06 Mar 20
@humy
Yes, at the beginning they had to use SR and GR equations, there was no way around that. But once the clocks were up and running and stable in their time flow they could be used as the standard even though in reality they were off from OUR clocks on Earth.
I don't see what MB has against that stance.
MB, do you think they would have just willy nilly launched dozens of very expensive GPS sats and hope for the best?
@sonhouse saidLets be grateful that an idiot just like him would surely have never been put in charge of GPS else we would be having airliners crashing to the ground killing all on board because of ignorant opinions about science especially relativity.
MB, do you think they would have just willy nilly launched dozens of very expensive GPS sats and hope for the best?
Can you imagine what would happen if GPS clocks were NOT ever adjusted for relativity!? It would make it best to avoid going on any modern airliners; Unless you have a death-wish.
07 Mar 20
@metal-brain saidI was going to post a reply to this, but I've forgotten it.
Sonhouse once admitted no relativity equations were used. Now he has reversed his opinion once again now that humy has reversed his opinion. All of this is on this thread. I can prove it all. They are idiots with poor memories.
@metal-brain saidI haven't changed my opinion about anything there.
now that humy has reversed his opinion.
Perhaps you would like to enlighten us what change in opinion you are talking about here, about what exactly, and provide evidence for this?
This you will never do because you are talking BS as usual.
And you have been proven wrong and wrong again many times about many things.
07 Mar 20
@humy said"And you have been proven wrong and wrong again many times about many things."
I haven't changed my opinion about anything there.
Perhaps you would like to enlighten us what change in opinion you are talking about here, about what exactly, and provide evidence for this?
This you will never do because you are talking BS as usual.
And you have been proven wrong and wrong again many times about many things.
Name 3 things I have been proven wrong about?
07 Mar 20
@sonhouse said" It seems GPS sats have atomic clocks onboard and the ground receivers read that time from 4 sats and just uses that time hack to reset its own clock and everyone is happy. So no Einstein needed. Clever use of signals. "
@Metal-Brain
A GPS satellite
Photo courtesy U.S. Army
On the previous page, we saw that a GPS receiver calculates the distance to GPS satellites by timing a signal's journey from satellite to receiver. As it turns out, this is a fairly elaborate process.
At a particular time (let's say midnight), the satellite begins transmitting a long, digital pattern called a pse ...[text shortened]... ia Drivers With No Tickets in 3 Years Should Do This On Saturday
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I'm glad you agree no Einstein equations are needed. You havn't changed your mind have you? I thought we settled this.
@metal-brain saidHe as not agreed with you that no Einstein equations are needed before GPS launch.
" It seems GPS sats have atomic clocks onboard and the ground receivers read that time from 4 sats and just uses that time hack to reset its own clock and everyone is happy. So no Einstein needed. Clever use of signals. "
I'm glad you agree no Einstein equations are needed.
Here is his quote again on that:
"@humy
Yes, at the beginning they had to use SR and GR equations, there was no way around that. "
You havn't changed your mind have you?He hasn't. See his quote above.
08 Mar 20
@humy saidNo Einstein equations are needed before GPS launch.
He as not agreed with you that no Einstein equations are needed before GPS launch.
Here is his quote again on that:
"@humy
Yes, at the beginning they had to use SR and GR equations, there was no way around that. "
You havn't changed your mind have you?He hasn't. See his quote above.
Even if they were you are contradicting your statement you never claimed that, because you are claiming it now. Before or after launch makes no difference. Needed is needed.
Your back peddling is pathetic. You exposed yourself as a liar again.
@metal-brain saidhttp://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html
No Einstein equations are needed before GPS launch.
" because the satellites are constantly moving relative to observers on the Earth, effects predicted by the Special and General theories of Relativity must be taken into account".
https://www.deccanherald.com/content/304036/einsteins-famous-equation-emc2-tested.html
"...Physicists have since validated Einstein's equation in countless experiments and calculations, and many technologies including mobile phones and GPS navigation depend on it...."
https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System
"...The effect of gravitational frequency shift on the GPS due to general relativity is that a clock closer to a massive object will be slower than a clock farther away. Applied to the GPS, the receivers are much closer to Earth than the satellites, causing the GPS clocks to be faster by a factor of 5×10−10, or about 45.9 μs/day. This gravitational frequency shift is noticeable.
