diff --git a/preparation.md b/preparation.md
index 69e1929..27e5663 100644
--- a/preparation.md
+++ b/preparation.md
@@ -15,11 +15,20 @@ Mobile phones are unproblematic regarding time. They usually already sync theirs
 Energy Saving options for apps might become a problem eventually, if your OS decides to send it into sleep mode. So you might want to define an exception:
 
 Android:
-![App energy saving][android_app_engerysave] ![Disable energy saving][android_app_exception]
+
+![App energy saving][android_app_engerysave]
+![Disable energy saving][android_app_exception]
 
 [android_app_engerysave]: images/android_app_energysave.png
 [android_app_exception]: images/android_app_exception.png
 
-### GPSLogger
+### GPS Logger
+My tool doesn't really care, which program created the gpx-file, as long as it follows GPX 1.0/1.1 standard.
+
+I got used to [GPS Logger](https://play.google.com/store/apps/details?id=com.mendhak.gpslogger) on Android. It seems to be free.
+To get precise locations for your photos, there have to be datapoints in the recording close to the time the picture was taken. But I don't want to stress the phone's battery too much. So I went with an interval of 5s and a distance of 5m between two datapoints. And I keep the GPS locked during the time it records.
+
+![App energy saving][android_app_engerysave]
+![Disable energy saving][android_app_exception]
 
 ## Geigercounter