Is GPS precision strictly relative to the device?

[photoleif]

Hi. On a consumer-grade device with no external GPS receiver, I have what appears to be 1-meter precision (ignore accuracy -- only asking about precision). Does AQ add digits / decimals to the position it displays, based on what the device or mock source provides? For instance, some on the forum have external bluetooth GPS, and if those have sub-meter precision, would AQ consequently scale the displayed position to show whatever greater number of decimals are provided by the hardware? For example 39.581735 N 105.632047 W might become 39.5817354 N 105.6320473 W if the receiver itself provides that?

Thanks

[Psyberia-Support]

Hi,
Short answer: no.
Long answer: the application internally stores all locations in degrees, with 7 decimals (like most programs do, so that a lat/long pair can be saved in 8 bytes). In meters, the worst precision is at the equator, and is around 1 cm.
This is independent from the location source precision (built-in GPS, external GPS, map). I don't know if the Android Location Framework is able to handle more precision, but I doubt. If the source provides more precision, extra decimals are ignored (rounded), if the source provides less precision, the last decimals will be zeros.
Finally, the application displays all locations in the Lat/Long degree format with 6 decimal digits, which is more than sufficient for most use cases, while reducing the complexity of the display and input. The initial precision is not known anymore here.
Note that you can change the number of digits to display to 7 (or less), using this user setting:

Code: Select all

core.crs.d.decimals=7

I hope it helps,
Best regards

[suntalla]

Hi,
Some posts on the forum are so informative that i would like the option to bookmark them, to make it easy for me to find them back and read again. If this was possible digging in old posts, bookmarking what is of personal interest, well, it would make things easier.
Friendly greetings
Jos

[Psyberia-Support]

Yes, unfortunately I don't think this feature is available in phpBB (the forum used here), but you can always bookmark pages from your browser or use the search tool in the forum.

[photoleif]

Hi,
Short answer: no.
Long answer: the application internally stores all locations in degrees, with 7 decimals (like most programs do, so that a lat/long pair can be saved in 8 bytes). In meters, the worst precision is at the equator, and is around 1 cm.

\snip\

I hope it helps,
Best regards

thank you! that was an excellent reply and i appreciate the time you put into answering. i had a look into the android docs and indeed it appears to be a signed int:

FORMAT_DEGREES Constant used to specify formatting of a latitude or longitude in the form "[+-]DDD.DDDDD where D indicates degrees.
Constant Value: 0 (0x00000000)

this starts to remind me of the (in)famous "who would ever need more than 640K of ram?" quip.

anyway, thanks again for your response and of course for the excellent app. i use it every day. really.

[Psyberia-Support]

It's true that on modern devices we don't really care much of a few extra bytes (or even a few extra MB), our smartphones have more RAM than our desktop computers a few years ago...