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Old September 18th, 2010, 08:40 PM   #1 (permalink)
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Default GPS cache problem workaround, tested, working

Note1: user boomerbubba was extremely helpful in thinking this through
Note2: Engadet finally posted a link to this workaround after three separate articles in which they completely botched testing of the Epics GPS and showed a total lack of knowledge of GPS systems. Thankfully their otherwise unfortunate readers of their poor "journalism" can at least now get a workaround as well.


I have three epics and have been testing GPS functionality for two weeks with quite a number of controlled tests.

As we know there is a problem with old "assistance" (the "a" in aGPS) ephemeris and almanac data in cache. this data can start expiring in a few hours and ephemeris will fully expire in about 8 hours.

The result is that sometimes users will experience the following symptoms in a GPS fail: the Epic will "see" sufficient satellites (4 to 11) but doesn't "use" them (expired ephemeris) or will see no satellites while under clear skies (expired almanac, rarer).

Although some user actions or program identified (eg reboot),and unidentified, can apparently flush the old data out of cache so that the network renews it with valid data, this isn't programmed by Samsung correctly and users intermittently are stuck with bad data in cache preventing lock. I have tested a workaround and it works

TESTED AND FUNCTIONING WORKAROUND:

Enter GPS debug/settings application by typing *#1472365#
click "Setup" tab
click "position mode"
Click "starting mode
Enable "Cold Start"
Back out.

Epic GPS will now call on data network for fresh valid ephemeris and almanac at every programing invocation of GPS and aGPS fixes will be very fast (usually less than 10 seconds).

There one downside. while cold start will be effectively warm start in aGPS mode (good). That is it will work very nicely in the presence of a 3G or 4g data connection. But absent data connection, ie in Standalone GPS mode, you will be always cold starting (starting with empty cache), meaning fixes will be 5 to 14 minutes if you are not on the network. If you are going to be off the network for a while you can simply set to warm start from same menu.

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Old September 18th, 2010, 08:54 PM   #2 (permalink)
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please do report your 24 and 48 hour findings here
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Old September 18th, 2010, 09:46 PM   #3 (permalink)
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Where do you start this:


Enter GPS debug/settings application by typing *#1472365#
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Old September 18th, 2010, 11:32 PM   #4 (permalink)
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Probably in the dialer. I'll try this tomorrow when I'm at my computer and post back.
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Old September 18th, 2010, 11:38 PM   #5 (permalink)
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have you tested GPS with latest firmware update?

the sprint community forum site have updated the list of fixes and it does include GPS, how much, don't know. time will tell.

Samsung Epic:9/16 - Samsung Epic Maintenance Release...
Fixes:
4G de-registration when activating Mobile Hotspot
Won't maintain Exchange credentials (emails stuck in outbox and disappearing email accounts)
GPS performance enhancement
HotSpot 3G Idle Battery Issues
32GB SD Card Fix - previously when formatting the card, it wouldn't be recognized
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Old September 19th, 2010, 04:35 AM   #6 (permalink)
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Personally, I think the GPS is no different at all after the D107 update.

In fact, for the first time ever yesterday, I had issues with GPStest and Sprint NAV even making contact.

Google MAPS absolutely could not find me (actually had me in TX and I was in MA) even after a battery pull / restart.
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Old September 19th, 2010, 05:25 AM   #7 (permalink)
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Quote:
Originally Posted by badankles View Post
have you tested GPS with latest firmware update?

the sprint community forum site have updated the list of fixes and it does include GPS, how much, don't know. time will tell.

Samsung Epic:9/16 - Samsung Epic Maintenance Release...
Fixes:
4G de-registration when activating Mobile Hotspot
Won't maintain Exchange credentials (emails stuck in outbox and disappearing email accounts)
GPS performance enhancement
HotSpot 3G Idle Battery Issues
32GB SD Card Fix - previously when formatting the card, it wouldn't be recognized
Yes, I did test it indeed I was lucky as I have three and one updated to new baseline as soon as the baseline came out and one updated 48 hours later. the new baseline (Di07))does still have the sticking cache.

