Re: The "CAPN" and the Marine Corp
PJR said.....running the CAPN Mosaic DNC and all of a sudden my course
predictor arrow rotated 90 degrees to the right, but the icon of the ship
merrily kept on the blue course line..........
Very interesting! I would love to know the answer too.
Let me suggest something for a plausible explanation. First Background...
- I've twice had the experience where a crane with and electromagnet pickup
that was loading scrap metal (East River Brunswick GA docks) got the
attention of my fluxgate compass and my autopilot took me 90 degrees to
starboard - bang.
2)I have a setup on Nobeltec where my autocomp 1000 heading indicator goes
to the PC (along with Nav info and depth). This way the boat points in the
right direction when I'm at anchor.
IF you have a heading indicator in your setup AND the Marines are playing
with magnetism COULD your Capn be pointing at where it thinks you're
pointing???
Bill
An article in Florida Today, today, indicated that the military is testing
a system for jamming signals from GPS satellites. The test began Friday
and will run through June 20th, as part of a NATO training exercise along
the Atlantic Coast. The Coast Guard said GPS signals will be unreliable or
unavailable in waters up to 60 miles off North Carolina, and along the
coast of northern and central Florida. - all this according to Florida Today.
At 03:40 PM 6/12/2004, Bill Boles wrote:
Very interesting! I would love to know the answer too.
<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
Bob McLeran and Judy Young Manatee Cove Marina
M/V Sanderling Patrick Air Force Base
Hampton 35 Trawler Melbourne, Florida
Had the same problem with my Garmin chartplotter when passing Pensacola
Naval Station. As the boat continued on the same course, the little boat on
the screen turned around backwards and the other readings when crazy. Sorry,
no large magnets in sight. Go figure !!
Dick Schroder
Gulfstar 43' trawler
Lying St Pete Florida
Great American Marina
Those who live by the sword usually die from a gunshot !!
-----Original Message-----
Subject: T&T: Re: The "CAPN" and the Marine Corp
PJR said.....running the CAPN Mosaic DNC and all of a sudden my course
predictor arrow rotated 90 degrees to the right, but the icon of the ship
merrily kept on the blue course line..........
Per the LNM, DOD and Homeland Security are screwing with GPS and cellular
communications until June 20th in this neck of the woods. I'd wait and see
if it happens again.
Best,
Ron Rogers
Willard 40 Akela (to be AIRBORNE)
Lying Oriental, NC
----- Original Message -----
From: "Bill Boles" billboles@mindspring.com
| PJR said.....running the CAPN Mosaic DNC and all of a sudden my course
| predictor arrow rotated 90 degrees to the right, but the icon of the ship
| merrily kept on the blue course line..........
|
| Very interesting! I would love to know the answer too.
Bob McLeran wrote:
An article in Florida Today, today, indicated that the military is testing
a system for jamming signals from GPS satellites. >>>snip<<<
The Coast Guard said GPS signals will be unreliable or unavailable >>snip<<
REPLY
Since the dawn of navigation, sailors have relied on the ability to measure
angles.
Both vertical and horizontal angles such as the latitude sailings by
measuring the elevation abover the n\horizon at local noon to the horizontal
bearings on two or more prominent land marks ashore.
Long before the mathematicians understood or could explain the theory beind
the practice, sailors knew how to accurately cross seas and arrive where
they expected.
In those days, the ability to measure angles beame first an art and later a
science.
I have been facinated by historical accounts detailing the development of
modern hydrography.
Not surprisingly land survey practice began with the army's need to
acurately pre-calculate the trajectory of cannon balls.
Consequently Army enginers quickly developed the scienjce of land
measurement for purposes of defense and attack on known targets.
From the early plane tables to the modern theodolites and transits, greater
accuracy in measurement was always the holy grail. When Hewlett Packard
first came out with the laser transit that incorporated electronic angular
measurements and a built in trig function calculator, surveyors thought they
had achieved the ultimate in tools.
Countless generations of sailors have worked had to achieve the skills
needed to make repeatable and acurate angle measurements in order to
determine their position. The sextant was perhaps the ultimae tool for
making such precision measurements.
Then along came GPS, another military development born of the need to know
exactly where to place artillery or rather ballistic missiles on the heads
of the enemy.
