if you are using a WAAS enabled GPS - the accuracy is as good as military - it compensates for the offset.
Sent from my iPhone > On Dec 6, 2014, at 19:34, Chuck S via CnC-List <cnc-list@cnc-list.com> wrote: > > Joel, > I've heard this argument years ago, that the gov't intentionally altered the > GPS signal. > I really think the system is not being jambed, but the number of satelites > connected could be limited. I think it's more to control bandwidth than to > intentially confuse non-military users. > > Don't think they want us to run off course and have to dispatch more > resources like coast guard helicopters to rescue boater > > > Chuck > Resolute > 1990 C&C 34R > Broad Creek, Magothy River, Md > > From: "CNC boat owners, cnc-list" <cnc-list@cnc-list.com> > To: "Rick Brass" <rickbr...@earthlink.net>, "CNC boat owners, cnc-list" > <cnc-list@cnc-list.com> > Sent: Saturday, December 6, 2014 10:18:58 PM > Subject: Re: Stus-List Navigation > > Civilian GPS equipment is intentionally less accurate than military > equipment. Your government doesn't want you to know exactly where you are! > > Joel > >> On Saturday, December 6, 2014, Rick Brass via CnC-List >> <cnc-list@cnc-list.com> wrote: >> Hope you are having a great, and warm, weekend, Dennis. It is rainy, gray, >> and the high was about 60 in NC today. Not a nice day for boating. >> >> >> >> We have all experienced the sort of GPS errors you mentioned at one time or >> another. And because we all know that our GPS receiver can calculate out >> position to an accuracy of 30 feet or so, we tend to think that the charts >> are wrong. But that might not be the whole truth. >> >> >> >> I’d bet NOAA had pretty good GPS location numbers on the buoys you “hit”, >> and is not far off on the position of the seawall. The 10 to 30 foot >> accuracy our GPS reports is based on things like the number and position of >> the satellites from which it is getting signals, allowing for things like >> the accuracy of its internal clock, inaccuracy in the chart datum, and the >> radio waves that carry the time signals from the satellites getting “bent” >> by the Earth’s magnetic field. But there is another variable that the GPS >> can’t allow for. >> >> >> >> I remember reading, a few years ago, about the GPS system in one of the >> science magazines aimed at geeks like me (Probably Scientific American or >> Air and Space, but I can’t recall for sure). Seems the GPS system is a good >> example of Einstein’s Theory of Relativity. Part of the theory says that >> when you go faster, time slows down relative to time measured in a location >> that is moving more slowly. >> >> >> >> The GPS satellites are traveling at something like 18000MPH faster than we >> are on the Earth’s surface. So the atomic clocks on the satellites “tick” >> just a wee bit more slowly than the clock on earth. There is a government >> facility outside of Omaha where military personnel are tasked with adjusting >> the clocks on the satellites, by a few microseconds or nanoseconds, several >> times per day to maintain the accuracy of the time signals relative to the >> earthbound time. As I recall, if the clocks were not adjusted for 24 hours, >> the calculated position of a spot on Earth would be off by something like 5 >> miles. >> >> >> >> That’s probably more than you wanted to know. But you can probably chalk up >> all those buoys the chartplotter boat ran into to Albert. >> >> >> >> Oh, and another bit of Einstein trivia: He issued the original patents for >> the recipe for Tolberone Chocolate, and the shape of the candy. Which is not >> boating related, unless your Admiral likes really good chocolate. >> >> >> Rick Brass >> >> Washington, NC >> >> >> >> >> >> >> >> From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Dennis C. >> via CnC-List >> Sent: Monday, December 01, 2014 8:48 AM >> To: Della Barba, Joe; cnc-list@cnc-list.com >> Subject: Re: Stus-List Navigation >> >> >> >> I was motoring up a harbor looking at a nice Raymarine system showing the >> boat going through a sea wall 200 feet west of our actual position. >> >> >> >> Yesterday while motoring in the ICW channel in Santa Rosa Sound near >> Navarre, FL, the chartplotter boat took out several of the buoys on the >> right side of the channel. >> >> >> >> Dennis C. >> >> Touché 35-1 #83 >> >> Mandeville, LA >> >> >> >> Currently on the hook at >> >> 30 23.054N 86 51.884W >> >> >> Sent from my iPhone > > > -- > Joel > 301 541 8551 > > _______________________________________________ > This List is provided by the C&C Photo Album > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go bottom of page > at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > > > _______________________________________________ > This List is provided by the C&C Photo Album > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go bottom of page > at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com >
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