why not just download the already calibrated charts from NOAA, for free? They are also going to be more up to date than the paper ones you purchased and scanned...I then scan any chart, use Oziexplorer PC version to calibrate the scanned chart and loaded it to my iPaq.
As I understand it, the assist does use the data connection to go out and query info about the tower(s) you are connected to when you first start up the GPS, it then sends those coordinates to the GPS receiver and tells it that is where you are. The receiver then goes and gets a fix like normal, but is speeded up because it already has a pretty good idea where you are on the globe to start with.Apple has said they have "agps" which means "assisted GPS" which in turn means it doesn't work without a data network connection. "agps" phones receive the gps satellite signal but are incapable of processing it. Or so I've been told.
That is generally false. I (and many others I know) have never once paid for the cell companies GPS service on any cell phone, and I frequently use the GPS features on my current, and previous phones.Without that plan--you can't use the apgs feature in the phones. There's no way to access the gps capabilities. As opposed to phones (mainly not available in the US except from Sprint/Nextel) which actually have on-board GPS that can be used stand-alone...
You are correct that without a data connection to the cellular network (it uses the cell tower to determine it's starting position) the "assist" feature will not function on the A-GPS receiver, but virtually all gps unites in phones are of the type that features a standalone receiver as well, and while they may take a long time (I've personally seen 30+ minutes, and heard of 45+ minutes in extreme cases with weak signals) to get the initial lock without the assist, they will still get the lock, and once done, they will operate as any other GPS unit.A typical A-GPS-enabled cell phone will use a data connection (internet, or other) to contact the assistance server or a standard network connection for A-GPS information. If it also has functioning autonomous or standalone GPS, it may use standard GPS, which is sometimes slower on Time To First Fix, but does not lead to network dependent downsides, such as failure to work outside of network range, or charges for data traffic. Some A-GPS solutions do not have the option of falling back to standalone or autonomous GPS.
I doubt NOAA has charts for my region at GMT +8.00hrswhy not just download the already calibrated charts from NOAA, for free? They are also going to be more up to date than the paper ones you purchased and scanned...
NOAA Raster Navigational Charts
edit: the URL won't save correctly because of the tag at the end, so I changed it to a tinyurl