GPS accuracy vs movement (speed)...so says Garmin

As I said, most GPS are pretty accurate (< 3 meters with WAAS) if you are moving greater than 2.5 mph. The GPS requires movement to help calculate location. Movement is part of the program algorithm.


Email from Garmin..................


Dear Tom,

I was able to find this article at gpsinformation.net that will hopefully answer your questions regarding why one has to travel at least 2.5 miles/hr with a gps unit.

GPS BEARING versus DIRECTION OF TRAVEL

Thank you for contacting Garmin.

Best Regards;
Bernardo R.
Product Support Specialists
Garmin International
1200 E. 151st Street
Olathe, KS 66062
1-800-800-1020
Follow the leader. Garmin.

I read your post a while back about the Navionics not being spot on and had not had a problem with it before. Worked well on the Lowrance I had and had worked OK so far on the 797. Last night I took my grandson out for some fishing under the lights on Old Hickory and as we were going out from the dock to where the creek ran into the river channel it showed me running about 40 feet up on the shore. I was dumbfounded. Thought maybe the aliens had been messing with the nav systems. After I read this article I realized I was travelling about 1.0 to 2.0 mph and playing with the sidefinder. I was familiar with the area, but if I had been somewhere new I would have been scre.......... in a hurt. I'll have to remember this. And besides we didn't get to catch anything because of all the idiots running up and down the lake. Even after dark. Oh well. Anyway, thanks for the info.

I was thinking to day, yes it hert but I done it anyway,if these satalites are in a stationary orbit with the Earth, changing its tilt on its axis from summer to winter should thow G.P.S off a lot????

The goverment may adjust for this? Just a 4.a.m. thought!!!!
Rowdy

Quote:

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Originally Posted by Rowdy

I was thinking to day, yes it hert but I done it anyway,if these satalites are in a stationary orbit with the Earth, changing its tilt on its axis from summer to winter should thow G.P.S off a lot????

The goverment may adjust for this? Just a 4.a.m. thought!!!!
Rowdy

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Nope. Only 2 sats are geo-referenced at the equator (WAAS), 1 east coast, 1 west coast. The others (24) rotate around the earth 2 times in about a 24 hour period.
The sats are 11k miles up and are hauling azz around the earth. They are so positioned (6 oribatial planes with 4 sats per plane) that anytime you look up you gonna see about 6-12 of them circulating ones regardless of the time of year. Besides, the sats are constantly getting repositioned by the "Smart Ones" of the military.

I usta know this stuff, but it is fading from memory.