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Querstion DannelJRusse is cared to answer

Dirty.Harry
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3/13/2016 5:03:13 PM
Posted: 8 months ago
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.
Ramshutu
Posts: 4,063
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3/13/2016 6:00:16 PM
Posted: 8 months ago
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.
Dirty.Harry
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3/13/2016 6:09:26 PM
Posted: 8 months ago
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.
Ramshutu
Posts: 4,063
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3/13/2016 10:59:07 PM
Posted: 8 months ago
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.
RuvDraba
Posts: 6,033
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3/14/2016 12:45:31 AM
Posted: 8 months ago
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
You have a stopwatch that you KNOW gains a second every minute. Can we use that to measure an athlete's speed?
Yes, as long as the stopwatch is running fast for the whole duration of the athlete's run. If the watch started gaining part-way through the run, then you won't know the athlete's speed or position with any accuracy, unless you also know when the watch started gaining time.

(This does connect to your previous thread, Harry, but it's a strained connection due to the strained nature of your analogy.)
Dirty.Harry
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3/14/2016 2:19:07 PM
Posted: 8 months ago
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Harry.
Dirty.Harry
Posts: 1,559
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3/14/2016 2:23:11 PM
Posted: 8 months ago
At 3/14/2016 12:45:31 AM, RuvDraba wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
You have a stopwatch that you KNOW gains a second every minute. Can we use that to measure an athlete's speed?
Yes, as long as the stopwatch is running fast for the whole duration of the athlete's run. If the watch started gaining part-way through the run, then you won't know the athlete's speed or position with any accuracy, unless you also know when the watch started gaining time.

(This does connect to your previous thread, Harry, but it's a strained connection due to the strained nature of your analogy.)

Indeed the stopwatch runs at the constant mathematical rate (relative to GMT) of 61/60 seconds per GMT second.

As you say - under these circumstances - it poses no problem to measure the athlete's speed we just take the measured stopwatch value in seconds and multiply it by 60/61.

This demonstrates that a clock suffering a fixed deviation in its rate can be used to measure time intervals with as much accuracy as a clock suffering no deviation, would you (or Dummel!) agree?

Harry.
Ramshutu
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3/14/2016 2:33:51 PM
Posted: 8 months ago
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Harry.

If you paid attention you would see I already had, in the post where you raised that question rather than having yet another thread where you can say the same thing. In that thread also, I also pointed that I don't approve of DJRs behavior, but explained that you have agreed with him on his original points and you changed your argument, indeed even here, im not defending him, just pointing out that you regularly do the same so by no means can claim any high ground here.
DanneJeRusse
Posts: 12,566
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3/14/2016 2:50:44 PM
Posted: 8 months ago
At 3/14/2016 2:23:11 PM, Dirty.Harry wrote:
At 3/14/2016 12:45:31 AM, RuvDraba wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
You have a stopwatch that you KNOW gains a second every minute. Can we use that to measure an athlete's speed?
Yes, as long as the stopwatch is running fast for the whole duration of the athlete's run. If the watch started gaining part-way through the run, then you won't know the athlete's speed or position with any accuracy, unless you also know when the watch started gaining time.

(This does connect to your previous thread, Harry, but it's a strained connection due to the strained nature of your analogy.)

Indeed the stopwatch runs at the constant mathematical rate (relative to GMT) of 61/60 seconds per GMT second.

As you say - under these circumstances - it poses no problem to measure the athlete's speed we just take the measured stopwatch value in seconds and multiply it by 60/61.

This demonstrates that a clock suffering a fixed deviation in its rate can be used to measure time intervals with as much accuracy as a clock suffering no deviation, would you (or Dummel!) agree?

You can read my signature line, Harry, in which you have accused me of exactly what you're doing.

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
DanneJeRusse
Posts: 12,566
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3/14/2016 2:52:31 PM
Posted: 8 months ago
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

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
DanneJeRusse
Posts: 12,566
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3/14/2016 2:53:20 PM
Posted: 8 months ago
Btw Harry, you sure made a mess out of the title. lol
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
Ramshutu
Posts: 4,063
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3/14/2016 3:15:18 PM
Posted: 8 months ago
At 3/14/2016 2:52:31 PM, DanneJeRusse wrote:
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

Harry.

D, I think he actually broadly understands relativity. He just don't have a firm grasp of what parameters of the system you can know to any degree of accuracy.

For example, to get an accurate timing, you need to know clock differentials between the two clocks (knowing one side isn't useful), and have a time when you know the clocks tell the same time, and know that to a high degree of accuracy even though the only way of agreeing the time needs to be based on a time you receive which has a time delay based upon the distance between sender and receiver; the very thing that is unknown and trying to be derived!
DanneJeRusse
Posts: 12,566
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3/14/2016 3:48:13 PM
Posted: 8 months ago
At 3/14/2016 3:15:18 PM, Ramshutu wrote:
At 3/14/2016 2:52:31 PM, DanneJeRusse wrote:
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

Harry.

D, I think he actually broadly understands relativity.

It doesn't seem that he does understand relativity, that he's just capitulating the fact relativistic effects have to be taken into consideration and that he wants to show it doesn't. To me, that warrants a lack of understanding.

He just don't have a firm grasp of what parameters of the system you can know to any degree of accuracy.

For example, to get an accurate timing, you need to know clock differentials between the two clocks (knowing one side isn't useful), and have a time when you know the clocks tell the same time, and know that to a high degree of accuracy even though the only way of agreeing the time needs to be based on a time you receive which has a time delay based upon the distance between sender and receiver; the very thing that is unknown and trying to be derived!

Agreed, but then Harry started making some sort of calculations that made no sense demanding others try and correct his misunderstandings.
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
Ramshutu
Posts: 4,063
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3/14/2016 3:56:23 PM
Posted: 8 months ago
At 3/14/2016 3:48:13 PM, DanneJeRusse wrote:
At 3/14/2016 3:15:18 PM, Ramshutu wrote:
At 3/14/2016 2:52:31 PM, DanneJeRusse wrote:
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

Harry.

D, I think he actually broadly understands relativity.

It doesn't seem that he does understand relativity, that he's just capitulating the fact relativistic effects have to be taken into consideration and that he wants to show it doesn't. To me, that warrants a lack of understanding.

