These days, few don't, at least the so-called "Smart phones". I'm not sure there's any smartphone without a GPS receiver any more. I have an old (3GS) iPhone with no service plan - can't make phone calls, but can use every other function. Mapping is fast and much more accurate than the GPS in the v. You can turn cellular data access off on an activated iPhone via Settings->General->Cellular. E911 location services (which use the triangualtion scheme) can not be turned off in any mobile cellular phone. I may make a test 911 call with it someday to see if that works without an activated plan. Problems with the Prius GPS are moot to me anyway. We found it to be unusable, compared to our old Garmin, which sits proudly, if not attractively, on the dash.
GPS systems do this automatically. GPS positioning is absolute, so you don't need a relative calibration unless you are dealing with something like a ship, where you need to tell the GPS system that the antenna is located 300 feet from the bow. ....................................................................................................................................... 2013 MERCEDES BENZ SL-CLASS
I am having the same issue with my GPS signal. The GPS icon on the navigation screen is greyed out. I have had to reposition the map manually several times now through the calibrating option. I also have 20% window tints all around except on the windshield on my car. I will have to get this issue checked at the dealer.
I should have printed out this issue when I had the TIS subscription these last two days. There is a software update available to dealers about the freezing issue.... I've had the NAV out when I installed the remote start and alarm, that one's not a biggie. I don't know how much was removed to get to the antenna though... I thought the GPS signal is scrambled a little, that only military/aviation grade get highly accurate data, but that this is rectified some by getting signal from many satellites at the same time, as well as dead reckoning...
That "scrambling" was called "Selected Availability" (SA). Selective Availability (SA) was an intentional degradation of public GPS signals implemented for national security reasons. In May 2000, at the direction of President Bill Clinton, the U.S government discontinued its use of Selective Availability in order to make GPS more responsive to civil and commercial users worldwide. The United States has no intent to ever use Selective Availability again.In September 2007, the U.S. government announced its decision to procure the future generation of GPS satellites, known as GPS III, without the SA feature. Doing this will make the policy decision of 2000 permanent and eliminate a source of uncertainty in GPS performance that had been of concern to civil GPS users worldwide. -- from GPS.gov: Selective Availability