GPS timestamp

Paul Kocsis pktemp50 at gmail.com
Thu Aug 14 18:06:43 EDT 2014


I posted this in the android forums but have not gotten a response yet, so
thought I'd ask here.  Here's my post from the forum:

Didn't know whether to post this in "Talking Livecode" or here, because
although I'm asking the following with android in mind, I'm really looking
for answers that apply to both android AND iOS.....

My baseline question is: when I query for a detailed=true location reading,
one of the items returned is "timestamp". In the documentation, there
really is nothing describing what or where this "timestamp" is coming from.
Is it from actual GPS packets? ...or from the cellular network if the
reading came from AGPS (tower triangulation)?

In reading about GPS timestamps in google's api's (IOS as well), there
seems to be different timestamps one can get depending upon which Location
object is queried.....and thus those "timestamps" can be and mean different
things.....

I'm simply trying to ascertain "what the heck timestamp am I getting from
LC"....

I don't know if its a LC thing, or if GPS timestamps from mobile devices in
general are unreliable, but when simply logging detailed location data in a
test app, I see all sorts of (seeming) anomalies with the "timestamp", and
it would be ultra-helpful to have some information/documentation on the
origin of what LC is returning as "timestamp"...

(BTW, I *only* do a detailed=true location mobileSensorReading when I
receive a locationChanged message)

For example, sometimes I'll get timestamps that are several minutes to over
an hour IN THE FUTURE......sometimes I'll see a timestamp that is indeed
"old", but cannot be *reliably* deemed as "old" since one can receive
readings WITH THE SAME "OLD" TIMESTAMP where the GPS coordinates are
changing and the "accuracies" are changing/improving. If a GPS reading has
"changed" (along with its calculated "accuracy"), then why would I get many
GPS readings with the EXACT same timestamp?

The above makes it difficult (impossible?) to discern actual "stale"
readings vs "usable" readings.....

Can anyone shed any light on what LC's "timestamp" actually is and/or why
I'm seeing some of the timestamp anomalies that I detailed above?



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