I'm working on a project in which I have to get current location at every 10 sec interval. I've used sim808 (GSM/GPRS & GNSS) using which I execute AT+CGNSINF command to get the location. I get that location string in terminal using serial communication. As I'm working with this device at my place. sim808 gives me complete data at every 10 sec with updated time and 4 satellites in view and works fine as I expected. But as I go with my car to test the project. sim808 do not give me the updated data. It freezes at a position and gives me that old data at every 10 sec even time also. Now I do not know what problem would be there? What should I do to make this thing work?
That's just how GPS works. Once you've locked to a position, the internal routines will have it easier to keep your position correct. As soon as you start moving, things get more complicated for GPS receivers.
Now, walking from a flat to a car shouldn't be much of a challenge. Check your antenna, the surroundings (is this an urban scenario where you in the middle of building canyons that simply not allow for reception?) and whether you simply need a better receiver.