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Old 23-11-2010, 15:32   #1
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Don't Rely on GPS ?

Do you think its probably not a good time to rely on GPS at the moment. If the Nth Korean problem escalates, we could see a few satelites being shut down/adjusted prior to any retaliations Similar to Iraq 1 and 2.

One would assume the USA would shut hers down to give the South Korean allies a chance to pop a few salvos off.

(I dont want to start a political thread. Trying mainly to get an idea what other people think. Particularly, people who have been affected previously and to what level.)

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Old 23-11-2010, 15:44   #2
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I should think that if the North Koreans are using GPS, they'd be using the Russian system.
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Old 23-11-2010, 15:59   #3
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Why would the US shut down GPS when they have very effective electronic jamming technology?

And so do the South Koreans. And the Israelis. And probably the Chinese. And a lot of other countries.
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Old 23-11-2010, 16:02   #4
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Why would the US shut down GPS when they have very effective electronic jamming technology?

And so do the South Koreans. And the Israelis. And probably the Chinese. And a lot of other countries.
Perhaps I got the type of technology wrong or the method. But what my point is, is that GPS was made unreliable prior to previous escalations.
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Old 23-11-2010, 16:21   #5
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Perhaps I got the type of technology wrong or the method. But what my point is, is that GPS was made unreliable prior to previous escalations.
That technology was called "selective availability." We all used to live with it. Instead of knowing where you were within ten meters, you had to do with a 100-meter fix. But most of us found that if you got us within 100 meters of a destination, we could take it from there.
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Old 23-11-2010, 16:29   #6
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How reliable is GPS?

There was a good article in the recent issue of "Good Old Boat" addressing the myriad of things that can affect GPS, including a US government shutdown, a 17 year old computer geek hacking the system and good old sunspots.

I recently proposed, under a thread "Is it time to buy a sextant?", the same sort of question and stirred a rather lively debate. Some folks are very trusting of technology, while others (like me) are mildly suspicious of anything requiring batteries, electricity or - more specifically - government permission.

God forbid I should loose my chartplotter, as I have become rather fond of the device and a little lax in keeping up my traditional navigation prowess.

Now that winter is here and sailing limited I suppose it would be smart to hone those outdated skills involving paper charts, compass and - yes - even my sextant.

So, to answer your question - rely solely on your GPS at your own peril.
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Old 23-11-2010, 16:33   #7
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Keep a backup. The satelites can be turned off or shut down. Or even destroyed, (by chinese antisatelite missile already successfully tested). Or your chartplotter can be knocked offline or fried by lightening. The sextant never fails.
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Old 23-11-2010, 16:45   #8
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...snip
The sextant never fails.
HUH??? It fails when under clouds and fog and every kind of inclement weather... probably mostly when you need it most.
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Old 23-11-2010, 17:16   #9
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I highly doubt we'll re-encrypt GPS any time soon. So much runs off GPS that we'd be shooting ourselves in the foot if we did.

That said, never rely on GPS alone. There are all kinds of things that interfere with reception and/or affect it's accuracy. A proper mariner utilizes all forms of navigation and is proficient with them.
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Old 24-11-2010, 05:13   #10
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FYI at the commencement of Operation Desert Shield, the (1st) Bush Administration discontinued selective availability signal dithering, which improved, not degraded, the accuracy of civilian GPS devices, as so many military units were relying on civilian rather than military spec units. Not long afterward, selective availability was discontinued altogether after which Wide Area Augmentation was implemented, reportedly to increase the accuracy of GPS enabled "smart bombs" (whether that is so or not I have no idea, but WAAS is a reality).
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Old 24-11-2010, 05:27   #11
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I've gotten to love my chartplotter and gps/laptop/charting program. Unfortunately it has allowed me to be very lax with things like dead reckoning and hourly charting. I still rely heavily on paper chartbooks. I've also found that whenever you get close to land, eyeball, compass, and binoculars are invaluable. Selective availability wouldn't really hurt because knowing where you are within 100 ft is probably good enough for 99+% of the time.

I doubt very seriously if the Govt will turn off the satellites but lightning or other electrical problems could seriously affect my gps service.

Here's an interesting link about Selective Availability in case anyone is interested Information about the End of GPS Selective Availability
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Old 24-11-2010, 06:13   #12
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A prudent and prepared sailor never relies on one source of information for their position. DR, celestial, or range and bearings should be used in conjunction with common sense and eyesight to make sure the gizmo is telling you the truth based on the view from the cockpit.
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Old 24-11-2010, 06:41   #13
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A prudent and prepared sailor never relies on one source of information for their position. DR, celestial, or range and bearings should be used in conjunction with common sense and eyesight to make sure the gizmo is telling you the truth based on the view from the cockpit.

Amen to that!
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Old 24-11-2010, 07:20   #14
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I"m a real estate appraiser. All of us now use GPS units in our jobs - it just makes sense. However, when we discuss it, we ALL lament how it has degraded our mapping skills AND our ability to recognize where we are (what part of town, what's nearby, etc.). I've made an effort to continue to use map books ("paper charts"), to keep my skills up.
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Old 24-11-2010, 07:46   #15
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A prudent and prepared sailor never relies on one source of information for their position. DR, celestial, or range and bearings should be used in conjunction with common sense and eyesight to make sure the gizmo is telling you the truth based on the view from the cockpit.
For anybody sailing out of sight of land and not heeding the above - you are really inviting your early demise.

- - On forums like this and other "specialized" forums there is a tendency to think that we are the only users of a specific service - like GPS in this case. Fact is, the whole world and world economy is tied into GPS and shutting it down is politically impossible short off Global Nuclear War - and probably not even then as it is needed to guide the H-bombs/bombers.
- - Every aspect of local transportation from cars, trucking, trains, airlines and private aircraft are all completely enmeshed in GPS location. Add in International commerce from airlines to super tankers who all rely on GPS for tracking and position reporting.
- - Simply put GPS is here to stay and will not be "turned off" in any way, shape, or form short of humans wiping themselves off the planet or Mother Nature doing the job for us.
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