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GPS and relativity

Dirty.Harry
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3/4/2016 2:58:19 PM
Posted: 9 months ago
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Harry.
chui
Posts: 507
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3/4/2016 3:32:42 PM
Posted: 9 months ago
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Harry.

Altitude of satellite is about 20,000 km. Altitude of HA aircraft <100 km. Assuming the aircraft is on the ground is less than a 0.5% error.

For GPS to work it is only necessary for the satellite clocks to synchronise. It is the difference in time stamp from simultaneous messages at the receiver that is important.
Akhenaten
Posts: 854
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3/4/2016 3:38:02 PM
Posted: 9 months ago
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Harry.

We have been deceived. Relativity has nothing to do with how satellites and GPS systems work. It is really done by triangulation between 3 satellites and the observer. The time delay is just a scientific fraud.
Ramshutu
Posts: 4,063
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3/4/2016 3:53:53 PM
Posted: 9 months ago
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Harry.

GPS signals are encoded with the satellite position, and time of signal broadcast compared to UTC. Have enough satellites received and you can triangulate your position, if you know the relative times the signal were received.

IE: if you receive a given UTC time at T=0, then another at T=1 and another at T=2, you can tell the distance to these satellites.

Importantly, you don't need the absolute UTC time but instead the relative UTC time of the satellites. IE: you don't need to know that satellite 2 broadcast on May 5th at 4:45.43.1234 pm, and Satellite 2 broadcast on May 5th at 4:45.43.1233 pm. You only need to know that they broadcast their signals 0.0001 seconds apart.

If you receive Sat1 signal at T=0, and Sat2 signal at T=0.0001 you can tell you are an equal distance away as the time you received is the same as the time as they were broadcast. If you receive Sat2 signal at T=0, and Sat1 signal at T=0.0001, you know that Sat1 took an additional 0.0002 seconds to travel to your location using the difference in those clocks.

It's the relative UTC time, and relative receive times that are most important. The absolute time is irrelevant as long as the time broadcast relative to each other is the same. More importantly, remember that satellites use atomic clocks; GPS devices do not; and as such the local clock error is going to easily be the dominant error in any time measurement.

As the satellites broadcast the UTC time, if they are not ALL synchronized with each other, then the UTC times will not be synchronized, and the relative times will be out of whack with each other.

What this means, is that with a good GPS receiver, the only time that has an effect on the GPS accuracy, is the internal clock tagging each received signal with a relative time of receipt. If you're receiving 1 GPS signal per second, even at 20,000km where you'll be getting around 40us per day in time dilation, this equates to only 0.4ns per measurement error per GPS signal measurement; which if my maths is right is about a 1m error.

The problem with time dilation in satellites, is that the error is cumulative, as they have their clocks, and if they tick at different rates that 38us per day error (of which 7-14us could be due to relative speed differences between satellites. That could throw off the time measurements by kilometers after a day.

Saying this there is an additional neat trick, if the GPS transmitter is broadcasting at a given frequency based on it's own time dilation, so that a 2GHz signal is received by someone on the ground at 2GHz, you can work out your own time dilation.

Most modern digital signals contain some sort of fixed and known sequence so that when the signal is received you can tell where the important parts of the signal are. Importantly when you do this, you can tell the positions of the data symbols in the signal, and from the time between them vs the time that should be between them, you can obtain a frequency error estimate for you as a receiver. From that estimate, you calculate the doppler shift of all the satellites signals compared to you, and an average of all of them vs what they should be (I think that information can be derived from information within the GPS signals). If there is enough time dilation to affect the accuracy at the receiver, you can use that estimate, to perform additional correction.

Hope that helps.
TBR
Posts: 9,991
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3/4/2016 3:56:22 PM
Posted: 9 months ago
At 3/4/2016 3:38:02 PM, Akhenaten wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Harry.

We have been deceived. Relativity has nothing to do with how satellites and GPS systems work. It is really done by triangulation between 3 satellites and the observer. The time delay is just a scientific fraud.

I read your link about the lack of necessity of adjusting the clock. Point is, even if the premise IS true that does not make the practice of adjusting the clock wrong, and sure as he11 not a "scientific fraud".
DanneJeRusse
Posts: 12,598
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3/4/2016 4:45:12 PM
Posted: 9 months ago
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.
Marrying a 6 year old and waiting until she reaches puberty and maturity before having consensual sex is better than walking up to
a stranger in a bar and proceeding to have relations with no valid proof of the intent of the person. Muhammad wins. ~ Fatihah
If they don't want to be killed then they have to subdue to the Islamic laws. - Uncung
Without God, you are lower than sh!t. ~ SpiritandTruth
Dirty.Harry
Posts: 1,585
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3/6/2016 3:42:37 PM
Posted: 9 months ago
At 3/4/2016 4:45:12 PM, DanneJeRusse wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.

Actually the word you were seeking is "purported" not "alleged" - just saying...

I have looked up numerous articles pertaining to this but have not had the time to rigorously dig into the details as I'd like to, opening up a discussion about this in the science forum isn't something I'd expect objections to but then again you are a rather odd individual.

Harry.
DanneJeRusse
Posts: 12,598
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3/6/2016 3:54:41 PM
Posted: 9 months ago
At 3/6/2016 3:42:37 PM, Dirty.Harry wrote:
At 3/4/2016 4:45:12 PM, DanneJeRusse wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.

Actually the word you were seeking is "purported" not "alleged" - just saying...

I have looked up numerous articles pertaining to this but have not had the time to rigorously dig into the details as I'd like to, opening up a discussion about this in the science forum isn't something I'd expect objections to but then again you are a rather odd individual.

Yes Harry, my point exactly. Yet, for some reason, you have plenty of time to post opposing, unscientific, nonsensical views of crackpots and cranks, and you call me the rather odd individual.

Harry.
Marrying a 6 year old and waiting until she reaches puberty and maturity before having consensual sex is better than walking up to
a stranger in a bar and proceeding to have relations with no valid proof of the intent of the person. Muhammad wins. ~ Fatihah
If they don't want to be killed then they have to subdue to the Islamic laws. - Uncung
Without God, you are lower than sh!t. ~ SpiritandTruth
Dirty.Harry
Posts: 1,585
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3/6/2016 4:39:06 PM
Posted: 9 months ago
At 3/4/2016 3:32:42 PM, chui wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Harry.

Altitude of satellite is about 20,000 km. Altitude of HA aircraft <100 km. Assuming the aircraft is on the ground is less than a 0.5% error.

For GPS to work it is only necessary for the satellite clocks to synchronise. It is the difference in time stamp from simultaneous messages at the receiver that is important.

Yes I see, the height of the aircraft is (almost) negligible I guess.

This chart makes it clearer to me:

http://demonstrations.wolfram.com...

But I don't think its strictly necessary to have adjusted the satellite's atomic clock frequencies in order to determine the altitude of the satellite (which is a core aspect of the GPS calculations).

What I'm not clear on is how the GPS receiver establishes the local time, the receiver of course has no atomic clock and must rely wholly on the received satellite info.

...

OK I can see now that the local clock gets set based upon combining multiple satellite signals.

The receiver can generate (and sync on that basis) the pseudo-random code for each satellite.

So satellite A sends "10101010 - its 10:00:00" - recvd at 10:00:01 and satellite B sends "10101010 - its 10:00:00" recvd at 10:00:02 then it can set its clock so that it begins to match future timestamp signals, four satellites are required it seems to uniquely track each signal with a single (local) clock. (Values highly exaggerated!).

Based on what I'm understanding then, once synchronized the local system can determine the absolute (line of sight) distance of each of these four satellites by simply computing the time-delta * speed_of_light.

