GPS switched off, but location still avaliable!

**yungwunn911** · 06-10-2010, 09:47 AM

I have my GPS switched off, but when playing with google town, my location was still found...

**qu1nn** · 06-10-2010, 09:48 AM

I noticed this too. I had the GPS off, and my weather location changed at work....
I assumed it had something to do with the 3g towers?

anyone?

qu1nn

**opg4759** · 06-10-2010, 09:51 AM

when you turn GPS off you are turning off the GPS receiver. You are not however turning off aGPS which does running off the towers for e911. aGPS is a federal mandate to help route mobile 911 calls to the correct 911 dispatch offices.

**yungwunn911** · 06-10-2010, 10:24 AM

So, what's the point of GPS reciever? More fine tune?

**cjpearson** · 06-10-2010, 10:31 AM

yes, the aGPS is only accurate withing 2500 meters (i.e. general area) so when you dial 911 in Dallas, you get a Dallas 911 Operator.

The GPS receiver is accurate within a couple of meters if i'm not mistaken.

**Caitlyn McKenzie** · 06-10-2010, 10:32 AM

Originally Posted by opg4759

when you turn GPS off you are turning off the GPS receiver. You are not however turning off aGPS which does running off the towers for e911. aGPS is a federal mandate to help route mobile 911 calls to the correct 911 dispatch offices.

Not technically correct.

When you turn off GPS, you disable the GPS receiver, yes. But this is used with aGPS. aGPS is a combination of both your GPS receiver, a lot of math and extra processing on Sprint's side, and the mentioned cellular towers.

Note that even if you turn off GPS receiver, it will turn on during an emergency call, by the way.

Anyway, for the OP, you want to go into settings > location > "Use wireless networks" and turn that off, if you want to disable location entirely. (Again, it will still turn on for purposes of 911)

**bobodobo** · 06-10-2010, 10:43 AM

Originally Posted by yungwunn911

So, what's the point of GPS reciever? More fine tune?

With the GPS receiver you can determine your position (e.g., for geotagging pictures) even where you have no cell coverage. Of course, maps and other services that require downloads through your data connection won't work if you have no coverage.

**opg4759** · 06-10-2010, 12:28 PM

Originally Posted by Vincent Law

Not technically correct.

When you turn off GPS, you disable the GPS receiver, yes. But this is used with aGPS. aGPS is a combination of both your GPS receiver, a lot of math and extra processing on Sprint's side, and the mentioned cellular towers.

Note that even if you turn off GPS receiver, it will turn on during an emergency call, by the way.

Anyway, for the OP, you want to go into settings > location > "Use wireless networks" and turn that off, if you want to disable location entirely. (Again, it will still turn on for purposes of 911)

aGPS (assisted GPS) runs on all modern phones regardless if you have the GPS chipset on. aGPS takes the GPS data from the cell site you are on and then based on the neighbors list that is in the PRL it will approximate where you are based on the signal from the other sites. Again not as accurate as having the GPS chipset on, yes on some phones it will turn on the GPS chipset, however in a 911 call, time is of the essence for making that call and aGPS generally does the e911 call routing with the switch.

Very high level, e911 was one of the projects I worked on at Nextel when we were rolling that out. Lots of headaches getting it to work.

**DirkBelig** · 06-10-2010, 02:29 PM

GPS can be as accurate as 6 feet. Cell tower triangulation can be a few hundred yards. Fire up Google Maps, turn on the satellite view, and see where a cell plot has you located. Now turn on the GPS and watch it snap to where you actually are. What's good about cell-based location is that for coarse uses, like wanting to find a restaurant in the area, it's fine and doesn't use the juice the GPS requires.

**laydros** · 06-10-2010, 02:53 PM

Additionally, there is probably some degree of location information from wifi. I'm not sure if Android implements this, but the information comes from Google so I expect it does. The iPod Touch, for example, has some degree of location awareness even though it has neither a cell radio or GPS.

I'm not sure if it uses your assigned IP address to narrow down region, or if the wifi network scanning Google does when taking pictures for street view is used, or both.

**Grung** · 06-10-2010, 07:36 PM

Originally Posted by laydros

I'm not sure if it uses your assigned IP address to narrow down region, or if the wifi network scanning Google does when taking pictures for street view is used, or both.

IP address...uses something like this...

**Aero** · 08-16-2010, 04:10 PM

Just to clear things up, in the exchange below Vince Law is entirely correct and opg4749 is entirely incorrect and does not understand the basics of gps implementation on mobiles handsets.

aGPS cannot work at all without satellite fixes. It only uses data from the network to locate satellites (GPS), OPG is confusing trangulation (often eGPS with aGPS and they are two entirely different things. All dumphones have by federal mandate ahve some type of implementation like egps which does not use satellites and is very inaccurate (1000 to 100m at best).

Standalone/autonomous GPS on handsets: handsets get precise location fix based on staellites. Does not use nor is it dependent on any carrier signal
aGPS/Assisted GPS: hadnset uses information from the carrier to locate Satellites faster. gets fix from sats. will not work outside of carrier range.
eGPS/Enhanced GPS: one of several mechanism to satisfy federal mandate to locate handset within a mile for emergency services. Uses cellular towers and ONLY towers, dos not use gps satellites, to calculate approximate position. Accurate from 2000 to 100 m

All phones have the latter by law. Mos new smartphones phones have agps. The best have agps and standalone gps

Originally Posted by opg4759

when you turn GPS off you are turning off the GPS receiver. You are not however turning off aGPS which does running off the towers for e911. aGPS is a federal mandate to help route mobile 911 calls to the correct 911 dispatch offices.

Originally Posted by Vincent Law

Not technically correct.
When you turn off GPS, you disable the GPS receiver, yes. But this is used with aGPS. aGPS is a combination of both your GPS receiver, a lot of math and extra processing on Sprint's side, and the mentioned cellular towers.
Note that even if you turn off GPS receiver, it will turn on during an emergency call, by the way.
Anyway, for the OP, you want to go into settings > location > "Use wireless networks" and turn that off, if you want to disable location entirely. (Again, it will still turn on for purposes of 911)

Originally Posted by opg4759

aGPS (assisted GPS) runs on all modern phones regardless if you have the GPS chipset on. aGPS takes the GPS data from the cell site you are on and then based on the neighbors list that is in the PRL it will approximate where you are based on the signal from the other sites. Again not as accurate as having the GPS chipset on, yes on some phones it will turn on the GPS chipset, however in a 911 call, time is of the essence for making that call and aGPS generally does the e911 call routing with the switch

**Yourdogsdead** · 08-16-2010, 04:39 PM

Originally Posted by Aero

Just to clear things up, in the exchange below Vince Law is entirely correct and opg4749 is entirely incorrect and does not understand the basics of gps implementation on mobiles handsets.

aGPS cannot work at all without satellite fixes. It only uses data from the network to locate satellites (GPS), OPG is confusing trangulation (often eGPS with aGPS and they are two entirely different things. All dumphones have by federal mandate ahve some type of implementation like egps which does not use satellites and is very inaccurate (1000 to 100m at best).

very informative