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Old 23-06-2017, 07:19   #1
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GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

I just came across a post on another forum concerning periodic GPS Signal unreliability along the gulf cost and thought the matter should be mentioned here as well. See FAA Signal Test Notice.

FWIW...
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Old 23-06-2017, 07:52   #2
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Re: GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

Centered on Egland, lot of spook work there.
I have seen many GPS Notams, but have never had any GPS issue with it, I had one frequency that if I tuned the VOR to that would knock my GPS out, that was interesting to me for two reasons, first the VOR is a receiver not a transmitter, and secondly when I looked on the internet, it was a known problem.
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Old 23-06-2017, 14:11   #3
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Re: GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

Sounds like the military are testing out some serious "denial of service" jammer, capable of denying an enemy from using the civilian portion of the GPS signal for a fairly large area. I wonder if that's good planning or a response to a specific threat.
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Old 23-06-2017, 14:39   #4
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GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

Military and civil use completely different frequencies, from day one the capability of turning off civilian signals even for specific areas was part of the design of the system, also degradation of accuracy and even spoofing location. Google "Selective availability"
Bill Clinton had SA disabled to help prevent adoption of another system, I guess maybe Glonass
I'd guess that are testing something, that could possibly cause interference with civilian GPS, but may have nothing at all to do with it directly, but cause it's possible, they issue a Notam.
Notams for possible GPS are pretty common, but I have never experienced and issue myself.
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Old 24-06-2017, 09:32   #5
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Re: GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

Remember that GPS satellites broadcast at about 60 watts. Any one can jam them for large areas of the country. The USCG is well aware that people who are smuggling will broadcast jammer signals to keep cops from finding themon interior roads. so if your GPs that you use for road travel suddenly refuses to get a signal, this is a likely situation. Also there are whackos who like to do it on the coast when it gets foggy just for fun. its a hefty fine, but the USCG has to triangulate them, and they are difficult to find if they keep moving.

It doesn't take a military operation to do it. The signal out of the sky is very very weak.
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Old 24-06-2017, 10:09   #6
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Re: GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

Plain jamming is old hat. And as A64 might know, the USAF and Army both have had the ability (for at least 15 years) to just launch an anti-radiation missile (commonly used against radar installations) to shut down any jammer in a military theater, very effectively.
You jam, they launch, end of story.

Conventional GPS jammers with a range of a mile or ten, easy. A 500 mile radius or larger, like in the advisory? Not so easy to work with microwave transmitters. And GPS spoofing, broadcasting a false signal to offset real positions, is of far more interest these days. A bit more subtle than jamming. If the military was testing a large-area spoofing device, that could explain the advisory.

"Also there are whackos who like to do it on the coast when it gets foggy just for fun. its a hefty fine, but the USCG has to triangulate them, and they are difficult to find if they keep moving." Nah. Someone just needs the right phone number for USAF assistance with that.

"The USCG is well aware that people who are smuggling will broadcast jammer signals to keep cops from finding themon interior roads." that makes no sense to me. You don't need a GPS to find someone on an "interior road". Nor have I heard even one news report of one criminal using GPS jamming or spoofing devices. Just one poor SOB trucker who didn't want his boss watching his truck, inadvertently jamming Newark airport and invoking the wrath of the Fed.
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Old 24-06-2017, 12:25   #7
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GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

Not jamming, but the Military tracking Radar is so efficient that in the first Iraqi war, no Iraqi artillery batter fired a second shot, more often than not rounds were on their way, before the rounds they fired had impacted.
Cell phone signals can be traced very, very effectively in real time as well.

Yes home made GPS jammers are very easy to construct, you can do what is called barrage jamming which is just jamming a broad spectrum of frequencies and wipe it out. I remember a case in the last few years where they caught someone in New Jersey I think that was jamming the airport by accident, what they were doing was trying to jam their own delivery truck so the boss didn't know where they were, they did so very effectively.
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Old 25-06-2017, 13:07   #8
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Re: GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

"someone in New Jersey I think that was jamming the airport by accident,"
That's the case I referred to. Buy didn't like the fact that his boss could see what he was doing in real time, because truckers are notorious for cooping, taking a break and saying "I got caught in traffic" while going to a bar or girlfriend or sometimes making a few bucks on a little indy work. (Also notorious for being underpaid or otherwise abused.)
So the guy bought a Chinese jammer from eBay, figured "the boss won't be able to watch me" and every time he went up or down the NJTurnpike, right past EWK Liberty International (still called Newark Airport by the non-jingoists amongst us) there were unspecified GPS problems at the airport.
FAA spoke to FCC and the RDF vans were sent out. Trucker got a nasty surprise, and the cell phone and gps jammers are now illegal to sell on ebay. Even if they do still get sold.