He just don't have a firm grasp of what parameters of the system you can know to any degree of accuracy.

For example, to get an accurate timing, you need to know clock differentials between the two clocks (knowing one side isn't useful), and have a time when you know the clocks tell the same time, and know that to a high degree of accuracy even though the only way of agreeing the time needs to be based on a time you receive which has a time delay based upon the distance between sender and receiver; the very thing that is unknown and trying to be derived!

Agreed, but then Harry started making some sort of calculations that made no sense demanding others try and correct his misunderstandings.

I think that last part is mostly correct. There is an element of truth to some of the things he's been saying, but some of his calculations and assertions have been very naive interpretations that don't understand the realities or practicalities of what is going on.
DanneJeRusse
Posts: 12,566
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3/14/2016 4:06:31 PM
Posted: 8 months ago
At 3/14/2016 3:56:23 PM, Ramshutu wrote:
At 3/14/2016 3:48:13 PM, DanneJeRusse wrote:
At 3/14/2016 3:15:18 PM, Ramshutu wrote:
At 3/14/2016 2:52:31 PM, DanneJeRusse wrote:
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

Harry.

D, I think he actually broadly understands relativity.

It doesn't seem that he does understand relativity, that he's just capitulating the fact relativistic effects have to be taken into consideration and that he wants to show it doesn't. To me, that warrants a lack of understanding.

He just don't have a firm grasp of what parameters of the system you can know to any degree of accuracy.

For example, to get an accurate timing, you need to know clock differentials between the two clocks (knowing one side isn't useful), and have a time when you know the clocks tell the same time, and know that to a high degree of accuracy even though the only way of agreeing the time needs to be based on a time you receive which has a time delay based upon the distance between sender and receiver; the very thing that is unknown and trying to be derived!

Agreed, but then Harry started making some sort of calculations that made no sense demanding others try and correct his misunderstandings.

I think that last part is mostly correct. There is an element of truth to some of the things he's been saying,

Perhaps, but the key components of what Harry is missing are the components requiring the taking into account of relativistic effects, Harry just doesn't get that, he can't seem to wrap his head around the counter-intuitive aspects of relativity and frames of reference.

but some of his calculations and assertions have been very naive interpretations that don't understand the realities or practicalities of what is going on.
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
RuvDraba
Posts: 6,033
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3/14/2016 5:17:56 PM
Posted: 8 months ago
At 3/14/2016 2:23:11 PM, Dirty.Harry wrote:
At 3/14/2016 12:45:31 AM, RuvDraba wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
You have a stopwatch that you KNOW gains a second every minute. Can we use that to measure an athlete's speed?
Yes, as long as the stopwatch is running fast for the whole duration of the athlete's run. If the watch started gaining part-way through the run, then you won't know the athlete's speed or position with any accuracy, unless you also know when the watch started gaining time.
(This does connect to your previous thread, Harry, but it's a strained connection due to the strained nature of your analogy.)
Indeed the stopwatch runs at the constant mathematical rate (relative to GMT) of 61/60 seconds per GMT second.
As you say - under these circumstances - it poses no problem to measure the athlete's speed we just take the measured stopwatch value in seconds and multiply it by 60/61.

Yes, if that's what you were doing, that would work.

Unfortunately, what you want with GPS satellites isn't their speed but the distance to their known position, calculated by the time delay between transmission and receipt as measured by two synchronised clocks.

If T1 is the time it sent the signal, T2 is the time you received it, and c is the speed of light, then the distance D is given by:

D = (T2 - T1) / c.

So far so good, yes?

Now, here's the complicating problem: at time T0, the satellite began running fast by amount k. So the corrected time of transmission is actually:
T1 / (1 + k.(T1 -T0))

So the corrected distance to the satellite is actually given by:
D = (T2 - T1 / (1 + (k.T1 - T0))) / c

We know k is constant for all satellites because they're at similar height and speed, we know T2 from the receiver clock, and each satellite sends us its own T1, but who sends us T0 for each satellite? Will the satellite send it? How can it be sure of its own precise T0 value? Will a NASA ground station publish T0 for each satellite? What if your receiver isn't in contact with a NASA ground station?

This is why the problem is more complicated than your analogy, Harry:
1) You have three or more satellites, each with their own clock, plus you have your own local clock'
2) You want distance to the satellite, not satellite speed;
3) Distance is calculated from the time delay between the send-time and receive-time of synchronised clocks;
4) The clocks aren't perfectly synchronised because each sending clock is running fast by a fixed amount; and
5) It's further complicated because to recover synchronisation, you need to know for each clock, how long it has been running fast.
Dirty.Harry
Posts: 1,559
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3/14/2016 6:55:25 PM
Posted: 8 months ago
At 3/14/2016 2:52:31 PM, DanneJeRusse wrote:
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

Harry.

But the cause of the stopwatch's deviation has no bearing on the calculations. Whether the clock used goes fast because of a mechanical fault, worn spring or because its orbiting 20,000 km up in a weaker gravitational field has no bearing.

So long we as know by how fast it runs, we can measure time fine and hence distance.

It's you who clearly has and always has trouble understanding, as is evidenced by this and many of your other confused, inaccurate and rambling responses to simple questions.

Harry.
Dirty.Harry
Posts: 1,559
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3/14/2016 7:15:05 PM
Posted: 8 months ago
At 3/14/2016 3:15:18 PM, Ramshutu wrote:
At 3/14/2016 2:52:31 PM, DanneJeRusse wrote:
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

Harry.

D, I think he actually broadly understands relativity. He just don't have a firm grasp of what parameters of the system you can know to any degree of accuracy.

For example, to get an accurate timing, you need to know clock differentials between the two clocks (knowing one side isn't useful), and have a time when you know the clocks tell the same time, and know that to a high degree of accuracy even though the only way of agreeing the time needs to be based on a time you receive which has a time delay based upon the distance between sender and receiver; the very thing that is unknown and trying to be derived!

Firstly a GPS receiver's clock is set (when switched on) ONLY by iteratively analyzing signals received from multiple satellites Ramshutu. It's clock has no ability to access a ground based clock or time service, everything is deduced from the satellite signals.

Transmitted messages are uniquely timestamped by the sender, all satellites are synchronized with one another.