Also device team indicated to me that they were still testing cache problems after the di07 was first sent to out 10 days ago. (it was sent to test devices a week before)
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Old September 19th, 2010, 08:53 AM   #8 (permalink)
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ugggggggg - I have 3 Bars of service inside my house. GPS and Wireless Networks on - it couldn't find me. Tried Google Maps and Nav - and Sprint NAV!
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Old September 19th, 2010, 03:39 PM   #9 (permalink)
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Originally Posted by DILands View Post
ugggggggg - I have 3 Bars of service inside my house. GPS and Wireless Networks on - it couldn't find me. Tried Google Maps and Nav - and Sprint NAV!
I have a lot of wireless network location/tower triangualtion fail inside my house as well. I dont want to address that in depth in this thread because although it is related, samsung and sprint have confused people a lot with there bogus "fix" of turning on wireless network location which doesn't affect GPS. But GPS can affect wireless networking since a stuck GPS may not fall back as it should to tower triangulation causing your symptom.

but I will ask you what occurs in that situation if you turn GPS off, and restart Epic, and if you have applied this cold start workaround. also do you or a close neighbor have an airave?
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Old September 19th, 2010, 03:53 PM   #10 (permalink)
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Quote:
Originally Posted by Aero1 View Post
I have a lot of wireless network location/tower triangualtion fail inside my house as well. I dont want to address that in depth in this thread because although it is related, samsung and sprint have confused people a lot with there bogus "fix" of turning on wireless network location which doesn't affect GPS. But GPS can affect wireless networking since a stuck GPS may not fall back as it should to tower triangulation causing your symptom.

but I will ask you what occurs in that situation if you turn GPS off, and restart Epic, and if you have applied this cold start workaround. also do you or a close neighbor have an airave?
I haven't done it - because I don't know "where to" enter *#1472365#

I don't have airave - not sure about the neighbors - but - we're in single houses - hopefully, that wouldn't be an issue.
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Old September 19th, 2010, 04:22 PM   #11 (permalink)
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Quote:
Originally Posted by DILands View Post
I haven't done it - because I don't know "where to" enter *#1472365#
In the phone dialer.
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Old September 19th, 2010, 04:34 PM   #12 (permalink)
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DOH - I didn't see the * - thanks!
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Old September 19th, 2010, 04:46 PM   #13 (permalink)
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People keep saying to enter the text in the dialer because it works. Enter the sequence, including the star and number signs, exactly as you would a phone number. Follow the prompts and then hit the back softkey until you're back to home view. Incredibly simple. Aero1 deserves thanks for his research and help. I'm testing his GPS fix now.
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Old September 19th, 2010, 04:47 PM   #14 (permalink)
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Aero1, you are the man. My GPS problems weren't too bad until the D107 update (ironically enough), but your "cold start" fix has cured my GPS (at least in terms of achieving solid lock with satellites-only every time). Perfect lock, perfect nav, My Tracks accuracy seems much better (is this possible from your fix?). I tested your fix under some circumstances that would give my GPS fits before, so far all's well.
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Old September 19th, 2010, 05:04 PM   #15 (permalink)
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Also: users who are having a problem with their GPS after the fix should remember to switch to warm restart when 3 and 4G networks are off. I mention this because people seem to be speed-reading Aero1's OP and he's made the fix's limitation clear: it doesn't work with wifi-only enabled.
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Old September 19th, 2010, 05:28 PM   #16 (permalink)
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Unless there are naysayers - the mods should sticky this.
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Old September 19th, 2010, 06:01 PM   #17 (permalink)
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Quote:
Originally Posted by Flaspeneer View Post
Also: users who are having a problem with their GPS after the fix should remember to switch to warm restart when 3 and 4G networks are off. I mention this because people seem to be speed-reading Aero1's OP and he's made the fix's limitation clear: it doesn't work with wifi-only enabled.
What are the consequences of setting to "warm start" when on 3G/4G?
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Old September 19th, 2010, 07:00 PM   #18 (permalink)
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Originally Posted by DILands View Post
Unless there are naysayers - the mods should sticky this.
I have tested his fix all day - only had the phone a week - however today is the FIRST day that it locks on REAL gps satellites within 30 seconds, EVERY TIME.