However (and this is what I've been trying to drum into Dummel) this process could still work (it seems to me) if the satellites did NOT have their atomic clock rate reduced (due to GR).

Since we KNOW the clocks run faster by X nS, we can easily factor that into the calculation.

Having adjusted atomic clocks certainly makes everything easier (debugging etc!) but in principle GPS could still be designed to work with satellite clocks that are uncompensated...

Harry.
Dirty.Harry
Posts: 1,585
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3/6/2016 4:52:37 PM
Posted: 9 months ago
At 3/6/2016 3:54:41 PM, DanneJeRusse wrote:
At 3/6/2016 3:42:37 PM, Dirty.Harry wrote:
At 3/4/2016 4:45:12 PM, DanneJeRusse wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.

Actually the word you were seeking is "purported" not "alleged" - just saying...

I have looked up numerous articles pertaining to this but have not had the time to rigorously dig into the details as I'd like to, opening up a discussion about this in the science forum isn't something I'd expect objections to but then again you are a rather odd individual.

Yes Harry, my point exactly. Yet, for some reason, you have plenty of time to post opposing, unscientific, nonsensical views of crackpots and cranks, and you call me the rather odd individual.

Let me make something very clear, I do not rely on your pop-science judgement of what is and what is not a sound scientific or technological claim.

The point upon which you and I disagree is simply this - I think a GPS system could still work, with uncompensated atomic clock's in the satellites. The calculation for 3D position on the globe's surface AND local UTC time could still be carried out - it would be a different calculation of course.

Since we know the magnitude of the clock rate difference (after all we must know it in order to have adjusted the clocks before launch) we can factor it into the calculation.

This is all I said - and was the only point upon which I agreed with the writer of the article I posted, he may well be a "crank" but I have decades of experience delivering successful complex systems and getting paid well for it, so I'm no stranger to these kinds of questions Dummel.

By all means question my abilities, skills and experience if you wish but that will lead nowhere since you know even less about me than you do about elementary science and technology.

By all means offer us your PROOF that a GPS system is impossible UNLESS the satellite's have compensated clocks, can you do that? can you offer even an article or paper perhaps that makes such a claim? Because if you cannot offer either your own or someone else's proof then I see no basis for making the allegations you are.

Harry.
DanneJeRusse
Posts: 12,598
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3/6/2016 5:22:28 PM
Posted: 9 months ago
At 3/6/2016 4:52:37 PM, Dirty.Harry wrote:
At 3/6/2016 3:54:41 PM, DanneJeRusse wrote:
At 3/6/2016 3:42:37 PM, Dirty.Harry wrote:
At 3/4/2016 4:45:12 PM, DanneJeRusse wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.

Actually the word you were seeking is "purported" not "alleged" - just saying...

I have looked up numerous articles pertaining to this but have not had the time to rigorously dig into the details as I'd like to, opening up a discussion about this in the science forum isn't something I'd expect objections to but then again you are a rather odd individual.

Yes Harry, my point exactly. Yet, for some reason, you have plenty of time to post opposing, unscientific, nonsensical views of crackpots and cranks, and you call me the rather odd individual.

Let me make something very clear, I do not rely on your pop-science judgement of what is and what is not a sound scientific or technological claim.

That's because I don't offer pop-science, Harry. Of course, you can't be trusted to understand the difference based on your posts here.

The point upon which you and I disagree is simply this - I think a GPS system could still work, with uncompensated atomic clock's in the satellites. The calculation for 3D position on the globe's surface AND local UTC time could still be carried out - it would be a different calculation of course.

Good for you, Harry. Too bad, you don't understand any of this that would allow you to make such a claim.

Since we know the magnitude of the clock rate difference (after all we must know it in order to have adjusted the clocks before launch) we can factor it into the calculation.

This is all I said - and was the only point upon which I agreed with the writer of the article I posted, he may well be a "crank" but I have decades of experience delivering successful complex systems and getting paid well for it, so I'm no stranger to these kinds of questions Dummel.

Yes, I have read many other believers like yourself who make extraordinary claims about their credentials and abilities, yet none have every demonstrated those credentials or abilities, you have shown to be no different than they.

By all means question my abilities, skills and experience if you wish but that will lead nowhere since you know even less about me than you do about elementary science and technology.

We have already observed your lack of ability, skill and experience with science, Harry.

By all means offer us your PROOF that a GPS system is impossible UNLESS the satellite's have compensated clocks, can you do that?

Ah yes, the typical shift the burden of proof onto others tactic. You believers are as hilarious as you are predictable.

can you offer even an article or paper perhaps that makes such a claim? Because if you cannot offer either your own or someone else's proof then I see no basis for making the allegations you are.

Harry.
Marrying a 6 year old and waiting until she reaches puberty and maturity before having consensual sex is better than walking up to
a stranger in a bar and proceeding to have relations with no valid proof of the intent of the person. Muhammad wins. ~ Fatihah
If they don't want to be killed then they have to subdue to the Islamic laws. - Uncung
Without God, you are lower than sh!t. ~ SpiritandTruth
Dirty.Harry
Posts: 1,585
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3/6/2016 6:24:39 PM
Posted: 9 months ago
At 3/6/2016 5:22:28 PM, DanneJeRusse wrote:
At 3/6/2016 4:52:37 PM, Dirty.Harry wrote:
At 3/6/2016 3:54:41 PM, DanneJeRusse wrote:
At 3/6/2016 3:42:37 PM, Dirty.Harry wrote:
At 3/4/2016 4:45:12 PM, DanneJeRusse wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.

Actually the word you were seeking is "purported" not "alleged" - just saying...

I have looked up numerous articles pertaining to this but have not had the time to rigorously dig into the details as I'd like to, opening up a discussion about this in the science forum isn't something I'd expect objections to but then again you are a rather odd individual.

Yes Harry, my point exactly. Yet, for some reason, you have plenty of time to post opposing, unscientific, nonsensical views of crackpots and cranks, and you call me the rather odd individual.

Let me make something very clear, I do not rely on your pop-science judgement of what is and what is not a sound scientific or technological claim.

That's because I don't offer pop-science, Harry. Of course, you can't be trusted to understand the difference based on your posts here.

The point upon which you and I disagree is simply this - I think a GPS system could still work, with uncompensated atomic clock's in the satellites. The calculation for 3D position on the globe's surface AND local UTC time could still be carried out - it would be a different calculation of course.

Good for you, Harry. Too bad, you don't understand any of this that would allow you to make such a claim.

Since we know the magnitude of the clock rate difference (after all we must know it in order to have adjusted the clocks before launch) we can factor it into the calculation.

This is all I said - and was the only point upon which I agreed with the writer of the article I posted, he may well be a "crank" but I have decades of experience delivering successful complex systems and getting paid well for it, so I'm no stranger to these kinds of questions Dummel.

Yes, I have read many other believers like yourself who make extraordinary claims about their credentials and abilities, yet none have every demonstrated those credentials or abilities, you have shown to be no different than they.

Very telling how you find the ordinary to be extraordinary.


By all means question my abilities, skills and experience if you wish but that will lead nowhere since you know even less about me than you do about elementary science and technology.

We have already observed your lack of ability, skill and experience with science, Harry.


Repeating this claim over and over Dummel isn't going to make it true you know.

By all means offer us your PROOF that a GPS system is impossible UNLESS the satellite's have compensated clocks, can you do that?

Ah yes, the typical shift the burden of proof onto others tactic. You believers are as hilarious as you are predictable.

