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GPS is stuck with a set of satellites - how to remove them from memory?
I seem to know why SOMETIMES it takes forever
to get a satellite lock with GPS. (I learn that many users experience this problem, including those on Bell, and including those with NSFSAN's ROM 1.10, like me). After you get a successful lock, a few satellite numbers (like those 4,2,9,12,22 etc, that you see in GPSViewer) are stored somewhere on the phone. Next, when after some time (overnight, let's say), you try to get another lock, the OLD satellites moved, they are not available anymore, but the phone tries to use them anyway, WITHOUT UPDATING... (my highly subjective perception after some observations is that if there's is one-two OLD satellites still avaialble, it may be still OK for the phone to find the new ones, but if NONE of the old satellites are available, the phone is stuck, and may sit forever looking for them.. what helps is a SOFT-RESET (which clears some memory, I suppose) - after that - ther's a A FAST (10ns) LOCK, with NEW SET OF SATELLITES (e.g .13. 15. 3. 7 etc ).. so my question is WHERE those satellite are stored, and how to clean them without doing a soft-reset? ("HTC GPS Tool" that has some "clear-memory" button does not seems to help, maybe because it is for another phone model?) EXPERTS, PLEAAASE! |
Re: GPS - how to remove satellites from phone's memory?
That doesn't make sense. GPS satellites don't move. They are geo-synchronous.
YOU move however. If you move a certain distance, GPS's have to go through a search process again. It's taken 20 minutes before with my Garmin handheld GPS to get a lock after traveling a couple thousand miles. |
Re: GPS - how to remove satellites from phone's memory?
Your wrong, GPS sats are in MEO (medium earth orbit). They Move and You move. Stop talking out of your @$$.
OP is correct, the chip does recall sats based on recently downloaded stattelite location information or Almanac. Thats why right after you get a lock its easier to get another one right after. But if you move, or they move, it still thinks the sats are their. That is also why HTC quick GPS data expires after a while. Now as to how to fix it, I have no IDEA |
Re: GPS - how to remove satellites from phone's memory?
The sats are not geo-synchronous. That is why they need to have location data (ephemeris) uploaded every 4 hours.
"Each satellite in the GPS constellation orbits at an altitude of about 20,000 km from the ground, and has an orbital speed of about 14,000 km/hour (the orbital period is roughly 12 hours - contrary to popular belief, GPS satellites are not in geosynchronous or geostationary orbits). The satellite orbits are distributed so that at least 4 satellites are always visible from any point on the Earth at any given instant (with up to 12 visible at one time)." http://www.astronomy.ohio-state.edu/...Unit5/gps.html |
Re: GPS - how to remove satellites from phone's memory?
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and.. for old man Galileo and for old man Einstein it is all the same anyway.. I suppose, for the GPS chip too .. ;) |
Re: GPS - how to remove satellites from phone's memory?
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and then from the old positions, it ( either the software or GPS chip itself?) tries to predict the new positions, somehow, I suppose? based on time difference? (because it cannot account for your movement).. Also I wonder if some info from the internet / third parties is used here (like that AssistedGPS etc?) And then, the problem is - why some ROM`s / some carriers' phones are able to update the sat positions correctly, and also use new sats if available, while SOME others (like Bell phones) are stuck with old useless sats/positions, and never search for the new ones before soft-reset.. hmmmm.. I've also seen around here written that there's a dedicated GPS area in memory, somewhere in the "radio" section? but the "radio" must be ROM, is not it? and this are must bes flashed often while GPS works... or only when it stops working? or GPS chip has some RAM/ROM itself? |
Re: GPS - how to remove satellites from phone's memory?
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hmmm... didn't you say in another thread that you were getting 10sec locks (cold fix)? Anyway, have you tried turning off the EnableGPSSmartMode in the SUPL AGPS registry? here is link to the post I'm looking at: http://forum.ppcgeeks.com/showpost.p...09&postcount=8 |
Re: GPS - how to remove satellites from phone's memory?
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thank you for the link, I'm reading right now something about AGPS, and I see that your link is something about AGPS too.. BTW, here are my AGPS settings, [HKEY_LOCAL_MACHINE\Software\HTC\SUPL AGPS] "EnableAGPS"=dword:00000001 "EnableGPSSmartMode"=dword:00000001 "GPSMode"=dword:00000002 "NumberFixes"=dword:3b9ac9ff "QoSAccuracy"=dword:00000032 "QosPerformance"=dword:00000059 "ServerIP"="195.207.101.126" "ServerPort"=dword:00001e6c "TimeBetweenFixes"=dword:00000001 _________________________ I wonder if all this is of any help for BEll users, for example, how a server located somewhere in Belgium can know about Bell.ca cell towers? also also I wonder if anyone could share their AGPS settings to compare? |
Re: GPS - how to remove satellites from phone's memory?
