significant errors, caused by say sunspots. I don't think anyone tries to pretend that these errors are anything to do with relativity though.

I did not say nor imply that anybody pretends the ionospheric adjustments are relativity effects. I said the magnitude of the ionospheric adjustments, which are highly irregular and have a random appearance, are far greater than the magnitude of the relativity adjustments. It's like trying to record the ripples of a stone falling in the ocean during the middle of a hurricane. There is no way to tell with certainty which ripples belong to the stone, and which to the hurricane. Similarly, there is no way to tell if relativistic corrections are needed when the ionospheric corrections are orders of magnitude greater.

Where do you get your information regarding this relativistic adjustment/correction?

Just a simple search of the Internet. Here is an example:
http://www.phys.lsu.edu/mog/mog9/node9.html

I have read many different papers on NASA related web sites over the years, as I am sure you have.

[Aardwolf]

Where do you get your information regarding this relativistic adjustment/correction?

Just a simple search of the Internet. Here is an example:
http://www.phys.lsu.edu/mog/mog9/node9.html

That link does not state there are "live" relativistic adjustments. The 2 types refered to are the initial clock adjustment (pointless as discussed) and an adjustment dependent on the eccentricity of the satellite, which is just a correction to the ephemeris data sent by the satellite to indicate any known pertubations to the orbit. There are also unpredictable pertubations which nothing corrects for. Effectively if a satellite strays too far out of its orbit parameter its taken off line and an orbit correction is made. This has nothing to do with relativity, it's so the receiver can better determine its position by correcting its internal expectation/mapping of the transmitters position when the signal was sent.

Of course we both agree that proof of relativity in the GPS system is nonsense, but it far simpler than the suggestion that the corrections are lost within other corrections, the fact is the vast majority of receivers make no such adjustments at all. Far better than trying to account for adjustments is to just take a reading from as many sattelites as possible for as long as possible. When that is done millimeter accuracy is possible which is far beyond anything any software or model can achieve.

Relativity within the GPS is just something that relativists like to cling to but when you look into the operational side to it there isn't any evidence to support it. The only reference to it is the initial clock adjustment which was and is pointless. As it states on the link;

At present one cannot easily perform tests of relativity with the system because the SV clocks are actively steered to be within 1 microsecond of Universal Coordinated Time (USNO).

If they can't even test for the existence of relativity in the system, how can it be possible for there to be adjustments to it.

[aetherwizard]

Just a simple search of the Internet. Here is an example:
http://www.phys.lsu.edu/mog/mog9/node9.html

That link does not state there are "live" relativistic adjustments.

That is correct. That paper also does not say relativity adjustments are "pointless" or that Little Red Riding Hood could have worn a blue bonnet. You are very observant and I give you credit for that.

The 2 types refered to are the initial clock adjustment (pointless as discussed) and an adjustment dependent on the eccentricity of the satellite, which is just a correction to the ephemeris data sent by the satellite to indicate any known pertubations to the orbit. There are also unpredictable pertubations which nothing corrects for. Effectively if a satellite strays too far out of its orbit parameter its taken off line and an orbit correction is made. This has nothing to do with relativity, it's so the receiver can better determine its position by correcting its internal expectation/mapping of the transmitters position when the signal was sent.

So says you. I respect your right to free speech. The author of the paper, however, does not agree with you. The author of the linked paper said, and I quote,

"Relativistic effects on satellite clocks can be combined in such a way that only two corrections need be considered. First, the average frequency shift of clocks in orbit is corrected downward in frequency by parts in . This is a combination of five different sources of relativistic effects: gravitational frequency shifts of ground clocks due to earth's monopole and quadrupole moments, gravitational frequency shifts of the satellite clock, and second-order Doppler shifts from motion of satellite and earth-fixed clocks. Second, if the orbit is eccentric, an additional correction arises from a combination of varying gravitational and motional frequency shifts as the satellite's distance from earth varies."

The author said, and not that I agree or disagree, that the orbit eccentricity correction is a relativistic effect. This is how the mainstream describes GPS corrections. If you don't believe me, actually read the paper rather than skim over it.

Of course we both agree that proof of relativity in the GPS system is nonsense

Yes, on this we are in complete agreement.

...but it far simpler than the suggestion that the corrections are lost within other corrections...

