gps navigation for iphone 3g
iPhone 3G with “Assisted GPS?” What is it mean?
my question is what is the difference between GPS and Assisted-GPS? for instance, can I just use Iphone 3G as just a GPS system? would it work without contract or services? like i would just turn it on and use it as my navigation system like Tomcat. I wanna hear answers from the experts. thanks!
People have such a horrible misunderstanding of assisted GPS (a-GPS) and often give incorrect answers. Assisted GPS is *better* than regular GPS. Assisted GPS works by using the signals from cell towers that have known geographic coordinates *in addition to* the signals received from GPS satellites. Assisted GPS allows you to determine your location when you are in a place that cannot receive GPS signals very well, like in a parking garage or between tall buildings. A-GPS will also help you get a position fix faster from GPS satellites since the GPS receiver will already have some sort of idea where it is on Earth based on the cell tower data, and will therefore know which GPS satellites to be looking for.
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