Using the GPS Features of Your Cell Phone?

travik asks: "I use a Nokia 3650. The cell phone already knows my co-ordinates (E911 service). It has Bluetooth. Why can't I send the coordinates using Bluetooth to my laptop, and use a mapping application to give me my location and directions to where i want to go. I've searched Google and also read up on old posts, no one seems to be doing it. Why?"

Comments

E911 isn't really GPS

[PenguinOpus]

E911 lets the service provider know where you are by your tower connection (and perhaps by other tower signal strengths). It's expensive to keep track of, but is required by law. They don't have enough financial interest in returning that location information to you yet.

AGPS (assisted GPS) also depends on the service provider to calculate your location, but it actually uses real GPS satellite signals to do it. The signal strengths are uploaded to a server which does the heavy-lifting of figuring out the location. Again, this depends on the SP servers and they aren't going to be terribly interested in returning lots of location points back to you.

Real GPS does the CPU work on the device. There are rumored to be a few phones with this capability, but I use a Garmin Gecko 301. $228, records 10K points, downloads via serial port (yuck), and burns a set of alkaline batteries in 7 hours (or less). IMHO, it'll be a while before location information is as easy to get to as the cheapest GPS. Battery power is just too valuable.

It's.... kinda possible

[EnglishTim]

I wrote a program for my palmpilot that queried my mobile (a T68i) for it's current cell. I was going to make this into a program that would give me reminders based on my location, but I never got around to finishing it...

The big problem is finding a record of all the cell values and their locations - I never found one for my service (O2), although I was able to get a list of all the cells on the way to work, just by running the program.

The accuracy isn't great, although it gets better in central London. Near Oxford Street I was getting a new cell every 100 yards or so...

Re:It's.... kinda possible

[spiff42]

I'm currently working on my PhD project involving location based services. From my research, I've discovered that a much more accurate location estimate is possible than the simple "strongest cell tower". Basically you meassure the signal strengths from all available towers (or access points), and do some calculations based on this information. Finally you find the best match in a database of location/signal-strengths, and interpolate a position.

I first saw this technology used on WLAN. Ehahau uses this technology to provide location based services on WLAN, and it works great. In our test setup at the university, we get arround 1 meter error in the position.

I've been in touch with a group of people at The IT-University of Denmark, who are working on using this technology on GSM cellphones. The biggest problem here is getting access to the data. The cellphone companies simply do not want to provide this information. Our collaborative guess was that they want to keep this information to themselves, probably to sell extra services.

The main drawback of this technology is that a huge amount of calibration is needed to make it work. On WLAN our buildings have been calibrated in a grid of 3x3 meters, which makes quite a lot of calibration points when we want coverage of the entire campus. But the cool thing about it is that it does not require any extra hardware to do the localization. A labtop or PDA with wireless will do the job.

/Spiff

Re:Privacy?

[bjpirt]

Yes, but anyone with a bluetooth gadget would have to be standing pretty much right next to you anyway.

Not exactly the same, but...

[oojah]

This guy tracks his location by phone.

Where is Calum?

Cheers,

Roger

Positioning Techniques

[neglige]

The cell phone already knows my co-ordinates (E911 service).

Careful not to mix up different positioning techniques :) Your cell phones does _not_ know its position. The _base station_ of the network does. This is assuming that you are _not_ using GPS, but let the network find out the position of the device by

• using the cell ID of your current radio cell - precision varies with cell size (100m to several km)
• using the 'angle of arrival' (AoA) of the radio waves to and from your mobile device
• triangulate the device with 'Enhanced Observed Time Difference' (E-OTD), requires additional base stations in rage

These are just a few, there are several more.

GPS, on the other hand, requires you to have a GPS receiver. If you have one, your device can determine its position. You do not require a mobile phone network for this, but you need at least 3 GPS satellites "in view" (meaning: you must see the sky, GPS won't work within buildings; there is "indoor GPS", but this is about creating 'artificial satellites' within a building).

GPS gives YOU your position, and YOU alone, unless you transmit the information (e.g. to a map service). The techniques described above give your position to the network operator, not you. The operator then has to give the information to you or some mobile service. With E911, in case of an emergency the network operator reports your position to the emergency units.

Why can't I send the coordinates using Bluetooth to my laptop, and use a mapping application to give me my location and directions to where i want to go.

As said above, if you do not have a GPS receiver, YOU do not have your position. You have to use whatever service your provider offers (if any). To use the laptop you need a GPS receiver. Connect that to the laptop, install the right software... and voila :)

Hope that helps ;) There are tons of information on this subject. If you'd like to have more details, I'll point you to some papers on that matter.

Solution right there:

[AdamInParadise]

WayFinder.

Basically, it provides you with a simple GPS module that communicates with your mobile through Bluetooth. Map and directions are provided by an online service and appear on the screen of your mobile. Neat!

All CDMA has GPS, but not carriers

[mockojumbie]

All CDMA phones in the last couple of years' generations have had GPS chipsets from Qualcomm, you can't get CDMA chips without it. The carriers OTOH, are waffling trying to figure out how to make money. All current CDMA phones must communicate with a SnapTrac server to using MS-assisted or MS-based; the carriers are not leaping to install these servers in their systems. We're authoring a Brew/Linux/PHP LBS system for a carrier, the first nationwide launch is still months away.

You can download the location of ~all cell towers from the FCC
http://wireless.fcc.gov/geographic/fcc_db.html
(big files) as they are publically licensed, but you can't know the carrier's private ID # of the tower without matching the tower's license to what you phone tells you, as some do.

The first test launch of a stand-alone GPS phone is several quarters away... The CDMA chips are basically capable, but need some extra hardware and firmware since they don't get a kick-start from the tower/server communication.

Right now, if your carrier doesn't have the PUBLIC servers installed (they will not use their e-911 servers for commercial use for liability reasons) then you can't have GPS.

And BTW, the carrier's servers do know your location because of the MS-* handshaking and communication (which allows the ephemeris calculations to be done faster on your phone), it's a question of whether it gets saved or tapped.

It's---a-small-world-after----all---...