All calculations are done in the device. No Internet connection is required, except for automatic updates of the sunspot numbers at regular intervals.
Due to the usage of a full fledged VOACAP-installation, the app has to be installed in the phone-internal memory (APP2SD is not possible). This is due to technical restrictions. It requires about 9 MB (after installation) flash storage plus approx. 120 kB / prediction
INTERNET: Required to download current SSN data
EXTERNAL STORAGE: Required for VOACAP runtime files
LOCATION: Required to use current position for a site