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All things GPS

Is this a poll?

  • Yes, it looks like a poll.

    Votes: 42 26.3%

  • No, there is no way this is a poll.

    Votes: 31 19.4%

  • Why in the world is there a poll here?

    Votes: 87 54.4%
  • Total voters
    160
EarlyMon said:
A comparison of your Garmin and Captivate tuned up with that app would be most welcome here, I'm sure.
Click to expand...

Ok, I took the suggestion and conducted a quick test running both my Garmin Nuvi 205 and my Captivate in a moving vehicle. The Garmin, of course, ran flawlessly. I do believe that the Garmin unit is programmed to place you "on the road" on the display even if there is a slight GPS drift. That's why it looks so accurate on the display. I say this because when I program a destination on the Garmin, I will follow it then deliberately drive on a parallel road right next to the path Garmin wants you to take but for a few seconds (like 5 to 10 secs) the display still shows me driving on the path that the Garmin determined to be the proper "road" instead being off to the right or left of the "road" by 50 feet or so. After the 5 to 10 seconds have lapsed, the Garmin I think averaged the last dozen or so GPS reading and determines at that time that I am in fact driving on a parallel road because the display will correct itself and show me on the parallel road correctly at which point I get the "recalculating" words across the screen. The Garmin was started from a cold boot (hadn't been turned on in about a month) and it took 13 seconds to place me on the road (dead-on accurate too). I took my Captivate, started GPS Status and deleted the cached GPS data and re-downloaded the A-GPS data. I did this standing outside my car with a clear view of the sky. It took about 40 seconds to get a lock on the satellites initially. I then started Google Maps and entered my car, and started driving while holding the Captivate up to the windshield. The Captivate held the satellite lock while moving but the screen updating was very slow. I was about 1/2 block further than the phone GPS was telling me where I was, but as soon as I slowed down or stopped, the display caught up and placed me dead-on where I was stopped. The faster I went, the slower the display updated to my correct location (and hence, completely inaccurate position fix). Here's an interesting observation during the testing. I made a sharp right turn and headed south on a street. The Garmin, of course, immediately updated the change in direction and placed me on the correct road heading southbound. The Captivate, on the other hand, continued showing me going eastbound then slowly placed me in an arc eventually heading southbound, like a ship doing a slow turn. It also showed me 1 block over to the east of where I actually was. As soon as I stopped, however, the arrow eventually caught up to the correct location on the display and placed me dead-on where I had stopped in the parking lot. This tells me two things; My Captivate is accurate for location checking and verification AS LONG AS I'M NOT MOVING QUICKLY. My Captivate does NOT have differential averaging as far as I can see. The arrow jumped around a bit as I was driving down the street trying to catch up to where I actually was at. As soon as I stopped and it caught up, it was dead-on accurate. The data processing for GPS coordinate seemed like it was being handled by the main CPU rather than a co-processor dedicated to GPS data processing only. I say this because of the sluggishness of the updating; it was like watching screen updates on a Vista OS running on a Celeron CPU.

Bottom line for me.... My Captivate is accurate for checking location when standing still but completely useless for mobile GPS application.
 
Holy Moly! I just discovered something interesting in my Garmin GPS. On the cheapy Nuvi 205, you can access the satellite info page if you press and hold the satellite signal display (the bars) for 30 seconds. If you press and hold the battery icon for 30 seconds, the test mode screen comes up. I pressed all kinds of buttons (and deleted the cksum data accidently). My Garmin took over 5 minutes to regain satellite signal after that!!! I thought I broke it. But after turning it off then back on several times, the warm boot lock on was around 5 seconds. Whew!
 
Here's info on what is needed by GPS receivers to calculate positions.

Why does it take so long for a GPS receiver to find its starting location? - GPS Basics FAQ

It says the almanac data is transmitted in full in 12.5 minutes from the GPS satellites. Almanac data is needed by the GPS receiver to calculate what satellites should be overhead at a given time and date. The internal GPS clock also needs to synchronize with the satellite timing signal and it is contained in the ephemeris data which takes 30 seconds to be transmitted in full from the satellites. So... modern GPS units receive the signal and store it onboard its memory so that when you turn it on, it can refer to the last updated data to start looking for satellites. It's a method used to locate and listen for satellites quickly rather than waiting at least 30 seconds (to download the ephemeris data) to start looking for and listening to satellites overhead. Somewhere, somehow, I think the Captivate is failing to store that data correctly. What I've done is open up GPS status and just let it sit running that app locked on to satellites for 20 minutes to see if it helps with acquisition time and precision. So far, my Captivate is dead-on and seems to lock up to satellites fairly quickly. Try it on yours. Can't hurt..... Oh, make sure your Captivate stays on when this app is running.
 
