GPS GNSS Accuracy

Please read this page, before.

Who more accuracy U-blox 6 generation (GPS) or U-blox 8 generation (GNSS)?

Global

Operational

NAVSTAR GPS accuracy - about 2-4* m

Glonass accuracy - 3-6** m, (may be I'm wrong, but outside of Russia accuracy fall down to 9 m)

In development

Galileo - first services should be launched at the turn of 2014 and 2015. Full completion of the Galileo system is expected by 2019

BeiDou - accuracy 10 m in Asia-Pacific (by 2020 global BeiDou-2 also known as COMPASS)

Regional

Indian Regional Navigation Satellite System - accuracy unknown (for India)

Quasi-Zenith Satellite System - accuracy unknown (for Japan)

How we see Global Position system is only Navstar GPS and Glonass, if use both of this system we will have GNSS that totally more accuracy than GPS or Glonas separate. To get more accuracy we must use our Satellite-based augmentation system (SBAS).

EU - EGNOS

USA - WAAS

Russia - SDCM

Japan - MSAS and QZSS

and else...

For example EGNOS with GPS give the horizontal position accuracy is at the meter level.