Ahh yes the typical "lets bring up religion" strawman as a desperate means to evade a direct question.

can you offer even an article or paper perhaps that makes such a claim? Because if you cannot offer either your own or someone else's proof then I see no basis for making the allegations you are.

Harry.

Well? where does anyone demonstrate that a GPS system is impossible UNLESS the satellite clocks are compensated?

Surely you don't believe without proof Dummel?

Harry.
DanneJeRusse
Posts: 12,598
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3/6/2016 8:03:19 PM
Posted: 9 months ago
At 3/6/2016 6:24:39 PM, Dirty.Harry wrote:
At 3/6/2016 5:22:28 PM, DanneJeRusse wrote:
At 3/6/2016 4:52:37 PM, Dirty.Harry wrote:
At 3/6/2016 3:54:41 PM, DanneJeRusse wrote:
At 3/6/2016 3:42:37 PM, Dirty.Harry wrote:
At 3/4/2016 4:45:12 PM, DanneJeRusse wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.

Actually the word you were seeking is "purported" not "alleged" - just saying...

I have looked up numerous articles pertaining to this but have not had the time to rigorously dig into the details as I'd like to, opening up a discussion about this in the science forum isn't something I'd expect objections to but then again you are a rather odd individual.

Yes Harry, my point exactly. Yet, for some reason, you have plenty of time to post opposing, unscientific, nonsensical views of crackpots and cranks, and you call me the rather odd individual.

Let me make something very clear, I do not rely on your pop-science judgement of what is and what is not a sound scientific or technological claim.

That's because I don't offer pop-science, Harry. Of course, you can't be trusted to understand the difference based on your posts here.

The point upon which you and I disagree is simply this - I think a GPS system could still work, with uncompensated atomic clock's in the satellites. The calculation for 3D position on the globe's surface AND local UTC time could still be carried out - it would be a different calculation of course.

Good for you, Harry. Too bad, you don't understand any of this that would allow you to make such a claim.

Since we know the magnitude of the clock rate difference (after all we must know it in order to have adjusted the clocks before launch) we can factor it into the calculation.

This is all I said - and was the only point upon which I agreed with the writer of the article I posted, he may well be a "crank" but I have decades of experience delivering successful complex systems and getting paid well for it, so I'm no stranger to these kinds of questions Dummel.

Yes, I have read many other believers like yourself who make extraordinary claims about their credentials and abilities, yet none have every demonstrated those credentials or abilities, you have shown to be no different than they.

Very telling how you find the ordinary to be extraordinary.


By all means question my abilities, skills and experience if you wish but that will lead nowhere since you know even less about me than you do about elementary science and technology.

We have already observed your lack of ability, skill and experience with science, Harry.


Repeating this claim over and over Dummel isn't going to make it true you know.

By all means offer us your PROOF that a GPS system is impossible UNLESS the satellite's have compensated clocks, can you do that?

Ah yes, the typical shift the burden of proof onto others tactic. You believers are as hilarious as you are predictable.

Ahh yes the typical "lets bring up religion" strawman as a desperate means to evade a direct question.

can you offer even an article or paper perhaps that makes such a claim? Because if you cannot offer either your own or someone else's proof then I see no basis for making the allegations you are.

Harry.

Well? where does anyone demonstrate that a GPS system is impossible UNLESS the satellite clocks are compensated?

http://ilrs.gsfc.nasa.gov...

Surely you don't believe without proof Dummel?

Harry.
Marrying a 6 year old and waiting until she reaches puberty and maturity before having consensual sex is better than walking up to
a stranger in a bar and proceeding to have relations with no valid proof of the intent of the person. Muhammad wins. ~ Fatihah
If they don't want to be killed then they have to subdue to the Islamic laws. - Uncung
Without God, you are lower than sh!t. ~ SpiritandTruth
Mhykiel
Posts: 5,987
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3/7/2016 1:33:05 AM
Posted: 9 months ago
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Harry.

Synchronization takes place from a ground station.

Also the relativistic effect differs for GPS altitude.

http://www.gps.gov...

It's interesting to note that in the early days of GPS the military was able to encode the messages to be accurate for military units and yet off as much as 100 meters for non encoded units. Due to GPS prevalence in many civilian systems it is unlikely such a feature will be used.
Dirty.Harry
Posts: 1,585
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3/7/2016 2:42:08 PM
Posted: 9 months ago
At 3/6/2016 8:03:19 PM, DanneJeRusse wrote:
At 3/6/2016 6:24:39 PM, Dirty.Harry wrote:
At 3/6/2016 5:22:28 PM, DanneJeRusse wrote:
At 3/6/2016 4:52:37 PM, Dirty.Harry wrote:
At 3/6/2016 3:54:41 PM, DanneJeRusse wrote:
At 3/6/2016 3:42:37 PM, Dirty.Harry wrote:
At 3/4/2016 4:45:12 PM, DanneJeRusse wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.

Actually the word you were seeking is "purported" not "alleged" - just saying...

I have looked up numerous articles pertaining to this but have not had the time to rigorously dig into the details as I'd like to, opening up a discussion about this in the science forum isn't something I'd expect objections to but then again you are a rather odd individual.

Yes Harry, my point exactly. Yet, for some reason, you have plenty of time to post opposing, unscientific, nonsensical views of crackpots and cranks, and you call me the rather odd individual.

Let me make something very clear, I do not rely on your pop-science judgement of what is and what is not a sound scientific or technological claim.

That's because I don't offer pop-science, Harry. Of course, you can't be trusted to understand the difference based on your posts here.

The point upon which you and I disagree is simply this - I think a GPS system could still work, with uncompensated atomic clock's in the satellites. The calculation for 3D position on the globe's surface AND local UTC time could still be carried out - it would be a different calculation of course.

Good for you, Harry. Too bad, you don't understand any of this that would allow you to make such a claim.

Since we know the magnitude of the clock rate difference (after all we must know it in order to have adjusted the clocks before launch) we can factor it into the calculation.

This is all I said - and was the only point upon which I agreed with the writer of the article I posted, he may well be a "crank" but I have decades of experience delivering successful complex systems and getting paid well for it, so I'm no stranger to these kinds of questions Dummel.

Yes, I have read many other believers like yourself who make extraordinary claims about their credentials and abilities, yet none have every demonstrated those credentials or abilities, you have shown to be no different than they.

Very telling how you find the ordinary to be extraordinary.


By all means question my abilities, skills and experience if you wish but that will lead nowhere since you know even less about me than you do about elementary science and technology.

We have already observed your lack of ability, skill and experience with science, Harry.


Repeating this claim over and over Dummel isn't going to make it true you know.

By all means offer us your PROOF that a GPS system is impossible UNLESS the satellite's have compensated clocks, can you do that?

Ah yes, the typical shift the burden of proof onto others tactic. You believers are as hilarious as you are predictable.

Ahh yes the typical "lets bring up religion" strawman as a desperate means to evade a direct question.

can you offer even an article or paper perhaps that makes such a claim? Because if you cannot offer either your own or someone else's proof then I see no basis for making the allegations you are.

Harry.

Well? where does anyone demonstrate that a GPS system is impossible UNLESS the satellite clocks are compensated?

http://ilrs.gsfc.nasa.gov...

Surely you don't believe without proof Dummel?

Harry.

That's a good paper, can't digest it all now though.

I did peruse it but found no indication that uncompensated clocks would make such a system impossible. All we'd do is what the system does now but apply and adjustment to the computed time.

That adjustment would be X days times the per-date nS delta etc etc.

Remember GPS provides position AND time, that is its used to enable remote recipients to determined the date/time locally.

I've been discussing only one thing with you dumass, namely can position be established with satellites that have uncompensated clocks and so far I think it's very possible.

