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Old 06-08-2014, 07:06   #226
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Re: What will Happen to you when GPS goes Down

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Actually not much - IFR = I follow roads.
That works well, until you get into the backcountry. When all you can see in any direction is trees, it's a lot like being out to sea
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Old 06-08-2014, 17:21   #227
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Re: What will Happen to you when GPS goes Down

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That works well, until you get into the backcountry. When all you can see in any direction is trees, it's a lot like being out to sea
Oh... Now you are talking cross country IFR = I Follow Railroad (tracks) - LOL.

I don't fly much any more - too difficult to arrange here and too many hobbies but the last plane I was getting significant time in was a Taylorcraft.

Good fun but only 300 fpm climb rates - LOL...
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Old 21-09-2014, 15:09   #228
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Exclamation Re: What will Happen to you when GPS goes Down

For those who think GPS jamming is 'not easy' or 'unlikely', have a look at these two documents:

http://www.navnin.nl/NIN/Downloads/G...Navigation.pdf

http://www.gps.gov/governance/adviso...whitepaper.pdf

What should Happen before your GPS goes Down: learn celestial navigation
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Old 21-09-2014, 15:55   #229
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pirate Re: What will Happen to you when GPS goes Down

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What should Happen before your GPS goes Down: learn celestial navigation
Mastering the art of Dead Reckoning should be adequate..
Just need to be carrying basic passage paper..
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Old 21-09-2014, 17:40   #230
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Re: What will Happen to you when GPS goes Down

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Mastering the art of Dead Reckoning should be adequate..
Just need to be carrying basic passage paper..
They used to reckon that ships crossing the North Atlantic in winter used to submerge as they cleared the St Lawrence and not surface again until they reached the Bar Light Vessel... they often managed well enough for an entire crossing on D/R.

Amazing what you can do with a good log, the sea temp, and by simply watching the bird and sea life.
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Old 21-09-2014, 17:43   #231
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Re: What will Happen to you when GPS goes Down

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Originally Posted by NAV View Post
For those who think GPS jamming is 'not easy' or 'unlikely', have a look at these two documents:

http://www.navnin.nl/NIN/Downloads/G...Navigation.pdf

http://www.gps.gov/governance/adviso...whitepaper.pdf

What should Happen before your GPS goes Down: learn celestial navigation

Nav,

Some things on the internet are written for reasons other than what they say (who would have thought). Sometimes people are trying to scare us into spending a few more billion $. Some of what is in these links is along those lines.

GPS can be jammed. Everybody knows that. Still, in the cruising grounds 99.4% of us visit it's not a threat to everyday navigation.

The armed forces are right that they can't depend on GPS in a war. There are solutions now and on the drawing tables for that. But for ordinary cruisers GPS is pretty darn reliable. If it fails then a compass and your eyes should be able to find land.
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Old 21-09-2014, 17:50   #232
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Re: What will Happen to you when GPS goes Down

GPS as it's not a frequency hopping system, is as easy to jam as any other low power single freq. signal.
But to jam it over large areas without many jammers would not be easy, then you gotta ask, what's the tactical purpose of an area in the middle of the ocean GPS coverage?
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Old 21-09-2014, 20:39   #233
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Re: What will Happen to you when GPS goes Down

You know, I was just wondering...
We went by a number of Naval Practice Areas while cruising. Some of those see pleasure boats all around them while they are trying to do drills. What if a naval group decided that jamming GPS was part of their drill (in order to discourage local traffic and allow them to work). I could see them doing it, to disrupt all the motor vessels buzzing across their areas before they could be caught (warned off).
I think some yachties are a hazard for people that make their living on the water. And they have the tools.
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Old 21-09-2014, 21:38   #234
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Re: What will Happen to you when GPS goes Down

Newt,

I don't think the Navy would do that intentionally. They would have to answer to some officials at NTIA that would be pretty upset. I also don't think many fishing vessels have GPS jammers. Mainly the jamming today is from state sponsored entities such as North Korea and some in the middle east. The PNW should be pretty safe from jamming.

You might want to check your charts because there are restricted areas and it's a good idea to know when you should avoid those.
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Old 21-09-2014, 23:58   #235
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Re: What will Happen to you when GPS goes Down

Having just had my GPS go down on a number of occasions a few comments.

