✔ 最佳答案
GPS and A-GPS is totally different, but they can do the same job.
GPS is a chip inside your phone/pda/computer/etc. that can connect to some 人做衛星. A-GPS is a system which can connect to the 電話信號發射臺.
Why A-GPS cost money is because the 發射臺 is belongs to 3/pccw/peoples/csl/one2free/new world/etc. although gps doesn't cost any money, you must stay outside otherwise you can't get your poistion. for agps, if you can recieve phone signle, that means you can use agps to confirm where you are.
You can't change your cellphone from a-gps to gps because there is no chip inside the cellphone/computer/pda and it cannot connect to the 人做衛星.