Having compensated clocks simplifies everything - I've said that several times - but that's not the point, any claim that position determination REQUIRES compensated clocks is bogus I think, i.e. you are bogus, a know all, a quote miner extraordinaire.

Had you any experience with technology, science, engineering. software you'd be aware that speculative "what if" questions like this one are an entirely normal part of life and often underpin advances.

Do us all a favor sonny, stick with foreign languages and leave the complicated stuff to those who understand it.

Harry.
slo1
Posts: 4,320
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3/7/2016 3:51:58 PM
Posted: 9 months ago
At 3/6/2016 4:52:37 PM, Dirty.Harry wrote:
At 3/6/2016 3:54:41 PM, DanneJeRusse wrote:
At 3/6/2016 3:42:37 PM, Dirty.Harry wrote:
At 3/4/2016 4:45:12 PM, DanneJeRusse wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.

Actually the word you were seeking is "purported" not "alleged" - just saying...

I have looked up numerous articles pertaining to this but have not had the time to rigorously dig into the details as I'd like to, opening up a discussion about this in the science forum isn't something I'd expect objections to but then again you are a rather odd individual.

Yes Harry, my point exactly. Yet, for some reason, you have plenty of time to post opposing, unscientific, nonsensical views of crackpots and cranks, and you call me the rather odd individual.

Let me make something very clear, I do not rely on your pop-science judgement of what is and what is not a sound scientific or technological claim.

The point upon which you and I disagree is simply this - I think a GPS system could still work, with uncompensated atomic clock's in the satellites. The calculation for 3D position on the globe's surface AND local UTC time could still be carried out - it would be a different calculation of course.

Since we know the magnitude of the clock rate difference (after all we must know it in order to have adjusted the clocks before launch) we can factor it into the calculation.

This is all I said - and was the only point upon which I agreed with the writer of the article I posted, he may well be a "crank" but I have decades of experience delivering successful complex systems and getting paid well for it, so I'm no stranger to these kinds of questions Dummel.

By all means question my abilities, skills and experience if you wish but that will lead nowhere since you know even less about me than you do about elementary science and technology.

By all means offer us your PROOF that a GPS system is impossible UNLESS the satellite's have compensated clocks, can you do that? can you offer even an article or paper perhaps that makes such a claim? Because if you cannot offer either your own or someone else's proof then I see no basis for making the allegations you are.

Harry.

Harry, sure you could do it without adjustments, however it will not be as accurare. The distance between gps reciever and satellite is measured by the duration the signal travels. If you don't adjust for time dialation it simply is not as accurate. The signal travels through the atmosphere which is not a vacuum, so there can be other variables such as humidity that impact the signal delay. That is where it gets very difficult to error correct. You error correct time dialation to eliminate that variable to signal delay, because if you dont when you add up all the other factors which can introduce errors plus time dialation you can be pretty far off. This wiki Pedia has good detail on factors which impact signal delay.

https://en.m.wikipedia.org...
Floid
Posts: 751
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3/7/2016 3:58:30 PM
Posted: 9 months ago
At 3/7/2016 2:42:08 PM, Dirty.Harry wrote:
I've been discussing only one thing with you dumass, namely can position be established with satellites that have uncompensated clocks and so far I think it's very possible.

A simple use of google would provide you with more than enough information to prove your "I think" wrong. You can establish position without compensating the clocks but you will drift at about Sure. It wouldn't be the correct position and it would drift to an unusable number in minutes with drift being approximately 11km per day.

I will leave to location of this information to you as practice using google.
Dirty.Harry
Posts: 1,585
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3/8/2016 2:43:54 PM
Posted: 9 months ago
At 3/7/2016 3:51:58 PM, slo1 wrote:
At 3/6/2016 4:52:37 PM, Dirty.Harry wrote:
At 3/6/2016 3:54:41 PM, DanneJeRusse wrote:
At 3/6/2016 3:42:37 PM, Dirty.Harry wrote:
At 3/4/2016 4:45:12 PM, DanneJeRusse wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.

Actually the word you were seeking is "purported" not "alleged" - just saying...

I have looked up numerous articles pertaining to this but have not had the time to rigorously dig into the details as I'd like to, opening up a discussion about this in the science forum isn't something I'd expect objections to but then again you are a rather odd individual.

Yes Harry, my point exactly. Yet, for some reason, you have plenty of time to post opposing, unscientific, nonsensical views of crackpots and cranks, and you call me the rather odd individual.

Let me make something very clear, I do not rely on your pop-science judgement of what is and what is not a sound scientific or technological claim.

The point upon which you and I disagree is simply this - I think a GPS system could still work, with uncompensated atomic clock's in the satellites. The calculation for 3D position on the globe's surface AND local UTC time could still be carried out - it would be a different calculation of course.

Since we know the magnitude of the clock rate difference (after all we must know it in order to have adjusted the clocks before launch) we can factor it into the calculation.

This is all I said - and was the only point upon which I agreed with the writer of the article I posted, he may well be a "crank" but I have decades of experience delivering successful complex systems and getting paid well for it, so I'm no stranger to these kinds of questions Dummel.

By all means question my abilities, skills and experience if you wish but that will lead nowhere since you know even less about me than you do about elementary science and technology.

By all means offer us your PROOF that a GPS system is impossible UNLESS the satellite's have compensated clocks, can you do that? can you offer even an article or paper perhaps that makes such a claim? Because if you cannot offer either your own or someone else's proof then I see no basis for making the allegations you are.

Harry.

Harry, sure you could do it without adjustments, however it will not be as accurare. The distance between gps reciever and satellite is measured by the duration the signal travels. If you don't adjust for time dialation it simply is not as accurate. The signal travels through the atmosphere which is not a vacuum, so there can be other variables such as humidity that impact the signal delay. That is where it gets very difficult to error correct. You error correct time dialation to eliminate that variable to signal delay, because if you dont when you add up all the other factors which can introduce errors plus time dialation you can be pretty far off. This wiki Pedia has good detail on factors which impact signal delay.

https://en.m.wikipedia.org...

But you need to understand something:

The receiver synchronizes its local clock to match the satellites, it does this iteratively. The only clock the receiver has to measure the transit time is its own, it does not sync up with any earthbound clock.

Time dilation does not impact transit time, it is the time difference between a sent timestamp message and the received timestamp message that is used.

If all clocks are running somewhat too fast or too slow it will have no impact on the signal duration. all that matters is that the clocks are synchronized.

If the two clocks are too fast/slow BUT by the exact same amount, then the measured transit time will be the same as if the clocks ran at the "correct" speed.

It just makes everything easier if all clocks run at the same rate as an earthbound clock but it does not make the measurement of satellite distance any more or less accurate.

Harry.
DanneJeRusse
Posts: 12,598
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3/8/2016 2:52:19 PM
Posted: 9 months ago
At 3/7/2016 2:42:08 PM, Dirty.Harry wrote:
At 3/6/2016 8:03:19 PM, DanneJeRusse wrote:
At 3/6/2016 6:24:39 PM, Dirty.Harry wrote:
At 3/6/2016 5:22:28 PM, DanneJeRusse wrote:
At 3/6/2016 4:52:37 PM, Dirty.Harry wrote:
At 3/6/2016 3:54:41 PM, DanneJeRusse wrote:
At 3/6/2016 3:42:37 PM, Dirty.Harry wrote:
At 3/4/2016 4:45:12 PM, DanneJeRusse wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.

Actually the word you were seeking is "purported" not "alleged" - just saying...

I have looked up numerous articles pertaining to this but have not had the time to rigorously dig into the details as I'd like to, opening up a discussion about this in the science forum isn't something I'd expect objections to but then again you are a rather odd individual.