SamsungCaptivated said:
Ok, I took the suggestion and conducted a quick test running both my Garmin Nuvi 205 and my Captivate in a moving vehicle. The Garmin, of course, ran flawlessly. I do believe that the Garmin unit is programmed to place you "on the road" on the display even if there is a slight GPS drift. That's why it looks so accurate on the display. I say this because when I program a destination on the Garmin, I will follow it then deliberately drive on a parallel road right next to the path Garmin wants you to take but for a few seconds (like 5 to 10 secs) the display still shows me driving on the path that the Garmin determined to be the proper "road" instead being off to the right or left of the "road" by 50 feet or so. After the 5 to 10 seconds have lapsed, the Garmin I think averaged the last dozen or so GPS reading and determines at that time that I am in fact driving on a parallel road because the display will correct itself and show me on the parallel road correctly at which point I get the "recalculating" words across the screen. The Garmin was started from a cold boot (hadn't been turned on in about a month) and it took 13 seconds to place me on the road (dead-on accurate too). I took my Captivate, started GPS Status and deleted the cached GPS data and re-downloaded the A-GPS data. I did this standing outside my car with a clear view of the sky. It took about 40 seconds to get a lock on the satellites initially. I then started Google Maps and entered my car, and started driving while holding the Captivate up to the windshield. The Captivate held the satellite lock while moving but the screen updating was very slow. I was about 1/2 block further than the phone GPS was telling me where I was, but as soon as I slowed down or stopped, the display caught up and placed me dead-on where I was stopped. The faster I went, the slower the display updated to my correct location (and hence, completely inaccurate position fix). Here's an interesting observation during the testing. I made a sharp right turn and headed south on a street. The Garmin, of course, immediately updated the change in direction and placed me on the correct road heading southbound. The Captivate, on the other hand, continued showing me going eastbound then slowly placed me in an arc eventually heading southbound, like a ship doing a slow turn. It also showed me 1 block over to the east of where I actually was. As soon as I stopped, however, the arrow eventually caught up to the correct location on the display and placed me dead-on where I had stopped in the parking lot. This tells me two things; My Captivate is accurate for location checking and verification AS LONG AS I'M NOT MOVING QUICKLY. My Captivate does NOT have differential averaging as far as I can see. The arrow jumped around a bit as I was driving down the street trying to catch up to where I actually was at. As soon as I stopped and it caught up, it was dead-on accurate. The data processing for GPS coordinate seemed like it was being handled by the main CPU rather than a co-processor dedicated to GPS data processing only. I say this because of the sluggishness of the updating; it was like watching screen updates on a Vista OS running on a Celeron CPU.

Bottom line for me.... My Captivate is accurate for checking location when standing still but completely useless for mobile GPS application.
Click to expand...

I mentioned above that I replaced my Captivate with a brand new one a few days ago. The new Captivate's GPS tracking has been absolutely flawless just like a stand alone GPS such as a Garmin or Tomtom. This is in a car tested up to highway speeds. It seems to me that they probably made some hardware improvements to the GPS in the latest builds. I have the feeling that the GPS issue for some isn't just a driver problem. I am 99% sure that the only way I was going to have a fully functioning GPS was to return my phone for a brand new one.

My friend and I did a test last night. He has an older Captivate and we tested it against my new Captivate for GPS tracking. We are both using stock 2.1 unrooted Captivates with the same firmware version. Both of us had 'Use wireless networks' disabled.

Firstoff, the new Captivate was flawless for the whole ride. It always showed exactly where we were and Navigation consistently showed a tight read on our position. Going around corners it updated immediately and had us in the right direction. Also, the initial lock was almost instant.

The older Captivate was always lagging about 50-100 feet behind the new Captivate. In about 3 miles of testing the older Captivate had us on parallel roads 3 or 4 times and started to incorrectly give out directions. The blue circle around the arrow was always medium to large meaning it couldn't figure out our exact position. At one point it fell behind and failed to update our position for a whole block. There were a few instances when it had us moving when we were completely still. The initial lock took about a minute or so.
 
