GPS timestamp

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pkocsis
Posts: 104
Joined: Sat Apr 15, 2006 7:20 am

GPS timestamp

Post by pkocsis » Thu Aug 14, 2014 12:49 am

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?

TIA!!

Paul

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