Re: FET and Global Positioning System
« Reply #40 on: March 17, 2018, 11:01:41 AM »
That's why [GPS] is usually used as supplementary data in positioning systems.
In aviation GPS is approved as primary means of navigation for descending in between mountains in cloud, at night.

Allow me to remind everyone that the key contention here is whether GPS works well or not. Accounts along the lines of Stinky's "I used it and it almost told me where I was!" are unlikely to swing it in either direction.
When you are in an aircraft descending as I described above, having a navigation system that "almost tells you where you are" is obviously useless to a pilot. Fortunately GPS is a lot more accurate than some more traditional means of radio navigation.

I'll repeat: GPS derived position accuracy is currently stated to be 100m or less, 95% of the time, and 300m or less, 99.9% of the time. It is also said that apparently the US DoD has guaranteed a maximum error of 500m.

The Aviation GPS receivers have a built in integrity monitoring of the position accuracy. When it receives GPS signal from 5 sources, it is able to do fault detection (it knows when the position is not accurate and will tell the pilot). If the receiver receives signal from 6 GPS sources, it is also able to exclude a faulty source, and maintain integrity of the position accuracy. This is called RAIM, and a pilot will check that RAIM is avialable as part of his pre-flight planning. Or he will do a RAIM check latest before he starts descent.



Obviously if RAIM is unavailable the pilot will decide to either divert to an alternate, or use another means of navigation if available.
« Last Edit: March 17, 2018, 11:07:56 AM by Treep Ravisarras »
As the saying goes "The internet belongs to the lunatics in their walled gardens" - Xiang Yu

I see a Flat Earth. And I can't imagine anything else.

I got work to do. 0.00018% of Christians believe in a Flat Earth. Pls help

Re: FET and Global Positioning System
« Reply #41 on: March 17, 2018, 12:57:21 PM »
I've just checked my phone, I am where it says I am.
That would not be thanks to GPS, not unless you're in the middle of the Australian outback or the Sahara desert. Both big players on the mobile phone OS market rely on non-GPS data to get your location. Wi-Fi access points are currently the most useful data points for urban areas, and mobile phone networks are a common source for less densely populated zones (possibly because Wi-Fi access points and mobile phone towers are not allegedly zooming through space).

https://en.wikipedia.org/wiki/Wi-Fi_positioning_system
https://en.wikipedia.org/wiki/Hybrid_positioning_system

And, shockingly enough, if you check your phone somewhere that doesn't rely on WPS or mobile network towers, your location data becomes quite inaccurate.

So either:
There's another global conspiracy by people who pretended they launched GPS satellites and other people pretending that GPS works by satellites, all to keep this very important secret that the earth is actually flat safe, because obviously it's very important that this truth is kept from the general public.
Or...GPS works exactly how it's stated it works, because we live on a globe.
Third option: You're not as tech-literate as you think you are and you fallaciously assume that GPS data is the only dataset used in mobile phone location tracking. You're attributing the efficacy of big data and very recent developments in fingerprinting to a rather simple system that's been conceived of 40 years ago. Round or flat, that ain't how it works.
You are confused between the mobile phone companies establishing where a mobile is and the user of a phone establishing their location.

Please give details of phones that use anything other than GPS to show the user their location.

*

Offline Science, bitch!

  • *
  • Posts: 39
  • 🌎🌍🌏
    • View Profile
Re: FET and Global Positioning System
« Reply #42 on: March 17, 2018, 02:19:58 PM »
I've just checked my phone, I am where it says I am.
That would not be thanks to GPS, not unless you're in the middle of the Australian outback or the Sahara desert. Both big players on the mobile phone OS market rely on non-GPS data to get your location. Wi-Fi access points are currently the most useful data points for urban areas, and mobile phone networks are a common source for less densely populated zones (possibly because Wi-Fi access points and mobile phone towers are not allegedly zooming through space).

https://en.wikipedia.org/wiki/Wi-Fi_positioning_system
https://en.wikipedia.org/wiki/Hybrid_positioning_system

And, shockingly enough, if you check your phone somewhere that doesn't rely on WPS or mobile network towers, your location data becomes quite inaccurate.