I've started using Runkeeper, and I have to say, on my little walk today, the GPS was dead on, sitting in my pocket! It gives you the opportunity to review your tracks, and it only wandered just a bit, twice - looked dead on for the rest of the two miles. I don't know if it is the app, the new ROM, or just the GPS gods shining down for a minute, but when I started Runkeeper, it got a lock within seconds.
 
reinbeau said:
I've started using Runkeeper, and I have to say, on my little walk today, the GPS was dead on, sitting in my pocket! It gives you the opportunity to review your tracks, and it only wandered just a bit, twice - looked dead on for the rest of the two miles. I don't know if it is the app, the new ROM, or just the GPS gods shining down for a minute, but when I started Runkeeper, it got a lock within seconds.
Click to expand...

My old Captivate was fairly accurate when walking or bicycling with Google Tracks (even when in my backpack) but the real test is using it inside of a car at higher speeds. In that instance my old Captivate always fell behind, lost GPS signal and was generally all over the place.
 
"All of the phones had the "GPS" icon... except the Captivate. "
Someone in that store probably got tired of hearing how well it didn't work.

"And they all moved down to the other end of the Group W bench."
[Alice's Restaurant]


" I don't understand why poeple are bitching about GPS.
My wife and I have the same phones and GPS works perfectly fine. "
Well, a billion customers say McD's makes a great hamburger. But that's "boxed beef" and if I want a real hamburer, my local pub makes one that McD's look like something I'd wipe off my shoes if I stepped in it. I would suggest "fine" is a matter of not knowing there's really a man behind the curtain, and what GPS can and should work like. Half the reviews and articles oyu see that mention GPS say that it is signalling UP to the satellites. It doesn't do that either.

The ephemeris data and the system corrections that are broadcast every 12(?) minutes should not affect cold or warm boot times if your GPS has a memory (most do) and hasn't moved hundreds of miles since last use. The correction data is fairly small and you may see the clock on a GPS bump by several seconds when that data is received and processed. But, that data won't prevent a GPS from initial lock-on or startup. It's icing on the cake.

FWIW Garmin makes some nice stuff, but they're also very protective about their proprietary information. Got a Nuvi? Garmin won't tell you how the Nuvi makes routing decisions, that's top secret. But among other quirks, they seem to be designed like J. Edgar Hoover: They don't like left turns. I've seen two of them consistently go "around the block" up to an extra half mile, making right turns instead of making a left across traffic to get to a location.

The IS a man behind the curtain, ignore him at your own peril. That's how folks follow their GPSes every year, and drive off ferry ramps and other good routes.
 
Well, I don't know if this is helpful or just sounds like gibberish to people, hope it makes some sense. It condenses earlier info from this thread, plus a little other, and I posted it in another forum.

It addresses the idea that some people don't have this issue, while others do.

Requiring agreement is not the right path to understanding this GPS issue. The right path might be to wonder why some people absolutely suffer this problem when others absolutely do not.

Samsung has flatly admitted, several times that this is a flaw they created (citations upon request).

Isn't it therefore counterintuitive or impossible for some to not suffer it?

No.

Following that set of observables, others have reasonably postulated that what seems to be at play here is inadequate cpu management of the gps services, especially in light of the servicing requirement for the gps chip used by your class of Samsung phones.

If true, then it's entirely possible and reasonable that no single gps-specific set of test conditions is going to expose this problem for those not suffering it - and that's because each user sets up their phone with apps uniquely, and the Linux process scheduler is stochastic, and therefore each user ends up with different execution profiles at the time of test from others.

This is a very common class of pernicious software defect and is usually the most difficult to isolate for correction. The validity of the observables that some do not suffer this tends to very strongly suggest that this isn't a hardware problem, per se.

The recent non-fix announced by Samsung for some models effectively cleared the gps caches. This seemed to work for some, or to work for a short while, or to work not at all.

In the meantime, flashing a new rom may or may not solve the problem - if true that this is an execution-time mismanagement of the gps chip's operating requirements, then it's true that changing the execution profile - such as occurs when a new rom is installed or cache is cleared and another app introduced (referring to the cache-clearing app mentioned above in Captivate) - _might_ alleviate this problem. I would NOT expect that to be an actual cure though, because it simply attacks an effect leading to the problem, not the problem itself.

I could be wrong, but thought you all here might have some interest in this.
Click to expand...

Not intended as an argument to Rred, just another piece of info for those interested.
 
"It addresses the idea that some people don't have this issue, while others do."
No argument, no problem, EarlyMon. What we DO in fact know, is that GPS is like all advanced technology. In Arthur Clarke's words, indistinguishable from magic to the average user.

