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Bad Info in GPS articles.


georgeandmary
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Come on Chicago people, tell the people at the Tribune like it is.

 

http://www.chron.com/cs/CDA/story.hts/nation/1789996

 

Near the bottom.

quote:

A network of 24 geo-stationary satellites broadcasts signals received by GPS devices. Using triangulation, the satellites help the devices gain a fix on their location anywhere on Earth.


 

george

 

39570_500.jpg

Pedal until your legs cramp up and then pedal some more.

 

[This message was edited by georgeandmary on February 24, 2003 at 09:13 AM.]

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I know I am going to regret this, but WHAT?

I don't see what you are talking about. Stating something that is not true? Stating something with bad grammar?

All I see is George saying, "Come one Chicago" instead of "Come on Chicago"

 

stealyourcache.gif Ever notice that anyone that caches less than you do is a moron, while anyone that caches more than you do is a maniac? -Dru Morgan

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Some tracking is meant to protect the vulnerable. Wherify Wireless Inc., for example, makes a high-tech bracelet containing a GPS device and tiny wireless phone that can be placed on the wrists of children or Alzheimer's patients to help locate them if they get lost.

 

"If you look at our (tracking) technology, it way overweighs the bad that people can do with it," said Timothy Neher, founder and president of the company. Neher got the idea for the devices after a scary moment during a zoo visit when he was momentarily separated from two young relatives in his care.

 

But with any situation, when you gain, you lose.

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OK, I knew I would feel stupid. I read right past 'geo-stationary'. It is 'geo-synchronous', right? When I took college physics, I learned how to determine the correct altitude a satellite would need to achieve that. I don't think I have that info still saved in the hard drive of my brain anymore.

 

stealyourcache.gif Ever notice that anyone that caches less than you do is a moron, while anyone that caches more than you do is a maniac? -Dru Morgan

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GPS satellites are NOT geosynchonous (with or without the hyphen) and not geostationary. They are in low orbits and move constantly relative to your view of the sky. That's why the "constellation" you see on your GPS's sky page is always different. It's also why you have good GPS accuracy on some days, and bad on others. Accuracy depends on how favorable the GPS "constellation" is (Horizontal Dilution of Precision or HDOP).

 

--

Scott Johnson (ScottJ)

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quote:
Originally posted by Dru Morgan:

I read right past 'geo-stationary'. It is 'geo-synchronous', right?


 

Nope, it's neither. Geosynchronous and geostationary are pretty much synonymous. Those satellites are lined up with the equator at a fairly constant distance from the planet's surface.

 

The GPS satellites are at an angled orbit.

 

A neat way to see all of this is this viewer which shows all the active satellites. The cloud around the equator are the stationary ones. The GPS satellites are among the ones scattered elsewhere.

 

- - - - -

Wisconsin Geocaching Association

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quote:
Originally posted by Cheesehead Dave:

A neat way to see all of this is http://liftoff.msfc.nasa.gov/RealTime/JTrack/3D/JTrack3D.html which shows all the active satellites. The cloud around the equator are the stationary ones. The GPS satellites are among the ones scattered elsewhere.


Anybody else bothered that NASA is using expired java security certs on their website?

 

3608_2800.gif

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I like the one where the radio station manager called and told him not to drive so fast. LOL

 

Don't you remember the car rental place (Hertz? I think) that charged renters money for speeding? That was wrong for sure!

 

How many of you believe in telekinesis? Raise my hand...

 

Let’s see, triangulation? Isn’t that what the FCC did to find me when I had a Pirate radio Station? hhmmmm

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quote:
Originally posted by Cheesehead Dave:
Originally posted by Dru Morgan:

Nope, it's neither. Geosynchronous and geostationary are pretty much synonymous.


 

No. Geostationary implies geosynchronous, but not vice-versa. I don't know if there are any non-geostationary geosynchronous satellites up there, but the orbits are certainly possible.

 

See this page for more details.

 

Actually, though, the two terms are often used interchangeably, so I am mostly picking a nit. I guess, being a geocacher, that should be picking a tick instead! icon_biggrin.gif

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But they are Geo-centric (with or without the hyphen) and apart from the inclined orbits they also have a relatively constant change (precession) from day to day. In other words at the same time each day the same satellite won't be in the exact same spot.

 

Oh, and "Triangulation" is also a misused term as in normal use it implies angles but GPS is "distance" based.

 

Cheers, Kerry.

 

I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

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I thought I had only one reason to feel stupid. Now I see I had two. I guess that is an example of everyone trying to use big words to impress people. Geo-stationary satellites sounds much more impressive, even if it is wrong.

Sad thing, after 200 finds, I DO know better. I just must have lost my sat lock there for a second. icon_biggrin.gif

 

stealyourcache.gif Ever notice that anyone that caches less than you do is a moron, while anyone that caches more than you do is a maniac? -Dru Morgan

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