So either:
There's another global conspiracy by people who pretended they launched GPS satellites and other people pretending that GPS works by satellites, all to keep this very important secret that the earth is actually flat safe, because obviously it's very important that this truth is kept from the general public.
Or...GPS works exactly how it's stated it works, because we live on a globe.
Third option: You're not as tech-literate as you think you are and you fallaciously assume that GPS data is the only dataset used in mobile phone location tracking. You're attributing the efficacy of big data and very recent developments in fingerprinting to a rather simple system that's been conceived of 40 years ago. Round or flat, that ain't how it works.
You are confused between the mobile phone companies establishing where a mobile is and the user of a phone establishing their location.

Please give details of phones that use anything other than GPS to show the user their location.

He's right on that mobile phones utilize not only GPS for estimating the location they show to the user, this is generally referred to as "Assisted GPS" as far as I know.

However that fact doesn't matter at all and is a pure strawmannery on Pete's part.

There are plenty of devices that rely solely on GPS and don't even have cellular or WiFi connectivity built in to do otherwise.

And no, Pete, a gyroscope, accelerometer and magnetometer can't be used to determine one's initial position. Those sensors can only help determine a change of position, as someone already pointed out.
And no, those devices don't prompt you to enter coordinates every time you turn them on.
« Last Edit: March 17, 2018, 02:23:35 PM by Science, bitch! »
Here am I floating in my tin can
far above the Moon
Planet Earth is blue
and there's nothing I can do

Offline StinkyOne

  • *
  • Posts: 805
    • View Profile
Re: FET and Global Positioning System
« Reply #43 on: March 17, 2018, 04:42:52 PM »
Allow me to remind everyone that the key contention here is whether GPS works well or not. Not whether or not it exists. Accounts along the lines of Stinky's "I used it and it almost told me where I was!" are unlikely to swing it in either direction.

No Pete, that is not the key contention. That is the strawman you're trying to build because you can't actually explain away the OP's actual question.

From OP:
Quote
Could we now please proceed to the essential part of my question?
My intention was not to spark a debate about the accuracy of GPS, and I deliberately left open whether those systems rely on satellites (which obviously I and most fellow round-earthers have no reason to doubt) or something else like ground-based radio beacons like some flat-earthers claim.

What I was getting at was why flat-earthers think it reasonable to claim that NASA and other space agencies are not aware of the shape of earth.

You admit it exists, so you're really close to seeing that the world is, in fact, round. Ground-based GPS wouldn't work for several reasons.(range, elevation calcs, no coverage in the oceans) Satellites don't work in FEH. Even if they could orbit your little Sun, the gravitational perturbations would not result in the nice, steady orbits we see. Beyond OP's question, I'd love to know how you think GPS works.
« Last Edit: March 17, 2018, 04:45:41 PM by StinkyOne »
I saw a video where a pilot was flying above the sun.
-Terry50

*

Offline Pete Svarrior

  • e
  • Planar Moderator
  • *****
  • Posts: 10567
  • (>^_^)> it's propaganda time (◕‿◕✿)
    • View Profile
    • The Flat Earth Society
Re: FET and Global Positioning System
« Reply #44 on: March 17, 2018, 08:44:02 PM »
No Pete, that is not the key contention.
Right. The two FE'ers that responded to this thread disagree with you on that matter. To me, that makes it a key contention. If you're not interested in the  FE'ers perspective, that honestly does not bother me, but... why would you bother asking your question to the Flat Earth Society? If you just want to talk about how right you are, why not take it to Reddit?

Ground-based GPS wouldn't work for several reasons.
Indeed, it would work very poorly, and it would perform much better in some areas than others. This is exactly why it's relevant to discuss the situations in which it works very poorly, and the criteria under which GPS is generally avoided as the main source of positioning data.
Read the FAQ before asking your question - chances are we've already addressed it.
Follow the Flat Earth Society on Twitter and Facebook!


*mic stays stationary and earth accelerates upwards towards it*

*

Offline Tumeni

  • *
  • Posts: 1831
    • View Profile
Re: FET and Global Positioning System
« Reply #45 on: March 17, 2018, 10:57:55 PM »
why would you bother asking your question to the Flat Earth Society? If you just want to talk about how right you are, why not take it to Reddit?

Your forum invites the general public to converse, right here. It's in the text under the Forum link on the homepage. If you don't really want to have these conversations, should the homepage not read differently?   


This is exactly why it's relevant to discuss the situations in which it works very poorly, and the criteria under which GPS is generally avoided as the main source of positioning data.

To which criteria or situations do you refer?
=============================
Not Flat. Happy to prove this, if you ask me.
=============================

Nearly all flat earthers agree the earth is not a globe.