Yes Harry, my point exactly. Yet, for some reason, you have plenty of time to post opposing, unscientific, nonsensical views of crackpots and cranks, and you call me the rather odd individual.

Let me make something very clear, I do not rely on your pop-science judgement of what is and what is not a sound scientific or technological claim.

That's because I don't offer pop-science, Harry. Of course, you can't be trusted to understand the difference based on your posts here.

The point upon which you and I disagree is simply this - I think a GPS system could still work, with uncompensated atomic clock's in the satellites. The calculation for 3D position on the globe's surface AND local UTC time could still be carried out - it would be a different calculation of course.

Good for you, Harry. Too bad, you don't understand any of this that would allow you to make such a claim.

Since we know the magnitude of the clock rate difference (after all we must know it in order to have adjusted the clocks before launch) we can factor it into the calculation.

This is all I said - and was the only point upon which I agreed with the writer of the article I posted, he may well be a "crank" but I have decades of experience delivering successful complex systems and getting paid well for it, so I'm no stranger to these kinds of questions Dummel.

Yes, I have read many other believers like yourself who make extraordinary claims about their credentials and abilities, yet none have every demonstrated those credentials or abilities, you have shown to be no different than they.

Very telling how you find the ordinary to be extraordinary.


By all means question my abilities, skills and experience if you wish but that will lead nowhere since you know even less about me than you do about elementary science and technology.

We have already observed your lack of ability, skill and experience with science, Harry.


Repeating this claim over and over Dummel isn't going to make it true you know.

By all means offer us your PROOF that a GPS system is impossible UNLESS the satellite's have compensated clocks, can you do that?

Ah yes, the typical shift the burden of proof onto others tactic. You believers are as hilarious as you are predictable.

Ahh yes the typical "lets bring up religion" strawman as a desperate means to evade a direct question.

can you offer even an article or paper perhaps that makes such a claim? Because if you cannot offer either your own or someone else's proof then I see no basis for making the allegations you are.

Harry.

Well? where does anyone demonstrate that a GPS system is impossible UNLESS the satellite clocks are compensated?

http://ilrs.gsfc.nasa.gov...

Surely you don't believe without proof Dummel?

Harry.

That's a good paper, can't digest it all now though.

I did peruse it but found no indication that uncompensated clocks would make such a system impossible. All we'd do is what the system does now but apply and adjustment to the computed time.

You do little more than make my point regarding your alleged credentials and your capacity to understand these things.

That adjustment would be X days times the per-date nS delta etc etc.

Remember GPS provides position AND time, that is its used to enable remote recipients to determined the date/time locally.

I've been discussing only one thing with you dumass, namely can position be established with satellites that have uncompensated clocks and so far I think it's very possible.

That is because you don't understand how GPS works.

Having compensated clocks simplifies everything - I've said that several times - but that's not the point, any claim that position determination REQUIRES compensated clocks is bogus I think, i.e. you are bogus, a know all, a quote miner extraordinaire.

Yes, you continue to bleat your nonsense over and over, while admitting to not having read all the information others provided that you failed to look up yourself that explains why you're wrong.

Had you any experience with technology, science, engineering. software you'd be aware that speculative "what if" questions like this one are an entirely normal part of life and often underpin advances.

Lying about your credentials again, Harry?

Do us all a favor sonny, stick with foreign languages and leave the complicated stuff to those who understand it.

And yet, the papers provided for you explain in great detail how the GPS systems work and why your assertions cannot possibly fly. And, then you go on to say others don't understand this stuff. You're classic, Harry, real classic piece of work.

Harry.
Marrying a 6 year old and waiting until she reaches puberty and maturity before having consensual sex is better than walking up to
a stranger in a bar and proceeding to have relations with no valid proof of the intent of the person. Muhammad wins. ~ Fatihah
If they don't want to be killed then they have to subdue to the Islamic laws. - Uncung
Without God, you are lower than sh!t. ~ SpiritandTruth
Dirty.Harry
Posts: 1,585
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3/8/2016 2:57:01 PM
Posted: 9 months ago
At 3/7/2016 3:58:30 PM, Floid wrote:
At 3/7/2016 2:42:08 PM, Dirty.Harry wrote:
I've been discussing only one thing with you dumass, namely can position be established with satellites that have uncompensated clocks and so far I think it's very possible.

A simple use of google would provide you with more than enough information to prove your "I think" wrong. You can establish position without compensating the clocks but you will drift at about Sure. It wouldn't be the correct position and it would drift to an unusable number in minutes with drift being approximately 11km per day.

I will leave to location of this information to you as practice using google.

What you're claiming here is absolutely wrong.

Your claiming that it's impossible to measure distance between a sender and receiver unless their clocks are a) synchronized with each other and b) synchronized with GMT.

But only a) is required, so long as the two clocks run at the same rate and we know the deviation from GMT, then we can calculate the true elapsed time at the receiver.

We know the deviation from GMT (that's the value they used when they compensated the satellites, its treated as a constant) so we can easily measure absolute duration fine so long as the two clocks run at the same rate - whatever the rate may be.

Harry.;
Dirty.Harry
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3/8/2016 3:08:51 PM
Posted: 9 months ago
At 3/8/2016 2:52:19 PM, DanneJeRusse wrote:

Lying about your credentials again, Harry?

Do us all a favor sonny, stick with foreign languages and leave the complicated stuff to those who understand it.

And yet, the papers provided for you explain in great detail how the GPS systems work and why your assertions cannot possibly fly. And, then you go on to say others don't understand this stuff. You're classic, Harry, real classic piece of work.

Harry.

You're a blabber mouth Dummel, you read to much pop-science and think you understand something just because you can say X means ABC - never grasping the essence of a subject.

First you ridicule Wikipedia (when I showed it states that dark matter is hypothetical) then you quote Wikipedia when you want to show something about GPS, what qualifies you to be the judge of which Wikipedia articles are trustworthy and which aren't?

You have no such qualification and simply pick and choose whatever source you think fits with your juvenile world view.

As I just explained to someone else - measuring transit time ONLY requires the sender and receiver clocks be synchronized - run at the same rate - any deviation they have from GMT can be easily applied using trivial arithmetic ONCE the send time has been subtracted from the receive time.

Think of measuring the speed of sound - you'll find (if you actually can think for yourself) that this is possible irrespective of a clock's rate - so long as sender and receiver run at SAME rate.

Then - if we know the deviation from GMT - we can convert the interval to a true GMT seconds and voilla ! we have the correct transit time - there, that wasn't too hard was it?

Dumass.
slo1
Posts: 4,320
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3/8/2016 3:33:15 PM
Posted: 9 months ago
At 3/8/2016 2:43:54 PM, Dirty.Harry wrote:
At 3/7/2016 3:51:58 PM, slo1 wrote:
At 3/6/2016 4:52:37 PM, Dirty.Harry wrote:
At 3/6/2016 3:54:41 PM, DanneJeRusse wrote:
At 3/6/2016 3:42:37 PM, Dirty.Harry wrote:
At 3/4/2016 4:45:12 PM, DanneJeRusse wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.

Actually the word you were seeking is "purported" not "alleged" - just saying...

I have looked up numerous articles pertaining to this but have not had the time to rigorously dig into the details as I'd like to, opening up a discussion about this in the science forum isn't something I'd expect objections to but then again you are a rather odd individual.

Yes Harry, my point exactly. Yet, for some reason, you have plenty of time to post opposing, unscientific, nonsensical views of crackpots and cranks, and you call me the rather odd individual.