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(I'll allow myself to quote it here too): Quote:
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Re: GPS - how to remove satellites from phone's memory?
Didn't read through the whole post...but all you need to do is download nadavi gps tool and theres an option to clear the gps chip of previous locks/locations.
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Re: GPS - how to remove satellites from phone's memory?
So then, an possible explanation of
the phone being stuck sometimes is the following: because it tries to update GPS sat positions using AGPS from an invalid server (which does not know/not allowed to share the data about Bell towers), and somehow it never arrives to the idea to search for the new satellites? |
Re: GPS - how to remove satellites from phone's memory?
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so I disabled it, soft-reset,, tested GPS, then enabled it, soft reset again, tested GPS, etc... a few times I got a lock within a minute.. once did not get a lock within few minutes, then GPS froze.. so there seems to be NO difference, and it looks like the phone DOES NOT download ephemeris data from that Belgium server and it DOES NOT help to Bell users ???? |
Re: GPS - how to remove satellites from phone's memory?
I guess you are lucky in that mine is stuck most of the time! HA HA.
My AGPS settings are basically the same except my GPSMode is at 4. Anyway, here are my random observations (please bear with me). 1. If I get a fix of about 4 sats, if I turn the GPS unit off (ie. quit all gps apps and put the phone to sleep), after about an hour or two, the time to fix is the same as my cold fix times (1-1.5 minutes). 2. I've been using the latest sprint radio (3.42.xx) for a few weeks now. Ever since then, when I go into Google Maps and select Use GPS, the blue dot puts me in the middle of nowhere. When I say nowhere, I mean a map doesn't even display. all I get is a blue dot on a background of row upon row of magnifying glasses with a minus sign in them. No amount of zooming in or out helps. Then yesterday, I downgraded to the Alltel radio (3.37.10) and tried google maps again. Upon selecting the Use GPS, 10 seconds later, it put me about 4 km from my actual position. Just tried it now and it put me about 1 km from actual position here at work. So my phone, with this radio, is finding my general location. That said, time to fix is still about 1-1.5 minutes. 3. In QPST, I've tried adding the PDE server that was recently discovered from the Telus ROM. On average, my cold fix times haven't changed much. I don't know if Bell users are authorized to use that PDE server or not, but it's not making any difference for me. Personally, I think the GPS units on Bell phones are falling back to Autonomous mode because the AGPS and PDE servers (from other providers) are not providing the correct information (if at all). I think that if we can figure out the Bell PDE and AGPS servers then we can expect some pretty quick cold fix times. BTW, when I did some searching for bell PDE servers, I came across a blackberry forum with Bell users with blackberrys with the same exact problem.... long cold fix times. |
Re: GPS - how to remove satellites from phone's memory?
Thank you for the info, ckl_88!
> My AGPS settings are basically the same except my GPSMode is at 4. afaik, it not only tries tro GET the ephemeris data, but also to send them to server, and to fine-tune? which should make no dofference if the server is not replying anyway... > 1. If I get a fix of about 4 sats, if I turn the GPS unit off (ie. quit all gps > apps and put the phone to sleep), after about an hour or two, the time > to fix is the same as my cold fix times (1-1.5 minutes). an hour is enough to lose a satellite.. makes sense? (their period is about 12 hours?) > 2. I've been using the latest sprint radio (3.42.xx) for a few weeks now. > Ever since then, when I go into Google Maps and select Use GPS, the > blue dot puts me in the middle of nowhere. When I say nowhere, I mean > a map doesn't even display. coordinates 0.0 0.0 ... Atlantic ocean somewhere near Africa? > Then yesterday, I downgraded to the Alltel radio (3.37.10) and tried > google maps again. Upon selecting the Use GPS, 10 seconds later, it put > me about 4 km from my actual position. Just tried it now and it put me > about 1 km from actual position here at work. So my phone, with this > radio, is finding my general location. That said, time to fix is still about > 1-1.5 minutes. might it be a coincidence? what's the relation between Google Maps and Radio? otherwise from your description it seems that AGPS works with this radio (though you just said it should not work with Bell phones)? > 3. In QPST, btw, do not you know where to get this QPST? > Personally, I think the GPS units on Bell phones are falling back to > Autonomous mode because the AGPS and PDE servers (from other > providers) are not providing the correct information (if at all). so far it is compatible with my obsrervations... > I think that if we can figure out the Bell PDE and AGPS servers then we > can expect some pretty quick cold fix times. would be very cool! |
Re: GPS - how to remove satellites from phone's memory?