Nearly?

JohnAdams1145

Re: FET and Global Positioning System
« Reply #46 on: March 18, 2018, 02:28:11 AM »
Sorry, but asserting that GPS doesn't work well in all locations where the receiver reports a workable signal is a dead-end road. Most of the anecdotal data regarding the not-working GPS involves the maps loaded into the navigation unit (aka not GPS), general complaining about things, human error, etc... It's well known that GPS-guided precision munitions hit their targets pretty well (otherwise it would be a colossal waste of money to make them). Also, can't you try this yourself? Get a GPS unit + Arduino/Raspberry Pi, take it to a known landmark, and get it to give you a fix? What about the personal locator beacons that mariners depend on when they run into trouble? The ELTs carried on aircraft?

Offline StinkyOne

  • *
  • Posts: 805
    • View Profile
Re: FET and Global Positioning System
« Reply #47 on: March 18, 2018, 03:55:21 AM »
Right. The two FE'ers that responded to this thread disagree with you on that matter. To me, that makes it a key contention. If you're not interested in the  FE'ers perspective, that honestly does not bother me, but... why would you bother asking your question to the Flat Earth Society? If you just want to talk about how right you are, why not take it to Reddit?

You seem to have had some bad experiences on Reddit. You should avoid it. I don't post there and all of my FEH stuff is limited to this site.

Quote
Indeed, it would work very poorly, and it would perform much better in some areas than others. This is exactly why it's relevant to discuss the situations in which it works very poorly, and the criteria under which GPS is generally avoided as the main source of positioning data.

Terrific, would you mind pointing out where it works poorly that is inconsistent with its design? Poor performance is expected around tall buildings, under heavy cover, in deep canyons, etc. If you were in a nice open field and the system consistently said you were in the ocean, that would be an issue. But given the fact that the system suffers from the exact problems one would expect from a satellite-based system, it makes some sense to conclude that it is, indeed, satellite-based.
I saw a video where a pilot was flying above the sun.
-Terry50

Re: FET and Global Positioning System
« Reply #48 on: March 18, 2018, 09:13:08 AM »
The two FE'ers that responded to this thread disagree with you on that matter. To me, that makes [the question whether GPS works well or not] a key contention.
Pete, understand your question. Would you agree with me that GPS works well in Aviation? Please read my post 8 posts up and comment what you think. I would be very interested if you thought that GPS didn't work well in aviation and explained why you thought it doesn't work well in aviation. If fact, realise that I'm putting my life in the hands of a GPS system when I descend between mountains in cloud at night, so if you have any concerns it doesn't work well, PLEASE let me know.

Also, I'm interested in what defines a 'well' working navigation system for you? It's obviously a very vague term. In the Middle Ages the way sail ships navigated worked "well", in the sixties navigation by NDB (non-directional radio beacons) worked well, or dead-reckoning. However these days we wouldn't even consider these inaccurate methods if we can avoid it. Having said that, dead-reckoning is surprisingly fun and accurate if you do it right!

Also Pete, are you aware that GPS is used in various applications to generate an extremely precise time? A good GPS receiver is able to produce a time that is accurate to within approximately 10 ns (nano-seconds or 0.00000001 second) of Universal Time, only based on the radio signals it receives. I have personally played with this to try to synchronise the signal of two FM radio station antennas that were in separate locations. Another interesting application is the Obstacle Lights on wind turbines that generate electricity. In some wind turbine farms you can notice that all the obstacle lights on top of these wind turbines flash at the exact same moment. They use GPS as their time base.

It's well known that GPS-guided precision munitions hit their targets pretty well (otherwise it would be a colossal waste of money to make them).
Not entirely true. Some of these use ground scanning techniques to help their navigation. For example Terrain Contour Matching. If you were the enemy and you knew these missiles were GPS guided, what would YOU do? ... jam the GPS frequency at 1575.42 MHz and 1227.60 MHz of course!

Most of the anecdotal data regarding the not-working GPS involves the maps loaded into the navigation unit (aka not GPS), general complaining about things, human error, etc..
I think it's also because of cheap receivers, I mean most people nowadays base their GPS experience on their iPhone/Samsung, which is a consumer device not specifically built for GPS. Having said that, if you have ever used the Google Maps or Apple Maps app for real-time navigation, it is still very, very impressive. Particularly using the Google Maps app with the photographic ('sattelite') maps during driving really looks like you are having a drone flying behind you that is generating a live video feed. Have you ever tried it?
« Last Edit: March 18, 2018, 10:18:37 AM by Treep Ravisarras »
As the saying goes "The internet belongs to the lunatics in their walled gardens" - Xiang Yu

I see a Flat Earth. And I can't imagine anything else.