Let me make something very clear, I do not rely on your pop-science judgement of what is and what is not a sound scientific or technological claim.

The point upon which you and I disagree is simply this - I think a GPS system could still work, with uncompensated atomic clock's in the satellites. The calculation for 3D position on the globe's surface AND local UTC time could still be carried out - it would be a different calculation of course.

Since we know the magnitude of the clock rate difference (after all we must know it in order to have adjusted the clocks before launch) we can factor it into the calculation.

This is all I said - and was the only point upon which I agreed with the writer of the article I posted, he may well be a "crank" but I have decades of experience delivering successful complex systems and getting paid well for it, so I'm no stranger to these kinds of questions Dummel.

By all means question my abilities, skills and experience if you wish but that will lead nowhere since you know even less about me than you do about elementary science and technology.

By all means offer us your PROOF that a GPS system is impossible UNLESS the satellite's have compensated clocks, can you do that? can you offer even an article or paper perhaps that makes such a claim? Because if you cannot offer either your own or someone else's proof then I see no basis for making the allegations you are.

Harry.

Harry, sure you could do it without adjustments, however it will not be as accurare. The distance between gps reciever and satellite is measured by the duration the signal travels. If you don't adjust for time dialation it simply is not as accurate. The signal travels through the atmosphere which is not a vacuum, so there can be other variables such as humidity that impact the signal delay. That is where it gets very difficult to error correct. You error correct time dialation to eliminate that variable to signal delay, because if you dont when you add up all the other factors which can introduce errors plus time dialation you can be pretty far off. This wiki Pedia has good detail on factors which impact signal delay.

https://en.m.wikipedia.org...

But you need to understand something:

The receiver synchronizes its local clock to match the satellites, it does this iteratively. The only clock the receiver has to measure the transit time is its own, it does not sync up with any earthbound clock.

Time dilation does not impact transit time, it is the time difference between a sent timestamp message and the received timestamp message that is used.

It is not a system where the reciever sends a signal to the satelite and it bounces back. The satellite transmits a pseudo code. The reciever starts to play the same code and it is the difference between the cadence of the received code and the receiver's code that gives you the amount of diolation because the satelite and receiver are in a different frame of reference.

Another way to think of it is that ifor the satelite sends a digit once every second and the receiver also does it once a second, when you match it up on the receiver, it will not be at the same rate. That is how you adjust for time diolation by resyncronizing the rate. The time can then be set on the receiver using the satellite's time adjusted for diolation at the receiver.

Now i am syncronized with time, i can measure time from satellite to receiver and calculate distance. If I didn't do that diolation adjustment I can't truly synchronize clocks which brings in error when measuring time of data to reach satelite to receiver.

If all clocks are running somewhat too fast or too slow it will have no impact on the signal duration. all that matters is that the clocks are synchronized.

You are exactly right. To synchronise them you have to adjust for their frame a reference. A tick of a second on a satelite is a longer duration of a tick of a second on the receiver frome the frame of reference of the receiver.

If the two clocks are too fast/slow BUT by the exact same amount, then the measured transit time will be the same as if the clocks ran at the "correct" speed.

It just makes everything easier if all clocks run at the same rate as an earthbound clock but it does not make the measurement of satellite distance any more or less accurate.

Harry.
Ramshutu
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3/8/2016 4:33:53 PM
Posted: 9 months ago
At 3/8/2016 2:57:01 PM, Dirty.Harry wrote:
At 3/7/2016 3:58:30 PM, Floid wrote:
At 3/7/2016 2:42:08 PM, Dirty.Harry wrote:
I've been discussing only one thing with you dumass, namely can position be established with satellites that have uncompensated clocks and so far I think it's very possible.

A simple use of google would provide you with more than enough information to prove your "I think" wrong. You can establish position without compensating the clocks but you will drift at about Sure. It wouldn't be the correct position and it would drift to an unusable number in minutes with drift being approximately 11km per day.

I will leave to location of this information to you as practice using google.

What you're claiming here is absolutely wrong.

Your claiming that it's impossible to measure distance between a sender and receiver unless their clocks are a) synchronized with each other and b) synchronized with GMT.

But only a) is required, so long as the two clocks run at the same rate and we know the deviation from GMT, then we can calculate the true elapsed time at the receiver.

We know the deviation from GMT (that's the value they used when they compensated the satellites, its treated as a constant) so we can easily measure absolute duration fine so long as the two clocks run at the same rate - whatever the rate may be.

Harry.;

With a drift of approximately 40us per day, or 1.67us per hour, or 27ns per minute, if you received a GPS signal, in order to work out how much time to add, you need to know how much time has elapsed since the satellite took off within 90 seconds (possibly 45 seconds if two satellites have to be accurate within 90 seconds, due to compound error) to generate a time within 40ns.

Moreover, prior to attaining the fixed 40us drift rate, the rocket is taking off, and is subject to many minutes of changing drift. It's easy enough to correct the satellite time in orbit without being able to know, or quantify this drift rate exactly, or indeed correct any tiny errors that accrue due to uncertainty. If it's on a handset, this exact time would have to be quantified down to within 40ns.

So, in the receiver calculation for each satellite, you have to work out (time now - launch time) * drift rate + initial drift.

Possible sources of error, that all have to come up with less than 40ns; is the error in your measured time, error in launch time, error in your calculated drift rate, and the error in the initial drift.

The complex error, is going to be in drift rate, because if there is any error in this calculation, with more time elapsed, the overall error in the resulting multiplied adjustment factor goes up.

If you knew the drift rate up to 1ppm of the 40us, yields a 40ns in 1000 days if you know the launch time exactly. If you only know the launch time within 30 seconds; that adds 15ns potential uncertainty. and drops the number of days before you lose 40ns accuracy to about 600 ish days.

Then you have orbital maneuvers, subtle speed changes which won't add a significant amount of contribution, but will need to be indicated to the receiver, as this would add error to whatever dilation values you have; and if a subtle change in orientation or inclination changes the overall dilation effects by a tiny amount; they would add up over time.

For your Quartz clock on you're receiver, which is never really that accurate; as you can't use the satellites to synchronize your own time accurately any more, you have to find some other way to ensure your quartz clock is showing the accurate time. ITP is only accurate to a few milliseconds, so that's a non-starter. You can use UTC time broadcasts but, you guessed it, unless you know where you are, the actual time is dependent on your distance from the transmitter. So even if you looked at UTC time, your local time could be several microseconds out, which leaves you in the same position in which you started.

In reality, you probably could work around all these problems; using iterative time approaches to derive the time from the satellites and iterate to the correct time on the handset, you could set up a different broadcast system to disseminate GPS adjustment factors to all handsets for regular updates and adjustments required; but the overall system would be slower, likely not as accurate and massively impractical.

The problem with you're statement, is that you seem to be taking a very simplistic view of measurements, uncertainty and error any of the values used are not known for certain, and there is a margin for error in all of them; and most of the errors introduced by the inaccuracies in the receiver are corrected for by having the satellites being accurate, you can do it the other way around but it makes no sense.

I guess, I don't fully understand why you're mentioning any of this at all, nor what the point of pointing something like this out. Sure, you can probably do this with massive changes in technology and impractical implications that no engineer would ever consider, get an accurate fix on the ground without correcting satellites for time dilation.

Why is that even worth mentioning it? Leave alone present it as if it's something important to the conversation?

Your posts in this thread seem a bit like asking questions about racing car aerodynamics and traction physics; and then deciding to start harping on about how it's possible for a farm tractor to have jet engines strapped on it, sheets of steel for downforce, changing the steering and suspension and then use it to beat F1 cars in a free race.