> Honestly I'm bit confused what's the relation between GPSmode # and
> EnableGPSSmartMode .. are not these setting redundant? I have no idea. > an hour is enough to lose a satellite.. makes sense? (their period is > about 12 hours?) This is just my observation. I have a feeling it may have something to do with the registry key TimeBetweenFixes which is at 1. Not sure what this key actually does, but my guess is that the value specified (whether in hours or days or whatever) is the expiry time for the downloaded data. In other words, the time elapsed in which the GPS will need to reacquire satellite information. DISCLAIMER: This is just my guess so I could be way off base. > coordinates 0.0 0.0 ... Atlantic ocean somewhere near Africa? If it was somewhere near there, I would expect a map with blue (to indicated water) and if I zoomed out far enough, probably see the coast of Africa. However, no amount of zooming out will give me any indication of where I am. Just magnifying glasses with a minus sign in them no matter what I do. > might it be a coincidence? what's the relation between Google Maps and > Radio? otherwise from your description it seems that AGPS works with > this radio (though you just said it should not work with Bell phones)? Yeah, that one got me confused. As a test, I removed the server IP and port in the SUPL AGPS and soft-reset. So now no AGPS is used right? Then I started google maps, searched for my home address which is about 30km away from where I am (at work), selected Use GPS and guess what happened next? IT FOUND MY APPROX. POSITION!!! 1 km away from my work place! I looked at the blue status message on the top right and it said Seeking GPS Satellites (0).... So I've removed the AGPS server, and yet it still found my approx. location. > btw, do not you know where to get this QPST? QPST is a commercial app and considered warez and risk possible banning if I say anything more about it so I'll leave it at that. > so far it is compatible with my obsrervations... Personally, if my GPS takes more than a minute to get a fix (cold) then AGPS is not working. It should be in the range of 20-30 seconds which is what my N95 can do when I upgraded it's firmware to support AGPS. |
Re: GPS - how to remove satellites from phone's memory?
> This is just my observation. I have a feeling it may have something to do > with the registry key TimeBetweenFixes which is at 1. Not sure what this > key actually does, but my guess is that the value specified (whether in
> hours or days or whatever) is the expiry time for the downloaded data. In > other words, the time elapsed in which the GPS will need to reacquire > satellite information. looks plausible >> coordinates 0.0 0.0 ... Atlantic ocean somewhere near Africa? > If it was somewhere near there, I would expect a map with blue (to > indicated water) and if I zoomed out far enough, probably see the coast > of Africa. However, no amount of zooming out will give me any indication > Yeah, that one got me confused. As a test, I removed the server IP and > port in the SUPL AGPS and soft-reset. So now no AGPS is used right? > Then I started google maps, searched for my home address which is > about 30km away from where I am (at work), selected Use GPS and > guess what happened next? IT FOUND MY APPROX. POSITION!!! 1 km > away from my work place! I looked at the blue status message on the top > right and it said Seeking GPS Satellites (0).... So I've removed the AGPS > server, and yet it still found my approx. location. curious! :) my guess is that GoogleMaps is able to retrieve the STORED "last known" location from the GPS chips or wherever, and then it is trying to center you around this location... from your story it looks like with the OLDER radio GoogleMaps retrieves this location correctly (or it is simply stored correctly), while with the newer radio GoogleMaps and radio could not agree on that... if Google maps gets some garbage as "last known location" from the new radio, and then tries to center you around it, then it explains those confusing screens you get< does not it? Maybe I should flash the older radio too.. Have you had the older radio from the Alltel rom (as per Tutorial?) did you install it over the newer one without problems? > QPST is a commercial app and considered warez and risk possible banning > if I say anything more about it so I'll leave it at that. thnx I had no idea what is it, that's why asked.. I'll not bother about it then until I see that it is really needed |
Re: GPS - how to remove satellites from phone's memory?
> coordinates 0.0 0.0 ... Atlantic ocean somewhere near Africa?