I'd say that samsung owes him some money because he has single handedly fixed the gps problems for me.

Just FYI- I did not ever reboot the phone, I read this post early this morning and tried using it with my marine nav program at various times during the day, with the longest time of no activity at 6 hours.

So far so good. Gps was non-functional for me (because I dont reboot my phone) until today.
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Old September 19th, 2010, 07:51 PM   #19 (permalink)
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Quote:
Originally Posted by rsage View Post
What are the consequences of setting to "warm start" when on 3G/4G?
I found warm start inadequate in some cases in flushing all the bad assistance data out of the cache. It helps with some of the stickiness, but cold start dumps the cache totally as far as I can tell and triggers download of all new data. that download only takes less than a few seconds os there is now downside to setting it for cold start as long as you have either 2g, 3g, 4g (0r I presume, but have not tested, wifi).

So I cannot tell you exactly. You are welcome to test it further. REmember setting things back to normal is simple, jsut do the same steps. Default was hot, you can alos try warm, but I now cold works. I would prefer to spend any more time on aGPS/GPS in looking at the xtra data settings in the same debug menu. xtra is a specific implementation of assistance data.
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Old September 19th, 2010, 07:53 PM   #20 (permalink)
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note: user boomerbubba was extremely helpful in thinking this through
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Old September 19th, 2010, 08:05 PM   #21 (permalink)
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Moving to "Tips and Tricks"

Will post a link to this as a possible fix for GPS Locating problem, in the "Epic 4G Guide"

*Edit* Moved to "Support and Troubleshooting" better suited to this sub-forum.
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Old September 19th, 2010, 08:46 PM   #22 (permalink)
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So after applying Aero's fix is it ok to leave the check on "Use wireless networks"? Or does this not have any real bearing on efficiency of the GPS lock?
Thanks in advance.
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Old September 19th, 2010, 10:27 PM   #23 (permalink)
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Fix works, thanks so much!
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Old September 20th, 2010, 05:25 AM   #24 (permalink)
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Quote:
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So after applying Aero's fix is it ok to leave the check on "Use wireless networks"? Or does this not have any real bearing on efficiency of the GPS lock?
Thanks in advance.
Use wireless networks has no affect whatsoever on the function or lock or accuracy of either standalone GPS or aGPS.

"use wireless networks" is an alternate method of location. It can also send location data to applications that want or need location (called LBAs or Location based applications). Usually navigation apparitions require GPS/aGPS, but plain google maps, weather programs etc can use the estimates provided by Use wireless networks.

Essentially the differnce on what you shoudl use depends on your RF situation. In short if you are under a roof, use wireless location, and if you have good view of >35% of sky use GPS. . I was asking one person to turn it off to test soemthing t. There seems to be no harm in leaving both on. I haven't fully tested if the preferences and way it attmpts each, waits to see, tries the other is perfectly tuned. Even within eitehr mode the device should be occassional attempting more precise refinement. eg within GPS, more sats. Within use wirless networks stepping from tower location, tower plus signal strength, triangualtion, hybrid, and occasional looking for sats.
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Old September 20th, 2010, 09:07 AM   #25 (permalink)
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Has this been posted anywhere on XDA? Methinks this fix needs a lot of exposure. It would help a lot of people.
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Old September 24th, 2010, 07:13 PM   #26 (permalink)
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This thread is already sinking far below the first page and the consciousness of Epic users. It needs either to be stickied or bumped continuously. Mods?
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Old September 26th, 2010, 06:38 AM   #27 (permalink)
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Tried and tested multiple times on 2 epics and the fix does not work. It sees up to 11 sats but won't lock on, good snrs of 20 to 30. Restart on both machines usually did solve the issue.
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Old September 28th, 2010, 06:15 AM   #28 (permalink)
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Quote:
Originally Posted by Inspekt View Post
Tried and tested multiple times on 2 epics and the fix does not work. It sees up to 11 sats but won't lock on, good snrs of 20 to 30. Restart on both machines usually did solve the issue.
I just posted something similar in a different thread. done cold start fix still need to reboot or airplane mode to get GPS to work. also hate the 30m 98.4ft hard coded accuracy, would love a fix to that.
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Old September 28th, 2010, 12:28 PM   #29 (permalink)
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Quote:
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Tried and tested multiple times on 2 epics and the fix does not work. It sees up to 11 sats but won't lock on, good snrs of 20 to 30. Restart on both machines usually did solve the issue.
Sorry not credible.
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Old September 28th, 2010, 12:30 PM   #30 (permalink)
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cold start fix workign for 90% of users wh tried. Others maybe having other problems but workaround works fine for me.

