On supported devices (currently iPhone 4, iPhone 3GS, iPads and 3rd gen iPods) running iOS4, Family Tracker is able to run in the background, continuously updating its GPS location without the need of user interaction. Furthermore, when the device is rebooted, Family Tracker will automatically resume tracking the GPS location.
We have 4 settings of operation for the background GPS tracking:
In "Driving Only" mode we are actually not powering on the GPS, as the location is being retrieved via the cell towers. The location is updated only when there is a cell tower change (usually while driving). If you do not need super precise locations, we strongly recommend using this setting as it allows for huge battery savings, as the power used by Family Tracker is practically insignificant. As an example, beginning a 3-hour drive starting with the iPhone fully charged results in still having a 97% charge left after those 3 hours.
Note - there is a bug in iOS4.1 that may prevent the Location Services from updating the phone position every time a cell tower changes. Apple has fixed this in iOS4.2. If this is affecting you, please either update to iOS4.2, or use the GPS mode described below - "Driving Only + 20' refresh"
The "Driving Only +20' refresh" mode works very similarly to the above "Driving Only" mode, but in addition Family Tracker refreshes the GPS position every 20 minutes even if the device is not moving. Please note that we are limited by Apple's guidelines when using these settings.
The "Always On" settings instead do keep the GPS radio in the device on at all times. This results in a better GPS accuracy, but will also result in a lower battery life (the charge won't likely won't last an entire day). With both the "Always On 1Km" and the "Always On 100m" settings, Family Tracker will continue to update it's position even if the phone is stationary in one position (in 5 minute intervals). This will allow you to know that Family Tracker is still running on the phone and that the position being marked on the map is fresh and accurate.
Notes: We are aware there are other apps that can provide more flexibility with these settings, but they are doing so violating their agreements with Apple. These apps can be forcefully removed by Apple at any time from the App store if they find out about this misuse.
When using "Driving Only" mode, we are briefly firing up the GPS for 20 seconds every time we detect the phone has stopped moving. This allows us to obtain a rather accurate position (often within 10-100 meters) as soon as the phone is still, while at the same time continue to maintain a very, very low battery consumption.