This we disagree on. The mainstream is saying that corrections are needed in the rate of the clock speed. Yes, this is a one-off down shifting of the clock frequency when the satellite is put in orbit. However, it is not like changing time zones, this is an actual change in the rate of time. Therefore, this means the correction is constantly adjusting for "live" signal passage down to Earth and back. The clock on the satellite is running slower than the clocks on Earth, which is the whole point behind relativity theory. This is an ongoing signal correction, and not just a one-time adjustment to the clock, like changing to daylight savings time.

the fact is the vast majority of receivers make no such adjustments at all.

That is a red herring. It depends upon what you plan to do with the signal and how much you want to pay for accuracy.

Far better than trying to account for adjustments is to just take a reading from as many sattelites as possible for as long as possible. When that is done millimeter accuracy is possible which is far beyond anything any software or model can achieve.

And here we agree, again. Nobody disputes the fact that the real accuracy of the GPS system is due to position monitoring, not clock synchronizing. As I said in a previous post, the clock is basically just a metronome that keeps the signal between target acquisitions. Once the target acquisitions have been made, the signals are adjusted to reflect the actual position of the satellites. No relativity is needed at all.

Relativity within the GPS is just something that relativists like to cling to but when you look into the operational side to it there isn't any evidence to support it. The only reference to it is the initial clock adjustment which was and is pointless. As it states on the link;

You have the misperception that the one-off initial adjustment is something like changing daylight savings time (although you did not use these words). The initial adjustment is a frequency downshifting, which means it is a perpetual adjustment to the clock rate. The clock in orbit has been made to run slower than the clock on Earth by an insignificant amount, which is hidden in the ionospheric noise adjustment.

And yet, for this tiny adjustment that isn't necessary or even practical, it is heralded as a glowing halo around Einstein's head. If this was an argument between political factions it would called a scandal.

At present one cannot easily perform tests of relativity with the system because the SV clocks are actively steered to be within 1 microsecond of Universal Coordinated Time (USNO).

If they can't even test for the existence of relativity in the system, how can it be possible for there to be adjustments to it.

What this refers to is the positional adjustment I have been talking about. Each time the satellite goes around the Earth and locks on to its target, the clock has to be "steered" toward accuracy. Again, we are in agreement.

[Aardwolf]

the fact is the vast majority of receivers make no such adjustments at all.

That is a red herring. It depends upon what you plan to do with the signal and how much you want to pay for accuracy.

Can you tell me which receivers account for the following errors;

Ionospheric effects
Multi-path errors
Orbital pertubations
Poor geometry
Clock drift
Tropospheric refraction
Rounding errors

Accuracy isn't attained by calculation, it's attained by waiting for hours together with some ground based help. In isolation no GPS receiver can attain any better than 10-15 meter accuracy no matter how much money you spend on it.

[Aardwolf]

...but it far simpler than the suggestion that the corrections are lost within other corrections...

This we disagree on. The mainstream is saying that corrections are needed in the rate of the clock speed. Yes, this is a one-off down shifting of the clock frequency when the satellite is put in orbit. However, it is not like changing time zones, this is an actual change in the rate of time. Therefore, this means the correction is constantly adjusting for "live" signal passage down to Earth and back. The clock on the satellite is running slower than the clocks on Earth, which is the whole point behind relativity theory. This is an ongoing signal correction, and not just a one-time adjustment to the clock, like changing to daylight savings time.

I'm aware it's a constant adjustment. My point was that it is a not a live on-the-fly correction to the receivers as should be expected considering that time dilation effects should be unique to each receiver. One single global adjustment should not work.

[aetherwizard]

the fact is the vast majority of receivers make no such adjustments at all.

That is a red herring. It depends upon what you plan to do with the signal and how much you want to pay for accuracy.

Can you tell me which receivers account for the following errors;

Ionospheric effects
Multi-path errors
Orbital pertubations
Poor geometry
Clock drift
Tropospheric refraction
Rounding errors

Accuracy isn't attained by calculation, it's attained by waiting for hours together with some ground based help. In isolation no GPS receiver can attain any better than 10-15 meter accuracy no matter how much money you spend on it.

You are still providing a red herring.