I got work to do. 0.00018% of Christians believe in a Flat Earth. Pls help

HorstFue

Re: FET and Global Positioning System
« Reply #49 on: March 18, 2018, 10:57:29 PM »
Nice rationalization there, but those explanations have not been demonstrated to be true. All we know is that GPS is wrong when attempting to determine distance.

That's a misconception.
The GPS system (those satellites etc.) is build to give you your current position, nothing more.
Distances are measured on charts. Or if you already have two positions, you could calculate the distance, offline, no GPS system needed.
These are additional features, that are build into GPS devices: Calculate distances between positions, or more convenient, nowadays most GPS devices have a build in electronic chart, so you can choose positions from this chart.

If tracking or odometer functions are not reliable, than this is an issue of these devices, not of the GPS system.

*

Offline Pete Svarrior

  • e
  • Planar Moderator
  • *****
  • Posts: 10567
  • (>^_^)> it's propaganda time (◕‿◕✿)
    • View Profile
    • The Flat Earth Society
Re: FET and Global Positioning System
« Reply #50 on: March 19, 2018, 10:45:11 AM »
If fact, realise that I'm putting my life in the hands of a GPS system when I descend between mountains in cloud at night, so if you have any concerns it doesn't work well, PLEASE let me know.
That depends on the mountains. If you're happy with 0.5km-1km accuracy, you're probably good to go. You should remember that, for obvious reasons, GPS precision will drop dramatically as you approach the mountain. That said, I wouldn't take the advice of some random techie on an Internet forum in a potentially life-threatening situation, nor would I ever ask for it. Please note that I will not mourn you if you crash yourself into a mountain by blindly trusting a machine.

Also Pete, are you aware that GPS is used in various applications to generate an extremely precise time?
"Extremely precise" is an overstatement, and your figures appear to have been sourced from the Moon, but yes, synchronising your receiver's clock with the GPS is generally a pre-requisite for GPS working at all. If I were you, I'd propose NTP for a much more practical source of time.

Also, I'm interested in what defines a 'well' working navigation system for you?
The contention we're currently discussing has been outlined within the first two posts of the thread.
Read the FAQ before asking your question - chances are we've already addressed it.
Follow the Flat Earth Society on Twitter and Facebook!


*mic stays stationary and earth accelerates upwards towards it*

Re: FET and Global Positioning System
« Reply #51 on: March 19, 2018, 12:04:07 PM »
That depends on the mountains. If you're happy with 0.5km-1km accuracy, you're probably good to go.
Sorry, but I think you are deliberately minimizing my point and I'm not sure why? GPS is approved as primary source of air navingation (I can provide links to legal texts if you like) Four billion air passengers are happy with this. 4,000,000,000 passengers with zero deaths in commercial passenger jets last year. Would you agree with me that GPS works well in Aviation?

You should remember that, for obvious reasons, GPS precision will drop dramatically as you approach the mountain.
This is actually untrue and contrary to Flat Earth Empirical Evidence guidelines. The alternative means of navigation are: Non-Directional Beacons (NDB), or VOR's. They are proven to drop dramatically in precision as you approach the mountain, where as GPS maintains it accuracy as proven in aviation.

"Extremely precise" is an overstatement, and your figures appear to have been sourced from the Moon, but yes, synchronising your receiver's clock with the GPS is generally a pre-requisite for GPS working at all. If I were you, I'd propose NTP for a much more practical source of time.
Please as fellow Flat Earther I can't believe what you say. You say 10ns is overstated as "Extremely precise", but you advise using NTP with has an accuracy of 1 ms at best??? You seem to be clever in other posts, why this statement?
No, I'm not talking about the Moon, as Flat Earther I don't believe we can get to the moon. I'm talking about a receiver that I have done some work with and empirically determined to work. An current example is this receiver that gives 15 ns accuracy:
http://www.trimble.com/Timing/RES-SMT-360.aspx that you can buy here quite cheap: https://novotech.com/Products/gps-timing/Trimble/modules
Pete, are you aware that GPS is used in various applications to generate an extremely precise time?