I am over the next few days testing eclipsims "GPS Staus" 9/27 update for same effect. GPS Status now will attempt to discern gps assistance age, and may better force clearing and upload of cache. I am testing it on one device with warm start without using gps status, one with warm start with using gps status, and one set at cold start.
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Old September 29th, 2010, 10:52 AM   #31 (permalink)
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Sorry not credible.
how so?

im having lockon problems too, even after trying your fix. im getting 11 sats in view with a snr of 20-30 for them as well and having problems locking on too.

it will eventually lock on, but it takes forever. upwards of 10+ minutes in some cases


edit: something interesting. im at work and in this building after i applied your "fix" i was only seeing one satellite. i thought this was odd because my previous phone did better. after i went back to factor defaults all the sudden it sees 9 satellites and i haven't moved. and it actually locked on as well in here. its the first time its EVER done that. and google maps is showing me almost spot on in the exact corner of the building im in. its not conclusive more testing needs to be done. but it is certainly worth looking into.
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Old September 29th, 2010, 04:44 PM   #32 (permalink)
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Sorry not credible.
Sorry your response isn't credible. Why don't you post some rationale here? You yourself admit it works for 90% of users only. I guess me and the other guy posting here are the exception so we don't count?


Wireless networks off, applied the fix, restarted, and used gps test to check # sats, lock and snr. I've also tried in several locations in Philadelphia. I'm not sure what else I can do to enhance my credibility. Do you need a credit report and background check?

I tried the fix on both my phones, but the problem still persists. No doubt lock is improved, but this fix isn't the end all be all. My GPS works better, no doubt about that, but this didn't completely solve the issue.

Don't take it so personal when you ask for people to post findings and they don't confirm what you want to believe is right. kthx
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Old September 29th, 2010, 06:51 PM   #33 (permalink)
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Quote:
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Sorry your response isn't credible. Why don't you post some rationale here? You yourself admit it works for 90% of users only.
Because I find the peopel I have known for a long timw and who have a history credible.

Your misunderstanding of my statement that it works for 90%, shows a misapprehension on your part. The other 10% were not experiencing the problem due to habits.

If someone wants to claim it makes things worse, fine. It just means hey have zero understanding how aGPS on Epic works. It is highly dependent on having valid cache.

With cold start, provided you are in data service area with data on you will get a perfect cache in seconds.

You are in Phili. I am near there. It has been overcast. The fact is the other GPS problem on the Epic, which this workaround does not address, is low inherent signal to noise, in other words, observably poorer GPS reception on the Epic than other handsets.

I am experimenting with resetting the SNR rejection on Epic. There is an android string. ("minSnr;") but I am also testing timed cache flushing as well and don;t want to add to many variables as I only have three Epics.Again there are scores and scores of reports of behaviors that are totally consistent with bad ephemeris in cache persisting. Cold star fixes this particular problem -- in the presence of a netork connection.
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Old September 30th, 2010, 06:25 AM   #34 (permalink)
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I'm not going to argue semantics, but what you wrote implies the fix is imperfect and fails 10% of the time. You did not write it works 100% of the time and when it doesn't it is a result of user error or low snr's.

My point, which you did not address, is that overcast or not in Philly my SNR's were not affected and are constantly between 25-30 for most sats, which should be plenty for a lock. I have also had the phone get high snr, lock and used it to navigate several times on overcast days in the past. I don't understand why cloud cover would affect the lock despite high snr. I will agree that when it is raining or extremely heavy cloud cover I have seen my snr's decrease quite significantly.