And since no users--absolutely none, as far as I can see, on any forum--have ever posted GPS signal to noise figures for these phones that match the numbers on real GPSes, we can only assume these GPSes are all sub-par and the "satisfied" users are simply satisfied with sub-par performance because that's all they've ever known.

If the only car you've ever driven is a Yugo...it's a magnificent car. Until you've been in a Chevy, a Mercedes, a Ferrari, a HumVee...."satisfaction" is just a matter of perspective, not an objective measure. By all objective measures, there's something wrong with perhaps all of these phones.

Before there was GPS, there was LORAN C. And sometimes that was off by a thousand miles--literally--but it was still marvelous, compared to the alternatives. Then GPS deployed and the occasional thousand mile error became unacceptable.<G>

If it was just a quality control issue, with some phones being good and others not so good, surely the folks with good phones would be able to post objective confirmation of that? Folks out there who simply haven't mentioned that they really have been able to get 50db or better signal strengths from the birds?

Forget the folks who are intimate with GPS, who navigate ships and planes and run surveys, but anyone? Anyone at all? Anyone seen a Captivate post the same s/n numbers as any GPS made in the past five years?
 
Anecdotally, the Evo is claimed as having astonishing performance, and many claim it's equal to any separate GPS unit.

While I don't know about that(*), I mention it because if true it suggests that it credentializes:

  • we must segregate aGPS from GPS solutions
    • compromise must exist with aGPS
    • it needn't be extreme for many consumers
  • Samsung isn't getting anywhere near what the Evo does in performance, not whatsoever
    • whether that's possible or not, it should be expected that some consistent behavior from the Sammys ought be a consumer right as it was advertised as a major feature

We've got people claiming to pilot light planes with their Evos and all sorts of other wonderful tricks. (I'd rather my pilot trust the sacred six for those that know what that means, before a cell phone - but there it is.)

I think of cell phone GPS like a cell phone camera.

I don't expect a cell phone to take stunning DSLR-quality pictures - but I expect it to surpass a Holga or a Diana (google those for fun, you'll get the idea), and I expect it to do a decent job as an digital add-on.

Right now, Samsung's admitted they're giving the GPS equivalent of a Holga, you should be getting at least better than an Instamatic or Brownie.

Some kinda metaphor like that. Rred, if we're on the same page, run with that for me.

(* and I think the Evo's GPS user claims are prolly exaggerated, but it tends to be scary-good for a cell phone)
 
Since right before I made the 1400 mile trip to and from NC, my GPS has been working exceptionally good. I have no problems with locks and while on the interstate, it was very accurate. I did the GPS Restore and took an eraser to the two white marks, that's it.

I think people don't read the most previous posts in a thread. :)
 
gcobb said:
Since right before I made the 1400 mile trip to and from NC, my GPS has been working exceptionally good. I have no problems with locks and while on the interstate, it was very accurate. I did the GPS Restore and took an eraser to the two white marks, that's it.

I think people don't read the most previous posts in a thread. :)
Click to expand...

Glad it's working for you. Others have done both of those things, not fared so well.
 
EarlyMon, I think we're on the same page. I don't expect survey-grade accuracy from my cell phone GPS. I do expect to see it read "0 mph" when I stop at an intersection, and not continue averaging while I'm not moving. Ahem.

All I ask is "commodity grade" performance, the same as the cheapest GPS units on the market TODAY. That means comparable to a SirfStarIII chip, which is one generation obsolete compared to 4th gen units that have been out for several years now. If I put the cheapest Nuvi on the front seat of my car, it still works. If my friend puts his no-name tne year old BT GPS on the sun visor in his car, and then flips it up AGAINST THE ROOF, it still works. If I take my 20+ year old Garmin (first gen) outside, it sees all the birds and locks up just fine, even if it is a little slower to start.

My Captivate? Doesn't match the performance of any of them. Can't see the sky unless it has a perfect view, and even then, doesn't hear the satellites that other units have no problem with.

If Samsung was marketing this as a free entry level phone, I'd say "whaddayawantfortwennybucks?" but they aren't. AMOLED screen, 16GB of memory onboard and space for 32 more...there's no excuse for having a GPS that simply CAN'T FUNCTION in normal circumstances. Mine won't work in the car unless it is right up there under the windshield glass, and even then, that's iffy.