Also, I'm interested in what defines a 'well' working navigation system for you?
The contention we're currently discussing has been outlined within the first two posts of the thread.
No, you said the contention was if GPS works well or not. I'll quote:
Allow me to remind everyone that the key contention here is whether GPS works well or not.
So I ask you, what defines a 'well' working navigation system for you? It's obviously a very vague term. In the Middle Ages the way sail ships navigated worked "well", in the sixties navigation by NDB (non-directional radio beacons) worked well, or dead-reckoning. However these days we wouldn't even consider these inaccurate methods if we can avoid it.
« Last Edit: March 19, 2018, 12:12:43 PM by Treep Ravisarras »
As the saying goes "The internet belongs to the lunatics in their walled gardens" - Xiang Yu

I see a Flat Earth. And I can't imagine anything else.

I got work to do. 0.00018% of Christians believe in a Flat Earth. Pls help

Re: FET and Global Positioning System
« Reply #52 on: March 19, 2018, 12:11:51 PM »
If fact, realise that I'm putting my life in the hands of a GPS system when I descend between mountains in cloud at night, so if you have any concerns it doesn't work well, PLEASE let me know.
That depends on the mountains. If you're happy with 0.5km-1km accuracy, you're probably good to go. You should remember that, for obvious reasons, GPS precision will drop dramatically as you approach the mountain. That said, I wouldn't take the advice of some random techie on an Internet forum in a potentially life-threatening situation, nor would I ever ask for it. Please note that I will not mourn you if you crash yourself into a mountain by blindly trusting a machine.

Also Pete, are you aware that GPS is used in various applications to generate an extremely precise time?
"Extremely precise" is an overstatement, and your figures appear to have been sourced from the Moon, but yes, synchronising your receiver's clock with the GPS is generally a pre-requisite for GPS working at all. If I were you, I'd propose NTP for a much more practical source of time.

Also, I'm interested in what defines a 'well' working navigation system for you?
The contention we're currently discussing has been outlined within the first two posts of the thread.
GPS is used in many timing applications. It is very accurate.

NTP may be a much more practical source of time in some cases but is dependent on transmission though networks and routers.

Where do you find a 0.5km accuracy with GPS, how many satellites would you be tracking?

*

Offline Pete Svarrior

  • e
  • Planar Moderator
  • *****
  • Posts: 10567
  • (>^_^)> it's propaganda time (◕‿◕✿)
    • View Profile
    • The Flat Earth Society
Re: FET and Global Positioning System
« Reply #53 on: March 19, 2018, 12:29:44 PM »
Would you agree with me that GPS works well in Aviation?
For a definition of "well" that's utterly irrelevant to the subject matter here, yes. I do note that you immediately backtracked from daredevil mountain stunts to civil aviation, though.

This is actually untrue
Well, then you disagree with the creators of GPS. Can't help you there.

You say 10ns is overstated as "Extremely precise"
No, I say that 10ns is an overstated figure.

but you advise using NTP with has an accuracy of 1 ms at best???
Again, no. I suggest NTP as a much more practical source of time. And, again, you decided to fudge the numbers in your favour.

You seem to be clever in other posts, why this statement?
Because you didn't strawman them to hell and back.

No, I'm not talking about the Moon
Neither am I.

Pete, are you aware that GPS is used in various applications to generate an extremely precise time?
I already answered this question. Asking it again is unlikely to help.

So I ask you, what defines a 'well' working navigation system for you? It's obviously a very vague term. In the Middle Ages the way sail ships navigated worked "well", in the sixties navigation by NDB (non-directional radio beacons) worked well, or dead-reckoning. However these days we wouldn't even consider these inaccurate methods if we can avoid it.
This is also a question I already answered. The contention is covered within the first two posts of this thread. You can pick one of the two sides presented there, or introduce your own.
« Last Edit: March 19, 2018, 12:48:32 PM by Pete Svarrior »
Read the FAQ before asking your question - chances are we've already addressed it.
Follow the Flat Earth Society on Twitter and Facebook!


*mic stays stationary and earth accelerates upwards towards it*

Re: FET and Global Positioning System
« Reply #54 on: March 19, 2018, 12:39:45 PM »
GPS is used for timing in broadcasting and communications because it is more accurate and reliable compared with NTP.

