The article has been updated successfully.There are several ways to determine if you have a valid GPS fix. One is to check the crosshairs icon on the toolbar. If this icon is dark, there is no valid fix.
If the crosshairs are bright (like the surrounding icons), clicking on the icon should move your location on the map to the center of the screen and show the position indicator. If you see the position indicator, but no map, it is possible that you do not have a map for this area or have not yet downloaded that portion of the map.
Another (if you have a position marker on the screen) is to verify the center dot is red and blinking. A gray center indicates no valid position and merely shows your last know position.
The first thing to verify is your location services. From the home screen, go to SETTINGS > GENERAL > LOCATIONS SERVICES. There will be the option to turn on / off the serivce for individual apps. Ensure that the app is turned on for the Memory-Map (Pocket Nav) app.
The second thing you want to check is your environment. Are you in an area where you should be getting a good signal from the satellites? Are there large buildings, canyon walls, or thick tree coverage around which may block view of the satellites?
NOTE REGARDING ASSISTED GPS:
All GPSs in mobile devices are "Assisted GPS" these days. They get assistance from the cell towers. this enables them to acquire a fix much faster, use less processing power, battery consumption, etc. Do they work without cell coverage? - yes and no. The problem is that each manufacturer has the option to dial the settings as they please.
On the first edition of the iPhone, the GPS was dialled down to save power and fails if deprived of a cell connection and the transmitted ephemeris (map of where the satellites are) when moved a significant distance (sorry-I'm not prepared to define what that distance is). In other words if you move too far from the last cell tower, the stored ephemeris becomes out of date, the satellites are not where the GPS expects them to be and the iPhone GPS doesn't have the power to find them on its own.
By the time the iPad came out and subsequently the iPhone4, Apple fixed the issue and dialled up the settings so the GPS does work independently
NOTE: If you are in a building (particularly a multi-level building), you will NOT get a good signal (if any at all). By nature a GPS only works accurately with a clear line of sight to the satellites. The more obstacles in the way, the less accurate the GPS fix. Glass and fibreglass are transparent to radio signals but your hand (80% water) is an effective barrier.