I am on the network 3g and 4g, so that isn't the problem. I went outside several times last night and I could see 7 sats with 25-30 SNR and it didn't lock. Modru and stringyquark also confirmed this behavior.

Like I said before, it is definitely working better and often locks all sats immediately now, but this didn't solve every instance of the problem.
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Old September 30th, 2010, 10:05 AM   #35 (permalink)
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Quote:
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cold start fix workign for 90% of users wh tried. Others maybe having other problems but workaround works fine for me.

oh did you know 90% of statistics are made up?

sorry couldn't resist. you also said you only believe people you know or have "history credible" lol ya need to reverse that.

Quote:
Originally Posted by Aero1
Your misunderstanding of my statement that it works for 90%, shows a misapprehension on your part. The other 10% were not experiencing the problem due to habits.
here your saying that it works for 100%. because 10% don't have the problem and for the 90% that do, your fix works according to you.
again these are made up numbers. and secondly, in your previous post you said that works for 90% and that it didn't work for others (the remaining 10% im assuming)

your contradicting yourself.

you need to rein your ego in. seriously. your "fix" isn't the end all be all you act like it is.

someone questions your fix or posts different findings and you attack their knowledge of the subject matter trying to defend your fix and your hugely inflated ego.

fact of the matter is, there appears to be other underlying issues and bugs with the gps. the cache, may or may not be, one part of it. i personally don't have any issues with my cache running on the hot start setting.
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Old October 1st, 2010, 08:08 AM   #36 (permalink)
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Why is it that you can have GPS locks, as indicated by the GPS Test app, but when you set your phone to Airplane mode, it loses all the sats? Very frustrating.
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Old October 2nd, 2010, 08:44 PM   #37 (permalink)
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Quote:
Originally Posted by modru2004 View Post
fact of the matter is, there appears to be other underlying issues and bugs with the gps. the cache, may or may not be, one part of it. i personally don't have any issues with my cache running on the hot start setting.
All you have shown is your didn't read the original post and now are just ranting with anecdotes that you actually simply confirm what I have and the other testers have already said.

There are other GPS bugs. The testers and I have diagnosed and discussed them.

This fix is a 100% fix for the cache bug.

You don't even understand everything you are reporting is an unwitting confirmation of what we have known and said for weeks now.

Look at your post below, it shows a profound misunderstanding of location systerms and how they works on Epic (or any smartphone):
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Originally Posted by modru2004 View Post
after some thought, i realized you could be referring the the cell tower triangulation not working right. is that what you meant? if so, mine has not even been attempting to use the cell towers reguardless of settings. if im indoors and can't lock satellites, even with wireless location enabled, it will never do it. it hangs on the gps.
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Old October 2nd, 2010, 08:48 PM   #38 (permalink)
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Originally Posted by Epicurean View Post
Why is it that you can have GPS locks, as indicated by the GPS Test app, but when you set your phone to Airplane mode, it loses all the sats? Very frustrating.
We are looking at that. Two most likely of a few possibilities:
a) airplane mode may disable GPS per se.
b) Epic may have no Standalone GPS capability (function without network connection.)

edit: also possible is that Epic simply has very poor standalone capability
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Old October 4th, 2010, 04:25 PM   #39 (permalink)
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Six days using your recommended changes with no problems getting GPS now. Sprint told me Sept. 16 update fixed GPS and it did not. Your method does! Props.
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Old October 28th, 2010, 05:20 PM   #40 (permalink)
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Quote:
Originally Posted by Aero1 View Post
Note1: user boomerbubba was extremely helpful in thinking this through
Note2: Engadet finally posted a link to this workaround after three separate articles in which they completely botched testing of the Epics GPS and showed a total lack of knowledge of GPS systems. Thankfully their otherwise unfortunate readers of their poor "journalism" can at least now get a workaround as well.


I have three epics and have been testing GPS functionality for two weeks with quite a number of controlled tests.

As we know there is a problem with old "assistance" (the "a" in aGPS) ephemeris and almanac data in cache. this data can start expiring in a few hours and ephemeris will fully expire in about 8 hours.

