Robthebrit
Explorer
Flame suite on, here comes Scotts tacoma army.
Tom Sheppard's GPS article is wrong.
- Thread starter Robthebrit
- Start date
Jonathan Hanson
Well-known member
Rob, for goodness sakes, now you're using partial quotes to support your arguments. The text says "only one of these points - or in a very, very small triangle." That's not rubbish, it's what happens on the surface of the earth, which as I have already explained (tired of hitting the italics here!) is the area of concern to most readers, and the only region we had the luxury of describing. The satellites' interface with the surface of the earth does not take the shape of a sphere - it can't. It takes the shape of a two-dimensional circle, and that was the best way to describe it, particularly in an article that at this point was barely half as long as your condemnation of it. All your comments have assumed we had unlimited space to explain GPS technology. We didn't.
Why didn't I run it by you? Well, errors you made have been pointed out by others here. I suspect I could gather a dozen more expert comments that would all clash with each other in details. However, if we ever run a 6,000-word article on GPS technology I'd be extremely grateful for your input. Seriously. This was simply not that article.
This has morphed into one of those endless, do-I-have-nothing-better-to-do? forum debates, so I'll sign off now. I don't feel I have egg on my face; I feel my point about your presentation is perfectly valid. I'm just not sure about your motives. I do greatly respect your knowledge of GPS systems; however, your knowledge of magazine articles and publishing realities is thin, and I wish you had taken that into account before your post and your public accusations against Scott and me. I think that's fair.
Ursidae69
Traveller
Any magazine is going to get some heat now and then, the 4WDTO caught some not too long ago on ExPo.
Constructive criticism is great and I'm sure the OJ team will take this as constructive criticsim and make the product even better. My only contention is that the subject line that the article is "wrong". It's a technical topic with books written about it, so getting it down to a magazine article size while still being educational is a fine balance that not everyone will agree with. Nature of the business I am sure. I have personally learned a considerable amount of new info from this thread and I appreciate that.
Constructive criticism is great and I'm sure the OJ team will take this as constructive criticsim and make the product even better. My only contention is that the subject line that the article is "wrong". It's a technical topic with books written about it, so getting it down to a magazine article size while still being educational is a fine balance that not everyone will agree with. Nature of the business I am sure. I have personally learned a considerable amount of new info from this thread and I appreciate that.
Jonathan Hanson
Well-known member
Uh, Mark drives a black Nissan. Come on, Rob, get your facts straight!
Also, "Tacoma" should be capitalized, you should have used a semicolon after "on," and "Scott's" needs an apostrophe.
See, Rob: We can help each other . . .
Also, "Tacoma" should be capitalized, you should have used a semicolon after "on," and "Scott's" needs an apostrophe.
See, Rob: We can help each other . . .
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1leglance
2007 Expedition Trophy Champion, Overland Certifie
I have stated my position that there are 2 levels of presentation:
The general overview that is meant to be "at a glance" and "invite someone to learn more if they desire"
The techincal informer, which should be peer reviewed, of a quality to act as a research tool, get someone a degree or justify the one they already have and bore you to sleep.....
I am not the only one that feels that OJ did a great job of what they meant to do and the majority of readers who have chimed in here agree.
Since that idea just doesn't sit well with you Rob (and I understand you have a higher level of knowledge in the field) then I will ask of you what I ask of everyone at this point in the conversation when each of us has pee'd on the ground and marked our territory...
Can you do better?
Since you have the article do a word count, and write something of the same length, that targets the same audience (someone with no prior knowledge of gps) and that will help sell the magazine (remember you can't bore folks since then they won't buy next time and your ad revenue goes away....and let me say that there is a deeper level of interaction there in a market based economy but we don't need that depth now).
Post it up and your point might be better understood....not that it would change the facts:
You posted in the general section vs navigation.
You posted the article is "wrong" vs "lacking in depth".
You accused the OJ team of not proofing or fact checking without doing any of that yourself.
But I am looking forward to your article...when can we expect it? There is also the deadline issue in the media world, let's not forget that.
The general overview that is meant to be "at a glance" and "invite someone to learn more if they desire"
The techincal informer, which should be peer reviewed, of a quality to act as a research tool, get someone a degree or justify the one they already have and bore you to sleep.....
I am not the only one that feels that OJ did a great job of what they meant to do and the majority of readers who have chimed in here agree.
Since that idea just doesn't sit well with you Rob (and I understand you have a higher level of knowledge in the field) then I will ask of you what I ask of everyone at this point in the conversation when each of us has pee'd on the ground and marked our territory...
Can you do better?
Since you have the article do a word count, and write something of the same length, that targets the same audience (someone with no prior knowledge of gps) and that will help sell the magazine (remember you can't bore folks since then they won't buy next time and your ad revenue goes away....and let me say that there is a deeper level of interaction there in a market based economy but we don't need that depth now).
Post it up and your point might be better understood....not that it would change the facts:
You posted in the general section vs navigation.
