FAQ: How Google Latitude locates you

Multiple wireless technologies help Google's new Latitude service pinpoint your location

February 4 2009 google Inc. released the real-time location tool Google Latitude and opened up a new world of location-based services (LBS) for both PC and mobile phone users.

Latitude enables you to track friends, family, employees and so on — 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 where your boss can track your every move, will be determined by how we'll 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. These 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 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 Global Positioning System 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 from Skyhook Wireless in the Latitude service. According to Nick Brachet, Skyhook's chief technology officer, the company's XPS hybrid-positioning system 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, Skyhook's software 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, Skyhook's 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 the addition of Skyhook's XPS can reduce TTFF to a few seconds.
I thought you had to have GPS to work out your location. How does Google/Skyhook get around that? The technique that Skyhook 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, cell 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 cell 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 the system know where Wi-Fi APs and cell towers are? Skyhook keeps a database of public Wi-Fi AP locations, and Google has a database of Wi-Fi AP and cell 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 iPod Touch or most PCs, it can only work out your location within about 200 meters. If you're using multiple cell towers, say you're in a city, you can get it down to a 100-meter circle. In the country, you may be as far out as 300 meters. And with GPS, you can lock down your location to a few meters. 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 the other, 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 they can also track you.

By Steven J. Vaughan-Nichols
computerworld

Microsoft Outlines Windows 7 SKUs; Targets Netbooks

Microsoft has officially announced the five versions of Windows 7 it will sell at launch within the United States, together with a version specifically designed for low-cost netbooks.

The five versions available for U.S. customers will be: Windows 7 Starter, Windows 7 Home Premium, Windows 7 Professional, Windows 7 Enterprise and Windows 7 Ultimate. But Microsoft will only sell Windows 7 Home Premium and Windows 7 Professional at retail, in a bid to eliminate some of the confusion caused by a plethora of Windows Vista versions.

A sixth version, Windows 7 Home Basic, will only be sold in emerging markets, Microsoft said.

Microsoft did not release the prices of the new Windows 7 versions, and offered no additional details as to when they would launch. Most expect Windows 7 to ship near the end of 2009, however. Microsoft also declined to say when it would stop selling Windows Vista.

"We've learned a lot over the years as we've released versions of Windows to the market. We spent a lot of time listening to customer and partner feedback," Microsoft said in a document describing the changes that was released to PCMag. "We heard from customers that they liked the choices Windows Vista offered, but that upgrading sometimes meant tradeoffs. Customers told us that they want us to make it simpler to identify which version is right for them."

And that means that a single version – Home Premium – will be offered to consumers, with a separate version – Professional – offered to businesses. Both the Home Professional and Business SKUs will contain discrete features that aren't overlapped to the other.

So why not leave it at that? "When you have a customer base of more than one billion, two options can't satisfy all of their varied needs," Microsoft explained. "For that reason we will continue to offer a few targeted SKUs for customers with specialized needs."

Windows 7 Ultimate Edition, meanwhile, won't be sold directly to consumers. Instead, Windows 7 Ultimate will be an upgrade offered only as an add-on, which also means that consumers will be forced to pay for Windows 7 Home Premium or Windows 7 Professional, and then pay again for the upgrade. However, Microsoft will roll out all of the versions on a single disc, allowing users the choice of either buying offline media or applying for an online upgrade key that will unlock the additional capabilities.

"Ultimate combines all of the features of Windows 7 Home Premium plus provides access to all of the Enterprise features including BitLocker, BitLocker To Go, AppLocker, BranchCache, DirectAccess (accessing a corporate network without Remote Access Server installed), MUI, etc.," Microsoft said. BitLocker and AppLocker lock down data and applications, respectively.

And Ultimate Extras? Gone. "Our new approach to planning and building Windows doesn't have the capacity to continue to deliver features outside the regular release cycle," Microsoft said.

Perhaps the largest change, however, is Microsoft's recognition of the netbook market. Previously, Microsoft sold its Starter software only into emerging markets. Now, the company has positioned Starter as an ideal entry point for extending Windows 7 into netbooks. The catch? Like other Starter editions, that netbook will only run three applications at a time, an arbitrary limitation the software imposes. Those limitations ignore background services like antivirus applications, but trigger when the controlling antivirus application is opened, Microsoft's documents say.

Starter is described as a "worldwide entry-level SKU". "Windows Starter has been our entry-level offering in emerging markets with Windows XP and Windows Vista," Microsoft's documents say. "With Windows 7 we are making Windows 7 Starter our worldwide entry-level offering for small notebook PCs (also known as netbooks).