But Samsung and AT&T have both covinced me that there's nothing wrong with the GPS and I've come to understand that I'M THE PROBLEM. Damned hairy wide-eyed barbarians from the lower kingdom like me are the problem. You see, if we had had the good sense to be born and live in Korea, we'd be closer to the Middle Kingdom and the Heavens, and the GPS obviously wouldn't need to work so hard.

Sadly reminds me of Samsung's earliest days in the US market, when their reputation was, ah, cheap. If I'm lucky, Moto will upscale the Defy and I'll have a new best friend.<VBG>

I know AT&T just doesn't give a damn, they've always been that way. And I guess Samsung figures that since THEY don't sell anything directly, they don't have any worries. But there are folks out there looking for real answers, and if the answer comes up that there is a serious flaw being concealed in these phones, making the GPS "unfit for use" or any of several other specific terms, I can see a class action suit and AT&T being forced to hand out a couple of million replacement phones. Which Samsung may have to pay for, if the GPS is having problems because of EMI/RFI from the other circuits int he phone, i.e. a concealed design and manufacturing defect.

It shouldn't have to be that way, but so far...the phones have a problem, a proven problem, and all three players (Broadcom, Samsung, AT&T) swear it doesn't exist. Some of us know that's a lie.

And since they've already issued three "fixes" that continue to use a disconnected AGPS server, it isn't hard to prove that they're sloppy and they're lying. As documented by their own firmware.

I can understand, and forgive, mistakes. Piles of lies? I won't.
 
Rred said:
I don't expect survey-grade accuracy from my cell phone GPS. ... All I ask is "commodity grade" performance, the same as the cheapest GPS units on the market TODAY.
Click to expand...

I'm with you. One of the most insulting things that happened to me recently was seeing how the crappy Motorola Backflip's GPS performed even a foot away from a window, compared to my Captivate when pressed right up against the same window.
 
You mean...the Backflip was worse?

Or that the cheaper backflip outperformed the Cappy? (I hope.)

I keep looking for alternatives, if I drop my old phone one more time I'm afraid it won't forgive me. The BT in it has already gone mildly insane. And since I want to stay GSM, that limits me to AT&T (Winphone, sure, right. Wrong.) or TMob (who sort of scare me) but at least I can use a Moto Defy when I'm stuck on the rain, without voiding the warranty.

Having been wet and miserable at times...I keep coming back to that thought. The Cappy is more phone, but sometimes less is more too.
 
Rred said:
You mean...the Backflip was worse?

Or that the cheaper backflip outperformed the Cappy? (I hope.)
Click to expand...

The Backflip was much, much better. And ran Android 1.5 (although I updated it to 2.1). Which should embarrass the hell out of Samsung.
 
Years ago, Motorola foolishly tried to stay competitive by jobbing out the manufacture of Startacs to Korea, teaching Samsung how to build cells phones as their jobber.

That came back to bite 'em in the ass.

Supposedly Moto split off their cell phone business and their game plan is to come back as the player they once were: Top quality, top engineering. I'm hoping they can do it, because they once did it SO WELL.
 
The reason for bad gps is software. I flashed a new rom with jk4 yesterday and I get a lock indoors within 10 seconds with an accuracy of 15 meters. I can walk outside and it locks automatically and spot on accuracy.
 
mi04se1 said:
The reason for bad gps is software. I flashed a new rom with jk4 yesterday and I get a lock indoors within 10 seconds with an accuracy of 15 meters. I can walk outside and it locks automatically and spot on accuracy.
Click to expand...

Let the author of JK4 ROM know, he's asked for feedback on that in his post:

[ROM] Insanity Remixed v8.25/8.26 - xda-developers

To confirm: Your GPS is in standalone mode,
all assistance off (especially Skyhook!)

This to make sure the GPS is really working, not getting AGPS feeds.

And whether all other radios on the phone are on/off, because there's some question of whether one or more of them is creating interference and deafening the GPS. (Does yours still work well with all other radios on?)

Are you getting s/n numbers for the satellites around 30-35db, the typical poor numbers from problem phones? Or has the ROM fix brought that up to 50db or higher, where other GPSes would see them?

Working is good, knowing how and why it works would be even better.<G> The author mentions the SGS gps fix tool kit, no custom gps work of his own, so no one really knows yet.
 
mi04se1 said:
The reason for bad gps is software. I flashed a new rom with jk4 yesterday and I get a lock indoors within 10 seconds with an accuracy of 15 meters. I can walk outside and it locks automatically and spot on accuracy.
Click to expand...

Give it a few weeks and report back if you can still get a lock.

FYI - ~48 feet is not accurate for GPS.
 
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