GPS Testing Results

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I've written up a full review of the GPS:
http://briefmobile.com/samsung-epic-4g-gps-test

YouTube Video: http://www.youtube.com/watch?v=U7PBs...layer_embedded

I tested the GPS with Google Navigation, Maps, and My Tracks applications.

Observations overall:
- Accuracy was slightly off (as shown by My Tracks... worked perfectly in Google Navigation)
- Worked reliably over hours of navigating to and from destinations --- NEVER lost my car
- Compass seems off in My Tracks, shows correctly in Google Navigation

Check out my article for more details. Overall... thumbs up. GPS works well. Always worked with navigation perfectly.

Glad to see it works but still concerned about the lack of accuracy. The Evo my wife has seems to have a much more accurate lock than what was shown in the video.

Originally Posted by kennethpenn

I've written up a full review of the GPS:
http://briefmobile.com/samsung-epic-4g-gps-test

YouTube Video: http://www.youtube.com/watch?v=U7PBs...layer_embedded

1) Thanks for this test. So far I see no results that would appear to be a hard stop. But in the other thread, you mentioned that your Epic GPS accuracy was not as good as your G1. So I am still concerned. I think performance on this new, expensive, high-end Android should be at least as good as the performance of the oldest Android model.

Also, driving is the least demanding test of the low-level GPS, and there are many applications for it besides vehicular navigation. On other Galaxy S platforms, the GPS tracks seem to get smoothed or interpolated, which in driving tests seems okay most of the time because the motion of the vehicle ovewhelms the underlying errrors in the smoothing algorithm. The result is that the GPS seems great while moving pretty straight, but can veer off-course on turns, corners and stops. You did mention similar symptoms. (And then navigation programs mask errors further by snap-to behavior layered onto the smoothed GPS output.)

I know it must seem that I am never satisfied, but I am always interested in more rigorous testing. Often a better My Tracks test is over a walking course, preferably along with a benchmark device such as the G1. And the whole track -- not just isolated snapshots -- then can be shared with us via upload to Google.

For example, look at my own tests of the Vibrant vs G1 here.

(If you are worried about your own privacy, just test in some location other than your home. I went to an apartment complex in my neighborhood.)

2) Another set of GPS-bug symptoms reported on other Galaxy S platforms is the failure to use and lock on to enough satellites. That is best seen not through tracking or navigation apps, but by utilities that read and report the detailed performance of the GPS from the Android system. The two most popular utilities for this testing are GPS Test and GPS Status. Among other things, they will tell you how many satellites the GPS thinks it sees, their signal strength as SNR, and how many are actually being used for a fix. Could you try those utilites and report the results?

3) You haven't told us exactly how your test unit came into your hands. But we do know from other intelligence that at least some pre-sales demo units were selectively shipped before the latest Samsung software was installed. So it is useful to know the build date of your unit, as shown by internal file date stamps. (Perhaps this can clear up some confusion about other reported tests.)

4) From the latest build dumps we have seen, it appears that the Epic -- uniquely among Samsung S variants -- has a system utility called GpsSetup. Can you see any evidence that this utility is installed on your unit? If so, what does it do? Are there configurable settings? If so, what are the default settings, and what settings are you using?

Thanks again for your work.

Regarding the compass ...

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From the review:

My Tracks Observations:

... Compass pointer totally off. ...

Google Navigation Observations:

... Compass points the right way.

I think this simply means that the compass sensor -- and/or the low-level software that drives it -- remain bad on the tested Epic unit. In My Tracks, the compass is driven by the on-board magnetometer of the phone and is supposed to move when the phone's physical orientation changes. In Google Navigation, the compass is fixed relative to the maps streamed from the app's servers.

The FUBAR compass on Samsung S phones is sort of related to the GPS bugs, because some apps read both sensors. So users often perceive them as the same problem. But they are two separate issues.

Looks like it's the defective compass spoils the accuracy.

