Maybe learning to use that Sextant wasn't so foolish - SailNet Community
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post #1 of 15 Old 05-19-2009 Thread Starter
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Maybe learning to use that Sextant wasn't so foolish

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post #2 of 15 Old 05-19-2009
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Holy cow...Albert was right?!?!?!
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post #3 of 15 Old 05-19-2009
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the US military is so dependent on gps, it will be maintained. they use it for planes, ships, subs, missiles, and bombs. it also has lots of redundancy built in. my old handheld gps will pick up 8 or so sats here in maryland, it only needs 3 for a good fix but the more the merrier
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post #4 of 15 Old 05-19-2009
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I truly doubt the information provided. There is no way the US military would let that system go down. Sounds like an article to "let people know that there might be blackouts" as they test certain systems to see if they work properly. One of those being encrypted GPS or something..
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post #5 of 15 Old 05-19-2009
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This is an article from a newspaper (website) in Britain, I wonder if they have an interest in selling the US system short as the article states that the Europeans are putting their own system called Galileo into service soon.

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post #6 of 15 Old 05-19-2009
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Quote:
Originally Posted by GraemeInCanada View Post
Sounds like an article to "let people know that there might be blackouts" as they test certain systems to see if they work properly. One of those being encrypted GPS or something..
the military has a switch that changes the codes, they can do it in mins from what i understand. the problem with this they also have a lot of civy equipment being used. i would not put money against the fact that they can do local black outs. the problem is local black outs can shut down half the world.

there is also commercially available jammers that can shut it down over a mile or so area, i am sure they can jam larger areas if need be
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post #7 of 15 Old 05-19-2009
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When in doubt...go to the source. The summary findings from the GAO:

It is uncertain whether the Air Force will be able to acquire new satellites in
time to maintain current GPS service without interruption. If not, some
military operations and some civilian users could be adversely affected.
• In recent years, the Air Force has struggled to successfully build GPS
satellites within cost and schedule goals; it encountered significant
technical problems that still threaten its delivery schedule; and it
struggled with a different contractor. As a result, the current IIF
satellite program has overrun its original cost estimate by about $870
million and the launch of its first satellite has been delayed to
November 2009—almost 3 years late.
• Further, while the Air Force is structuring the new GPS IIIA program
to prevent mistakes made on the IIF program, the Air Force is aiming
to deploy the next generation of GPS satellites 3 years faster than the
IIF satellites. GAO’s analysis found that this schedule is optimistic,
given the program’s late start, past trends in space acquisitions, and
challenges facing the new contractor. Of particular concern is
leadership for GPS acquisition, as GAO and other studies have found
the lack of a single point of authority for space programs and frequent
turnover in program managers have hampered requirements setting,
funding stability, and resource allocation.
• If the Air Force does not meet its schedule goals for development of
GPS IIIA satellites, there will be an increased likelihood that in 2010,
as old satellites begin to fail, the overall GPS constellation will fall
below the number of satellites required to provide the level of GPS
service that the U.S. government commits to. Such a gap in capability
could have wide-ranging impacts on all GPS users, though there are
measures the Air Force and others can take to plan for and minimize
these impacts.
In addition to risks facing the acquisition of new GPS satellites, the Air Force
has not been fully successful in synchronizing the acquisition and
development of the next generation of GPS satellites with the ground control
and user equipment, thereby delaying the ability of military users to fully
utilize new GPS satellite capabilities. Diffuse leadership has been a
contributing factor, given that there is no single authority responsible for
synchronizing all procurements and fielding related to GPS, and funding has
been diverted from ground programs to pay for problems in the space
segment.
DOD and others involved in ensuring GPS can serve communities beyond the
military have taken prudent steps to manage requirements and coordinate
among the many organizations involved with GPS. However, GAO identified
challenges to ensuring civilian requirements and ensuring GPS compatibility
with other new, potentially competing global space-based positioning,
navigation, and timing systems.

Full Text Ducument of 65 pages here:http://www.gao.gov/new.items/d09325.pdf
********
My take...fear mongering in the newspaper. Screw ups in the government. Needs attention or the GAO scenario...of LESS THAN OPTIMUM coverage has a 20% liklihood of happening. It WILL get that attention now.

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post #8 of 15 Old 05-19-2009
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In my humble opinion, and I know most of you know more and better than I do, the GPS should be cseen as a colorful back-up tool only meant to verify that the navigation calculations are correct.
I however agree it makes life soooo much easier

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post #9 of 15 Old 05-20-2009
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I subscribe to the "four missed meals from anarchy" theory of seamanship, I suppose. I will happy use GPS as it is available, but I will make it one block in a foundation consisting of celestial, pilotage, chart work and plain old "does this look right to you?" or the instinctual input fostered by using compass, pelorus, landmarks, sea state, the look of the sea near river deltas you can't see, the look of the sea near reefs, presence of birds, flotsam in the water...a whole array of evidence that will alert me to the fact I may not be exactly where I think I am.

The day some years ago when, despite having a five-satellite lock while I was driving a straight course at four knots, I saw the GPS briefly clock me at 60 knots SOG until my position was "recalculated" at a NM southwest of where I had reportedly been five seconds previously, was the day I decided my faith in this technology should be somewhat less than total.

Prudent seamanship relies on being conversant with a wide range of skills, techniques and even habits of mind, some of which fall outside of rational analysis. Because the GPS system has no stake in whether it's knocked out of orbit by solar storms or if its receivers get a free trip to the sea bed, and I do, I reserve the right to take its little numerical opinions with a grain of sea salt.

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post #10 of 15 Old 05-20-2009
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This whole navigation thing is the next huge step for me. It's good to see how you guys think about each piece of the toolkit. It's so easy from the learner's side to think GPS is the nuts and not worry too much about the other techniques.

Well - on to the next step in the progression of pointing a boat towards the blue!
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