Because each signal/message contains both time_sent and current_position the receiver is able to deduce where it must be in order for signals sent at the same time to be received at the times they are received.

Each satellite might send a message at 12:00:00 (their time) along with their respective positions.

These will be sent at the same instant but get received at differing time depending on the proximity of the receiver to each satellite.

If the receiver receives these messages for example:

Sat_A 12:00:00 arriving at 12:00:00.008
Sat_B 12:00:00 arriving at 12:00:00.010
Sat_C 12:00:00 arriving at 12:00:00.035
Sat_D 12:00:00 arriving at 12:00:00.027

then it's able to deduce where it must be situated on the earth's surface in order to receive these signals (which arrive at different times) and what the local time must be in order to make these time self-consistent.

None of this is impacted if these message times are off by 3 picoseconds.

Of course IF the satellites are compensated THEN the receiver clock will match true GMT and I've stated this several time, but leaving aside the ability for the receiver to know the true time, its position finding ability will work fine with uncompensated satellite clocks.

Harry.
Dirty.Harry
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3/14/2016 7:31:39 PM
Posted: 8 months ago
At 3/14/2016 4:06:31 PM, DanneJeRusse wrote:
At 3/14/2016 3:56:23 PM, Ramshutu wrote:
At 3/14/2016 3:48:13 PM, DanneJeRusse wrote:
At 3/14/2016 3:15:18 PM, Ramshutu wrote:
At 3/14/2016 2:52:31 PM, DanneJeRusse wrote:
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

Harry.

D, I think he actually broadly understands relativity.

It doesn't seem that he does understand relativity, that he's just capitulating the fact relativistic effects have to be taken into consideration and that he wants to show it doesn't. To me, that warrants a lack of understanding.

He just don't have a firm grasp of what parameters of the system you can know to any degree of accuracy.

For example, to get an accurate timing, you need to know clock differentials between the two clocks (knowing one side isn't useful), and have a time when you know the clocks tell the same time, and know that to a high degree of accuracy even though the only way of agreeing the time needs to be based on a time you receive which has a time delay based upon the distance between sender and receiver; the very thing that is unknown and trying to be derived!

Agreed, but then Harry started making some sort of calculations that made no sense demanding others try and correct his misunderstandings.

I think that last part is mostly correct. There is an element of truth to some of the things he's been saying,

Perhaps, but the key components of what Harry is missing are the components requiring the taking into account of relativistic effects, Harry just doesn't get that, he can't seem to wrap his head around the counter-intuitive aspects of relativity and frames of reference.

but some of his calculations and assertions have been very naive interpretations that don't understand the realities or practicalities of what is going on.

The ONLY effect relativity has here is that orbiting clocks tick faster than ground based clocks, that is they count 24 hours and 38 ms when the ground clock ticks 24 hours and 0 ms.

I'm not denying or misunderstanding anything, everything I've written above is correct, true statements.

You seem obsessed with relativity and your supposed intimate knowledge of it, that's fine and your choice but I was studying the subject in the 70s including many original publications by the likes of Weyl, Eddington, Gauss and others.

However there is no objective way in this forum for me to demonstrate anything to your satisfaction, there's no real-time chat we can both have with a Prof of theoretical physics to judge our respective understandings.

What you've completely misunderstood here all along is that the cause (relativity) is unimportant but the effect (faster ticking when in orbit) is all important.

Harry.
Dirty.Harry
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3/14/2016 7:45:41 PM
Posted: 8 months ago
At 3/14/2016 3:48:13 PM, DanneJeRusse wrote:
At 3/14/2016 3:15:18 PM, Ramshutu wrote:
At 3/14/2016 2:52:31 PM, DanneJeRusse wrote:
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

Harry.

D, I think he actually broadly understands relativity.

It doesn't seem that he does understand relativity, that he's just capitulating the fact relativistic effects have to be taken into consideration and that he wants to show it doesn't. To me, that warrants a lack of understanding.

To you perhaps but that means very little since I consider your understanding to be not only naive but also confused.

One doesn't even need to understand relativity at all, all that matters is that orbiting clocks at 20,200 km tick too fast - by 38 ms per day - that's it, period. The origin of that is immaterial be it relativity or mechanical defects or poor design or anything else.

My position was and is (after seeing your and other's replies and reading more on GPS each week) that it is not essential to compensate satellite clocks for relativity if one is ONLY concerned with establishing geographic position at the receiver.

Establishing true GMT at the receiver though does require compensation.

Harry.
Ramshutu
Posts: 4,063
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3/14/2016 7:57:35 PM
Posted: 8 months ago
At 3/14/2016 7:15:05 PM, Dirty.Harry wrote:
At 3/14/2016 3:15:18 PM, Ramshutu wrote:
At 3/14/2016 2:52:31 PM, DanneJeRusse wrote:
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

Harry.

D, I think he actually broadly understands relativity. He just don't have a firm grasp of what parameters of the system you can know to any degree of accuracy.

For example, to get an accurate timing, you need to know clock differentials between the two clocks (knowing one side isn't useful), and have a time when you know the clocks tell the same time, and know that to a high degree of accuracy even though the only way of agreeing the time needs to be based on a time you receive which has a time delay based upon the distance between sender and receiver; the very thing that is unknown and trying to be derived!

Firstly a GPS receiver's clock is set (when switched on) ONLY by iteratively analyzing signals received from multiple satellites Ramshutu. It's clock has no ability to access a ground based clock or time service, everything is deduced from the satellite signals.

Transmitted messages are uniquely timestamped by the sender, all satellites are synchronized with one another.

Because each signal/message contains both time_sent and current_position the receiver is able to deduce where it must be in order for signals sent at the same time to be received at the times they are received.

Each satellite might send a message at 12:00:00 (their time) along with their respective positions.

These will be sent at the same instant but get received at differing time depending on the proximity of the receiver to each satellite.

If the receiver receives these messages for example:

Sat_A 12:00:00 arriving at 12:00:00.008
Sat_B 12:00:00 arriving at 12:00:00.010
Sat_C 12:00:00 arriving at 12:00:00.035
Sat_D 12:00:00 arriving at 12:00:00.027

then it's able to deduce where it must be situated on the earth's surface in order to receive these signals (which arrive at different times) and what the local time must be in order to make these time self-consistent.