You posted the article is "wrong" vs "lacking in depth".
You accused the OJ team of not proofing or fact checking without doing any of that yourself.
But I am looking forward to your article...when can we expect it? There is also the deadline issue in the media world, let's not forget that.
Andrew Walcker
Mod Emeritus
This thread has been very interesting and knowing some of the participants, I am optimistic that this will not turn into any type of flame war but stay a lively and informative debate with all sides contributing their ideas in a polite and respectful manner.
Rob, if I were in your shoes I probably would have started voicing my initial concerns regarding the article via PM instead of the public forum. You have to understand that you have put OJ in a very defensive position with doing it the way you did.
Rob, if I were in your shoes I probably would have started voicing my initial concerns regarding the article via PM instead of the public forum. You have to understand that you have put OJ in a very defensive position with doing it the way you did.
Andrew Walcker
Mod Emeritus
Nice, I like that idea Lance!
Robthebrit
Explorer
Rob, for goodness sakes, now you're using partial quotes to support your arguments. The text says "only one of these points - or in a very, very small triangle." That's not rubbish, it's what happens on the surface of the earth, which as I have already explained (tired of hitting the italics here!) is the area of concern to most readers, and the only region we had the luxury of describing. The satellites' interface with the surface of the earth does not take the shape of a sphere - it can't. It takes the shape of a two-dimensional circle, and that was the best way to describe it, particularly in an article that at this point was barely half as long as your condemnation of it. All your comments have assumed we had unlimited space to explain GPS technology. We didn't.
That IS complete rubbish, its WRONG WRONG WRONG. I don't care if god wrote it. You defending it, especially as the publisher, look like an idiot. Nothing happens on the surface of the earth, you know nothing about the earth, that is what you are trying to solve. This is the hand waving, assuming you know something about the earth makes the problem trivial, you have to solve the problem with the information provided - If i can make information up and treat it as fact, I'll just make up my position. If the solution happened on the "Surface of the Earth" altitude wound not be required, your explanation is full of holes.
How about my other points, are you going to argue them too?
None of the technical info that I wrote here is wrong. I explained it mathematically, geometrically and algorithmically. All of my explanations line up in a nice clear picture. Yes there are holes but they are not relevent at this level, if you implemented a system you'd find problems with my explanation, I assume its a static system when it isn't an dopler is not being accounted for, elipical corrections, relativity corrections are not being accounted for and signal errors and cross checking are not being accounted for.
I have nothing to hide and nothing to protect, I don't know Tom from the next person. I started off by pointing out some errors, all magazines print errors. The fact I wrote on it on the forum is irrelevent, as the editor of the magazine you should learn some PR techniques fom this. Rather than getting into a big argument, throwing out random quotes from powers that be and trying to make something stick, you should of gone away reviewed the complaint, figured out if the scope of the error was relevent and not got all bent out of shape about it. The more your argue an incorrect point, in public, the more credibility the magazine loses. What are member of the public going to think when they read this, espeically ones that know how GPS works.
I just scanned the page and sent it without any preface to a friend who works at JPL, I don't 100% know if he knows how GPS works but he's a really smart guy. I'll post his reply.
Rob
That IS complete rubbish, its WRONG WRONG WRONG. I don't care if god wrote it. You defending it, especially as the publisher, look like an idiot. Nothing happens on the surface of the earth, you know nothing about the earth, that is what you are trying to solve. This is the hand waving, assuming you know something about the earth makes the problem trivial, you have to solve the problem with the information provided - If i can make information up and treat it as fact, I'll just make up my position. If the solution happened on the "Surface of the Earth" altitude wound not be required, your explanation is full of holes.
How about my other points, are you going to argue them too?
None of the technical info that I wrote here is wrong. I explained it mathematically, geometrically and algorithmically. All of my explanations line up in a nice clear picture. Yes there are holes but they are not relevent at this level, if you implemented a system you'd find problems with my explanation, I assume its a static system when it isn't an dopler is not being accounted for, elipical corrections, relativity corrections are not being accounted for and signal errors and cross checking are not being accounted for.
I have nothing to hide and nothing to protect, I don't know Tom from the next person. I started off by pointing out some errors, all magazines print errors. The fact I wrote on it on the forum is irrelevent, as the editor of the magazine you should learn some PR techniques fom this. Rather than getting into a big argument, throwing out random quotes from powers that be and trying to make something stick, you should of gone away reviewed the complaint, figured out if the scope of the error was relevent and not got all bent out of shape about it. The more your argue an incorrect point, in public, the more credibility the magazine loses. What are member of the public going to think when they read this, espeically ones that know how GPS works.
I just scanned the page and sent it without any preface to a friend who works at JPL, I don't 100% know if he knows how GPS works but he's a really smart guy. I'll post his reply.
Rob
Robthebrit
Explorer
1leglance said:
My facts have been checked, none of them are wrong, I have been verifying with people that know just in case I forgot something important. Where are my facts wrong?