You asked a question and without explanation gave a conclusion as though your answer was self-evident. No, I cannot tell you what receivers account for the listed errors. But then, do you have some reason for why I should be expected to have this information? I am not a GPS electronics technician or programmer. I am not even defending the mainstream interpretation of GPS technology. I am not even making claims about the accuracy of GPS technology. It is enough that I repeated the claim in the technical paper that receivers were designed to make relativity corrections.

I'm aware it's a constant adjustment. My point was that it is a not a live on-the-fly correction to the receivers as should be expected considering that time dilation effects should be unique to each receiver.

The satellite clock adjustment is a live on-the-fly adjustment, which affects the whole system at once. And yes, based on different altitudes and geoid locations, the relativity theory would calculate the GPS signal different for each receiver. Not that I think these adjustments are necessary, but that it fits with the relativity theory. Why would the mainstream miss an opportunity to apply their Einsteinism belief in such cases?

We both agree the relativity correction is a farce and provides no meaningful contribution to the operation of the GPS system. Can't we just agree to agree?

[Biggins]

Below is a good paper which characterises many of the problems mentioned (table 1) - relativity is not mentioned
http://www.hindawi.com/journals/ijno/2008/178927/

Another http://ec.europa.eu/dgs/energy_transpor ... _09_02.pdf
...user terminals can use to adjust the effective range of each satellite to correct for ephemeris and clock inaccuracies
and to compensate for tropospheric, and in the case of signal frequencies, ionospheric delay errors....

There was a document that went into detail on each of the errors, but I can't find it any more , but in all the documentation I have, they only talk about atmospheric and internal clock errors.

[Aardwolf]

Probably because the ESA engineers realised from the outset that clock adjustments are unnecessary. The only requirement for the satellite clocks is that they are synchronised to a common time. In fact a particular time isnt even necessary; you could just make them send a pulse every second and just make sure that is synchronised.

I remember some years ago that they put out a statement that the receivers software will account for the relativity adjustments which is completely absurd. For mutilateration you don't even need a clock on the receiver itself; the position is mathematically derived from the various differences of the time taken from each of the satellites, caused by the length of delay. I suspect the statement was put out just to appease relativists.

[celeste]

If it's true that electric fields alter decay rates
http://link.springer.com/article/10.1007%2FBF00417612
that would explain this:
http://physicsworld.com/cws/article/new ... lear-decay
that is that decay rates on earth vary with earth sun distance.
But then that would explain GPS clock rates as well. Basically, satellite clocks should run at a different rate, simply because they are farther out in the earth's radial electric field. That seems to be a good EU explanation.
If that is right, that would also give us a good way to measure relative electric fields in space. The problem of measuring voltage differences by sending a space probe, is that the probe itself would gain/lose charge on the way. But if decay rates are only dependent on the electric field at that location, then a comparison of clock rates between two astronomical bodies should give us the field difference, right?

[jone dae]

hello,
I am not new to thunderbolts, just new to this thread. Things got very technical, and I stopped reading every word before finishing the page. BTW not a criticism; for this kind of thing I think that technical discussions are good and appropriate. And I am not trying to further complicate things, when I point out that c the speed of light, is itself not a constant. It has varied widely in measurements over the last 200 years or so. Even after subtracting errors due to, say, observational or instrumental inaccuracies, statistically, it has still varied too widely across all the measurements to be considered constant. That it is a universal, unchangeable constant is one of the cornerstones of mainstream theory. But like much else in mainstream science today, it should not be accepted blindly.
The relevance to the alleged measurement error of either the satellite clock relative to the ground clock, or vice versa, is that a certain amount of error can come from just this non-constant c. Yes, it is probably 90% constant (I don't have the technical papers in front of me right now), but it was never 100% constant. So, this might account for some variation in the GPS measurements, w/o relativity and without the EU model (although I support and teach the EU model).
I do think that the ground clock - satellite clock error is made moot when that is not the accepted way of measuring the error in GPS. And I too know that 4 satellites would be needed for the 3d case, since in the planar case (taking the earth's surface to be a plane), the method is known as 'triangulation'.
I should point out that some non-scientists do read and follow these forums. I'm only considered a scientist since I'm a mathematician, I have no degrees in the natural or physical sciences. Luckily, my science education was solid enough to read these forums w/o difficulty and with comprehension. But I often invite my friends to come and join in, and some of them are not scientists. So, a summary or overview in simpler terms is often useful here.
One such overview is Rupert Sheldrake's book, 7 Experiments That Could Change The World. It is in that book, for example, that a less technical presentation is made of the wide variations in the measurements of the speed of light, c. Therefore, I recommend it especially to the non-scientists reading this forum.
There are, and have been for years, lots of natural phenomena that call into question, the mainstream view, and relativity. So -called mystery spots, also called geodetic anomalies or geomagnetic anomalies, are one such natural phenomena. I mention this in passing. Lots of constants and expected results are upset by those kinds of things.
Jone Dae