None of this is impacted if these message times are off by 3 picoseconds.

Of course IF the satellites are compensated THEN the receiver clock will match true GMT and I've stated this several time, but leaving aside the ability for the receiver to know the true time, its position finding ability will work fine with uncompensated satellite clocks.

Harry.

Far be it from me to question your ever changing position that you seem to pretend is the same thing all along, but if the satellites or receiver don't have the right time, they won't have the right position either which adds error, which has to be corrected for regularly. Moreover this method can't account for receiver clock error, which could be wrong by between 6-50ppm given standard Quartz clocks, If the receiver is not synced to the satellite, and it's wrong by 50ppm, a time received delta of 10ms, could actually report a time delta of between 60ns and 500ns. That would grossly effect height accuracy. So you need to sync clocks, UTC broadcasts and NTP isn't going to be accurate enough to measure your clock difference, because they'll suffer the same problems of sync accuracy.

In reality though, as I said in the other thread, the system needs to have 40ns accuracy including stuff that can't be corrected for; the stuff that can be corrected for, position and clock errors, for example, can only be done accurately by syncing to a satellites clock over multiple iterations. If you do that, you will take into account time dilation: your receiver clock will show a 38us/drift against an atomic clock. Which isnt a problem, but is a practical concern as you now cannot sync to UTC so as to acquire a more accurate lock more quickly on the satellite, or sync to the satellite to gain a more accurate time than you would by UTC.
Dirty.Harry
Posts: 1,559
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3/14/2016 8:57:12 PM
Posted: 8 months ago
At 3/14/2016 7:57:35 PM, Ramshutu wrote:
At 3/14/2016 7:15:05 PM, Dirty.Harry wrote:
At 3/14/2016 3:15:18 PM, Ramshutu wrote:
At 3/14/2016 2:52:31 PM, DanneJeRusse wrote:
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

Harry.

D, I think he actually broadly understands relativity. He just don't have a firm grasp of what parameters of the system you can know to any degree of accuracy.

For example, to get an accurate timing, you need to know clock differentials between the two clocks (knowing one side isn't useful), and have a time when you know the clocks tell the same time, and know that to a high degree of accuracy even though the only way of agreeing the time needs to be based on a time you receive which has a time delay based upon the distance between sender and receiver; the very thing that is unknown and trying to be derived!

Firstly a GPS receiver's clock is set (when switched on) ONLY by iteratively analyzing signals received from multiple satellites Ramshutu. It's clock has no ability to access a ground based clock or time service, everything is deduced from the satellite signals.

Transmitted messages are uniquely timestamped by the sender, all satellites are synchronized with one another.

Because each signal/message contains both time_sent and current_position the receiver is able to deduce where it must be in order for signals sent at the same time to be received at the times they are received.

Each satellite might send a message at 12:00:00 (their time) along with their respective positions.

These will be sent at the same instant but get received at differing time depending on the proximity of the receiver to each satellite.

If the receiver receives these messages for example:

Sat_A 12:00:00 arriving at 12:00:00.008
Sat_B 12:00:00 arriving at 12:00:00.010
Sat_C 12:00:00 arriving at 12:00:00.035
Sat_D 12:00:00 arriving at 12:00:00.027

then it's able to deduce where it must be situated on the earth's surface in order to receive these signals (which arrive at different times) and what the local time must be in order to make these time self-consistent.

None of this is impacted if these message times are off by 3 picoseconds.

Of course IF the satellites are compensated THEN the receiver clock will match true GMT and I've stated this several time, but leaving aside the ability for the receiver to know the true time, its position finding ability will work fine with uncompensated satellite clocks.

Harry.

Far be it from me to question your ever changing position that you seem to pretend is the same thing all along,

My position has not changed: "it isnt necessary to compensate satellite clocks for relativistic effects in order to be able to determine geographic position".

but if the satellites or receiver don't have the right time, they won't have the right position either which adds error, which has to be corrected for regularly. Moreover this method can't account for receiver clock error, which could be wrong by between 6-50ppm given standard Quartz clocks, If the receiver is not synced to the satellite, and it's wrong by 50ppm, a time received delta of 10ms, could actually report a time delta of between 60ns and 500ns. That would grossly effect height accuracy. So you need to sync clocks, UTC broadcasts and NTP isn't going to be accurate enough to measure your clock difference, because they'll suffer the same problems of sync accuracy.


The receiver is concerned ONLY with counting the interval between receiving a message with some pseudo-random-code and the prior generation of that same code locally.

The purpose of receiver clock synching is to get it generating pseudo-random-code at the same time that satellites generate them, then it can measure transit intervals.

http://gpsinformation.net...

In reality though, as I said in the other thread, the system needs to have 40ns accuracy including stuff that can't be corrected for; the stuff that can be corrected for, position and clock errors, for example, can only be done accurately by syncing to a satellites clock over multiple iterations. If you do that, you will take into account time dilation: your receiver clock will show a 38us/drift against an atomic clock. Which isnt a problem, but is a practical concern as you now cannot sync to UTC so as to acquire a more accurate lock more quickly on the satellite, or sync to the satellite to gain a more accurate time than you would by UTC.

To establish our position ONLY we don't care what "time it is" only how far away is each satellite and we can establish that by syncing which is explained in that article.
DanneJeRusse
Posts: 12,566
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3/14/2016 9:03:58 PM
Posted: 8 months ago
At 3/14/2016 6:55:25 PM, Dirty.Harry wrote:
At 3/14/2016 2:52:31 PM, DanneJeRusse wrote:
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

Harry.

But the cause of the stopwatch's deviation has no bearing on the calculations. Whether the clock used goes fast because of a mechanical fault, worn spring or because its orbiting 20,000 km up in a weaker gravitational field has no bearing.

That is not correct, Harry, and that is the same mistake you keep making over and over. A clock that is built from the ground up to take relativistic effects into consideration are not simply indistinguishable from a mechanical fault or worn spring on a regular clock. These effects are real, Harry, on the function and purpose of the entire mechanical operations and are continuous as long as the satellite is in orbit.

So long we as know by how fast it runs, we can measure time fine and hence distance.