The result is that sometimes users will experience the following symptoms in a GPS fail: the Epic will "see" sufficient satellites (4 to 11) but doesn't "use" them (expired ephemeris) or will see no satellites while under clear skies (expired almanac, rarer).

Although some user actions or program identified (eg reboot),and unidentified, can apparently flush the old data out of cache so that the network renews it with valid data, this isn't programmed by Samsung correctly and users intermittently are stuck with bad data in cache preventing lock. I have tested a workaround and it works

TESTED AND FUNCTIONING WORKAROUND:

Enter GPS debug/settings application by typing *#1472365#
click "Setup" tab
click "position mode"
Click "starting mode
Enable "Cold Start"
Back out.

Epic GPS will now call on data network for fresh valid ephemeris and almanac at every programing invocation of GPS and aGPS fixes will be very fast (usually less than 10 seconds).

There one downside. while cold start will be effectively warm start in aGPS mode (good). That is it will work very nicely in the presence of a 3G or 4g data connection. But absent data connection, ie in Standalone GPS mode, you will be always cold starting (starting with empty cache), meaning fixes will be 5 to 14 minutes if you are not on the network. If you are going to be off the network for a while you can simply set to warm start from same menu.
I enter that in the dialer but it just tries to make a phone call, does not enter any special mode.

What gives?
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Old October 30th, 2010, 04:02 PM   #41 (permalink)
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This is depressing that Samsung still can't do gps. I had a saga and the gps was also junk. Omnia was the same. Had to reboot often to get it to work. Had to stand still to catch birds. Had to be outside. Had to load ephemeris data via AT commands to get a lock in minutes vs ten minutes. Sad. An htc or moto phone will lock in seconds, even indoors.
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Old October 30th, 2010, 07:50 PM   #42 (permalink)
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I did the fix, My GPS is still on fail 1/2 the damned time.......it's really frustrating because right now nothing short of a G2 can touch this phone hardware wise but I use GPS and GPS related apps.......A LOT

I might have to downgrade to an Evo.
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Old October 31st, 2010, 05:47 PM   #43 (permalink)
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I can't get into the GPS setup with that dialer code. Nothing happens. I dial it, it tries to connect, then it disconnects as if it were a regular number.

Any ideas?
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Old October 31st, 2010, 05:51 PM   #44 (permalink)
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Well, I do have a Fascinate and someone directed me here...sorry, guys!
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Old November 1st, 2010, 09:42 AM   #45 (permalink)
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All Things GPS



read post 81 of this thread
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Old December 9th, 2010, 03:22 PM   #46 (permalink)
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Quote:
Originally Posted by boomerbubba View Post
In the phone dialer.

This doesnt work
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Old December 9th, 2010, 09:09 PM   #47 (permalink)
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Quote:
Originally Posted by MikeyLee View Post
This doesnt work
Are you on the 2.2 leak? No, it doesn't work on that version any more.
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Old December 10th, 2010, 10:42 AM   #48 (permalink)
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I have what was supposed to be the Official release so yes I guess I'm screwed unless there is another fix but thus far I've found nothing
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Old December 11th, 2010, 10:33 AM   #49 (permalink)
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Default GPS errors on 2.2

I see from this forum that the dialer code *#1472365# doesn't work anymore on Android 2.2.1 Froyo (DK28) and I can confirm that it's not working on my DK28.

My GPS was working great until I went to 2.2. Everything on 2.2 works great and the battery life seems better, but ZERO GPS.

I'm using GPS Status & Toolbox to flush the cache and download aGPS, but still no lock and no report of any satellites. (. . . Is there somewhere else to look on the phone for # of satellites? . . . Found it. GPS Test by Chartcross is what others recommend and I have tried it now, but of course I see ZERO satellites due to 2.2. . . .)

Anyone have any suggestions on how to get into the GPS debug/settings application on 2.2? Is there a different code to apply the fix listed at the beginning of this forum?
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Old December 12th, 2010, 03:10 PM   #50 (permalink)
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Ditto pvanwagner, the code doesn't work on my 2.2.1 either and neither does my GPS any longer (no problem before the update). Of course, that's on me for installing what we all now know to not be the real update, but still, kinda sucks

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