> If it was somewhere near there, I would expect a map with blue (to > indicated water) and if I zoomed out far enough, probably see the coast > of Africa. However, no amount of zooming out will give me any indication > of where I am. Just magnifying glasses with a minus sign in them no > matter what I do. Hey ckl_88, I just tried to experiment with GoogleMaps it does put you in the (0.0, 0,0) - Guinea Bay - position even with the new radio (I have the one 3.42.30 or something).. in order to see it, you shoud enable internet, so that GoogleMaps can download, and also I switched on Satellite View instead of just MAP.. so it seems that there's no difference betweedn new and old radio wrt this... P.S. if it is not too difficult, will you please try a test of Google Maps with the old radio, in your spare time - right after SOFT-resetting phone, and resetting google maps (menu, options, reset), and when sats are NOT available, but internet IS - to osee if it still puts you in the middle of the ocean - (thsi way I think the last known location will be cleared even wi the older radio).. thnx a lot in advance, I'd like to se if it is indeed useful to downgrade the radio! |
Re: GPS - how to remove satellites from phone's memory?
You're right, of course. I was thinking of the WAAS satellites.
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Re: GPS - how to remove satellites from phone's memory?
useful info for those interested:
Almanac and Ephemeris Data as used by GPS receivers (4 July 1998) The satellites broadcast two types of data, Almanac and Ephemeris. Almanac data is course orbital parameters for all SVs. Each SV broadcasts Almanac data for ALL SVs. This Almanac data is not very precise and is considered valid for up to several months. Ephemeris data by comparison is very precise orbital and clock correction for each SV and is necessary for precise positioning. EACH SV broadcasts ONLY its own Ephemeris data. This data is only considered valid for about 30 minutes. The Ephemeris data is broadcast by each SV every 30 seconds. When the GPS is initially turned on after being off for more than 30 minutes, it "looks" for SVs based on where it is based on the almanac and current time. With this information, appropriate SVs can be selected for initial search. When the GPS receiver initially locks onto a SV, the Garmin display then shows "hollow" signal strength bars. At this time, the Ephemeris data has yet to be completely collected. Once the ephemeris data is collected from EACH SV in turn, the associated signal strength bar will turn "solid" black and then the data from that SV is considered valid for navigation. If power is cycled on a GPS unit, and when turned back on, the Ephemeris data is less than 30 minutes old, lock-on will be very quick since the GPS does not have to collect new Ephemeris data. This is called a "warm" start. If it is later than 30 minutes, this is considered a "cold" start and all Ephemeris data will have to be recollected. If the GPS has moved more than a few hundred miles or accurate time is lost, the Almanac data will be invalid and if you are far enough off, none of the SVs that the Almanac thinks should be overhead will be there. In such case, the GPS will have to "sky search" or be reinitialized so it can download a new Almanac and start over. (Note: Yes! We know this is somewhat simplified information. Yes, we know that the Ephemeris data may not have to be updated as often as the G-12XL does it to get data to the G-12XL accuracy.) Joe Mehaffey ================================================== ============== http://gpsinformation.net/main/almanac.txt |
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Oh, the other thing is with the old radio (the one I'm using now) it puts me close to my workplace whereas the new radio would put me who knows where. Okay, so soft reset - done. Internet On - Yep. Reset Google Maps - done. Quits the program automatically. Restart Google Maps. Accept agreement - map of San Fran is displayed. Clicked Use GPS. Blue status of Seeking GPS Sats (0) is displayed. wait... here it comes... YES! puts me about 1km away from where I am (at work). NOT in the middle of the ocean. So there is a difference between the old and new radio. With the old, it's close to your actual position. With the new, it puts you in the ocean. But even so, it still takes > 1 minute to get a lock because we don't have any kind of assistance server from Bell to get the ephemeris data to speed up lock times. EDIT> Strange. While I got the blue dot that's close to my work place, I walked over to the other side of my office, and the blue dot moved to a different location. Now it's about 4km from my actual position.... a different cell tower perhaps. |
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I just tried to experiment too with the google maps , in the same way again (GPS screened, internet /wireless available) and ... o, surprise, now it locates me too - not precisely, GPS satellites (0), but roughly, to the nearest cell tower (top of a high-rise bulding about 3 km away from my home). and I.m using the NEW 2.32.40 radio !! This time I did reset google maps to show me San Francisko first, but I did NOT soft-reset the phone (an it had many fast locks today ) however, after I do soft-reset the phone, it puts me again in the Guinea Bay :) So I guess it is: - AGPS ("Location service") at work??? (maybe not in the part of that Belgian server, though.. but it has to use SOME AGPS server.. this means that Bell does HAVE one.. hmmm.. how to find out the IP.. the trouble is that the phone probably does not communicate with it directly, otherwise one could try to use netstat to figure out which one .. or it does?) - AGPS needs a good guess of the last-known position (which is (0.0,0.0) after a soft-reset - at least in the NEW radio - that is why Guinea Bay shows) |
Re: GPS - how to remove satellites from phone's memory?