I checked my facts and got the right answer, OJ checked theirs and got the wrong answer. Fair enough. Maybe its a case of reading what you want to read. They could of read "Howstuffworks.com" and got a better answer than they got from Garmin. The Garmin text matched what they had and kind of already knew, call it a false positive. We have all done it.
The article is fairly vanilla but verges on technical, its talking about wavelengths and frequenices, time computations etc. The concepts are correct at the level of "Intersect some geometry with a time stamp", this is the most basic level. The article tried to explain some of the concepts and that is where it goes wrong, not vauge, wrong.
Finally, you don't know who I am or what I do. I used to write embedded systems code but then I moved to the US to make video game. So let me tell you about media - OJ is such a tiny scale its irrelevent. I just shipped a $30m video game, in 17 laguages and 5 regions, it will probably sell 3-5million copies and will get more testing in the first day than we could ever give it. To do this you need to understand the systems you create. I also shipped the Xbox, I was the system architect, a $2bn project. I was involved with Playstation3 hardware and I have worked on the windows kernel. I write papers for video games all the time, I do talks at developer conferences and at places like E3 and Siggraph. I also write magazine articles, in fact I have a weekly article that I just posted. I have written chapters of books and have also been interviewed for numerous news pieces in all forms of media. Before you patronize poeple, becareful who you pick.
Obviously its what you want to read so lets leave it be and pretend people are stupid, no skin from my nose.
Rob
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mightymike
Adventurer
I'd rather be considered slow and uneducated than rude and pretentious!:1888fbbd:
teotwaki
Excelsior!
mmtoy said:I find this discussion fascinating.
In my field, I consistently come across articles targeted at the "layman" that incorrectly describe how something works. Usually the justification for the incorrect explanation is that the target audience "doesn't need to know the details." This annoys me to no end because usually the correct explanation doesn't take up any more space and would give the audience a true understanding of the topic.
With the knowledge that I may be getting myself into trouble, I'd like to point out that Rob's first post is also "wrong." The clocks of each of the GPS satellites are not in perfect sync, and are especially not in sync with any clocks on the earth.
Because the satellites are moving within different frames of reference and within different gravitational fields, General and Special Relativity come into play. Because they're in weaker gravitational fields, the satellite's clocks tick faster than a clock on the ground. Because they're moving at higher velocities, they tick more slowly than a clock on the ground. These affects have to be taken into account. If they aren't, the satellite clocks will gain time faster than an identical clock on the ground, at a rate of about 38 microseconds/day. The GPS system works in nanoseconds, and 38,000 nanoseconds/day is a lot of accumulating error.
My understanding is that relativity is taken into account when the clocks are built; the satellite's planned orbital altitude, velocity, etc. are used to calculate the difference in clock rates on the ground and in orbit. The satellite clock is then adjusted so it ticks about 38 microseconds/day slower while on the ground. When it gets to its orbit, the clock should now be ticking at about the right rate. The GPS receivers still have to do the relativistic calculations when they receive the signal.
I guess my point is that there are details that shouldn't be left out and then there are even more details that are terribly interesting but may not be necessary to further the basic knowledge of how a system works. Since I'm a math geek, I find I would prefer Rob's mathematically correct solution (with the relativistic explanation included) to Garmin's hand-wavy explanation.
Just my $0.02 to add to the fire.
--Moses
"Tick"???
Is that the Atomic Frequency Standard with a quartz crystal oscillator phase locked to either a cesium or rubidium physics package? Well, ticking is a lot easier to say to a layman.... :wings:
Scott Brady
Founder
Rob,
You have relegated yourself to name calling and chest pounding, and you are talking in circles to defend your ego.
...just go talk a walk.
You go from this
To this
The most simple of facts is that Tom's article is supported by dozens of authoritative sources. Whether the video game programmer is right, and Carnegie Mellon University and Garmin are wrong is nearly irrelevant to this point. Tom used known and credible sources to form his article, which were fact checked against known and credible sources. I find it highly unlikely that a half-dozen, well documented experts are wrong, and you are correct; what I do find possible is a mater of semantics, i.e., your definition and their definition are both correct, but articulated at two different levels of detail or vernacular.
You have relegated yourself to name calling and chest pounding, and you are talking in circles to defend your ego.
...just go talk a walk.
You go from this
Robthebrit said:
To this
Robthebrit said:
The most simple of facts is that Tom's article is supported by dozens of authoritative sources. Whether the video game programmer is right, and Carnegie Mellon University and Garmin are wrong is nearly irrelevant to this point. Tom used known and credible sources to form his article, which were fact checked against known and credible sources. I find it highly unlikely that a half-dozen, well documented experts are wrong, and you are correct; what I do find possible is a mater of semantics, i.e., your definition and their definition are both correct, but articulated at two different levels of detail or vernacular.
Tucson T4R
Expedition Leader
expeditionswest said:
Well said. We have beat this one to death. All interesting detail but in the end, we should now agree that we see this in slightly different lights and let it go at that.