Re: FET and Global Positioning System
« Reply #55 on: March 19, 2018, 12:58:47 PM »
Pete, I have no idea where you got an accuracy of 500m-1km from
GPS is way more accurate than that.

https://www.gps.gov/systems/gps/performance/accuracy/

Tom's post about problems in GPS are all about GPS being used for something which it isn't primarily designed for.
If GPS is only accurate to within a 4.9m radius then if you're travelling then, over time, those inaccuracies will add up.
This has been explained. If you want to know the difference between A and Z and GPS can tell you the location of each to within a 4.9m radius then the overall accuracy will be pretty good (if A and Z are reasonably far apart, if they're 5m apart then not so much).
If you take readings ever so often so you're measuring the distance from A to B, B to C, C to D...Y to Z then each of those small inaccuracies will add up.

That does NOT mean that GPS - the P is for Positioning, it's primary purpose is to tell you your position - is in itself inaccurate.

Were this a navigation forum we could continue to argue the toss about how accurate it is, but it isn't.
In any case, it is widely used and it works using a fleet of satellites orbiting our globe, or so it is claimed.
Do you have any evidence that this is not the case? If you don't then it's another nail in the coffin of flat earth theory.
If you are making your claim without evidence then we can discard it without evidence.

Nearly all flat earthers agree the earth is not a globe.

Offline ShowmetheProof

  • *
  • Posts: 90
  • We are fellow scientists, and should act as such.
    • View Profile
Re: FET and Global Positioning System
« Reply #56 on: March 19, 2018, 01:08:16 PM »
As this is an argument about the existence of GPS, and not accuracy, my family's old(Last used 3 years ago, so not too old) GPS will be the hammer for this nail in the TFES's coffin.  Our old GPS consistently told us where we were when the cell phones couldn't, but that isn't all.  It also showed us where the satellites it was getting information from were, how many there were, how strong they were, and more.  Also, why would the government lie about GPS?  They would have to create millions of fake devices to keep this incredibly important secret.  GPS exists, and it works too. 

Re: FET and Global Positioning System
« Reply #57 on: March 19, 2018, 01:14:51 PM »
As this is an argument about the existence of GPS, and not accuracy, my family's old(Last used 3 years ago, so not too old) GPS will be the hammer for this nail in the TFES's coffin.  Our old GPS consistently told us where we were when the cell phones couldn't, but that isn't all.  It also showed us where the satellites it was getting information from were, how many there were, how strong they were, and more.  Also, why would the government lie about GPS?  They would have to create millions of fake devices to keep this incredibly important secret.  GPS exists, and it works too.
And there is also the Russian GPS system and others.

Offline StinkyOne

  • *
  • Posts: 805
    • View Profile
Re: FET and Global Positioning System
« Reply #58 on: March 19, 2018, 01:17:05 PM »
For a definition of "well" that's utterly irrelevant to the subject matter here, yes. I do note that you immediately backtracked from daredevil mountain stunts to civil aviation, though.

For aviation, GPS is very accurate. (within 1-2 meters 95% of the time) I would submit if 1-2 meters is an issue in mountain flying, you're doing it wrong and aren't long for this world. The inaccuracy is generally introduced by the device, not GPS. Consumer level devices can get you close, industrial devices will put you within a few steps, at most. Again, highly accurate given the Earth is almost 42 million feet around.

Quote
No, I say that 10ns is an overstated figure.

You are correct. The system is accurate to within 40ns 95% of the time. Which is to say it is fantastically accurate at time frames a human can comprehend. Your NTP comment was highly overstated if you start thinking about the applications where GPS is used. NTP is great for a network, but is useless, obviously, once your connection to said network is broken. (assuming you had one to begin with)

I saw a video where a pilot was flying above the sun.
-Terry50

Re: FET and Global Positioning System
« Reply #59 on: March 19, 2018, 01:46:47 PM »
Once more a circular argument ensues, bogged down in debates about the measurable accuracy and technical specifications, and avoiding the core issue - what do you think enable GPS if it is not satellites?

All the RE contributors believe GPS (however "accurate" it is) is a result of a network of satellites that allow devices to triangulate their position on the Earth. Their evidence for this are the effective operation of millions of SatNav systems, the plethora of devices on the market, the documentation, the industries, the consumer products available, individual experience of working withing GPS technology etc etc

Tom/Pete and any FE faithful - What do you think enables GPS to work, however accurate or not you might think it is?