Two weeks ago, Google launched Google Latitude - a new function for its Google Maps for Mobile app that allows users to share their location with friends and family. We've found out everything you need to know about the service and how to use it.

Google Latitude is a real-time tool that's opened up the world of location-based services for both PC and mobile phone users.

But controversy goes hand-in-hand with any tool that allows you to track other people's whereabouts, and it wasn't long before privacy campaigners slammed the new service. Whether the tool is a good thing remains to be seen, after all it could create a corporate '1984' world in which your boss can track your every move.

While we're not addressing the privacy issue, we have answered all our burning questions about the service and how to use it.

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 colour 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 US, 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 personalised 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, mobile towers or GPS to work out your location.

How does Latitude do that?

Google is using technology that's a software-only location solution, which allows any mobile device with Wi-Fi, GPS or a cellular radio to determine its position with an accuracy of 10 to 20 metres. What sets it 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 time to first fix (TTFF). TTFF for some devices can be up to a minute, but by using multiple reference sites, Latitude can reduce TTFF to a few seconds.

NEXT PAGE: How Google Latitude works

  1. We explain just how Google's new location pin-pointer works
  2. How Google Latitude works

Two weeks ago, Google launched Google Latitude - a new function for its Google Maps for Mobile app that allows users to share their location with friends and family. We've found out everything you need to know about the service and how to use it.

How does Google Latitude work without GPS?

The technique that Google uses to work out your location is actually the same one that any GPS device uses: triangulation.

Here's how it works: when Latitude turns on, it automatically tries to reach any available GPS satellite, mobile tower or Wi-Fi access point (AP). Once it establishes three or more links, it starts working out your location.

It does this essentially by figuring out, for example, that if you're two blocks from the mobile tower at the church, and you're right under the Wi-Fi AP at the coffee shop, and you're at x distance from a GPS satellite, you must be at Buster's Coffee Shop. Typically, devices can use up to 24 reference points to work out your location.

Now, by itself your mobile device doesn't have the CPU horsepower to work that out. It takes the raw data and transmits it via a GSM, CDMA or Wi-Fi link to an assistance server. This technique is called A-GPS (assisted GPS). Your mobile device or computer works together with the server to plot out your location.

And this is the important part for Latitude: since the assistance server has the results of the calculation, it's easy to share your position with anyone else who uses Latitude and has your permission to see your location.

How does Google Latitude know where Wi-Fi and mobile towers are?

Google uses a database of Wi-Fi AP and mobile phone tower locations. Together, these tens of millions of fixed locations give Latitude the grid it needs to work out your location.

How accurate is Latitude?

It depends. If all you're working with is Wi-Fi APs, as would be the case with an Apple iPod touch or most PCs, it can work out your location only within about 200m. If you're using multiple mobile towers - say you're in a city - you can get it down to a 100 metre circle. In the country, you may be as far out as 300 metres. And with GPS, you can lock down your location to a few metres. If you combine systems, you can be within GPS's accuracy range.

Many variables can interfere with your accuracy, however. Unfortunately, there are no hard and fast rules on determining how accurate Latitude or any other LBS application will be at any given location. For example, if you're inside a large building, you probably won't get a GPS signal. On the street, you may get the GPS, but you'll lose the Wi-Fi signals.

One way or another, though, we're entering an age where you can always keep track of where you're at, who's near you and what businesses are close by. The flip side, of course, is that others can also track you.

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  1. We explain just how Google's new location pin-pointer works
  2. How Google Latitude works

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