[jone dae]

replying to Celeste,
Yes, I think you are right about that. Note also, that electrical effects can cause satellites to lose altitude, slow down, or both. These have been measured after solar flares and CMEs.
Note also that the EU model includes an alternative theory of gravity itself, based on the electrical dipoles. Therefore, EU model has more information about how gravity is affecting objects, etc., than does the mainstream model, which doesn't know what gravity is, and can't account for how if affects objects. In my writings, I call it "the weak electromagnetic force", with that phrase being based on and in analogy to "the weak nuclear force". But science is improved by bringing gravity into the electromagnetic spectrum, rather than keeping it isolated, as a mysterious entity that is not in the EM spectrum, as mainstream science does. The EU model does this.
Jone Dae.

[jone dae]

I also wanted to add, if I might, both in reply to Celeste and in reply to the others posting here, as in my first reply, that the so-called universal gravitational G is not constant; that is, both G and g (big-gee and little-gee) vary. And again, the EU model accounts for this, the Einstein-Newton model does not.
G and g are constants that Rupert Sheldrake discusses in his book, 7 Experiments That Could Change The World. This book is an excellent intro for non-scientists, but technical enough for scientists to enjoy it. No, I don't know him, I'm just providing resources to this group that may be of use to some.
Jone Dae.

[Aardwolf]

Please bear in mind that the speed of light has never been measured in a true vacuum. All measurements are retarded to some degree and the speed of light in a vacuum could be anything from 299,792.458 km/s to infinity.

Gravity propagates faster than c and the speed of sound can also theoretically exceed c as well. It's likely that there are no limits to any kind of transmission of information and science's obsession with c at circa 300,000 km/s is just because that's the speed we measure locally, combined with an almost religious infatuation with Einstein's stature.

[aetherwizard]

Gravity propagates faster than c

I beg to differ.

Gravity does not propagate at all. It is a static force inherent to the structure of Aether. It is not much different from the static force that binds a large rubber sheet under tension.

The apparent lag in gravitational effect for large objects moving long distances is due to the elasticity of the Aether, just as the transmission of a wave across a rubber sheet depends upon its elasticity.

The idea that light travels at c is also erroneous. Light does not travel at all, it is photons that travel. Light is the flow of photons just like a river is the flow of water molecules. The river stays where it is even though the water is flowing.

Photons are nothing more than the transfer of angular momentum from one quantum of Aether to the next. It is due to the structure of the Aether that the only speed angular momentum can be transferred to an adjacent Aether unit is c. The Aether (which is the structure of space) does not normally flow, but it can be made to do so in special situations.

When the Aether does get distorted or forced into a flow, that is what causes the relativity effects. Aether units are always transferring angular momentum at the same speed, but if the Aether unit is also moving, then there will be a Doppler effect.

Dave

[Aardwolf]

The apparent lag in gravitational effect for large objects moving long distances is due to the elasticity of the Aether, just as the transmission of a wave across a rubber sheet depends upon its elasticity.

There is no lag in calculations regarding gravity (or whatever you want to call the force/wave/particle/sheet that results in planets travelling in stable orbits). That's the reason relativists needed to invent unproven new science to explain the lack of lagging.

The idea that light travels at c is also erroneous. Light does not travel at all, it is photons that travel. Light is the flow of photons just like a river is the flow of water molecules. The river stays where it is even though the water is flowing.

OK. Then my point is that the speed of photons has never been measured in a true vacuum. All we have is an arbitrary speed limit taken from the speed of photons travelling in a known to be retarding environment. The pioneeer anomaly is IMO clear evidence for the increase in the speed of photons the further away from the solar systems atmosphere. The satellite is not anomalously accelerating toward the sun; the speed of the photons at that distance is increasing which gives the appearance of said acceleration.