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Around reference 20, we allege that the program's formal proper name has been shortened from "NAVSTAR GPS" to simply "GPS".

That reference, and other sources including the website of the NAVSTAR GPS Joint Program Office suggest that this is not true, and indeed, "GPS" is no longer sufficiently definitive, given the existance of the Russian Glonass and upcoming European Union Galileo systems. Unless someone can convince me that interpretation is incorrect, I propose to adjust that section, and move the page back to NAVSTAR, where it belongs.
--Baylink (talk) 19:04, 25 March 2015 (UTC)[reply]

GPS is the name of the system of navigation satellites operated by the United States. The general term for satellite systems of this type is GNSS, or Global Navigation Satellite System. The shift from GPS to GNSS has been reflected in the changing names of publications (e.g. Inside GNSS ) and conferences (like the Institute of Navigation's GNNS+ conference). NAVSTAR is indeed no longer the name of the system, and has not been for decades; it is simply the Global Positioning System, as referred to by the US government and the US Air Force. siafu (talk) 22:04, 25 March 2015 (UTC)[reply]

GPS is probably more in line with

GNSS- the term "GPS" is enough of a distinction for the US system. Cheers! Skyraider1 (talk) 00:44, 26 March 2015 (UTC)[reply

]

I have always been rather suprised by the identification of 'a' GPS (system) with 'the' American GPS (system). We should split this article accordingly. Woodstone (talk) 12:00, 27 March 2015 (UTC)[reply]

"GPS" really is the name of the American system, and nobody uses the term "a GPS" to refer to such a system in general; the term for that is GNSS. The other GNSS's, namely

QZSS-- are never referred to as "GPS" except by analogy. I'm unclear of the intent of your comment, but if you believe there is some ambiguity here, I would challenge you to present some sources that show it. siafu (talk) 03:26, 30 March 2015 (UTC)[reply

]

I think that what is stated in the paragraph above is just government-speak. The general public uses GPS as a generic term, according to the words it abbreviates. In daily practice the word GNSS is hardly used. Woodstone (talk) 03:58, 30 March 2015 (UTC)[reply]

It's not just government-speak, it happens to be the terminology in use in the GNSS community. I can easily provide dozens of sources to back that up (there are a few given above already). In daily practice, most people use the word "GPS" to refer to GPS-based guidance systems, like when the car rental agent asks if you would like "a GPS", meaning something like a TomTom. IMO, relatively few members of the public are aware that other GNSS's exist, so a fortiori they aren't using it to refer to GNSS's in general. I would once again challenge you to produce some sources to back up your claim that the term "GPS" is used to refer to Galileo, GLONASS, Beidou, etc. siafu (talk) 08:03, 2 April 2015 (UTC)[reply]

I agree on GPS vs. GNSS but I disagree on GPS vs. Navstar GPS: all the latest official documents retain "Navstar" somewhere, e.g.: the Interface Control Document (ICD) -- also known as Interface Specification (IS) and User Interface (UI) -- is still titled "Navstar GPS..." as of 2014 [1]; the "Standard Positioning Service (SPS) Performance Standard" is even more explicit: "The Navstar Global Positioning System, hereafter referred to as GPS, is a space-based radionavigation system owned by the United States Government (USG) and operated by the United States Air Force (USAF)." (the current version is admittedly a bit dated -- 2008) [2]; the "Wide Area Augmentation System (WAAS) Performance Standard", Section B.3, Abbreviations and Acronyms, states: "GPS: Global Positioning System (or Navstar Global Positioning System)" [3]; not to mention the

The claim that the name has been shortened is sourced to Rip, "The Precision Revolution." I don't have that book but a search of the book on Google turns up 95 instances of "Navstar GPS" including a chapter title. Searches for things like "rename" and "shorten" turn up nothing. The first time the term "GPS" is used in the book, on page 4, the full name is given as "Navstar Global Positioning System (GPS)." Finally, the citation is for page 65, and there is nothing on that page about the name being shortened. I submit that the claim is not supported by the source. Kendall-K1 (talk) 20:04, 27 April 2015 (UTC)[reply]

Thanks; I wonder if we should mention Navstar more prominently -- not necessarily much more frequently -- in this page, e.g., "The official complete name of the system is "Navstar Global Positioning System"?