Hard to use an antiradiation missile on the NJTurnpike, all that collateral damage tends to create bad press.

Anyone who wants to find out, can look up the old hackers magazine called ALT2600. Around 2000 they published plans for what and how to do, and how to launch it in a balloon, so the missile wouldn't mess up your house.
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Old 25-06-2017, 18:02   #9
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Re: GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

Very interesting post. I wonder how many on this Forum would be disabled/lost in the water if their GPS/Chartplotters didn't work, even temporarily? I also wonder if they have the ability to interfere with a compass? Once, when coming into Marathon from the Gulf of Mexico our compass needle began to spin in circles. We called the CG to tell them of the problem and they had "no response." My personal opinion is that the US could be disabled completely with a cyber attack far worse than a nuclear attack on select cities. Imagine if your phones, internet, electricity no longer worked. I suppose this is why Naval Cadets are once again learning Celestial Navigation. Good luck and safe sailing.
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Old 26-06-2017, 09:55   #10
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Re: GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

If I was two or three days out from somewhere in the middle of nowhere with only five days of water onboard, I'd be in trouble. On the other hand, if I had enough water and was only five days off some continental shore...no problem, head for the sunset or sunrise, and try to follow that coast before impacting on it.

If you have a sextant but hit three days of solid overcast, or even worse, DROP IT because some idiot forgot to turn off the local gravity, you're in the same boat.

If the GPS system goes down, you're probably better off not making land until the first wave of missiles and riots has ended, because WW3 just started.
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Old 26-06-2017, 10:32   #11
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Re: GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

Definitely makes a good case for maintaining the skills and practicing the art of real navigation, doesn't it? At the very least, all yachtsmen who venture out of sight of land should be able to keep a reasonably accurate DR and check set and drift by fathometer, radar ranges, etc.

Nobody should be scared to learn basic celestial navigation. It's NOT rocket science. A complete newb can learn how to take LAN in a day, and will have an extremely useful tool in itself, without getting into the slightly more complex business of taking a proper fix. If you can keep a DR and get a latitude every day and maybe in the evening from Polaris, you can get around fairly well even if GPS, Glonass, etc are on the blink. Add basic coastal piloting, even without the aid of Radar, and you will never find yourself looking for your dock in say Port Lavaca when you really meant to go to Freeport, just because the GPS isn't working.

I will admit I have been pretty lax myself. I have FOUR Samsung Note 3 phones, and a Tab 2 tablet, all with excellent onboard GPS chips, and a couple of USB GPS devices for the laptops, and multiple charging sources. I figured that was enough backup extra redundancy. GPS never fails, right? Compare two devices and if they don't agree, turn on another one and pick the two that do agree. Simple, right? But a good reality check tells us that any system can break down, no matter how rugged and decentralized it is. I haven't even taken the boat out in the gulf in 4 years but I think it is time for me to buy a fresh almanac and get some practice shots on paper chart. Maybe leave the smart phones turned off next time I go fishing, and cross a few bearings.
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Old 26-06-2017, 11:45   #12
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Re: GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

I am not surprised and I would expect to see more disruption in the years to come. A year ago or two in the spring, the British MOD (Ministry of Defense) published a notice that due to military exercises GPS may not be available or worse, may give a false signal. The North Koreans recently were interfering with GPS signals as aircraft were flying into Seoul, South Korea.

As others have pointed out, it's a good time to brush up on your traditional navigation and orienteering skills.
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Old 26-06-2017, 11:56   #13
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Re: GPS Singnal Unreliability--Gulf Coast 19 June to 14 July

The North Koreans are eventually going to be listed in the dictionary alongside the phrase "You don't tug on Superman's cape". Or in this case, ANYONE's cape.

On fathometers...the one time I had any use for one, aside from "Can we make it in here?", was rounding Montauk Point heading up toward Plum Gut. GOS was fine, but charts had Loran lines on them still. And there is so much background clutter out there that lights are not very useful when you're concerned about now now now because you're racing. Damned fathometer would only say "---" and finally I realized, it maxxed out at 200' which meant we were in the main channel and there was no longer any question about it.

Off the continental shelf? No really, how many fathometers in sailboats are going to say anything besides "---" ?
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Old 26-06-2017, 12:30   #14
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Re: GPS Singnal Unreliability--Gulf Coast 19 June to 14 July



\If anyone has the time or can remember, there was a guy who mentioned that he was just closing on his first sailboat in Texas. The story was contained his surprise as to how long it was taking to close, cost of staying in motel, & was planning on provisioning then single handling her to Florida after the weather "Cindy".

I am hoping that one of y'all can get a message to him about this so he can be aware if he was going to depend on GPS to navigate.

Thanks in advance,

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