Originally Posted by Stitchawl
I just started up both apps again, this time out on the veranda and the open sky, and this time both are identical, but both are off by one full block. Surprising to me as I figure it can use satellite, cell tower, and wi-fi to get pinpoint accuracy. At the same time I started up my Garmin Zumo GPS bike navigator, and that shows me actually on the correct side of my building, but that is showing that it's picking up nine different satellites.
Once the GPS is locked on it is correct. Maps are a different matter. Some mapping programs use road lock to pull the location to the nearest road and sometimes get this wrong, particularly if the two roads are not the same size. Other factors include the fact that most maps are really wrong. They were made before GPS and not updated. Of course many phones use a really poor implementation of GPS using poor antennas and minimum hardware depending on other methods to fill in the gap. Your Garmin is much better. Garmin now makes a Bluetooth model for the iPad, iPhone now that includes both the US and the Russian satellites for even better accuracy. It is called GLO and has the special Apple proprietary features needed to make Bluetooth work.