Question

I want to pass a parameter between two activities at a certain time interval. The passed parameter is an int, that represents the number of satellites seen by the device and is used to draw a chart in the second activity.

Answer 1

It is very likely that you are trying to do something in a strange way because you do not fully understood yet how activities in Android are working.

There is only one active Activity in your whole app. Sending data from one activity to another is only needed if the users changes the active Activity, either through clicking on a button and switching to a new Activity or through clicking back and going back to the previous Activity. Please read the Activity Lifecycle very carefully to understand how activities should be used.

I assume that you have registered a location listener in one activity and try to use the values of this listener in other activities. Normally you would use the onPause method to deactivate the listener in the first activity and then activate a new one in the new activity. This will get you the number of known satellites in every activity. If the user goes back you will have to reregister the listener in the onResume method to reenable the gps updates for the new Activity.

Keeping an active GPS Listener in a paused Activity will lead to an active GPS Sensor even if your App is in the background and not used anymore. This will drain the battery of the phone very fast and very likely have your app uninstalled in an instance.