GPS vs. A-GPS

June 14, 2008

in iPhone,Tech

After reading through some blogs and comments regarding Assisted GPS and the new Iphone 3G, I became more and more confused about what Assisted GPS was. So I went to Wikipedia and read the explanation that they had. This is what I understand at this point. The cell phone carrier has a server on their network called an Assistance Server. When the phones GPS chip initially starts up, it contacts the Assistance Server to determine orbital data for the GPS satellites. It also allows the GPS chip to provide location data when it has a poor signal from the satellites. The confusing part is, I have heard that the 3G signal is required for the GPS on the iPhone to operate. Insinuating the GPS chip is not capable of operating on its own. I also understood that because of this there is a lag in the location information from the GPS. The other thing that I have heard is that by having this Assistance Server it allows the phone to offload the data crunching which extents the battery life. I did find information that could support both of these claims on http://en.wikipedia.org/wiki/AGPS.

“Some A-GPS solutions require an active connection to a cell phone (or other data) network to function, in others it simply makes positioning faster and more accurate, but is not required.”

“As an additional benefit, it can reduce both the amount of CPU and programming required for a GPS Phone by offloading most of the work onto the assistance server.”

So it sounds like depending on the type of implementation of A-GPS these claims just may be true. If so this raises the question of if TomTom and Garmin can sell GPS software through the application store that will provide turn for turn navigation? Let me know what you have heard and if my understanding on this subject is accurate.

Related Link: iPhone 3G Thoughts

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