I know it's not going to prove much, but here is a video with another user saying the GPS is fine on the Epic:

http://androidandme.com/2010/08/news...-4g-qa-part-1/

6 minutes in.

It's also a good video worth watching if you'd just like to see the phone in action some more. I'll post this in the reviews thread as well I suppose.

Originally Posted by hydralisk

I know it's not going to prove much, but here is a video with another user saying the GPS is fine on the Epic:

http://androidandme.com/2010/08/news...-4g-qa-part-1/

6 minutes in.

It's also a good video worth watching if you'd just like to see the phone in action some more. I'll post this in the reviews thread as well I suppose.

With the correct gps settings no sgs phone has issues standing still. You wont see anything wrong with the gps until you use it while driving. Everyone with a sgs phone should know this. If I had a sgs phone & a epic the first thing I would do would test the gps while driving and post a video. I think its weird how no one will do this. I am getting a epic first thing tues am and will post video of speed of the epic vs sgs phone with lag fix, gps test while driving & video\pic quality. Since these are the main things in question.

Originally Posted by shep211

With the correct gps settings no sgs phone has issues standing still. You wont see anything wrong with the gps until you use it while driving. Everyone with a sgs phone should know this. If I had a sgs phone & a epic the first thing I would do would test the gps while driving and post a video..

Actually, in my experience the opposite tends to be true about SGS phones. Driving tests tend to obscure the accuracy problems. Standing still and walking tracks are tougher tests of accuracy. And videos are not as detailed as actual My Tracks output uploaded to Google, where we can all zoom in an explore ther results in detail on a map or satellite background. Some problems that can show up driving are the cases where the GPS track veers off-road on turns and stops.

I have seen plenty of driving "reviews" and "tests" of the GPS in other variants of the phone that erroneously report everything is fine (which is why I still take the OP's results with a grain of salt, no offense). My own testing with Vibrants showed relatively decent tracking while driving, but very poor accuracy when stopped or moving as a pedestrian.

EDIT: I finally found and watched the newly linked Youtube video here, and was totally unimpressed by this reviewer. He was cluelessly misinformed about the status of the GPS problems on other platforms, and his andecdotal report of using the GPS on the Epic through Google Navigate app proved nothing at all.

BTW, for a good summary of the GPS problems on Samsung Galaxy S phones generally, see this post at the international I9000 forum. These issues are much more complex than superficial reviews engage.

Originally Posted by boomerbubba

Actually, in my experience the opposite tends to be true about SGS phones. Driving tests tend to obscure the accuracy problems. Standing still and walking tracks are tougher tests of accuracy. And videos are not as detailed as actual My Tracks output uploaded to Google, where we can all zoom in an explore ther results in detail on a map or satellite background. Some problems that can show up driving are the cases where the GPS track veers off-road on turns and stops.

I have seen plenty of driving "reviews" and "tests" of the GPS in other variants of the phone that erroneously report everything is fine (which is why I still take the OP's results with a grain of salt, no offense). My own testing with Vibrants showed relatively decent tracking while driving, but very poor accuracy when stopped or moving as a pedestrian.

I understand what you are saying. Going over 60 mph the gps performs better then when going slow and making turns or tracking a run. But standing still I have never had it not lock and work. The only videos of the epic are of standing still lock times.

Originally Posted by shep211

I understand what you are saying. Going over 60 mph the gps performs better then when going slow and making turns or tracking a run. But standing still I have never had it not lock and work. The only videos of the epic are of standing still lock times.

I'm not talking about an apparent locking problem. I'm talking about the other symptom of the GPS bug: lack of accuracy.

There are many reports -- and I have experienced this myself on Vibrants -- where the satellite signal appears to lock. But the accuracy of the lat/lon coordinates being reported is all over the place. And they can be outside the theoretical range of accuracy being reported. For example, GPS Test or GPS Status --reading the ouptut of the Android listeners, which in turn are reading the onboard GPS chip -- may say the fix is supposed to bee accurate within 20 feet. But the coordinates are a couple hundred feet away from the actual location, and meandering over time.