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regulus is offline regulus
2013-03-24 , 14:55
Posts: 131 | Thanked: 42 times | Joined on Apr 2012 @ Europe
#1
I've noticed that my N900 can take quite a while to get hold of GPS satellites (especially has problems indoors). On the other hand, newer devices (e.g. iPhone, Samsung Galaxy Note etc.) immediately, sometimes within seconds, report a very accurate location, at the same position as N900.
Is this simply a matter of better receivers built in these new devices, or are they using some sort of other enhancements to make the process quicker?
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sixwheeledbeast is offline sixwheeledbeast
2013-03-24 , 15:01
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#2
http://wiki.maemo.org/N900_The_Perfe...rk_Positioning

If you use GPS without assistance (supl server) it can take up to 10 minutes to get a fix.
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krutznikov is offline krutznikov
2013-03-24 , 15:32
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#3
For sure new 3G chipsets are more efficient (look at the old GPS devices, it's the same), but I think devices are also retrieving satellites positions throw 3G (and nokia servers doesn't seems to work...)
 

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regulus is offline regulus
2013-03-24 , 15:34
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#4
That was probably it. I changed supl from Nokia to Google and it works almost instantly now. Next time I'll try somewhere without wifi/3g coverage.
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pichlo is offline pichlo
2013-03-24 , 21:56
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#5
My N900 can take up to 20 minutes without WiFi assistance. That's more than enough for Nokia Maps to time out. I've found some thread on some Nokia forum about this, they reluctantly agreed to increase the timeout to 10 minutes ("10 minutes ought to be enough for everybody!"), even though there were people even then telling them that no, 10 minutes is not enough. Fortunately Modrana is not so fussy and waits as long as it needs to.
 

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Wikiwide is offline Wikiwide
2013-03-25 , 01:40
Posts: 2,000 | Thanked: 3,345 times | Joined on Jun 2010 @ N900: Battery low. N950: torx 4 re-used once and fine; SIM port torn apart
#6
Quick reply...
Theoretically, as long as you have no other source of information (Wi-Fi or cellular Internet), the GPS satellite can take about fifteen minutes to load the almanac information about other satellites. That's the primary bottleneck: weak and slow satellite signal. I wonder if it is possible to store all the satellites' information on N900, instead, so that the device would still have to catch the signal and identify the satellite, but downloading the data would no longer be necessary.
Now, tell me why it was not done before. Tell me why storing information about GPS satellites' orbits on the device is a stupid idea. I know, it would need updates when old satellites crash, and new satellites are launched. Besides that, what are other obstacles?
[Edit]Is there any way to set up an A-GPS server on Nokia's Linux-phone-computer itself?[/Edit]
Best wishes.
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Last edited by Wikiwide; 2013-03-25 at 04:28.
 

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cheve is offline cheve
2013-03-25 , 03:00
Posts: 362 | Thanked: 143 times | Joined on Mar 2008
#7
Originally Posted by regulus View Post
I've noticed that my N900 can take quite a while to get hold of GPS satellites (especially has problems indoors). On the other hand, newer devices (e.g. iPhone, Samsung Galaxy Note etc.) immediately, sometimes within seconds, report a very accurate location, at the same position as N900.
Is this simply a matter of better receivers built in these new devices, or are they using some sort of other enhancements to make the process quicker?
I don't know what other devices do. However, if you want to improve the performance on N900, you may want to install the GPSJinni. I would start this application 1st and it seems to allow the GPS on N900 to have a good lock in about 2 minutes or so outdoor. Once the GPSjinni get a lock on then I start map -- This is done without wifi or gsm network connections. YMMV,

btw, I now run an external blue tooth reciever, so my locks are less than 15 sec.

Cheers
Last edited by cheve; 2013-03-25 at 03:06.
 

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juiceme is offline juiceme
2013-03-25 , 05:50
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#8
Originally Posted by Wikiwide View Post
Now, tell me why it was not done before. Tell me why storing information about GPS satellites' orbits on the device is a stupid idea. I know, it would need updates when old satellites crash, and new satellites are launched. Besides that, what are other obstacles?
Well unfortunately it is not that simple. The positional deltas are not something you have to update just when satellites are crashing

The satellite orbits are constantly changing due to small gravitational influences and relativistic drag, and more so, the delta of each satellite has no simple relationship to any of the other satellites. Hence, the positional correction tables have to be constantly updated...

Originally Posted by Wikiwide View Post
[Edit]Is there any way to set up an A-GPS server on Nokia's Linux-phone-computer itself?[/Edit]
I am sorry that would not really help with it, as the server does need to get the table information from somewhere...
 

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reinob is offline reinob
2013-03-25 , 08:08
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#9
Originally Posted by Wikiwide View Post
Now, tell me why it was not done before. Tell me why storing information about GPS satellites' orbits on the device is a stupid idea. I know, it would need updates when old satellites crash, and new satellites are launched. Besides that, what are other obstacles?
That's something that Tomtom did. I think it was called "quickgpsfix", and you had to download it once a week.

I don't know though how hard it would be to integrate that into Maemo.
 

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Wikiwide is offline Wikiwide
2013-03-25 , 10:30
Posts: 2,000 | Thanked: 3,345 times | Joined on Jun 2010 @ N900: Battery low. N950: torx 4 re-used once and fine; SIM port torn apart
#10
Originally Posted by reinob View Post
That's something that Tomtom did. I think it was called "quickgpsfix", and you had to download it once a week.

I don't know though how hard it would be to integrate that into Maemo.
Quick reply...
So, current ephemeris and almanac can be found, for instance, at:
http://www.wwu.edu/huxley/spatial/GPS/ephemeris.htm
I don't know whether there are any license restrictions on the usage, though.
The easiest way to integrate it into Maemo would be to set up an A-GPS server on localhost, instead of using Nokia's or Google's one.
And updating orbital data once a week would not be a problem; I check for updates, with aptitude, more often than that. It's not like I would go into wilderness without Internet for any long time; a place without Internet is also likely to lack electricity to charge the device.
Best wishes.
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Last edited by Wikiwide; 2013-03-25 at 10:32. Reason: misprint
 

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