Joe youre out of date ... you need to get with waterproof dustproof 10 inch tablets:

Sony Xperia Z2 Tablet review - PC Advisor

Errr the satellites do NOT determine a users position. As far as any normal user is concerned they get a signal from the GPS/GLONASS satellites and the users device determines its own position based on those signals.. the users device sends no signal outwards (such a system would need a larger antenna and a much larger battery on the users GPS).

No ground stations in various parts of the world for political/safety reasons. My understanding is that if there were no new outgoing signals from ANY ground station then there would be a slow degradation of the GPS systems accuracy. For normal car navigation use .. well even one ground station could maintain the system to an acceptable accuracy! 20 meters should be good enough? Why have so many ground stations? To get better accuracy for the defense enabled GPS systems. And as a side benefit it allows; faster tuning of new satellites, faster detection of faults and redundancy.

The GLONASS system has less horizontal positioning accuracy that the GPS system .. better in the vertical! But .. the more satellites your system can see and use to get an average off, the better its accuracy will be. So best to get one with both GPS and GLONASS capability.

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You want water and dust resistant? Plastic bag it... much cheaper. And you get a wider selection of cheaper products.

No tab!
Won't fit on the bike...
Z1 or Z2 SMARTPHONE is the one.

Xperia™ Z2 | Android Phone - Sony Smartphones (Global UK English)

Smart Phones Keep Getting Smarter
 

Another cool APP for smart phone as we travel in Russia,, daunting Cyrillic.
Download Word Lens from Google Play,, and you can instantly translate simple signs, directions . menus and notices into English, without need for DATA.

It can translate following languages.
Language packs must be downloaded before traveling - but are currently free.
Once downloads, the user does not need a network connection.
Supported translations are:
Russian
Spanish
French
Italian
German
Portuguese

Introducing Word Lens - YouTube

Went to buy Z2 ,, yesterday ,, compared it to my Sam Sung Note II ,, found the screen real estate actually smaller than my Note II , it was thinner,, yes it had metal body but much narrower than I am used to. Deceivingly sophiscated for such a rugged phone. Sam Sung S5 has same 20MP camera and same dust and water proof,, but feels plasticky ,,the price is USD 950 vs Sony' USD 790, here in Korea. Sony is made in China,, Sam Sung is made here in Korea.
I will wait till, Sam Sung comes out with a metal body.

I gotta wonder, how accurate do you need to be FFS, your trying to find a road, not guide in smart bombs!!
25m accuracy is adequate, 30cm, get a grip!!:taz:

Ditto!

Apparently its all going to be fine. Gps to keep operating in Russia