So, instead, the clocks are built and programmed how fast we want them to run, taking into consideration the effects of velocity and gravity transformation. Simple.

It's you who clearly has and always has trouble understanding, as is evidenced by this and many of your other confused, inaccurate and rambling responses to simple questions.

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
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3/14/2016 9:25:25 PM
Posted: 8 months ago
At 3/14/2016 9:03:58 PM, DanneJeRusse wrote:
At 3/14/2016 6:55:25 PM, Dirty.Harry wrote:
At 3/14/2016 2:52:31 PM, DanneJeRusse wrote:
At 3/14/2016 2:19:07 PM, Dirty.Harry wrote:
At 3/13/2016 10:59:07 PM, Ramshutu wrote:
At 3/13/2016 6:09:26 PM, Dirty.Harry wrote:
At 3/13/2016 6:00:16 PM, Ramshutu wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
"Just imagine you have a stopwatch that you KNOW gains a second every minute. Well can we use that to measure an athlete's speed? Do we need to know what time it is in order to measure that speed?"

Everyone please watch and note how Dannel refuses to answer, how he habitually refuses to answer whenever pressed, preferring vacuities and insults.

Surely anyone who considers themselves scientifically literate Dannel would leverage that literacy, demonstrate their expertise by honestly answering questions about science?

Anyway, lets see shall we, perhaps he will attempt to rescue his credibility and answer now that I've posted directly about his problem.

Harry.

Why have you added another post on the same topic.

That should be obvious - I want Dannel to provide and answer and by emphasizing his refusal by creating a dedicate thread, perhaps he'll step up and act like the man he keeps claiming to be.

Harry.

DJR aside, considering you've often not answered questions, and refusing to provide any justification of your position after repeated engagement in other threads, here, you've changed your position and implying what you changed it to was what you mean now was what you meant all along, and have now posted threads in which you say you have been arguing for two mutually exclusive positions all along; and ignoring the fact that you've basically agreed with everything DJR initially objected for, as I pointed out but you seem to have ignored.

It's probably not particularly useful of you to make such accusations.

By all means rush to his defence, perhaps you'd like to take a stab at answering? what's the fuss over such a simple science question that a high school kid could answer!

Yes, but we were talking about how GPS works and relativity, which you didn't understand, so it's probably a good thing you work on high school level problems before taking on much more advanced topics.

Harry.

But the cause of the stopwatch's deviation has no bearing on the calculations. Whether the clock used goes fast because of a mechanical fault, worn spring or because its orbiting 20,000 km up in a weaker gravitational field has no bearing.

That is not correct, Harry, and that is the same mistake you keep making over and over. A clock that is built from the ground up to take relativistic effects into consideration are not simply indistinguishable from a mechanical fault or worn spring on a regular clock. These effects are real, Harry, on the function and purpose of the entire mechanical operations and are continuous as long as the satellite is in orbit.

The only impact relativistic effects have on the orbiting clock is to make it tick too fast by 38 us / day as observed from the earth, there's no other effect that I'm aware of.


So long we as know by how fast it runs, we can measure time fine and hence distance.

So, instead, the clocks are built and programmed how fast we want them to run, taking into consideration the effects of velocity and gravity transformation. Simple.

How does that prove that it's not possible to determine position using uncompensated satellite clocks?


It's you who clearly has and always has trouble understanding, as is evidenced by this and many of your other confused, inaccurate and rambling responses to simple questions.

Harry.

Dummel GPS is designed to enable position AND time to be determined by GPS receivers. This requires orbiting clocks to be compensated for the effects of relativity BUT IF we were not concerned about being able to tell the time of day at the receiver and ONLY be able to determine position, then relativity can be ignored.

Harry.
Ramshutu
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3/14/2016 11:51:44 PM
Posted: 8 months ago
At 3/14/2016 8:57:12 PM, Dirty.Harry wrote:
To establish our position ONLY we don't care what "time it is" only how far away is each satellite and we can establish that by syncing which is explained in that article.

Lets spell this out Harry.

You argued that you don't need to correct for relativity at all.

Then you argued that you did, but you don't need to do it on the satellite.

Then you argued, that the effects of relativity in real life have a negligible affect on the signal, and so don't need to be accounted for.

Now your arguing that as long as you lock your clocks, relativity doesn't matter.

What's worse, is that you've spread all four of these claims across 4 threads and pretended as if you've been making the same argument all along; and accused DJR of not answering specific questions about your claims, even though half of the time you've been saying exactly the same thing.

How do you not fall down more?

So lets break it down to the most utterly simple parts, and hope you don't go changing your argument half way through.

If you, as a receiver, do not have a clock that ticks pretty close to once per second, your measurement of distance is going to be wrong, whether you use absolute, or relative time. If you think a signal has travelled 100ms, and it's actually travelled 99.99ms, that error is going to be massive.

This means, with a bunch of satellites, given one measurement, you will not be able to know your exact position because all of the relative receipt times of all the signals you are receiving will be a %age lower or higher than they should be. The effect of this, will be to give a different location to where you are really at; in general, it will give the appearance of being closer to all the satellites, or further away from all the satellites than you are; which will generally cause you to show a different elevation at least.

Using an incorrect clock on your receiver (which we KNOW due to the XO's they use, they will be inaccurate) would mean that your estimation of distance is wrong; what you think all these satellites clocks are reading when they broadcast their timestamp will also be wrong; meaning you have an out-of-step clock.

If you are using this method to simply "reset" your clock to what it should be each time; your accuracy will be completely screwed because your receiver can't determine distance, because it will be off based on what it thinks time is; and certainly will be unlikely to be within a few meters accuracy attainable by GPS.

So, to solve this, you make multiple measurements, knowing not just the relative arrival times of the signal, but also you measure the exact time between satellite pings. If the satellite pings once per second, and you receive the pings at just a little more than once per second, you can use this to adjust your own clock; this is effectively what your link is saying.

If you don't do this, and you do not sync your clock rates; after the first broadcast, your clocks WILL drift, and in most cases for a typical GPS receiver, will drift substantially, and you will never be able to obtain an accurate location if you use relative arrival times of the incoming signal.

