S2APRS - A Simple APRS Client for iPhone

Setup

1. Go to the Settings view.
2. Enter your callsign and SSID (e.g., -5 for a mobile cellphone station).
3. Enter your 5-digit APRS-IS passcode. If you do not have one, contact me.
4. Return to the Home view.
5. Check if the Beacon button at the top left corner has turned orange.

Operation

• Press the Beacon button.
• Go to the aprs.fi view and check if your icon appears at the center of the map.
• Note that the Beacon button turns gray immediately after being pressed and shows a countdown timer. You cannot resend the beacon until the timer reaches zero. The timer duration is determined by "Min beacon interval" in the Settings view.

Automatic Beaconing

• Enable "Auto" toggle in the Home view.
• The app will automatically send a beacon
  • when you move a predefined distance from your last reported location, or
  • when a predefined time interval has elapsed since your last beacon, or
  • when your direction of movement changes by more than a predefined angle.

Other setting parameters in the Settings view

• "Min Beacon Interval": Minimum time interval between two consecutive beacons.
• "Ambiguity": Intentionally reduces location accuracy.
• "APRS Symbol": Choose the symbol. Use "Custom" to specify a symbol with any two letters of your choice.
• "Comment": Text included in the beacon packet.
• "Server Address": APRS-IS server address that accepts UDP. Most APRS-IS servers accept TCP, but not all accept UDP connections.
• "Server Port": UDP port number, which varies by server.
• "Debug Mode": Displays location data in the Home view, useful for troubleshooting.

Background run

• Turning on "Background Run" in the Home view allows the app to continue running in the background. This means S2APRS will keep sending packets even when another app is in the foreground or the screen is locked.
• Note that continuous GPS usage in the background can significantly drain the battery.
• Be sure to turn off automatic beaconing when you no longer wish to upload your location to APRS-IS; otherwise, your current location could be continuously disclosed to the world.