Apr 10 AT 12:00 PM Christopher Earle 5 Comments

Skyhook Wireless: Hybrid Location Pinpoints for the G1shop

If you’ve ever tried to use Global Positioning System (GPS) in a deep urban environment, like a heavily built up downtown area, you’ve likely experienced one of the weaknesses of the GPS system. GPS requires line of sight to the satellites. If you turn on the G1s GPS system walking among a forest of skyscrapers, the buildings block the satellite signals that the GPS system relies on. Skyhook Wireless uses a unique system of hybrid location detection to pinpoint your location much more accurately when good GPS signals are not available.

The Three Sources

One of the main data sources that Skyhook Wireless uses is, of course, the GPS system. When signals are available, the GPS system provides positioning accuracy of between 10 and 15 meters. Other than the line of sight requirement for GPS systems, GPS can also be slow to start due to satellite acquisition times.

The second common positioning component of Skyhook Wireless is cell tower triangulation. It is less accurate, with accuracy ranging from 200 to 1000 meters. Its advantage is speed. It takes a few seconds for most devices to calculate location based on cellular tower triangulation.

The third, and by far most unique, component of the Skyhook Wireless system is their Wi-Fi positioning system. Skyhook maintains a database of global Wi-Fi locations. When a Skyhook Wireless enabled app tries to determine location in deep urban environments and can’t acquire adequate GPS signals, it scans for nearby Wi-Fi networks. By triangulating Wi-Fi networks based on a larger location triangulated from cell towers, a much more accurate location can be determined.

By combining all three of these data sources, Skyhook enabled apps are able to calculate far more accurate position estimates in a wider variety of conditions than simple GPS or cell tower triangulation.

Skyhook Enabled G1 Apps

There are two apps currently available in the Android Market that use Skyhook’s technology. The first is a handy app called Locale. The second is ShopSavvy.


Getting a location fix in Locale.

Getting a location fix in Locale.

Locale allows you to change aspects of your G1 based on location. Do you often turn off your phone during meetings at a particular location? Locale can pinpoint your location and turn off the features that are most invasive during the meeting. Were you expecting a call from a particular person during the meeting, but wanting to send all other calls to voicemail? Locale can accomplish that by a prioritized list of rules. Placing the address book entry for the expected caller above the block all callers rule will allow that call, and only that call, to come through.

Do you want particular people to know where you are? Through the use of plug-ins, your location can be automatically sent to specified numbers via SMS or Twitter.


Product detail page in ShopSavvy

Product detail page in ShopSavvy

ShopSavvy is one of those applications retailers love to hate, especially retailers whose prices are higher than the rest of the market. Using ShopSavvy, you can scan a barcode. The app will then show you a list of internet retailers and local retailers with the product. It will display the best price available locally and via the internet. The product can then be added to a wish list, or a price alert can be set to notify you when it drops below a pre-defined price. ShopSavvy allows for product scans to be automatically publicized via Twitter and shows available product reviews.

ShopSavvy uses Skyhook Wireless technology to see if there is a shop nearby that carries the product that you’ve scanned. At this point, there aren’t a lot of retailers signed up for the system, but more and more are coming on board.


Skyhook Wireless has a good solution to the inherent weaknesses of all three positioning technologies. By using a hybrid system of all three and frequently updated Wi-Fi and cell tower databases, it provides one of the best and most accurate systems for positioning in situations where GPS is partially or completely ineffective.

Skyhook Wireless offers three location components.

Skyhook Wireless offers three location components.

Christopher Earle has been working as a freelance writer since 1987. He currently lives in the Denver, Colorado area with his wife, son, and their two cats. He has been a fan of open source software for many years.

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  • Roy

    Good to see people actually talking about this, because it’s a great addition to a lot of apps.

    There are plenty more apps using this though (AndNav, Milage registration, twitli, sms commander).

  • oj

    But what is this? an external library ? free or commercial?

  • http://blogs.zdnet.com/Burnette Ed Burnette

    Android is supposed to do this kind of multi-mode location for you automatically. If the built-in locator is not as good as the commercial one, can the built-in one be improved using some of the same techniques?

  • http://androidandme.com Taylor Wimberly

    Android does not do WPS (Wi-Fi Positioning System) location by default. iPhone has integrated the Skyhook technology into their OS, but Android devs have to go license it on their own from my understanding.

  • Gammax

    1984, ever read the book? big brother is watching! but still very cool apps