Sure, it's possible, but isn't relevant to the original question, and is entirely pointless in a discussion about the relative technical factors issues you face designing race cars.
DanneJeRusse
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3/8/2016 4:38:17 PM
Posted: 9 months ago
At 3/8/2016 3:08:51 PM, Dirty.Harry wrote:
At 3/8/2016 2:52:19 PM, DanneJeRusse wrote:

Lying about your credentials again, Harry?

Do us all a favor sonny, stick with foreign languages and leave the complicated stuff to those who understand it.

And yet, the papers provided for you explain in great detail how the GPS systems work and why your assertions cannot possibly fly. And, then you go on to say others don't understand this stuff. You're classic, Harry, real classic piece of work.

Harry.

You're a blabber mouth Dummel, you read to much pop-science and think you understand something just because you can say X means ABC - never grasping the essence of a subject.

And yet, I provided links to information that has nothing to do with pop-science, while you provide links to cranks and crackpots. We can add bald faced liar to your credentials.

First you ridicule Wikipedia (when I showed it states that dark matter is hypothetical) then you quote Wikipedia when you want to show something about GPS, what qualifies you to be the judge of which Wikipedia articles are trustworthy and which aren't?

We've already been through this.

You have no such qualification and simply pick and choose whatever source you think fits with your juvenile world view.

Once again, your credential of bald face liar is showing.

As I just explained to someone else - measuring transit time ONLY requires the sender and receiver clocks be synchronized - run at the same rate - any deviation they have from GMT can be easily applied using trivial arithmetic ONCE the send time has been subtracted from the receive time.

Think of measuring the speed of sound - you'll find (if you actually can think for yourself) that this is possible irrespective of a clock's rate - so long as sender and receiver run at SAME rate.

Then - if we know the deviation from GMT - we can convert the interval to a true GMT seconds and voilla ! we have the correct transit time - there, that wasn't too hard was it?

Too bad you refused to read the material provided for you as you would then gain an understanding rather than just repeating yourself.

Dumass.

So, you've changed your signature from Harry to Dumass? Very appropriate.
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Accipiter
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3/8/2016 7:07:34 PM
Posted: 9 months ago
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Harry.

Whether or not science is right or wrong is immaterial. If time dilation (what ever it may be) is not included in GPS calculations GPS will not work. Time dilation is technology now anyway so you don't need to argue with the science anymore then you need to argue with the science that gave us computers, cell phones or the monitor you are reading this on right now, unless you are a total moron.
slo1
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3/8/2016 10:38:38 PM
Posted: 9 months ago
I've reread this string Harry, including my inept English and spelling when I type on my cell phone. I really think the thing you are missing is the fact that from the frame of the receiver a one second duration from the satellite is longer than the duration of one second on the receiver. That tiny difference makes an impact when calculating the time it took the satellite to send some data to the time the receiver receives the data, which in turn impacts the calculated distance.
Dirty.Harry
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3/9/2016 1:32:52 PM
Posted: 9 months ago
At 3/8/2016 3:33:15 PM, slo1 wrote:
At 3/8/2016 2:43:54 PM, Dirty.Harry wrote:
At 3/7/2016 3:51:58 PM, slo1 wrote:
At 3/6/2016 4:52:37 PM, Dirty.Harry wrote:
At 3/6/2016 3:54:41 PM, DanneJeRusse wrote:
At 3/6/2016 3:42:37 PM, Dirty.Harry wrote:
At 3/4/2016 4:45:12 PM, DanneJeRusse wrote:
At 3/4/2016 2:58:19 PM, Dirty.Harry wrote:
AS you may know the satellite's used for GPS each contain very very stable atomic clocks (these are the most stable oscillators we can devise, far beyond what's possible with quartz crystal designs).

What is less know is that the clocks in the satellites have been adjusted to run at a lower frequency to compensate for relativistic effects. The goal being that when observed from the ground they'll be seen to run at the same rate as a local atomic clock and they'll remain synchronized (to a greater degree).

My question is that how can we make such an adjustment when the magnitude of the relativistic effect differs among different observers?

The largest effect is that due to gravitation and this varies with the altitude of the observer, so how can one compensate for both ground based and high altitude aircraft with a single adjustment to the satellite's clock?

Once again, Harry, your alleged credentials fail you, considering this is information you could have easily looked up yourself, that is, if you are accredited to having the credentials you claims to have. Will you now be presenting some more wacky woo woo websites?

Harry.

Actually the word you were seeking is "purported" not "alleged" - just saying...

I have looked up numerous articles pertaining to this but have not had the time to rigorously dig into the details as I'd like to, opening up a discussion about this in the science forum isn't something I'd expect objections to but then again you are a rather odd individual.

Yes Harry, my point exactly. Yet, for some reason, you have plenty of time to post opposing, unscientific, nonsensical views of crackpots and cranks, and you call me the rather odd individual.

Let me make something very clear, I do not rely on your pop-science judgement of what is and what is not a sound scientific or technological claim.

The point upon which you and I disagree is simply this - I think a GPS system could still work, with uncompensated atomic clock's in the satellites. The calculation for 3D position on the globe's surface AND local UTC time could still be carried out - it would be a different calculation of course.

Since we know the magnitude of the clock rate difference (after all we must know it in order to have adjusted the clocks before launch) we can factor it into the calculation.

This is all I said - and was the only point upon which I agreed with the writer of the article I posted, he may well be a "crank" but I have decades of experience delivering successful complex systems and getting paid well for it, so I'm no stranger to these kinds of questions Dummel.

By all means question my abilities, skills and experience if you wish but that will lead nowhere since you know even less about me than you do about elementary science and technology.

By all means offer us your PROOF that a GPS system is impossible UNLESS the satellite's have compensated clocks, can you do that? can you offer even an article or paper perhaps that makes such a claim? Because if you cannot offer either your own or someone else's proof then I see no basis for making the allegations you are.

Harry.

Harry, sure you could do it without adjustments, however it will not be as accurare. The distance between gps reciever and satellite is measured by the duration the signal travels. If you don't adjust for time dialation it simply is not as accurate. The signal travels through the atmosphere which is not a vacuum, so there can be other variables such as humidity that impact the signal delay. That is where it gets very difficult to error correct. You error correct time dialation to eliminate that variable to signal delay, because if you dont when you add up all the other factors which can introduce errors plus time dialation you can be pretty far off. This wiki Pedia has good detail on factors which impact signal delay.

https://en.m.wikipedia.org...

But you need to understand something:

The receiver synchronizes its local clock to match the satellites, it does this iteratively. The only clock the receiver has to measure the transit time is its own, it does not sync up with any earthbound clock.

Time dilation does not impact transit time, it is the time difference between a sent timestamp message and the received timestamp message that is used.

It is not a system where the reciever sends a signal to the satelite and it bounces back.

Thanks for telling me something I already know!

The satellite transmits a pseudo code. The reciever starts to play the same code and it is the difference between the cadence of the received code and the receiver's code that gives you the amount of diolation because the satelite and receiver are in a different frame of reference.

Another way to think of it is that ifor the satelite sends a digit once every second and the receiver also does it once a second, when you match it up on the receiver, it will not be at the same rate. That is how you adjust for time diolation by resyncronizing the rate. The time can then be set on the receiver using the satellite's time adjusted for diolation at the receiver.

Now i am syncronized with time, i can measure time from satellite to receiver and calculate distance. If I didn't do that diolation adjustment I can't truly synchronize clocks which brings in error when measuring time of data to reach satelite to receiver.

If all clocks are running somewhat too fast or too slow it will have no impact on the signal duration. all that matters is that the clocks are synchronized.