Fgnievinski (talk) 20:35, 27 April 2015 (UTC)[reply

]

Kkddkkdd (talk) 12:56, 21 May 2015 (UTC)---[reply]

The true reception time of message ${\displaystyle t_{i}}$ in the section "6.1 Problem description" doesn't depend on a satellite ${\displaystyle i}$. Thus it should be denoted as ${\displaystyle t}$. Kkddkkdd (talk) 01:54, 11 June 2015 (UTC)[reply]

The solution is at the intersection or near intersection of four or more, not three, sphere surfaces. It should be emphasized that the solution is at the intersection or near intersection of sphere surfaces not at the intersection of spheres. RHB100 (talk) 20:15, 17 June 2015 (UTC)[reply]

• I'm starting to think someone is suffering from amnesia:
  Fgnievinski (talk) 05:34, 20 June 2015 (UTC)[reply
  ]

I think it is possible that we have some editors who love hyperboloids but hate spheres. There may be others who love spheres but hate hyperboloids. Actually this geometric interpretation as spheres or hyperboloids reflect different methods of solution of the equations in the "Problem description" section. These equations can be solved analytically by the Bancroft method, numerically by multidimensional Newton-Raphson, or by a least squares method. Also these equations can be solved by performing subtraction operations so as to eliminate the unknown clock bias and obtain the equations of hyperboloids. The intersection of these hyperboloid surfaces is then a solution. But also a solution of the equations in the "Problem description" section is at the intersection of four or more sphere surfaces since these equations according to Wikipedia describe the surfaces of spheres. Thus those who hate spheres and love hyperboloids should realize that when we say that the solution is at or near the intersection of four or more sphere surfaces, we are not denying that the solution is at or near the intersection of hyperboloid surfaces. RHB100 (talk) 18:42, 20 June 2015 (UTC)[reply]

The above answer contains a few misconceptions. I don't think anybody proposes to actually convert 4 equations to the ones for 3 hyperboloids and then solve them. Main reason being that hardly ever just 4 satellites are used. In case of more than four satellite signals, the problem is first stated as a least squares system, which can subsequently be solved by either an analytical (Bankroft) or iterative (Newton Raphson) method. You cannot say that an intersection of sherical surfaces is sought, because depending on the clock bias the spheres grow or shrink, each creating a spherical cone. −Woodstone (talk) 13:29, 21 June 2015 (UTC)[reply]

The equations in the problem description section are equations of spheres in which x, y, z, and b are unknowns. The solution of the equations is the value of (x, y, z, b) which satisfies all of the 4 or more equations. This is true regardless of whether the solution is obtained directly as in the Bancroft method or by an iterative method. When the value of (x, y, z, b) is known these equations describe spheres with specific radii. Since the solution of the problem requires four or more spheres, comments about the solution being at the intersection of three sphere surfaces are misleading. RHB100 (talk) 17:24, 22 June 2015 (UTC)[reply]

No unsourced claims shall be considered.

Fgnievinski (talk) 18:26, 22 June 2015 (UTC)[reply

]

The material I have written is certainly well sourced in the Problem description and will be repeated in the Geometric interpretation section. RHB100 (talk) 20:59, 22 June 2015 (UTC)[reply]

There's no mention of the word "sphere" in the text of either of the two sources cited in the Problem description section; the mathematical equations of pseudoranges are well sourced, your interpretation of them as spherical radii is not.

Fgnievinski (talk) 00:19, 23 June 2015 (UTC)[reply

]

It's like deja vu all over again. Unless something has changed-- you have a new source, or your position is different-- you can only expect the outcome of this discussion to mirror the outcomes of the last three times you tried to push this interpretation. siafu (talk) 00:28, 23 June 2015 (UTC)[reply]

I have thoroughly documented and given a straightforward reference to what should have been obvious. However, some people act as though they do not understand so I have provided this thorough and complete explanation.

This is exactly the same rational and interpretation suggested, and rejected, multiple times before. Repeating the same action with the expectation of different results is not generally a productive strategy. I have reverted your edits again. siafu (talk) 01:48, 23 June 2015 (UTC)[reply]

I have thoroughly documented and given a straightforward reference to what should have been obvious. However, some people act as though they do not understand so I have provided this thorough and complete explanation. RHB100 (talk) 01:57, 23 June 2015 (UTC)[reply]

Fgnievinski, The fact that the equations in the Problem description are equations for spheres is certainly well known and should be obvious. Nevertheless, I have provided a detailed explanation of what should be obvious. Authors may not always point out that these equations are spheres but this is because it is obvious. RHB100 (talk) 01:57, 23 June 2015 (UTC)[reply]

