GPS accuracy


dg

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My etrex Vista will say: "weak signal, need clear view of the sky" or something near to that. I've never seen an "error" message though. It has WAAS, but I've never turned it on. I'm no expert, but I think you have to have relatively flat ground so that the gps unit will pick up the land based WAAS signals. If the accuracy was 100 yds, it wasn't picking up the better satellite signals.

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Re: GPS accuracy

GPS is Global positioned satellite meaning it works off of satellite in the lower orbit above the earth ALL satellites work off line of sight so no line of sight no work its pretty simple and its also there only downfall if we could put satellites in the attics off ppls house we wouldnt need cable companys lol but unfortunately they work off line of sight no way around it

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Re: GPS accuracy

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flat ground so that the gps unit will pick up the land based WAAS signals

[/ QUOTE ]

There are only two WAAS satellites. One over the Atlantic Ocean, and one over the Pacific Ocean. The WAAS satellites will be numbered 33 or HIGHER! I just got a Etrex Vista (for $218 I might add!) and reading the manual will tell you this! Although I have much to learn yet. I will master this thing! LOL!!!

jnamo, was there a lot of leaves still on the tree's? If so I believe you just were not picking up a good signals from the satellites! The manual clearly states foliage will interferre with the signal!

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Re: GPS accuracy

[ QUOTE ]

[ QUOTE ]

flat ground so that the gps unit will pick up the land based WAAS signals

[/ QUOTE ]

There are only two WAAS satellites. One over the Atlantic Ocean, and one over the Pacific Ocean. The WAAS satellites will be numbered 33 or HIGHER! I just got a Etrex Vista (for $218 I might add!) and reading the manual will tell you this! Although I have much to learn yet. I will master this thing! LOL!!!

jnamo, was there a lot of leaves still on the tree's? If so I believe you just were not picking up a good signals from the satellites! The manual clearly states foliage will interferre with the signal!

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Really? Maybe you can explain the WAAS system better than GARMIN? grin.gif

The origins of WAAS

The Federal Aviation Administration (FAA) and the Department of Transportation (DOT) are developing the WAAS program for use in precision flight approaches. Currently, GPS alone does not meet the FAA's navigation requirements for accuracy, integrity, and availability. WAAS corrects for GPS signal errors caused by ionospheric disturbances, timing, and satellite orbit errors, and it provides vital integrity information regarding the health of each GPS satellite.

How it Works

WAAS consists of approximately 25 ground reference stations positioned across the United States that monitor GPS satellite data. Two master stations, located on either coast, collect data from the reference stations and create a GPS correction message. This correction accounts for GPS satellite orbit and clock drift plus signal delays caused by the atmosphere and ionosphere. The corrected differential message is then broadcast through one of two geostationary satellites, or satellites with a fixed position over the equator. The information is compatible with the basic GPS signal structure, which means any WAAS-enabled GPS receiver can read the signal.

Who benefits from WAAS?

Currently, WAAS satellite coverage is only available in North America. There are no ground reference stations in South America, so even though GPS users there can receive WAAS, the signal has not been corrected and thus would not improve the accuracy of their unit. For some users in the U.S., the position of the satellites over the equator makes it difficult to receive the signals when trees or mountains obstruct the view of the horizon. WAAS signal reception is ideal for open land and marine applications. WAAS provides extended coverage both inland and offshore compared to the land-based DGPS (differential GPS) system. Another benefit of WAAS is that it does not require additional receiving equipment, while DGPS does.

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Re: GPS accuracy

[ QUOTE ]

[ QUOTE ]

flat ground so that the gps unit will pick up the land based WAAS signals

[/ QUOTE ]

There are only two WAAS satellites. One over the Atlantic Ocean, and one over the Pacific Ocean. The WAAS satellites will be numbered 33 or HIGHER! I just got a Etrex Vista (for $218 I might add!) and reading the manual will tell you this! Although I have much to learn yet. I will master this thing! LOL!!!

[/ QUOTE ]

This is my reference: http://www.garmin.com/aboutGPS/waas.html

What is yours and we can compare notes!

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Re: GPS accuracy

I had gotten a GPs for a birthday present and wanted to see how good it was, so I went out to one of our land navigaton courses with all the grids and points. Well at every point I was off by atleast 300m and the closest I got was 250m . I tried this 3 times before I took it back. I went out about 3 months later and had to verify the course with a military GPS(plugger) and was right on every time!!! I took back my GPS and used the money on something else.

GPS are garbagge!!!

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Re: GPS accuracy

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Hi DJR!

"GPS are garbage".

I hope you never go grouse or sharptail hunting in the Sandhills of Nebraska or hunt the Fort Pierre National Grasslands in foggy weather. If you try either of these WITHOUT a GPS, you will never find you way back to your truck.

the dog

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I have never been lost!!! All I need is a map and a compass , terrain assosiation, resection , intersection?????? If you know what those are then you know I wont get lost!!!!!

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Re: GPS accuracy

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What is yours and we can compare notes!

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I going by what the manual says! The manual says there are two satellites, one on each coast. If you lock on one of them satellites, your accuratacy will greatly increase! My unit said this morning on my way to work. Accurate to 9 FEET! This was with the WAAS satellite lock in. For some reason I dont always lock that satellite in. Then the accuratcy drops to about 15-30 feet. You have more info on these units than I do, but thats why I also said I am still learning! Also, the manual says nothing about land based WAAS stations! But I see they are there!

wink.gif

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Re: GPS accuracy

[ QUOTE ]

What is yours and we can compare notes!

[/ QUOTE ]

I going by what the manual says! The manual says there are two satellites, one on each coast. If you lock on one of them satellites, your accuratacy will greatly increase! My unit said this morning on my way to work. Accurate to 9 FEET! This was with the WAAS satellite lock in. For some reason I dont always lock that satellite in. Then the accuratcy drops to about 15-30 feet. You have more info on these units than I do, but thats why I also said I am still learning! Also, the manual says nothing about land based WAAS stations! But I see they are there!

wink.gif

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