You are exactly right. To synchronise them you have to adjust for their frame a reference. A tick of a second on a satelite is a longer duration of a tick of a second on the receiver frome the frame of reference of the receiver.

If the two clocks are too fast/slow BUT by the exact same amount, then the measured transit time will be the same as if the clocks ran at the "correct" speed.

It just makes everything easier if all clocks run at the same rate as an earthbound clock but it does not make the measurement of satellite distance any more or less accurate.

Harry.
Dirty.Harry
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3/9/2016 1:40:44 PM
Posted: 9 months ago
At 3/8/2016 4:33:53 PM, Ramshutu wrote:
At 3/8/2016 2:57:01 PM, Dirty.Harry wrote:
At 3/7/2016 3:58:30 PM, Floid wrote:
At 3/7/2016 2:42:08 PM, Dirty.Harry wrote:
I've been discussing only one thing with you dumass, namely can position be established with satellites that have uncompensated clocks and so far I think it's very possible.

A simple use of google would provide you with more than enough information to prove your "I think" wrong. You can establish position without compensating the clocks but you will drift at about Sure. It wouldn't be the correct position and it would drift to an unusable number in minutes with drift being approximately 11km per day.

I will leave to location of this information to you as practice using google.

What you're claiming here is absolutely wrong.

Your claiming that it's impossible to measure distance between a sender and receiver unless their clocks are a) synchronized with each other and b) synchronized with GMT.

But only a) is required, so long as the two clocks run at the same rate and we know the deviation from GMT, then we can calculate the true elapsed time at the receiver.

We know the deviation from GMT (that's the value they used when they compensated the satellites, its treated as a constant) so we can easily measure absolute duration fine so long as the two clocks run at the same rate - whatever the rate may be.

Harry.;


With a drift of approximately 40us per day, or 1.67us per hour, or 27ns per minute, if you received a GPS signal, in order to work out how much time to add, you need to know how much time has elapsed since the satellite took off within 90 seconds (possibly 45 seconds if two satellites have to be accurate within 90 seconds, due to compound error) to generate a time within 40ns.

Moreover, prior to attaining the fixed 40us drift rate, the rocket is taking off, and is subject to many minutes of changing drift. It's easy enough to correct the satellite time in orbit without being able to know, or quantify this drift rate exactly, or indeed correct any tiny errors that accrue due to uncertainty. If it's on a handset, this exact time would have to be quantified down to within 40ns.

So, in the receiver calculation for each satellite, you have to work out (time now - launch time) * drift rate + initial drift.

Possible sources of error, that all have to come up with less than 40ns; is the error in your measured time, error in launch time, error in your calculated drift rate, and the error in the initial drift.

The complex error, is going to be in drift rate, because if there is any error in this calculation, with more time elapsed, the overall error in the resulting multiplied adjustment factor goes up.

If you knew the drift rate up to 1ppm of the 40us, yields a 40ns in 1000 days if you know the launch time exactly. If you only know the launch time within 30 seconds; that adds 15ns potential uncertainty. and drops the number of days before you lose 40ns accuracy to about 600 ish days.

Then you have orbital maneuvers, subtle speed changes which won't add a significant amount of contribution, but will need to be indicated to the receiver, as this would add error to whatever dilation values you have; and if a subtle change in orientation or inclination changes the overall dilation effects by a tiny amount; they would add up over time.

For your Quartz clock on you're receiver, which is never really that accurate; as you can't use the satellites to synchronize your own time accurately any more, you have to find some other way to ensure your quartz clock is showing the accurate time. ITP is only accurate to a few milliseconds, so that's a non-starter. You can use UTC time broadcasts but, you guessed it, unless you know where you are, the actual time is dependent on your distance from the transmitter. So even if you looked at UTC time, your local time could be several microseconds out, which leaves you in the same position in which you started.

In reality, you probably could work around all these problems; using iterative time approaches to derive the time from the satellites and iterate to the correct time on the handset, you could set up a different broadcast system to disseminate GPS adjustment factors to all handsets for regular updates and adjustments required; but the overall system would be slower, likely not as accurate and massively impractical.

The problem with you're statement, is that you seem to be taking a very simplistic view of measurements, uncertainty and error any of the values used are not known for certain, and there is a margin for error in all of them; and most of the errors introduced by the inaccuracies in the receiver are corrected for by having the satellites being accurate, you can do it the other way around but it makes no sense.

I guess, I don't fully understand why you're mentioning any of this at all, nor what the point of pointing something like this out. Sure, you can probably do this with massive changes in technology and impractical implications that no engineer would ever consider, get an accurate fix on the ground without correcting satellites for time dilation.

Why is that even worth mentioning it? Leave alone present it as if it's something important to the conversation?

Your posts in this thread seem a bit like asking questions about racing car aerodynamics and traction physics; and then deciding to start harping on about how it's possible for a farm tractor to have jet engines strapped on it, sheets of steel for downforce, changing the steering and suspension and then use it to beat F1 cars in a free race.

Sure, it's possible, but isn't relevant to the original question, and is entirely pointless in a discussion about the relative technical factors issues you face designing race cars.

All I've said is that its possible, I've also repeatedly said that it simplifies everything if we DO adjust the atomic clocks, no argument about that, I've simply been trying to educate Dumass to think for himself once instead of regurgitating every little Wikipedia article he reads verbatim.

The satellite clocks are calibrated daily anyway (from an earthbound station) so I'm well aware of the practicalities.

Harry.
Dirty.Harry
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3/9/2016 1:42:44 PM
Posted: 9 months ago
At 3/8/2016 4:38:17 PM, DanneJeRusse wrote:
At 3/8/2016 3:08:51 PM, Dirty.Harry wrote:
At 3/8/2016 2:52:19 PM, DanneJeRusse wrote:

Lying about your credentials again, Harry?

Do us all a favor sonny, stick with foreign languages and leave the complicated stuff to those who understand it.

And yet, the papers provided for you explain in great detail how the GPS systems work and why your assertions cannot possibly fly. And, then you go on to say others don't understand this stuff. You're classic, Harry, real classic piece of work.

Harry.

You're a blabber mouth Dummel, you read to much pop-science and think you understand something just because you can say X means ABC - never grasping the essence of a subject.

And yet, I provided links to information that has nothing to do with pop-science, while you provide links to cranks and crackpots. We can add bald faced liar to your credentials.

First you ridicule Wikipedia (when I showed it states that dark matter is hypothetical) then you quote Wikipedia when you want to show something about GPS, what qualifies you to be the judge of which Wikipedia articles are trustworthy and which aren't?

We've already been through this.

You have no such qualification and simply pick and choose whatever source you think fits with your juvenile world view.

Once again, your credential of bald face liar is showing.

As I just explained to someone else - measuring transit time ONLY requires the sender and receiver clocks be synchronized - run at the same rate - any deviation they have from GMT can be easily applied using trivial arithmetic ONCE the send time has been subtracted from the receive time.

Think of measuring the speed of sound - you'll find (if you actually can think for yourself) that this is possible irrespective of a clock's rate - so long as sender and receiver run at SAME rate.

Then - if we know the deviation from GMT - we can convert the interval to a true GMT seconds and voilla ! we have the correct transit time - there, that wasn't too hard was it?

Too bad you refused to read the material provided for you as you would then gain an understanding rather than just repeating yourself.

Dumass.

So, you've changed your signature from Harry to Dumass? Very appropriate.

So, is Wikipedia an authoritative source when discussing science? yes or no?

If not then why should we rely on your judgement to decide which articles are trustworthy and which are not?

If so, then do you agree that dark matter is considered hypothetical, not experimentally verified?

Harry.