If you DO lock your clocks, your clock will be ticking at approximately the same time as the clock in the satellite; meaning that you have just adjusted your clock to account for relativistic time dilation. As you average more and more incoming pings, you can establish more accurately how much faster or slower your clock is ticking and adjust your clock more accurately.

You can't do this accurately any other way other than via satellite without following the same methodology with multiple paths and known locations of broadcast stations; NTP is not accurate enough; and UTC broadcast is going to be highly subject to availability, movement, drift, atmospheric conditions.

So locking your clock will avoid the majority of timing and position errors; but has inherently more error in it than adjusting the satellite clocks because a) distance measurements will be different by 1/2 a foot for every second travelled. b) The position of the satellite, save any relativistic correction will not be as accurate as with relativistic correction as the satellite position is calculated based on time.

As you rightly point out, most receivers will only be able to measure down to a few ns; and your time correction will be a few ns/s out here and there because you just can't measure it that accurately. And right now, this and relative timing errors that still accumulate and cause distance to be computed incorrectly as time is being updated are the primary source of GPS errors.

Adding more to them, is going to make it more inaccurate; You'll add a few centimeters inaccuracy with the difference in distance measurement, and at about 1ppb timing error in the satellite computations, you'll get around 2-3 feet of satellite positioning error per day that you simply do not get if you adjust the satellite clocks, or adjust for relativity.

That's approaching 25% or 10% of the total quoted accuracy of GPS. Most of which is based upon the inherent innaccuracies of how well you can measure time in each case; which seems to be a massive, massive oversight in your arguments: there is an inherent accuracy limitation based on how well you can measure any of these parameters based on all the limitations on the underlying devices.

So, what should be abundantly clear is this, and you've pretty much agreed to it:

GPS is more accurate if you use relativity.

What I will agree to, is that if you lock your clock to the satellite, you will not be wrong by an accumulated 18km per day; if you do not lock your clock to the satellite, you WILL be wrong by an accumulated 18km per day. But, to get the desired accuracy you do need to lock your clock anyway, so I will agree that if satellites did not account for relativity they wouldn't necessarily be wrong by 18km per day...

However, while the specifics are misleading, what is true is you could never get the accuracy we can out of GPS without accounting for relativity; and second, if you locked your clock independently of the satellite so that you had a highly correlated clock on the ground and used absolute times, based on the conventional, non relativistic way you'd think about the problem, yes you would be out by 18km accumulating error per day, so indeed yes, in terms of it's popular presentation, it's not actually that misleading even though on technical terms, it is misleading.
Akhenaten
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3/15/2016 12:27:18 AM
Posted: 8 months ago
The important thing is that relativity doesn't exist. Its the aetheric pressure reduction that makes the clock tick faster in outer space.

http://www.dailymail.co.uk...

Gravity is a pushing force as proved by this experiment.

http://www.gravityforces.com...
Dirty.Harry
Posts: 1,559
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3/15/2016 2:22:59 PM
Posted: 8 months ago
At 3/14/2016 5:17:56 PM, RuvDraba wrote:
At 3/14/2016 2:23:11 PM, Dirty.Harry wrote:
At 3/14/2016 12:45:31 AM, RuvDraba wrote:
At 3/13/2016 5:03:13 PM, Dirty.Harry wrote:
You have a stopwatch that you KNOW gains a second every minute. Can we use that to measure an athlete's speed?
Yes, as long as the stopwatch is running fast for the whole duration of the athlete's run. If the watch started gaining part-way through the run, then you won't know the athlete's speed or position with any accuracy, unless you also know when the watch started gaining time.
(This does connect to your previous thread, Harry, but it's a strained connection due to the strained nature of your analogy.)
Indeed the stopwatch runs at the constant mathematical rate (relative to GMT) of 61/60 seconds per GMT second.
As you say - under these circumstances - it poses no problem to measure the athlete's speed we just take the measured stopwatch value in seconds and multiply it by 60/61.

Yes, if that's what you were doing, that would work.

Unfortunately, what you want with GPS satellites isn't their speed but the distance to their known position, calculated by the time delay between transmission and receipt as measured by two synchronised clocks.

If T1 is the time it sent the signal, T2 is the time you received it, and c is the speed of light, then the distance D is given by:

D = (T2 - T1) / c.

So far so good, yes?

Now, here's the complicating problem: at time T0, the satellite began running fast by amount k. So the corrected time of transmission is actually:
T1 / (1 + k.(T1 -T0))

So the corrected distance to the satellite is actually given by:
D = (T2 - T1 / (1 + (k.T1 - T0))) / c

We know k is constant for all satellites because they're at similar height and speed, we know T2 from the receiver clock, and each satellite sends us its own T1, but who sends us T0 for each satellite? Will the satellite send it? How can it be sure of its own precise T0 value? Will a NASA ground station publish T0 for each satellite? What if your receiver isn't in contact with a NASA ground station?


As you said "as measured by two synchronised clocks" this (correctly) means that the satellite and receiver clocks are in step - any error will be present and equal therefore in each clock. Then you introduce T0 but never clearly define it.

Remember also that the receiver (once synced) is in step so it too will be offset by whatever this accumulated quantity is, subtracting times will therefore result in that offset being eliminated - only the deviation during transit will remain (which I showed was around 3 picoseconds for a satellite at 20,200 km).

If you review your algebra and include the same correction for the receiver clock (remember these are in step, syned) you'll find that T0 can be eliminated (if I follow you correctly anyway).

This is why the problem is more complicated than your analogy, Harry:
1) You have three or more satellites, each with their own clock, plus you have your own local clock'
2) You want distance to the satellite, not satellite speed;

I never said we needed satellite speed, I only said we can measure time intervals even if a clock is running fast/slow - that's not the same thing.

3) Distance is calculated from the time delay between the send-time and receive-time of synchronised clocks;
4) The clocks aren't perfectly synchronised because each sending clock is running fast by a fixed amount; and
5) It's further complicated because to recover synchronisation, you need to know for each clock, how long it has been running fast.

That isn't how they sync. The receiver receives messages that contain the absolute time their position and a unique code identifying that satellite. It initially sets its clock to one of these values and then builds a table of intervals based on the time messages are received from each satellite.

This gives it an (incorrect) table of time intervals initially.

