Anyone boat close to a nuclear power plant?

[Presentation]

I’m wondering if something I heard is rumor or true.

I heard that if you boat close (relative term) to a nuclear power plant your GPS unit will give you a false higher speed reading. This is due to a technology that will prevent terrorists from using GPS to guide a missile to a nuclear power plant.

If true, cool! Score one for the good guys. :smt038

 

[Four Suns]

My boat is across the river from the Surry Nuclear Plant. Never heard of or noticed such a thing and I go by within a mile of it all the time. With all the shipping traffic around here, I can't imagine they would do that. Also, when the military does operations around here that may interfere with GPS signals, they make a big deal about it and announce it in the paper, on the VHF, etc. for days/weeks before hand and it is in the weekly Local Notice to Mariners from the Coast Guard with the dates and locations.

 

[Turtlesboat]

I go by indian point about as close as anyone can get without being shot. never noticed anything strange or out of place with my gps and i've been by it about 30 times this year.

 

[J Levine]

Oyster Creek in on the Barnegat Bay..... never noticed anything

 

[chuck1]

Never noticed anything on the TN river, but yes the Gov can induce a variance when needed.

 

[wkearney99]

GPS *can* be interrupted entirely or made inaccurate. But the gov't does not do this on a per-location basis. It would interfere with FAR too much equipment using it. Planes, trucks, automobiles and the like. Since the signals are coming down from orbit, and they move, it's impractical to do it on any sort of tight area. It's an all-or-nothing sort of thing. Likewise, it'd be possible to use a terrestrial jammer to disrupt the signals. But that would once again disrupt a considerable amount of legitimate use.

So, no, they don't do anything to GPS because of secure areas. It'd be FAR too disruptive.

 

[Dave S]

My boat glows in the dark when I pass our nuclear plant at night. That's normal isn't it? :smt043

 

[Presentation]

Thanks guys.
:thumbsup:

 

[Morpheus]

My boat glows in the dark when I pass our nuclear plant at night. That's normal isn't it? :smt043

It must be normal, the water here glows green at night in the Port of Tampa (I'm told this is the high amount of sulpher in the water) so if you got that water on your boat your boat would glow.

 

[comsnark]

When GPS was first introduced to the public, there was a deliberate "inaccuracy" built into the signals transmitted. With the end of the cold war, and increased commercial use of GPS systems -> the government eventually REMOVED the deliberate inaccuracy in the GPS signal for commercial units.

BTW: If you had "inaccuracy", the speed would still read correctly. Afterall, the unit is looking for CHANGE in position, and that would still be accurate. However, because of the INACCURACY, you would probably be running through a sand bar instead of the channel.

 

[osd9]

As I remember it, the intentional inaccuracy that was transmitted within the GPS signals was random. In other words, you couldn't mark a waypoint or a track/route and then expect to be at the same spot or on the same track/route line the next time out.

That was why LORAN was so important to keep, especially in the diving and fishing community. LORAN was inaccurate, but, its was very reliable and "repeatably" inaccurate......in other words, if a wreck was at a given set of TDs, I couldn't give you my TD #'s and expect you to be on the wreck. However, once you found the wreck on your own Receiver, at stored those TD's, you would be guaranteed to find the wreck again. With GPS, you could have been right on top of a wreck, store the waypoints, and then go back next week, and have to search all over again for the wreck. You would be in the vicinity, but with wreck diving, expecailly in the NE where visibility is 15-20 feet of shadows, vicinity just isn't good enough.

In the early days of GPS receivers, do to the Randomness of the scrambling, you could actualy have been going foward, but your position, could look like you were standing still....or, in extreme cases, going sideways or backwards. It was computer generated algorithm, with "random" programmed in. Speed was not as accurate a reading on GPS as it was on LORAN. And if you setup your filters for a slow signal update....all bets were off.

That was what Differential GPS (a big deal, and expensive, back in the day) would try and "filter" out. You could always guarantee the repeatability of LORAN, a statement not always shared with GPS users...even with Differential GPS antennas/receivers..



With the new WAAS (Modern day Differential so to speak), and the government signal "scrambling" turned off, the accuracy of GPS is now reliable AND repeatable within a negligible 3 feet or so.

 

[aquadancer]

I pass by Salem Nuclear plant whenever I'm on Delaware Bay.

Never noticed anything unusual, but the chart shows the area as "Local Magnetic Disturbance"

 

[270SLX]

Interesting. Next time I go out, I'll check the Navman as I pass the Cordoba Illinois nuke plant.

How would this work? Doesn't a receiver always receive signals from satellites in a straight line and triangulate at least three satellites?

Dennis

 

[Dave M.]

The receiver does in fact receive the signal in a straight line from the satellites. Each satellite broadcasts a wide beam to the whole earth, there is no way for it to send a different signal to the area around a nuke plant. Also, it takes 4 satellites to establish a location. This is because the receiver has to determine 4 variables. You can think of them as latitude, longitude, elevation, and time. But it is pretty common for the receiver, once it gets a lock on 4 satellites, to also lock on to more. My chartplotter probably gets 7 or 8, and my Garmin handheld sometimes has 10. I doubt there is any way for the satellites to send a signal that would be wrong only at the nuke plant.

That does not mean that the signal can't be jammed in the vicinity of the nuke plant. That is certainly possible, but I don't know if it is ever done. The intentional error that was introduced in previous years was called Selective Availability, or SA. That error has been turned off, and I believe the gov't. is working on other techniques to prevent use of GPS for attacking US installations.

The GPS signal is now commonly used for purposes that were not imagined when it was place into operations. As an example, for telecommunications, digital channel banks need to talk to each other at precisely the same rate. Since they can talk to many other such devices, often owned by different companies, they all need to agree on exactly what that rate is. GPS provides a common time/frequency standard that all can use.

Another example. Long and short high voltage power lines make up the infrastructure for power transmission in this country. These power lines can fail, such as when an "insulator sportsman" shoots out a set of insulators, or a tree falls into a line. The power line may be several hundred miles long, so it would obviously be an advantage to know where to start looking on a failed line. One way, and there are others, is to use GPS receivers at each end of the line with additional circuitry that looks for transients on the power line. These receivers know the time precisely. When a fault occurs on a line, a fault pulse travels down the line from the location of the fault, going in both directions. At each end of the line, the GPS receiver detects the fault pulse and time tags it, normally with within a microsecond or two. Knowing that the pulse traveled down the line each way at the speed of light (about 5 microseconds per mile), a computer can take the time tagged data and determine the location of the fault on the power line, normally to within a quarter mile or so. That is where you send the repair crew.

I mentioned in a post some time back the GPS technology was now built into the infrastructure of the country, and I thought it would never be turned off. These are a couple of examples of that.

 

[comsnark]

I am only 41, and I never thought I would have a handheld mapping device before I had one in my car -> and I have had such units for about 8 years now.

Today, it is becoming increasingly common to have GPS devices in phones. I bet in five years, it will be COMMON to have GPS tracking on individual phones. Imagine the sales pitch: You know where your kids are to within a distance of 10 feet. Sure. . the kids can ditch the phone -> but what kid today would be without text messaging? And if they ditch the phone. . you will know it.

It would not be a great stretch to have government tracking of cell phones. All it will take is one national emergency.