# Absolute coordinate system of GPS satellites

Discussion in 'General Science & Technology' started by Saint, Dec 31, 2019.

1. ### SaintValued Senior Member

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What is the absolute coordinate system of GPS satellites?
Is it the center of the earth?

3. ### originHeading towards oblivionValued Senior Member

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That is determined by scientists and you think scientists are liars so it the answer is irrelevant.

5. ### James RJust this guy, you know?Staff Member

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Not sure. What do you mean by an absolute coordinate system?

7. ### Michael 345New year. PRESENT is 72 years oldlValued Senior Member

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Fairly certain not centre of Earth

I know London, guess most other large cities, have nominal centres, London being

The coordinates of the nominal centre of London, traditionally considered to be the original Eleanor Cross at Charing Cross near the junction of Trafalgar Square and Whitehall, are about 51°30′26″N 00°07′39″W.

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

Also a plaque may mark the centre from which distances can be calculated to other parts of the city

https://gssc.esa.int/navipedia/index.php/Satellite_Coordinates

The app I have in my phone requires 3 satellites to be in view before it will locate within a few metres my house

Uber makes good use of the system showing me the car which has accepted my request, shows on a roadmap where the car is and tracks its travel

8. ### RainbowSingularityValued Senior Member

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a question about the evolution of a round earth ?

9. ### SaintValued Senior Member

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After major earthquake, will the plate coordinates be shifted?

10. ### RainbowSingularityValued Senior Member

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i thought you did not believe in science ?

11. ### James RJust this guy, you know?Staff Member

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Possibly.

How do you think that the average rate of continental drift is determined for the various tectonic plates?

12. ### HalcRegistered Senior Member

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None of the coordinate systems mentioned are absolute.
If center of Earth is used, then it is relative to that accelerating coordinate system, not absolute. Earth is hardly an inertial object.

No, I am personally unfamiliar with the details of programming of GPS and what coordinate system might be used for the computations.
Center of Earth seems a reasonable choice in my opinion.

13. ### spidergoatpubic dioramaValued Senior Member

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It's the system of longitude and latitude established long ago with Greenwich, London at its center. This position system is coordinated with satellites using more than 8 tracking stations around the world, who's locations have been precisely established using other methods.

While a single tracking station could move due to plate tectonics, it's role would just be removed temporarily until it's new location was established.

14. ### SaintValued Senior Member

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if one or two of the satellites break down, what will happen?

15. ### Janus58Valued Senior Member

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There are 9 satellites held in reserve. If a
satellite fails, one of them will take up the slack. A new satellite will be launched in order to get the number of reserve satellites back up to 9.

16. ### SaintValued Senior Member

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which country pays for the satellite cost?

17. ### spidergoatpubic dioramaValued Senior Member

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It's primarily a US system. There is a separate Russian system, and the data can be combined for greater accuracy. Satellites are regularly taken off line until their positions can be corrected.

18. ### SaintValued Senior Member

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Do the satellites have commercial values to make money by providing services to broadcasting companies?

19. ### Janus58Valued Senior Member

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GPS satellites, which orbit with periods of 12 hours would not make good communication satellites. Those orbit at geosnyc altitudes, which are a good deal higher.

20. ### spidergoatpubic dioramaValued Senior Member

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GPS is a free service provided by the US government to help general commerce. Also there are military applications.

21. ### Write4UValued Senior Member

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And now some state governments demand that home healthcare workers acquire GPS tracking applications on their phones so they can track the healthcare provider's movements during the day. You log in when you arrive at your client and activate your GPS tracking, and the government now can track every move you make and the required on-line progress notes and match that information to your paper billing hours. This time-consuming activity is not compensated and basically reduces the hours spent on hands-on care. Something is wrong here!

For most home health workers this involves buying a new expensive phone with GPS tracking abilities and learn to sign in to a tracking center that compiles your every movement, and in effect forces you to spy on yourself.

I have several questions related to the legality of having to pay a fee to work and transmitting private health care information over an unsecured internet. AFAIK, these practices are both prohibited by law.

Any knowledgeable minds out there?

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