"While these PCs with sufficient hardware will be able to run any Windows 7 SKU and we believe that most consumers will want the rich experience offered by Windows 7 Home Premium or Windows 7 Professional, we recognize that some consumers want a very low price point for their small notebook PC and only have basic computing requirements," Microsoft added. "Windows 7 Starter meets the needs for a certain segment of customers with reduced computing requirements."

One interesting twist: Microsoft claims that any netbook should be able to run essentially any version of its Wndows 7 operating system: "However, Windows 7 was designed in a way that any edition of the OS should be able to run on small notebook PCs with sufficient hardware," the documents say.

That, in part, is because the company said it has "invested significantly in engineering efforts around improving performance, reliability, and compatibility in Windows 7."

On the business front, Microsoft will offer Windows 7 Professional, with the capabilities of joining a managed network, backing up data over the network, and encrypting data. The software will also allow users the option of location-aware printing, such as printing to a home printer while at home, and defaulting to a shared printer in an office environment.

Enterprise will offer a step up for Professional users, and will only be available through volume licensing. With that version, business users will have the option of using BitLocker data encryption on internal and external drives, locking apps with AppLocker, improved remote access without the need for a VPN with DirectAccess, and a decrease in the time to open a shared file with a service called BranchCache. Both of the latter services will require Windows Server 2008 R2, Microsoft says.

by Mark Hachman

www.pcmag.com

Microsoft to offer XP-to-Windows-7 upgrades

Microsoft Corp. today confirmed that it will sell what it calls "upgrades" for Windows 7 to users running the aged Windows XP operating system.

Those users, however will have to do a "clean" installation of Windows 7, meaning that all data on the machine will be lost.

"Regarding XP, customers can purchase upgrade media and an upgrade license to move from Windows XP to Windows 7," a company spokeswoman said in an e-mail this morning. "However, they will need to do a clean installation of Windows 7."

In a follow-up reply to questions, the spokeswoman fleshed out what Microsoft means by upgrade. "The 'upgrade' part is referring to the license," she said. "You will be able to get the discounted 'upgrade' license, but it will include full bits."

That's how David Smith, an analyst at Gartner Inc., interpreted "upgrade" in Microsoft's description of what it would offer XP owners. "They're talking about the upgrade price," he said, pointing out that most software vendors use the term upgrade to designate a lower-priced version aimed at existing customers.

Although Microsoft today spelled out the six planned versions of Windows 7, it declined to provide pricing for them, or for the XP upgrade licenses.

Typically, an operating system upgrade offers users the choice between an in-place migration of the machine -- including installed applications and all data -- and a fresh installation, which overwrites the hard drive's contents. When Microsoft launched Windows Vista in January 2007, for example, it offered those upgrade paths to people then running XP .

Smith and other analysts applauded Microsoft's decision to not provide in-place upgrades from XP to Windows 7. "I'm not a big fan of them," said Smith. "They're tough enough from one version to the next, and from two versions [behind], it would be pretty challenging, technically."

Michael Gartenberg, formerly an analyst at JupiterResearch and now a vice president of mobile strategy with JupiterMedia, agreed. "For most end users, it will probably mean that they end up with a more reliable installation," he said.

Microsoft benefits, too. "It makes life a lot easier for Microsoft by not having to support an XP to Windows 7 transition," said Gartenberg, who is a Computerworld.com columnist. "It means that it's something they can get out the door earlier."

Microsoft has been aggressively pushing Windows 7's timetable. Just two weeks after it launched the first -- and in the end, the only -- public beta of the new operating system, the head of Windows development said the company is moving directly to a "release candidate" version of the operating system.

But the process of upgrading a PC from Windows XP to Windows 7 won't be easy, Gartenberg predicted. "It's a double-edged sword. For many consumers who may be looking to go directly from XP to Windows 7, the idea of doing a clean install, backing up their applications, backing up their data, can lead to a lot of hassles," he said.

"Considering that there's a lot of XP out there, one has to wonder why Microsoft is taking this approach," Gartenberg added. "It's not going to be the simplicity of sticking a disc in the drive and upgrading. We'll have to see if that affects the upgrade market."

Microsoft said it was working on ways to help Windows XP users make the move, but it did not get more specific. "Microsoft plans to have other tools and ways to help people get through that process, but we don't have full details on that at this time," a company spokesman said today.

By Gregg Keizer
computerworld