China use - GPS coordinates?

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rayonline

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#195537 23-Apr-2016 13:42

Just a question of curiosity. Folks went to China, he had a Samsung J5, got a China Mobile simcard. Some photo's have GPS co-ordinates and some do not. What is happening here, is this China or was it simply they were in a area outside cell coverage? Also how does the device get the co-ordinates - do they need a simcard or mobile data? Does it work with a bare phone?

Cheers.

Jase2985

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#1540654 23-Apr-2016 13:49

GPS comes from the sky (satellites). I can still use google maps to display my location with no mobile data or wifi connection, it just wont update/render the maps in locations it hasnt cached.

unsure if you need mobile data for it to tag the photos though.

oxnsox

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#1540740 23-Apr-2016 17:13

As Jase says GPS is a space based system and does work in China ( used it on a Nokia up there last year), although the Chinese do now have their own system....FWIW.

Tagged photos may be geting cell site derived/assisted positions.

For any GPS device to work it needs to spend some time getting the latest (local) Almanac (or ephemeris) data. If you've shifted a distance of hundreds of km or more ( NZ to China counts!) since you last used it this can take 15minutes or so, and you have to be outside and with a clear horizon view of the sky. This last bit can be tricky to achieve in urban China, which means it could take a lot longer.

And if your folks hop on a plane and fly a few hours east ( or any direction), then they're back to square one.
Even on a train journey you won't get reliable coverage

Technofreak

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#1547845 6-May-2016 22:10

As already mentioned a cellphone doesn't need a mobile connection for the GPS to work, but it can take a while to provide a position fix if it has been shifted some distance from the last place it was used.

A mobile connection or cellular data will speed up the time it takes for the phone to provide a position fix. The phone is able to get basic position data to help pin point it's position while it updates it's GPS almanac.

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rayonline

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#1605734 7-Aug-2016 08:50

We are planning a family trip together to China this time ... upon some research. Google Maps are blocked in China. The other time when they were there, we were trying to check their photo co ordinates maybe that uses Google services? But when we tried to track their phone using Google sign-in as they travelled around in China - that for sure didn't work. Will probably have to use a offline map with maybe routing ability. I do know Navmii has it, Maps.Me doesn't provide a China map for download. Bit of a bummer cos I was planning to use Google Street View to better plan the trip of what to do and see ....... There is the way of roaming with a foreign SIM but that is expensive. That isn't blocked at all ......

Not even sure if we can get a SIM b/c what I read they say they need to scan your Chinese ID Card and we don't' have that. But then there are smaller shops available too ... Also 1 of the 3 telco's work with foreign phones. 2 of them run on China specific frequencies.