Suddenly skill had nothing to do with the ability to determine position at
sea. All you had to do was read some numbes off the display and plot them.
But even that was too difficult for some people who transposed digits or
suffered from sloppy pencil work in laying off lines with a parallel ruler.
Now that we have electronic chart plotters integrated with GPS and radar, it
seems like almost any fool can cros oceans and arrive at a pre-deermined
destination. Kinda takes the fun and challenge out of the sport doesn't it?
(and no slight intended to all those list members who do cross oceans with
or without GPS.) < SMILE>
Offshore sailors could rightly claim they possessed more than average skill
if they could take a sextant sight and reduce it to a line of position.
Today the ability to use a sextant is rarely considered more than a clever
anachronism.
Given the latest developments in GPS jamming etc. is it time to revive those
time honored skills involving precise angular measurements?
Cheers
Arild
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Nah, just make sure they keep LORAN active! <VBG>
Keith
__
In the 60's, people took acid to make the world weird. Now the world is
weird and people take Prozac to make it normal.
----- Original Message -----
From: "A Jensen" elnav@uniserve.com
<snip> Offshore sailors could rightly claim they possessed more than average
skill
if they could take a sextant sight and reduce it to a line of position.
Today the ability to use a sextant is rarely considered more than a clever
anachronism.
Given the latest developments in GPS jamming etc. is it time to revive
those
time honored skills involving precise angular measurements?
Cheers
Arild
That's incredible! Since COG (which is normally used for the projected
courseline) is computed by the GPS from successive calculated positions
(averaged in different ways by different chartplotters and nav packages) it
seems to me that the calculated boat position would have to shift in the
direction the predicted courseline points.
I think this is worth trying to figure out.
Anyone have a clue??
Bill Boles
Gulfstar 60' trawler
G8 Georgia
----- Original Message -----
From: "Dick Schroder" oilpans@thepoint.net
To: "'Bill Boles'" billboles@mindspring.com;
trawlers-and-trawlering@lists.samurai.com
Sent: Saturday, June 12, 2004 5:54 PM
Subject: RE: Re: The "CAPN" and the Marine Corp
Had the same problem with my Garmin chartplotter when passing Pensacola
Naval Station. As the boat continued on the same course, the little boat
on
the screen turned around backwards and the other readings when crazy.
Sorry,
no large magnets in sight. Go figure !!
Dick Schroder
Gulfstar 43' trawler
Lying St Pete Florida
Great American Marina
Those who live by the sword usually die from a gunshot !!
-----Original Message-----
Subject: T&T: Re: The "CAPN" and the Marine Corp
PJR said.....running the CAPN Mosaic DNC and all of a sudden my course
predictor arrow rotated 90 degrees to the right, but the icon of the ship
merrily kept on the blue course line..........
I had this occur to me in Pensacola Bay...the course and speed changed
rapidly and to over 200 knots, then in a minute or less returned to my
original course line ..it did this repeatedly over some distance, until I
was in a Bayou. I checked my Furuno GPS/radar and it was doing the same
thing...
two different GPS units, two different plotters
same thing a day or so later but for only a short time.
Ted Brustowicz MD(ret)
trbrustowicz@cox.net
"MOONSHINE", DeFever 43
Niceville, Florida
Bill Boles wrote:
That's incredible! Since COG (which is normally used for the projected
courseline) is computed by the GPS from successive calculated positions
(averaged in different ways by different chartplotters and nav packages) it
seems to me that the calculated boat position would have to shift in the
direction the predicted courseline points.
I think this is worth trying to figure out.
Anyone have a clue??
Bill Boles
REPLY
While that was true of the earlier sets the new design uses doppler methods
to determine direction of movement.
This gives almost insantaneous updates on receiver movement compared to the
sometimes slow progress when a number of sucesive positions had to be
calculated then averaged etc.
It would appear that the new GPS jamming is taking the form of doppler or
phase shifting.
The advantages include the fact that this method is less obvious than
simply shuting GPS down and if done in a sophisticated enough manner, could
even allow the US to mis-direct hostile forces into a trap or unfavorable
locations such as a mine field.
Cheers
Arild
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