Comments on: Skyhook combines GPS and Wi-Fi for location

Skyhook Wireless adds GPS to its geolocation technology so useres can get accurate location information whereever they are.

[dsstroud]

Does this work with the original iphone? It seems that my skyhook service is more exact than it was before, though not as exact as GPS of course.

[Norseman]

Just one question. If you have GPS in the phone, why do you need Skyhook to tell you where you are?

Phones are not dedicated GPS unit. GPS signals from the satalite are not very strong and are vulnerable to interference from buildings and other signals. Purely relying on the GPS signal consumes battery power and does not necessarily yield an accurate location.

Because of this phones use what is called assisted GPS. The phone connects with a backend service that has a better connection to GPS satalite. The phone is able to send what GPS data is has, as well as WiFi signal location and tower triangulation information. The backend service is able to quickly calculate the data and quickly give an accurate real time location. Without using the phones limited processing power or battery life.

[Noitacol]

Yes, GPS may not work everywhere and every time. In most cases, it requires at least 4 satellites visibility. This may be difficult in some city areas, for example. Therefore we have A-GPS. A-GPS is not good enough though. Then we have hybrid approaches which combine A-GPS with network positioning technologies, such as TOA, TDOA, .... see


http://to.swang.googlepages.com/lbs

[LBSgeek]

WiFi based solutions are not the best complements to A-GPS either. The iPhone may have in-built WiFi but not all other phones in the market today have WiFi capabilities. Even if new phones were to be shipped with WiFi capabilities, it would take years before they achieved a meaningful level of penetration. The reliability of WiFi based solutions is also worth thinking about since the Access Points (AP's) are always a moving target. In order to keep the information up-to-date one has to physically drive areas across the country periodically which turns out to be an expensive proposition.