Siafu, no one has ever shown that the equations in the Problem description are not spheres. And no competent engineer would do so. It is quite obvious to any competent engineer that these equations are the equations of spheres. RHB100 (talk) 01:57, 23 June 2015 (UTC)[reply]

Siafu, please read the references before irresponsibly reverting edits. RHB100 (talk) 02:06, 23 June 2015 (UTC)[reply]

So we really are doing this all over again. Is this the part where you mention your engineering degrees? Please review the talk archives if you forget the reasons that your interpretation failed to gain consensus the last time. siafu (talk) 02:10, 23 June 2015 (UTC)[reply]

You are now in violation of

WP:3RR. I suggest you familiarize yourself with the rules of wikipedia before proceeding any further. siafu (talk) 02:18, 23 June 2015 (UTC)[reply

]

Since you have gone past four to five reverts, I have created a new report at Wikipedia:Administrators' noticeboard/Edit warring. I suggest you revert yourself to avoid a potential block. siafu (talk) 02:42, 23 June 2015 (UTC)[reply]

Now that the article is locked, I think we should try to reach consensus as to the content dispute. I've gone back over the three previous discussions of this "equations of spheres" dispute and don't see anything new here, so I would argue in favor of leaving out the "equations of spheres" material. But I'm open to persuasion if someone can provide supporting quotes from the source material (quotes, not your own interpretation). Kendall-K1 (talk) 13:59, 23 June 2015 (UTC)[reply]

Yes this is a good opportunity to discuss editing changes. There have been a lot of complaints that the fact that the equations in the Problem description section describe spheres is not documented. I think that these complaints are just excuses since it is obvious to me that they are the equations of spheres. However to call the bluff of these people doing the complaining, I have provided a reference along with explanation to show that they are the equations of spheres. This explanation is shown below. This explanation will aid the understanding of GPS so if you are a supporter of improving the GPS document making it more readable and understandable, you will support including the explanation below as a part of the GPS document. On the other hand if you want to degrade the GPS document make it less understandable, you may oppose the inclusion of this explanatory material. So let's find out who the good people are and who the enemies of Wikipedia are or otherwise explain your position. RHB100 (talk) 18:27, 23 June 2015 (UTC)[reply]

Problem description

The receiver uses messages received from satellites to determine the satellite positions and time sent. The x, y, and z components of satellite position and the time sent are designated as [x_i, y_i, z_i, s_i] where the subscript i denotes the satellite and has the value 1, 2, ..., n, where n ≥ 4. When the time of message reception indicated by the on-board receiver clock is t̃, the true reception time is t = t̃ - b, where b is the receiver's clock offset from the much more accurate GPS system clocks employed by the satellites. The receiver clock offset is the same for all received satellite signals (assuming the satellite clocks are all perfectly synchronized). The message's transit time is t̃ - b - s_i. Assuming the message traveled at the speed of light, c, the distance traveled is (t̃ - b - s_i) c.

For n satellites, the equations to satisfy are:

${\displaystyle (x-x_{i})^{2}+(y-y_{i})^{2}+(z-z_{i})^{2}={\bigl (}[{\tilde {t}}-b-s_{i}]c{\bigr )}^{2},\;i=1,2,\dots ,n}$

or in terms of pseudoranges, ${\displaystyle p_{i}=\left({\tilde {t}}-s_{i}\right)c}$, as

${\displaystyle {\sqrt {(x-x_{i})^{2}+(y-y_{i})^{2}+(z-z_{i})^{2}}}+bc=p_{i},\;i=1,2,...,n}$ .^[1][2]

Comparison of these equations with the Equations in R3 section of Sphere in which ${\displaystyle (x-x_{i})}$ corresponds to ${\displaystyle (x-x_{0})}$, ${\displaystyle (y-y_{i})}$ corresponds to ${\displaystyle (y-y_{0})}$, ${\displaystyle (z-z_{i})}$ corresponds to ${\displaystyle (z-z_{0})}$, and ${\displaystyle {\bigl (}[{\tilde {t}}-b-s_{i}]c{\bigr )}}$ corresponds to ${\displaystyle r}$ shows that these equations are spheres as documented in Sphere.

Since the equations have four unknowns [x, y, z, b]—the three components of GPS receiver position and the clock bias—signals from at least four satellites are necessary to attempt solving these equations. They can be solved by algebraic or numerical methods. Existence and uniqueness of GPS solutions are discussed by Abell and Chaffee.^[3] When n is greater than 4 this system is overdetermined and a fitting method must be used.

With each combination of satellites, GDOP quantities can be calculated based on the relative sky directions of the satellites used.