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TommyTuttle t1_j5roxpm wrote

Precision of GPS is intentionally limited. It was created by the defense industry after all.

Edit: this info is out of date.

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42gauge t1_j5rrh9p wrote

Not since May 2000

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NedIsakoff t1_j5sd0zp wrote

It still is. GPS satellites broadcast many codes for positioning. Civilians do not have access to military P(Y) or M codes which are far more accurate then the civilian C/A or L2C codes.

Your thinking of when they turned off Selective Availability, which is an intentional degradation of the C/A code to reduce accuracy.

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john22544 t1_j5rxtfx wrote

If you have your own base station within a few miles of your job you can get repeatable sub 2 centimeter vertical accuracy.

Selective availability that intentionally limited the accuracy was turned off May 1, 2000.

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apeowl OP t1_j5u8p7c wrote

Yeah, but with GPS you can reach a maximum precision of about 20-30 cm (this signal is encrypted), while Galileo's encrypted signal provides about 1 cm. Note that these are the values that are possible to get almost instantly, and by only using a single signal band (with long-term measurements, and by using several signals, you can get a sub-millimeter precision with both GPS and Galileo)

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