When combining the time dilation and gravitational frequency shift, the discrepancy is about 38 microseconds per day, a difference of 4.465 parts in 1010.[16] Without correction, errors in the initial pseudorange of roughly 10 km/day would accumulate. This initial pseudorange error is corrected in the process of solving the navigation equations. In addition the elliptical, rather than perfectly circular, satellite orbits cause the time dilation and gravitational frequency shift effects to vary with time. This eccentricity effect causes the clock rate difference between a GPS satellite and a receiver to increase or decrease depending on the altitude of the satellite.
To compensate for the discrepancy, the frequency standard on board each satellite is given a rate offset prior to launch, making it run slightly slower than the desired frequency on Earth; specifically, at 10.22999999543 MHz instead of 10.23 MHz.[17] Since the atomic clocks on board the GPS satellites are precisely tuned, it makes the system a practical engineering application of the scientific theory of relativity in a real-world environment.
To calculate the amount of daily time dilation experienced by GPS satellites relative to Earth we need to separately determine the amounts due to special relativity (velocity) and general relativity (gravity) and add them together. ..."
The above clearly tells any non-moron that GPS system does take into account relativity equations.
Even if they were you are contradicting your statement you never claimed .
If I never claimed it then it doesn't matter if I contradict it. (whatever 'it' is, which you never explain)
that, because you are claiming it nowWhat am I claiming now that I claimed differently from before? Answer; nothing.
Before or after launch makes no difference. Needed is needed.Those exact words seem to be telling us you finally admit to all of us here you were wrong by admitting that, contrary to what you were claiming, Einstein equations are 'needed' ( from your above "Needed is needed" ) for GPS and it doesn't matter if that's before or after GPS launch ( from your above "Before or after launch makes no difference" ). So now you finally agree with us and the science and admitted you were wrong, what are you still angrily arguing about?
@humy saidThe article you posted is wrong. No relativity equations are required at all. The receiver's clock is periodically reset to atomic clocks in the satellites. You can use SR and GR to predict how much the clocks will be different by microseconds if you want to, but it is not necessary. We already know from experience how much the difference is so equations are not necessary and they are not really used to improve any accuracy.
http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html
" because the satellites are constantly moving relative to observers on the Earth, effects predicted by the Special and General theories of Relativity must be taken into account".
https://www.deccanherald.com/content/304036/einsteins-famous-equation-emc2-tested.html
"...Physicists have since validated ...[text shortened]... agree with us and the science and admitted you were wrong, what are you still angrily arguing about?
https://electronics.howstuffworks.com/gadgets/travel/gps.htm
It comes down to this. You don't need to know the time difference before launch because all you need to do is reset the receiver clock to the atomic clocks after they are in orbit. Any subsequent resetting of the receiver clock does not use any SR or GR equations.
08 Mar 20
@metal-brain said
The article you posted is wrong. No relativity equations are required at all. The receiver's clock is periodically reset to atomic clocks in the satellites. You can use SR and GR to predict how much the clocks will be different by microseconds if you want to, but it is not necessary. We already know from experience how much the difference is so equations are not necessary ...[text shortened]... ey are in orbit. Any subsequent resetting of the receiver clock does not use any SR or GR equations.
Any subsequent resetting of the receiver clock does not use any SR or GR equations.Yes, that is what we all said and never said anything to the contrary. Yet another one of your straw mans. We were talking about BEFORE launch, not after.
You can use SR and GR to predict how much the clocks will be different by microseconds if you want to, but it is not necessary.
http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html
"...the high-precision required of the GPS system requires nanosecond accuracy, and 38 microseconds is 38,000 nanoseconds. If these effects were not properly taken into account, a navigational fix based on the GPS constellation would be false after only 2 minutes, and errors in global positions would continue to accumulate at a rate of about 10 kilometers each day! The whole system would be utterly worthless for navigation in a very short time. ..."
So it's necessary.
08 Mar 20
@humy saidYou don't need to know the time difference before launch because all you need to do is reset the receiver clock to the atomic clocks after they are in orbit.Any subsequent resetting of the receiver clock does not use any SR or GR equations.Yes, that is what we all said and never said anything to the contrary. Yet another one of your straw mans. We were talking about BEFORE launch, not after.
[quote] You can use SR and GR to predict how much the clocks will be different by microseconds if you want to, but it is ...[text shortened]... le system would be utterly worthless for navigation in a very short time. ..."
So it's necessary.
You have not given a logical reason for a before launch adjustment when clocks can be synchronized at any time. FAIL!