However it then solves a simultaneous equation that yields a unique solution for the various transit times that's consistent with the satellite position.

e.g. there's only one place where a receiver can be to "see" a certain set of time intervals for a certain set of satellite positions.

The satellite are all synced with each other, they tick with high stability - after the above processing and syncing the receiver is more or less constantly in step with the satellite clocks.
Dirty.Harry
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3/15/2016 2:25:53 PM
Posted: 8 months ago
At 3/14/2016 11:51:44 PM, Ramshutu wrote:
At 3/14/2016 8:57:12 PM, Dirty.Harry wrote:
To establish our position ONLY we don't care what "time it is" only how far away is each satellite and we can establish that by syncing which is explained in that article.

Lets spell this out Harry.

You argued that you don't need to correct for relativity at all.

Then you argued that you did, but you don't need to do it on the satellite.


You're not following are you? I argued that we DO need to compensate at the satellite ONLY IF WE WANT GPS TO ENABLE RECEIVERS TO DETERMINE THE CORRECT TIME OF DAY.

Can you read that now please? Once again, after me:

1. YES we must compensate IF WE WANT TO TELL THE TIME OF DAY AND GET POSITION.
2. NO we need not compensate IF WE ONLY WANT TO GET POSITION.

Then you argued, that the effects of relativity in real life have a negligible affect on the signal, and so don't need to be accounted for.

Now your arguing that as long as you lock your clocks, relativity doesn't matter.

What's worse, is that you've spread all four of these claims across 4 threads and pretended as if you've been making the same argument all along; and accused DJR of not answering specific questions about your claims, even though half of the time you've been saying exactly the same thing.

How do you not fall down more?

So lets break it down to the most utterly simple parts, and hope you don't go changing your argument half way through.


If you, as a receiver, do not have a clock that ticks pretty close to once per second, your measurement of distance is going to be wrong, whether you use absolute, or relative time. If you think a signal has travelled 100ms, and it's actually travelled 99.99ms, that error is going to be massive.

This means, with a bunch of satellites, given one measurement, you will not be able to know your exact position because all of the relative receipt times of all the signals you are receiving will be a %age lower or higher than they should be. The effect of this, will be to give a different location to where you are really at; in general, it will give the appearance of being closer to all the satellites, or further away from all the satellites than you are; which will generally cause you to show a different elevation at least.

Using an incorrect clock on your receiver (which we KNOW due to the XO's they use, they will be inaccurate) would mean that your estimation of distance is wrong; what you think all these satellites clocks are reading when they broadcast their timestamp will also be wrong; meaning you have an out-of-step clock.

If you are using this method to simply "reset" your clock to what it should be each time; your accuracy will be completely screwed because your receiver can't determine distance, because it will be off based on what it thinks time is; and certainly will be unlikely to be within a few meters accuracy attainable by GPS.

So, to solve this, you make multiple measurements, knowing not just the relative arrival times of the signal, but also you measure the exact time between satellite pings. If the satellite pings once per second, and you receive the pings at just a little more than once per second, you can use this to adjust your own clock; this is effectively what your link is saying.

If you don't do this, and you do not sync your clock rates; after the first broadcast, your clocks WILL drift, and in most cases for a typical GPS receiver, will drift substantially, and you will never be able to obtain an accurate location if you use relative arrival times of the incoming signal.

If you DO lock your clocks, your clock will be ticking at approximately the same time as the clock in the satellite; meaning that you have just adjusted your clock to account for relativistic time dilation. As you average more and more incoming pings, you can establish more accurately how much faster or slower your clock is ticking and adjust your clock more accurately.

You can't do this accurately any other way other than via satellite without following the same methodology with multiple paths and known locations of broadcast stations; NTP is not accurate enough; and UTC broadcast is going to be highly subject to availability, movement, drift, atmospheric conditions.

So locking your clock will avoid the majority of timing and position errors; but has inherently more error in it than adjusting the satellite clocks because a) distance measurements will be different by 1/2 a foot for every second travelled. b) The position of the satellite, save any relativistic correction will not be as accurate as with relativistic correction as the satellite position is calculated based on time.

As you rightly point out, most receivers will only be able to measure down to a few ns; and your time correction will be a few ns/s out here and there because you just can't measure it that accurately. And right now, this and relative timing errors that still accumulate and cause distance to be computed incorrectly as time is being updated are the primary source of GPS errors.

Adding more to them, is going to make it more inaccurate; You'll add a few centimeters inaccuracy with the difference in distance measurement, and at about 1ppb timing error in the satellite computations, you'll get around 2-3 feet of satellite positioning error per day that you simply do not get if you adjust the satellite clocks, or adjust for relativity.

That's approaching 25% or 10% of the total quoted accuracy of GPS. Most of which is based upon the inherent innaccuracies of how well you can measure time in each case; which seems to be a massive, massive oversight in your arguments: there is an inherent accuracy limitation based on how well you can measure any of these parameters based on all the limitations on the underlying devices.

So, what should be abundantly clear is this, and you've pretty much agreed to it:

GPS is more accurate if you use relativity.

What I will agree to, is that if you lock your clock to the satellite, you will not be wrong by an accumulated 18km per day; if you do not lock your clock to the satellite, you WILL be wrong by an accumulated 18km per day. But, to get the desired accuracy you do need to lock your clock anyway, so I will agree that if satellites did not account for relativity they wouldn't necessarily be wrong by 18km per day...

However, while the specifics are misleading, what is true is you could never get the accuracy we can out of GPS without accounting for relativity; and second, if you locked your clock independently of the satellite so that you had a highly correlated clock on the ground and used absolute times, based on the conventional, non relativistic way you'd think about the problem, yes you would be out by 18km accumulating error per day, so indeed yes, in terms of it's popular presentation, it's not actually that misleading even though on technical terms, it is misleading.
Dirty.Harry
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3/15/2016 2:27:52 PM
Posted: 8 months ago
At 3/15/2016 2:25:53 PM, Dirty.Harry wrote:
At 3/14/2016 11:51:44 PM, Ramshutu wrote:
At 3/14/2016 8:57:12 PM, Dirty.Harry wrote:
To establish our position ONLY we don't care what "time it is" only how far away is each satellite and we can establish that by syncing which is explained in that article.

Lets spell this out Harry.

