FAQ: How Google Latitude locates you

Computerworld - Yesterday, Google Inc. released the real-time location tool Google Latitude and opened up a new world of location-based services for both PC and mobile phone users.

Latitude enables you to track friends, family, employees and others — and vice versa — in real time. Whether this is a good thing (hey, you'll always know where your buddy is in the stadium parking lot) or a preview of a corporate 1984 world in which your boss can track your every move will be determined by how people use the service. It's no surprise that at least one privacy group has already voiced security concerns over Latitude.

For now, though, most questions center on how people can use Latitude and how it does its location voodoo.

Can I use Google Latitude? According to Google, if you have any mobile device that supports Google Maps for Mobile v3.0 and above, you're probably good to go. Those include Android-powered devices with Maps v3.0 and above; most color BlackBerry devices; most Windows Mobile 5.0 and above devices; and most Symbian S60 devices.

In the near future, you'll also be able to use Latitude on the iPhone and iPod Touch with the Google Mobile App in the U.S., and on many Sony Ericsson devices. In addition, you can use Latitude today on a Linux, Mac or Windows PC by using the Latitude iGoogle gadget (you'll need a Google Account) and iGoogle, Google's personalized Web portal.

How do I get it? Mobile users need to first have Google Maps 3.0 or above installed. After that, you can install Latitude. PC users can install the gadget by starting from the Google Latitude site.

I don't have a GPS chip in my phone. Can I still use Latitude? You betcha. Latitude can use Wi-Fi access points, cell towers or GPS to work out your location.

How does Latitude do that? Google is using technology that's similar to that of Skyhook Wireless in its Latitude service. Like Skyhook, it is a software-only location solution that allows any mobile device with Wi-Fi, GPS or a cellular radio to determine its position with an accuracy of 10 to 20 meters. What sets XPS apart is that it uses land-based Wi-Fi access points, GPS satellites and cellular towers to determine location information.

In other words, Latitude can use any of the three kinds of signals — Wi-Fi, 2G/3G/4G mobile or GPS satellite — that a device can pick up to work out its location. By leveraging these wireless capabilities, the software can combine positioning data from satellites, carrier assistance servers and Wi-Fi base stations to significantly speed up positioning, or TTFF (time to first fix). TTFF for some devices can be up to a minute, but by using multiple reference sites, Latitude can reduce TTFF to a few seconds.