different gps problem??
Hi... I'm very familiar with the difficulty the epic gps has with locking. I do experience this problem, but the thing that bothers me even more is that when it *does* lock (after a reboot or whatever), it's surprisingly inaccurate. When I open up google maps, it will have me down the street a ways, off anywhere from 50-200 feet To be clear, yes I'm locking with the actual gps and not a-gps... no there is no large blue circle around me. It works fine for navigation... when I'm moving and it can "snap" to the road and whatnot. But if I'm just stationary, it's off by an unacceptably large amount.
In the same location, I've used my pre and my girlfriend's EVO, and found that those gps get them within just a few meters at max.
Has anyone else experienced this? Found a solution? Or at least an explanation... Is this a known issue that I've just missed until now?
- 09-18-2010, 10:56 PM #2
- 09-19-2010, 03:04 AM #3
- 09-19-2010, 05:14 AM #4
you are confused by the language samsung uses which is incorrect. You have two totally different locations systems.
1) GPS/aGPS, requires minimum four satellites
2) Wireless tower location (usually triangulation of towers)
Google maps on "car navigation" , as well as sprint nav will force requirement for aGPS/GPS. On use as Google maps and walking GMaps may well use wireless network which has an accuracy of 4000 meters to about 7 meters.
Wireless tower triangulation not necessarily give you a blue dot.
Are you testing with wireless location off? To confirm what you are using what do the market application of gpsstsatus or gpostest tell you when this is occurring. specifically: How many sats "in use"?
- 09-19-2010, 08:46 AM #5
I am having the same issue. When I put my wife's EVO next to it then my EVO shows the right location while the Epic shows me consistently over at the next house to the right (East) which is across a street. Sit looks to be 2 houses off. Looks like Samsung still has fixing to do.
BTW I have all GPS features on.
Last edited by ChanceWells; 09-19-2010 at 09:18 AM.
- 09-19-2010, 08:48 AM #6
- 181 Posts
This particular bug in the Epic GPS -- there are also others, related to satellite locking behavior over time -- is that the programmers apparently hard-coded that reported value always to be 30.0 meters (98.4 feet) no matter what. That might be more or less than what should be reported as the estimate.
The actual accuracy, in my experience, can be much better when satellite locking is achieved. I have tracked the Epic's GPS performance in walking and driving tests using Google's My Tracks, compared to a known good device (my venerable G1) as a benchmark. The Epic's actual accuracy was just as good. But while the G1 was estimating its own accuracy in a variable range typically 2.0-4.0 meters, the Epic always reported a bogus estimate of 30.0 meters.
Just to clarify, I misspoke. I do know the difference between a-gps and "use wireless networks." Apologies for the misunderstanding.
Just using the regular gps/a-gps, I *do* lock. After a reboot, gpsstatus reports 7/7 satellites locking.
Regardless, google maps displays me down the street a ways, NOT in a larger blue circle. Like it's actually pinpointing me somewhere that is wrong... and it can range from like 50-200 feet from where I actually am. Chancewells appears to be experiencing the same problem. And my pre/evo gets me within a few feet, so I know it's not the signal in my area.
My question is... is this is known problem... a problem everybody else is having also that we should look forward to being fixed in an update. Or do I have a defective epic that I should return?
- 09-19-2010, 04:36 PM #8
ChaceWells, when you say you have all GPS enabled, do you mean you have "use wireless networks" on? turn it off. Because of Epics bugs with GPS you maybe getting no GPS satellites
a) are you certain you have wireless location off?
b) did you attempt the workaround?
My precision with 7/7 is adequate. I have seen better but it isn't unacceptable or ever a few blocks off. You have to remember that software on dedicated GPS devices and in car devices, and navigation software such as sprint nav and google maps on "car" navigation) will "snap" you to a street, reducing the appearance of lateral inaccuracy. And it can also utilize accelerometers (present in Epic) and the speed reading predicatively to reduce forward and back inaccuracy. Google maps outside of car navigation wont do that as far as I know thus increasing the appearance if inaccuracy.
So it is ironic and counter-intuitive, but those accuracy enhancing movement hardware and algorithms, along with the fact that multipath from marginal signals is easier rejected while moving, make GPS in practical terms more accurate while moving.
If you are constantly observing 30% worse accuracy than your Evo, under identical situations I would try exchange your Epic. But I am not convinced that location on this device will ever be excellent or even average. Epic is an excellent phone. But it has two HUGE problems, location and 3G speeds. Sprint is a small player in the Galaxy line and, while the 3G speeds may get fixed I don't think they have the juice to get sasmung to rework the location systerm as it should be. If you know how these devices are brought to market, the team that developed the GPS has probably been gutted and moved to the next product.
Last edited by Aero; 09-19-2010 at 07:21 PM.
- 09-19-2010, 04:40 PM #9
- 09-19-2010, 06:05 PM #10
So to clarify also my problem is the same as rmt5. I am getting a lock but will be half a block off. I would say this is a bug because all other Android devices I have "tested" do not have this issue. I had one problem with an HTC device that would not constantly lock on when I was qualifying it for launch. I had to get HTC to fix it.
- 09-19-2010, 07:24 PM #11
please install gpstest or gps status from market and give us the number of sats seen and used. Unfortunately I have not seen a android gps debug program that will give us hdop, vdop and other dops (dilution of precision). my biggest inaccuracy seems to be high vdop (altitude)
I definitely have use wireless location off (though, in my experimentation, this behavior doesn't appear to change whether it is on or off). And gpsstatus has me seeing anywhere from 7-9 satellites and locking just about all of them. Still, I'm usually marked as 100-200 feet away from where I actually am. Often, I'll reload maps and after my new lock, I'm marked as somewhere totally different (though still 100-200 feet off).
I mean, it's definitely notably worse than both the pre and evo. I doesn't affect navigation, but basically anything with augmented reality, or if a friend is trying to find you in a crowd... would be totally and utterly useless.
If very few others are having this problem, maybe I should try an exchange? But I mean, what are the odds that a few epics are defective in this one, random, particular way?
Maybe I'll go in and see if the other epics in stock have the same problem, and if so, just exchange for an evo.