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#11
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External GPS antenna and WAAS?
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#13
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External GPS antenna and WAAS?
On Sun, 18 Jan 2004 19:57:09 GMT, Short Wave Sportfishing
wrote: It is my understanding that the software in WAAS enabled receivers do not check constantly - that is my understanding. Curiously enough, I have a Magellon 315 and 330M and the 315 is a tad more accurate (will show zero error for instance) than the 330 (I never get zero error) which is WAAS enabled. When I first noticed that, I thought that the WAAS receiver would be more accurate. Aboard Lionheart, leaving the Raymarine Raystar 120 Seatalk WAAS-GPS and its RL70CRC Plus radar display/chartplotter on for long periods of time tied to E-dock, I plot the Raystar 120's position centered around its position on the hard top varying from about 30' off the stern to near the bow to about halfway across the boats next door to port and starboard, easily within the 3 meter accuracy circle that's specified. The boat's in Charleston, SC, so has good WAAS view at about 45 degrees elevation. It's not quite good enough for ILS approach, but damned close! Clicking the waypoints on top of a bouy symbol is NOT a good idea.... Larry W4CSC |
#14
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External GPS antenna and WAAS?
On Sun, 18 Jan 2004 14:11:09 -0800, "Chuck Tribolet"
wrote: That "error" calculation may not include the accuracy added by WAAS. And it is a SWAG based on satellite geometry at the moment, and the two receivers may use different SWAGs. Good point. Later, Tom S. Woodstock, CT ---------- "My rod and my reel - they comfort me." St. Pete, 12 Lb. Test |
#16
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External GPS antenna and WAAS?
On the west coast, the WAAS birds are only about 15 degrees above
the horizon . . . If the DirecTV test below is accurate, it's 33.4 degrees @ Portland, still quite blockable in terrain and urban canyons. |
#17
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External GPS antenna and WAAS?
The drift you get corrected for is
VERY slow moving, so if it had a lock on WAAS data every few minutes that should be good enough for good correction, shouldn't it? On a good day, yes, but on a bad day in some parts of the globe ionospheric propagation delay can change rapidly, to the point of scintillation. |
#18
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External GPS antenna and WAAS?
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#19
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External GPS antenna and WAAS?
The DirecTV test is wrong because the DirecTV bird is much closer to due south
of the western US than either of the WAAS birds. I dug up the orbital elements for the WAAS birds and plugged them into a satellite position calculator I had. It's about 15 degrees. -- Chuck Tribolet http://www.almaden.ibm.com/cs/people/triblet Silicon Valley: STILL the best day job in the world. "Mark" wrote in message om... On the west coast, the WAAS birds are only about 15 degrees above the horizon . . . If the DirecTV test below is accurate, it's 33.4 degrees @ Portland, still quite blockable in terrain and urban canyons. |
#20
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External GPS antenna and WAAS?
Here are URLs for calculating how high above the horizon the WAAS birds a
http://www.lyngsat.com/tracker/inmar3f3.shtml http://www.lyngsat.com/tracker/inmar3f4.shtml -- Chuck Tribolet http://www.almaden.ibm.com/cs/people/triblet Silicon Valley: STILL the best day job in the world. "Chuck Tribolet" wrote in message ... The DirecTV test is wrong because the DirecTV bird is much closer to due south of the western US than either of the WAAS birds. I dug up the orbital elements for the WAAS birds and plugged them into a satellite position calculator I had. It's about 15 degrees. -- Chuck Tribolet http://www.almaden.ibm.com/cs/people/triblet Silicon Valley: STILL the best day job in the world. "Mark" wrote in message om... On the west coast, the WAAS birds are only about 15 degrees above the horizon . . . If the DirecTV test below is accurate, it's 33.4 degrees @ Portland, still quite blockable in terrain and urban canyons. |
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