You argued that you don't need to correct for relativity at all.

Then you argued that you did, but you don't need to do it on the satellite.


You're not following are you? I argued that we DO need to compensate at the satellite ONLY IF WE WANT GPS TO ENABLE RECEIVERS TO DETERMINE THE CORRECT TIME OF DAY.

Can you read that now please? Once again, after me:

1. YES we must compensate IF WE WANT TO TELL THE TIME OF DAY AND GET POSITION.
2. NO we need not compensate IF WE ONLY WANT TO GET POSITION.

Then you argued, that the effects of relativity in real life have a negligible affect on the signal, and so don't need to be accounted for.

Now your arguing that as long as you lock your clocks, relativity doesn't matter.

What's worse, is that you've spread all four of these claims across 4 threads and pretended as if you've been making the same argument all along; and accused DJR of not answering specific questions about your claims, even though half of the time you've been saying exactly the same thing.

How do you not fall down more?

So lets break it down to the most utterly simple parts, and hope you don't go changing your argument half way through.


If you, as a receiver, do not have a clock that ticks pretty close to once per second, your measurement of distance is going to be wrong, whether you use absolute, or relative time. If you think a signal has travelled 100ms, and it's actually travelled 99.99ms, that error is going to be massive.

This means, with a bunch of satellites, given one measurement, you will not be able to know your exact position because all of the relative receipt times of all the signals you are receiving will be a %age lower or higher than they should be. The effect of this, will be to give a different location to where you are really at; in general, it will give the appearance of being closer to all the satellites, or further away from all the satellites than you are; which will generally cause you to show a different elevation at least.

Using an incorrect clock on your receiver (which we KNOW due to the XO's they use, they will be inaccurate) would mean that your estimation of distance is wrong; what you think all these satellites clocks are reading when they broadcast their timestamp will also be wrong; meaning you have an out-of-step clock.

If you are using this method to simply "reset" your clock to what it should be each time; your accuracy will be completely screwed because your receiver can't determine distance, because it will be off based on what it thinks time is; and certainly will be unlikely to be within a few meters accuracy attainable by GPS.

So, to solve this, you make multiple measurements, knowing not just the relative arrival times of the signal, but also you measure the exact time between satellite pings. If the satellite pings once per second, and you receive the pings at just a little more than once per second, you can use this to adjust your own clock; this is effectively what your link is saying.

If you don't do this, and you do not sync your clock rates; after the first broadcast, your clocks WILL drift, and in most cases for a typical GPS receiver, will drift substantially, and you will never be able to obtain an accurate location if you use relative arrival times of the incoming signal.

If you DO lock your clocks, your clock will be ticking at approximately the same time as the clock in the satellite; meaning that you have just adjusted your clock to account for relativistic time dilation. As you average more and more incoming pings, you can establish more accurately how much faster or slower your clock is ticking and adjust your clock more accurately.

You can't do this accurately any other way other than via satellite without following the same methodology with multiple paths and known locations of broadcast stations; NTP is not accurate enough; and UTC broadcast is going to be highly subject to availability, movement, drift, atmospheric conditions.

So locking your clock will avoid the majority of timing and position errors; but has inherently more error in it than adjusting the satellite clocks because a) distance measurements will be different by 1/2 a foot for every second travelled. b) The position of the satellite, save any relativistic correction will not be as accurate as with relativistic correction as the satellite position is calculated based on time.

As you rightly point out, most receivers will only be able to measure down to a few ns; and your time correction will be a few ns/s out here and there because you just can't measure it that accurately. And right now, this and relative timing errors that still accumulate and cause distance to be computed incorrectly as time is being updated are the primary source of GPS errors.

Adding more to them, is going to make it more inaccurate; You'll add a few centimeters inaccuracy with the difference in distance measurement, and at about 1ppb timing error in the satellite computations, you'll get around 2-3 feet of satellite positioning error per day that you simply do not get if you adjust the satellite clocks, or adjust for relativity.

That's approaching 25% or 10% of the total quoted accuracy of GPS. Most of which is based upon the inherent innaccuracies of how well you can measure time in each case; which seems to be a massive, massive oversight in your arguments: there is an inherent accuracy limitation based on how well you can measure any of these parameters based on all the limitations on the underlying devices.

So, what should be abundantly clear is this, and you've pretty much agreed to it:

GPS is more accurate if you use relativity.

What I will agree to, is that if you lock your clock to the satellite, you will not be wrong by an accumulated 18km per day; if you do not lock your clock to the satellite, you WILL be wrong by an accumulated 18km per day. But, to get the desired accuracy you do need to lock your clock anyway, so I will agree that if satellites did not account for relativity they wouldn't necessarily be wrong by 18km per day...

However, while the specifics are misleading, what is true is you could never get the accuracy we can out of GPS without accounting for relativity; and second, if you locked your clock independently of the satellite so that you had a highly correlated clock on the ground and used absolute times, based on the conventional, non relativistic way you'd think about the problem, yes you would be out by 18km accumulating error per day, so indeed yes, in terms of it's popular presentation, it's not actually that misleading even though on technical terms, it is misleading.

Relativity has negligible impact on signal propagation time - calculate it yourself its 3 picoseconds for a satellite at 20,200 km and that equates to a distance of 0.8 mm.

Do you agree with this at least? If not why?
DanneJeRusse
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3/15/2016 3:18:45 PM
Posted: 8 months ago
At 3/14/2016 9:25:25 PM, Dirty.Harry wrote:


Dummel

Here you go again - the descent into insulting anyone who dares to disagree with you, how predictable you're becoming. -Dirty Harry.


Funny Harry, you are the ultimate hypocrite and liar. You accuse others who are not insulting you at all, yet you are childishly calling others names. And, the only reason you're calling others names is because they expose your nonsense and foolishness.

GPS is designed to enable position AND time to be determined by GPS receivers. This requires orbiting clocks to be compensated for the effects of relativity BUT IF we were not concerned about being able to tell the time of day at the receiver and ONLY be able to determine position, then relativity can be ignored.

That is entirely wrong and shows you still understand how GPS works, despite the fact plenty of material has been provided for you so you may learn, but you refuse to learn anything. You can't even learn that you are the one insulting others yet you accuse them.

Harry.
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