Don
Moderator
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Message Posted: Dec 4, 2012 2:47:13 PM
The actual logic behind which location service is used to collect location data is handled by the phone OS, the GasBuddy app only queries all the available services to see which one is most accurate at that time (this being a radius in meters).
You should be able to post prices no matter what as long as you have some sort of a data connection (to connect to our servers) and a fix on your location, whether that fix be from the use of cellular towers or GPS satellites is independent from the app.
You must remember that, even though information can appear to be very accurate, it is still approximate, and GasBuddy will try to use the most accurate location info that the device has available.
-Don
[Edited by: Don at 12/4/2012 2:49:20 PM EST]
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regulate_now
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Indiana
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Message Posted: Dec 4, 2012 10:41:32 AM
Sounds like what I may have seen would be this... One system (either cell or gps) is down/bad or just too far out of tolerance to be used thus leaving you with only one left... If it is experiencing a large radius or error but it is better than the first one- then the app uses it. If it places you outside of posting tolerances then you can't post no matter where you are actually... Does this fall within all you have learned?
Also if the cell tower you normally use (closest/closer to the station) is not used for any reason, does a farther away tower play into this if multiple towers are triangulating your position?
[Edited by: regulate_now at 12/4/2012 10:43:06 AM EST]
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Don
Moderator
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Message Posted: Dec 4, 2012 10:20:27 AM
The real issue is when a user makes a GPS/location search while they're moving. That search is locked to a specific location using specific Geo-coordinates while the user is still traveling, until it is next updated or refreshed by the user.
There is a difference between the device querying the location, and the user performing another search. Your location can be updated while you're still looking at a certain list of results, it just won't become apparent until you search again.
This generates feedback for us stating "the app shows prices behind me", there really is not much that we can do about that, unless you're using the Follow Me option which will update your GPS location in real time (major battery draw can come of this, mind you) the app cannot predict where you're traveling. It uses your current - or most recent last known - location.
Note that the location is queried about every 40 seconds, but the location can remain valid for up to 2 minutes. A location that is 2 minutes old will be used again only if the next query cannot resolve a location using information that was more accurate than the last.
-Don
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regulate_now
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Message Posted: Dec 4, 2012 8:22:03 AM
That makes sense but I see an issue where this can cause problems. The accuracy is determined by the one with the smallest radius, even if it is farther away from your real location. This can be worsened taken with the two minute function because a car at 50-60 MPH on a state highway/county road travels a couple of miles which could be just enough to place it outside of some posting tolerances... BTW, thanks for the time to get a detailed answer from your engineers...
[Edited by: regulate_now at 12/4/2012 8:24:16 AM EST]
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Don
Moderator
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Message Posted: Dec 3, 2012 4:32:34 PM
If you need any further information I'd recommend visiting the Android development community boards etc, after having a discussion with the Android OS development team this is what I can report to you.
Every 40 seconds (IIRC) GasBuddy will request an update on the device location, this information is pulled from all available sources at that time (ex. cellular towers, GPS satellites, maybe even WiFi if available), once these are all queried, the one that is considered most accurate is selected.
"Accuracy" is qualified by each different location service method's radius in meters. For example, a cellular tower location could place you somewhere within a 2 mile radius, and GPS could place you somewhere within a 2 meter radius, the GPS location info will be used over the cellular tower location.
All queried locations are valid for only 2 minutes. If the previous location was more accurate than all the new ones, but it is older than 2 minutes, the location info will get overridden by the most accurate one all the new location queries (this is not necessarily always going to be a GPS location).
If the newest location query data has worse accuracy than the previous location info overall, and the previous location is less than 2 minutes old, then it will not get overridden.
This way GasBuddy can keep the most reliable sources of providers as the selected one, as long as they are still relevant.
I hope this explanation helps.
-Don
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Don
Moderator
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Message Posted: Nov 28, 2012 5:48:00 PM
"Do the location based parameters use the closest one to the station if there is a tower/gps disagreement? "
I will need to inquire further about the logic behind this check, as far as I know the use of a wireless network signal or cellular towers (best when no data signal, or a slower data signal) or GPS satellites (best when there is a strong data connection) depends entirely on the device location services.
-Don
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regulate_now
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Indiana
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Message Posted: Nov 28, 2012 1:26:37 PM
Thank you... The reason for my post or my concern was to bring this up for discussion or thought. I have used mobile reporting since before the app just using the old favorites lists on a Windows smartphone... I have used the app from its inception and have seen it work more efficiently. However I know you have worked hard to stop abuse and to prevent errors or mis-use... Many of these barriers or protections are taking their toll on rural areas with less cell coverage- not an issue in NYC, Chicago, LA, etc... It becomes frustrating when a member reports a price to only be rejected (when this never used to happen). I do drive slightly out of my way along a more favorable or more friendly GBs route to help the cause and to help other members. So if you are aware of the pitfalls or the negative impact technical changes make- I guess that is all I could ask... Do the location based parameters use the closest one to the station if there is a tower/gps disagreement?
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Don
Moderator
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Message Posted: Nov 28, 2012 10:31:33 AM
This sounds like a coverage problem. Unfortunately there's not much that we can do to improve upon this.
Generally most smartphone GPS info is always approximate (even when it appears to be extremely accurate), and it can be skewed by the data connection type - but once again, there is not much that we can do to improve upon this. GPS is used to validate prices, in the event your location is being based off of cell towers and the approximate location is over 10 miles out, the prices may not validate properly.
An offline feature had been considered but the Android OS development team is hesitant to do this to prevent abuse, ie. having users "pretending" to be reporting prices where they are not.
If you're having issues posting prices in an area where your connection is spotty, then it could very well take that much longer for the info you're sending to reach the servers, but if it takes too long then it could time out.
-Don
[Edited by: Don at 11/28/2012 10:39:02 AM EST]
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