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You said — well I hate to destroy the myth ... lol, not really

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We’re not talking about a myth here. Keep in mind, that the military did, for a long while purposely introduce error into the GPS systems, but part of that was removed. Those errors I was talking about in the GPS systems that you can get on the market — are real errors.

It’s only people who have not used them, in real-life situations who may think that they are super-accurate. They are not, and all you have to do is try it out yourself, besides you seeing those figures that I already gave you for errors.

NOW..., the *qualifier* here is whether you think an error of up to about 30 feet one way or another is not an error or not. I say it’s a big error. But, if you’re trying to find a particular building or a house, a 30-foot error is not going to make too much difference. You’ll find the house.

If you’re trying to map something that is on the ground and put it to paper, that 30-foot error is going to trip you up. If all you want is something approximate, perhaps you don’t care about that kind of 30-foot error. That’s the key — whether you care about an error of 30 feet that can go one way or the other.

You can’t get around the *fact* of that 30-foot error, in the GPS system that we have and use everyday in our cars or phones or GPS tracking devices and so on. It’s there...

And once again, I include the following for the documentation for what I’m talking about...

Ionospheric effects — ± 5 meters
Shifts in the satellite orbits — ± 2.5 meter
Clock errors of the satellites’ clocks — ± 2 meter
Multipath effect — ± 1 meter
Tropospheric effects — ± 0.5 meter
Calculation- und rounding errors — ± 1 meter

Altogether this sums up to an error of ± 15 meters. With the SA still activated, the error was in the range of ± 100 Meter. Corrections by systems like WAAS and EGNOS, which mainly reduce ionospheric effects, but also improve orbits and clock errors, the overall error is reduced to approximately ± 3 - 5 meters.

[ http://www.kowoma.de/en/gps/errors.htm ]

The Wide Area Augmentation System (WAAS) is a form of differential GPS (DGPS) giving enhanced position accuracy developed primarily for aeronautical navigation but usable by other users. Each Wide Area Reference Station (WRS) provides correction data to a Wide Area Master Station (WMS), which computes a grid of correction data to be uplinked to a geostationary satellite (GEO) via a Ground Earth Station (GES) in the Ground Uplink System (GUS). The geostationary satellite transmits the correction data (and also navigation data) to the user on the L1 GPS navigation frequency (1575.42 MHz). The user GPS receiver uses the downlink WAAS data to correct received navigation data. The goal of WAAS is to obtain at least a 7-meter horizontal and vertical accuracy.

[ http://users.erols.com/dlwilson/gpswaas.htm ]