Most comments here relate to the GPS going down in the open ocean. Doing coastal cruising I can't comment on that but when it goes down (or starts "acquiring satellites") it's very nice to have a pretty good idea of where you're heading.

In particular having visual contact with navigation aids (port and starboard markers, buoys, cardinal marks etc.) and leads makes life much more pleasant.

As for losing GPS on a long passage a reliable autopilot can also make life much more pleasant.
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Old 22-09-2014, 00:39   #236
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Re: What will Happen to you when GPS goes Down

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The armed forces are right that they can't depend on GPS in a war. There are solutions now and on the drawing tables for that. But for ordinary cruisers GPS is pretty darn reliable. If it fails then a compass and your eyes should be able to find land.
The solution they had (LORAN) was turned off by DoHS, saved $35M/yr.


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Newt,

I don't think the Navy would do that intentionally. They would have to answer to some officials at NTIA that would be pretty upset. I also don't think many fishing vessels have GPS jammers. Mainly the jamming today is from state sponsored entities such as North Korea and some in the middle east. The PNW should be pretty safe from jamming.
Since the NTIA assigned the frequencies to the DoD for GPS, they don't have a lot of leverage to say that it can't be jammed any more than they have leverage to say that the GPS signals can't be turned off. SA was turned off under executive order, to the best of my knowledge no further steps were taken, such as statute, to force the DoD to continue providing coverage for civilians.

No it is not primarily state sponsered jamming. The second link pointed out that the FAA was having trouble with their new GPS landing systems at one airport one or more time per day. Ultimately they discovered that truckers were using short to medium range jammers to spoof the GPS trackers freight companies are increasingly putting on their trucks and loads. That means that if your are in coastal waters near a freeway, you too may suddenly be subjected to GPS service interruption.
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Old 22-09-2014, 03:08   #237
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Re: What will Happen to you when GPS goes Down

Firstly talk of any sort of widespread failure of the worlds GNSS is similar to saying all electricity production might fail, yes its " technically" possible, but practically impossible.

Equally we have more then one GNSS up there ,and soon there will be several.

The military has long since determined that its can selectively deny battle areas, even though in practice ( like the various adventures in the gulf) it too needs GPS, and in fact it needs it even more today, so its unlikely to interfere with it.

Of all the things we need to worry about, this isn't one of them


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Old 22-09-2014, 04:11   #238
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Re: What will Happen to you when GPS goes Down

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The military . . . . it too needs GPS, and in fact it needs it even more today, so its unlikely to interfere with it.
Hmmm. . . . If you think that you are unaware of what the U.S. Military has been doing ever since the Iranians hijacked that stealth drone by fiddling the gps system.

Plan: Micro-Technology for Positioning, Navigation and Timing (Micro-PNT)

And the result: 2013/04/10 Extreme Miniaturization: Seven Devices, One Chip to Navigate without GPS

The U.S. Military very clearly intends to deny enemy forces uses of GPS, while it uses these more protected systems.
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Old 22-09-2014, 04:22   #239
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Re: What will Happen to you when GPS goes Down

How many cruise in areas where US military is encountering hostile forces dependent on GPS? I would guess something approaching zero percent. Failure of GPS is a worry for almost no cruisers.
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Old 22-09-2014, 04:33   #240
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Re: What will Happen to you when GPS goes Down

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The solution they had (LORAN) was turned off by DoHS, saved $35M/yr.
Yes, that seemed stupid at the time but you have selective memory. The replacement system was a few hundred million and that was part of budget cutting. Since there was no money to modernize a 50 year old system that no one used they decided to save the op-ex.

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No it is not primarily state sponsered jamming. The second link pointed out that the FAA was having trouble with their new GPS landing systems at one airport one or more time per day. Ultimately they discovered that truckers were using short to medium range jammers to spoof the GPS trackers freight companies are increasingly putting on their trucks and loads. That means that if your are in coastal waters near a freeway, you too may suddenly be subjected to GPS service interruption.
If within a few hundred meters of a highway then most cruisers can pretty easily navigate without GPS. But the reality is that these truckers are getting busted. And then they are getting fired. And any disruption to inland navigation is temporary as they drive on by. And because my boat moves a bit slower than an airliner I'm not worried about this at all.
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