My Experiences with International GPS

[mrcrumbsnatcher]

I'm curious of others experiences with using the gps droid x overseas (specifically non cdma networks). currently i am in barcelona. before i left for my trip, i set up many offline maps using maverick pro and atlas creator. for those of you who don't know, barcelona is 100% gsm network.... no cdma at all. my original thought was that i could take my phone, turn on gps and everything would be okay (since it's supposed to have "true" gps). that turns out not the case.

for the first day, i could not get a lock to any gps satellite with maverick pro. only after fiddling around with some stuff was i able to make gps work. i downloaded an app called gpstest. turned it on, no locks on satellites. turned on wifi put the droid x near the window of the hotel room and all of the sudden gps test found a bunch of satellites. Turned on maverick pro and it found my location. Hmm.... I guess there needs to be an initial lock via wifi or cdma (if you are in a country like japan).

once i got this initial lock, maverick pro and gps test worked like a charm. heck, i could even turn my phone off and then back on and both apps still worked great. once i swapped my battery, only then i lost my satellite locks. i can walk around the city all day and open and close both apps numerous times, and i can still find satellite locks. again, if i swap my battery, that is when i lose my gps capabilities. i have to connect to wifi again, and then run gps test to find a lock and then disconnect from wifi. luckily in barcelona, there are enough free public wifi networks.

i guess i have muliple questions. first off why do i have to get an initial lock for gps to work? do you think this is a mis-representation of being able to call your product of having gps (more like assisted gps)? why do i keep my gps connection when i restart my phone, but lose it when i swap out the battery?

thanks.

 

[RETG]

I'll take a guess on some of this. I know GPS, but I am not familiar with this phone or using it overseas.

Sounds like when in CDMA they are using eGPS and require the cell tower to supply the almanac information for satellite locations. Once locked on, the ephemeris data is downloaded from each sat to the phone. (Almanac info is sent out by all sats and is the general location of all the sats. Ephemeris is particular to a sat and is sent only from that sat, and is more exact information for that sat.)

When it wifi, evidently the phone knows there is no CDMA to connect to, so it allows the almanac info to be downloaded from the sats.

It also appears that turning it off/on is not a problem since the battery is supplying power to the GPS chip.

However, when the battery is removed, the memory is wiped out. Evidently, the GPS chip has volatile memory and is erased when power is removed.

Again, I'm only guessing, but is sure sounds correct.:icon_ banana:

 

[mrcrumbsnatcher]

Thanks for the info. What you are saying is makes some sense to me for someone who has no technical gps knowledge.


Just an FYI for using the Droid X gps overseas:


Going to a CDMA country
1. Make sure your data connection is on (I am not referring to WiFi). Make sure you droid x is not in airplane mode to get the initial satellite lock. (you should not be charged any type of international charge... just don't answer your phone if it's ringing).
2. Open up gps test (free from the app market) and/or your offline gps navigation app.
3. Generally it takes about 30 seconds for GPS test to find the satellites, but sometimes it has taken me up to a couple of minutes.
4. Once you get the lock, you should be able to turn your phone into airplane mode.

Going to GSM country
-- Pretty much the same steps as above but you need to have a WiFi connection established. You also have to make sure that your data connection is on as well even though your chipset is CDMA and does not work in GSM (don't ask me why, but that has been my experience).