Using GPS Log with no data connection on iOS hardware that includes a real GPS (Wifi + Cellular iPad models and all recent iPhones) is fully supported.
We understand that international data roaming is expensive (so most people disable it), and many iPhone's are locked to accept only one companies SIM cards, meaning that most travellers outside their own countries do not have a cellular data connection. Thus, one key feature of GPS Log is that it can function with no cellular data connection. However, it has some limitations, so please read this advise.
First Fix in a New City
When you first arrive in a new country (or change your location drastically, e.g. by plane/train/bus), GPS Log may take a long time to get the a position fix without data, as it needs to cache some satellite data specific to your new location. There are two ways to get this first position fix:
- Start GPS Log updating your position from a new log entry. Ensure you have a clear view of the sky, and leave the App running without interruption for several minutes (up to 10 minutes, typically less than 5). Do not tap the "Update from GPS" button during this process, unless it stops updating by itself, instead tap the 'Lock' toolbar icon and leave the App stationary for several minutes.
- Use a data connection (e.g. a Wifi hot spot) to get your first position fix. This may be faster, however a clear view of the sky may still be required.
NOTE: GPS Log will NOT work if Airplane mode is enabled.
Be aware that Airplane mode is not the same as not having a data connection. Airplane mode will prevent the iPhone from using the GPS and you won't be able to get any sort of fix.
If you wish to use your iPhone with the "phone" part disabled (or simply test a "no data" situation), either remove the SIM card completely, or add set a PIN code to it, toggle airplane mode and don't unlock it when prompted.
Once you have this initial fix in your new location - future fixes without data should be much faster. Be aware that a clear view of the sky is generally needed to use GPS Log without a data connection (even with a data connection, a clear view of the sky is needed for the highest accuracy).
Manually Adding the Location
If you were unable to use the GPS to get your position for an entry, there are several ways you can manually set the position from within GPS Log.
Airports are a good example of something that may be hard to log – as you are often in a rush, and indoors – but since Airports have a known (and easy to find) location, you can generally set the position after the fact. Create the log entry like normal, but don't worry about the location. When you are back on Wifi, search for the location.
Stay Up to Date!
Testing this Feature
If you want to get used to this operating mode before you need it, the best way to test is to eject the SIM card. Or, if you use a SIM password, to reboot your iphone (hold down the 'sleep' button) and don't enter your password when prompted. This simulates an environment where you have no data connection.
During this simulation, unless you have travelled a great distance, the fixes you get will be in the category of Subsequent Fixes in regards to the speed of getting a fix. If you really want to test the ability of GPS Log to get First Fix in a New City, eject the SIM when you travel to a new city (> 100km).
Turning on Airplane mode disables the GPS hardware, thus this mode cannot be used to test this feature.