BTW, a G. , a friend of mine, did bring me that QPST, but I`m stumbled
upon a stupid thing - - how to connect the phone? via USB cable activesync? QPST does not see it, but wants some serial connection instead.. any help much appreciated.. |
Re: GPS - how to remove satellites from phone's memory?
wasnt the HTC GPS Tool, have a Clear Memory option, that i heard people run when they goto a new Location or just want to clear satelittes from gps chip so can get faster locks when sat data old/new location.
doesnt help me though. Verizon GPS sucks. sometimes works. sometimes takes forever if i leave the phone by the window. never works when i want it to downtown hehe. heard running EPST helps other non vz peeps |
Re: GPS - how to remove satellites from phone's memory?
I have this same issue, usually it will work perfect for a day (after a fresh install/hard reset) then the next day i have issues ALLLLLLLLLLLLLLLLLLLLL day, its super annoying. I dont have this issue with my external gps... Im gonna try some stuff i read in here and see if it helps...
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Re: GPS - how to remove satellites from phone's memory?
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Thanks. |
Re: GPS - how to remove satellites from phone's memory?
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I sent you a PM. |
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but you know ... this little behavior of Google Maps locking you at the nearest cell tower when sats are not available (yet) may not be directly related to GPS. I guess even a phone withOUT GPS can detemine what cell tower is closest, cannot it? the apparently related to GPS part of this is that if the last known GPS location is = to ZERO (as after soft-reset with NEW radio), the Google maps gets confused, and does not even try the cell towers.. |
Re: GPS - how to remove satellites from phone's memory?
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Re: GPS - how to remove satellites from phone's memory?
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than in the middle of the ocean off the coast of africa LOL! Even so, sometimes I need to use Google Maps and get an approx location of my position right away because I don't time to wait 1-1.5 minutes for the GPS to get a real lock. Especially indoors when a real lock may take about 10 minutes. That's what I'm after. Having it pinpoint me in the middle of the ocean doesn't really help much. |
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Re: GPS is stuck with a set of satellites - how to remove them from memory?
I have another example of weird behavior of my phone, when it is stuck
forever and never gets a lock.. maybe someone knowledgeable may tell me what's this about? For a few hours I had fast locks with 5 satellites - 3, 7, 25, 27, 28 (seen in GPSview) then, while I was moving 15 km away on the way, (it does not matter, I may have just powered it off and then on) it loses the lock, and the new set of satellites shows up 6,8,11,19,26, all in the range of 20-30 dB signal strength, but NEVER gets a lock, no soft power on heaven and earth can make it lock, I tried HTC GPS Tool, switch on and off Location setting, switch on and off AGPS in registry, etc etc.. What's funny, while it is stuck on those satellites, sometimes, almost instantaneously , another 4 show up, 28,27, 7,25, they blink, and disappear... Soft reset helps, though.. it Cold Locks with 1,2,5,9,12,28,30 in a minute or two.. any ideas? Anyone else experiences this, probably with different ROM? |
Re: GPS is stuck with a set of satellites - how to remove them from memory?
TimeBetweenFixes key has nothing to do with Sat data storage. It's the amount of time (in seconds) that the chip updates your location. If you change it to 2, or 5, and use Garmin or GoogleMaps and drive around, you'll see that it updates less often. Saves battery, but makes it very laggy.
That's what it's supposed to do anyways. |
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I suppose. Google maps is often way off with location though. Sometimes almost 10km off for some people. I've had it go maybe 4 or 5km away from where I'm at, which in the search for a close restaurant, could make a big difference! The best thing to do in that case is to ask some locals! :P But yeah I see what you're saying, I just wanted to be an ***. lol -P |
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Re: GPS is stuck with a set of satellites - how to remove them from memory?
I've found that any setting I do in SURL AGPS has no effect on GPS performance.
After closing the GPS, one can see in the Debug screen that the GPS sats are not getting cleared... Seems like something that should be done when the GPS is closed. Also, it seems the GPS receiver is ignoring Cold/Warm/Hot start commands in GPS viewer as well. (I'm using 3.02 OMJ) |
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WAAS, Wide Area Augmentation System is NOT a server developed by garmin. It's owned by the US Govt, DOT and FAA for precision flight approaches. Its designed to correct signal errors and it uses ground stations AND satellites. http://www8.garmin.com/aboutGPS/waas.html |
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http://forum.ppcgeeks.com/showthread.php?t=33156 "-Under HKLM/Software/HTC/SUPL AGPS added dword key "EnablePDEIPFromNV " and value of 1 " I'm not sure what does it do... |
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