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Old 28-10-2006, 08:14   #16
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Thread Moved. More germane forum.
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Old 28-03-2007, 04:19   #17
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PRECISE GPS HEADING INFORMATION ~ by Chuck Husick
excerpted from “GPS and Nautical Charts” ~ by Chuck Husick
Chuck Husick on BoatUScom

“GPS will soon provide another valuable service for mariners, calculation of precise heading information ...
... GPS systems capable of providing precise heading information, regardless of vessel speed, including vessels that are stationary, will be introduced in the near future.
The systems will use two or three separate GPS antenna spaced a meter or more apart. They will determine heading by comparing the position data from each of the individual antennas. Since the normal cyclic errors inherent in the GPS signal will affect the signals arriving at all antennas almost identically those errors will be largely cancelled-out in the heading data calculation. This approach to finding magnetic or true heading will join the mechanical north-seeking gyro compass as the only real time source of heading reference data that does not rely upon sensing of the earth's magnetic field. When fully developed the cost of these systems will likely be competitive with today's gyro aided flux gate systems and will be very useful in demanding applications such as autopilots and radar overlay chart plotters. Due to cost and somewhat to the need for the multi-antenna array, these new systems will initially be used on larger vessels ...”
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Old 28-03-2007, 07:44   #18
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Cruising World had an article a few months ago about trying to use the GPS to steer. He was in a fog, in a narrow channel with current. He kept spinning in circles and finally bailed out of his plan to enter another channel.


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Old 28-03-2007, 16:54   #19
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ComNav have had this on their website for quite a while now. I think the news you posted Gord is old news...

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ComNav Marine leading the way with the new Vector G2 GPS Satellite Compass
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Old 28-03-2007, 20:15   #20
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As a seafarer I had a lot of difficulty navigating on land or ice by magnetic compass south of the south magnetic pole in Antarctica so had to get used to operating a vehicle in whiteout conditions using GPS (principally the XTE function). It is extremely difficult and certainly not good enough for navigating known crevasse fields where an XTE of 50 metres could put you over the edge. The options were ground penetrating radar on a long probe in front of the vehicle or a tethered walker in front with a long pole.
Interestingly, the speed of the vehicle didn't make much difference to the ease of navigation in fact sometimes faster was better.
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Old 28-03-2007, 20:48   #21
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cal40john, this is very different than just using a single GPS.
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Old 28-03-2007, 22:27   #22
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Quote:
Originally Posted by DeepFrz
cal40john, this is very different than just using a single GPS.
Sorry, I should have been using quotes from previous posts to be clear that trying to steer a course using a normal GPS can be near impossible in certain situations, I was not trying to say that the specific device, a GPS compass does not work.

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