Tom Sheppard's GPS article is wrong.

[Scott Brady]

Rob,

You have made a very good point in all of this, which is the necessity of great detail, auditing and review for technical articles. We will be sure to do make that a focus as we grow this new publication. Overland Journal and it's editors are absolutely not immune from making mistakes, and we will learn from them.

How you went about it destroyed my confidence in you as a resource and friend. Completely classless in my opinion, but I am sure that my opinion in that regard maters little at this point.

Social/business acumen and technologists are often times mutually exclusive. Our search continues...

I am done here...

 

[Robthebrit]

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.

The more big names you throw around you more stupid you look. Tom and I are not saying the same thing, not even close. The 4 or 5 things I pointed out earlier are errors, what do you say to that?

Rob

 

[ntsqd]

Well, this has gone on long enough.
Unsubscribing from this thread.

 

[Scott Brady]

Let's not stoke the fire or add to the insults please.

While Rob is intent on making personal attacks, I would ask that anyone else responding to this thread not act in same.

Let's keep the discussion about the article or gps stuff, or preferably, just let the thread stop where it's at.

Thanks

 

[flywgn]

Wow folks! I go fly-fishing for a couple of days and come back to this thread. Yikes!

I didn't even use my GPS on this trip. Sextant and a little dish of oil kept me in practice, and along with my barometer I determined our altitude.

In any event I was only interested in the hatches taking place. (Size 24 blue-winged olives really tested my eyesight.)

Didn't hook a fish either, damn it. Maybe the moon is in the wrong phase—or the fourth satellite never showed up. I think a better fly-fisher would have hooked fish. Only managed to get two to look at my pattern.

I don't know diddley-squat about how GPSs work, and I haven't read Tom's article yet. When I was finally able to withdraw the issue from Diana's hands, other articles caught my attention first. You can bet I'll read it now.

It took me a lot longer to read this thread than I think it'll take me to read the article.

Allen R

 

[kellymoe]

Holy crap!!! Move on guys. There are maybe 2% of OJ readers who would get uptight over this. OJ is a great publication, informative and visually pleasing, that combination is not easy to find these day. Get over it and move on to important and interesting stuff that the 98% of us care about.

 

[crawler#976]

no doubt...move on!

This is getting down right ... pirate4x4'ish

 

[1leglance]

I often encounter folks who like my gps setup and want to know more about gps as regarding off highway travel...much like the general readership of Overland Journal.
Rob my question is even more significant now that you have helped us to see that you do have a media background, have written magazine articles and been a live presenter.
Now not only will I ask...Can you do better?
But please would you do better?
Since your concern is that the article in Overland Journal was "wrong" please write one of similar length and targeted to the same audience so that when folks ask me questions about gps as related to off highway travel I have something printed to pass on to them.
Thanks in advance and looking forward to seeing it soon.

 

[Photog]

Rob,
I thought I understood how GPS worked; but I think I must be looking at it from a point on a flat surface (the ground where I drive). The problem is, I don't drive on flat ground, I drive on a sphere, just like the shape of the transmitted signal from the satellites. With this new lightbulb coming on in my head, I have a couple questions.

1) Does the GPS receiver discount the fact that it is on or close to a sphere to begin with? (Although the Earth sphere is not very round).

2) The description you are providing sounds like the GPS unit could find its location in open space, if it had a coordinate system to give as a local description (e.g., Sector 3 of the Alpha Quadrant).

If this is true, we need to stop preceiving the first signal as puting us on a circle, on the surface of the Earth. The first signal actually puts us on a sphere, around that satellite. The next satellite signal puts us on the circle of the intersection of those two spherical signals. And so on, down to one point in space. Then that one point is listed in Lat/Lon coords for us to relate to. Is this correct?

I have always perceived it as projecting a signal (like a flashlight) down onto a flat surface. Then when you get 3 lights, there would be a very small area of intersection. I can see that really would not work, from a signal transmission and reception, point of view.

That would be a hard concept to expain to a lot of folks.

 

[slooowr6]

If this is true, we need to stop preceiving the first signal as puting us on a circle, on the surface of the Earth. The first signal actually puts us on a sphere, around that satellite. The next satellite signal puts us on the circle of the intersection of those two spherical signals. And so on, down to one point in space. Then that one point is listed in Lat/Lon coords for us to relate to. Is this correct?

Not Rob, but that's how I understand from reading the whole thread. Software has no idea about Earth. The 3rd satellite will form a 3rd sphere. With 3 spheres the intersection becomes 2 points and there is a logic to pick which point and that is the location of the receive/GPS unit.

Rob,
Please jump in make sure we understand the concept correctly.

Thx
Alex

 

[Photog]

It is unfortunate that Garmin gave up on presenting the actual process for GPS, and it caused this firestorm. Very regretful!

Never the less, I am glad I have learned more about the systems that support my little GPS unit.

 

[slooowr6]

Dave,
Thanks for the detail info! Finally I understand how GPS works. Never thought I would use what math I learn in school. :wings:

Alex

 

[chrismc]

Wow, I sure learned a lot about GPS this morning. Thanks guys!

I think the "sphere vs. circle" argument can easily be won by bringing up non-terrestrial use of GPS, for example airplanes. If you are not on the earth's surface, then your position in relation to a single satellite is definitely a sphere, not a circle.

Here's a smilie because I like it. :1888fbbd:

 

[jim65wagon]

Wow! I find that I really don't care how my GPS works, just like I don't care how my computer, video camera, digital camera, or myriad of other things I own and use works. They work and I'm happy.

I did have one beef with the article though. It seemed mixed. I would have like to see a series of articles. One for portable unit, (like my double-duty mount it in the car-carry it hiking Magellan); another for the larger vehicle-only types and then another for the laptops. I realize it wasn't really a shoot-out type article but it felt like it wanted to be. Which is better apples or oranges?

 

[Photog]

Wow! I find that I really don't care how my GPS works, just like I don't care how my computer, video camera, digital camera, or myriad of other things I own and use works. They work and I'm happy.

Many people don't care how their modern cars work either. As long as it works, they are happy.

BUT: I have issues.!!! I want to know how everything works. It is a real sickness, I know.