I made an Android app for APRS, named U2APRS, more than 10 years ago. As I was busy on my own business, I stopped the development of U2APRS. Although I did not touch its code, I occasionally used it for fun. In February 2022, I replaced my old Android phone with a new Samsung Galaxy S21, and noticed that U2APRS did not run on the new phone. I was not surprised because U2APRS uses many old, deprecated, legacy APIs of Android OS. Galaxy S21 uses the newest Android OS version 12, and obviously does not want to run such an old app.
I decided to make a simple APRS app for my new Android phone from scratch. The name of the app is S2APRS. S stands for Simple. It focuses on sending APRS beacons.
| Function | S2APRS | U2APRS |
|---|---|---|
| Send position packets to APRS-IS | Yes | Yes |
| APRS symbol selection | Partial | Yes |
| Send and receive APRS messages | No | Yes |
| Google map interface | No | Yes |
| aprs.fi web page | Yes | Yes |
| Built-in audio packet decoder | No | Yes |
| Built-in APRS gateway | No | Yes |
| User changeable fixed position | No | Yes |
| Friends finder | No | Yes |
| APRS-IS socket interface | UDP only | TCP/UDP |
Download APK and install it on your phone. The installation procedure is different on different phones and different OS versions. Before the installation, be sure to allow the installation of the apps that are not on Google Play store in the setup menu of your phone.
At the very first run, you will be asked to give the location permission to S2APRS.
Select "While using the app". Then you are asked to restart S2APRS with a pop-up window at the bottom of the screen. Tap the Exit button at the right bottom corner.
You might have to manually set the permissions to S2APRS in the setup menu of your phone.
Restart S2APRS by tapping the S2APRS icon.
Input your callsign and APRS-IS passcode. If you are not familiar with the passcode, contact me.
That's it. Very simple.
| Beacon button | Tap the button to manually send an APRS beacon. |
| Auto switch | When it is on, S2APRS sends a beacon if any of the following conditions - Beacon interval, Travelling distance, or Direction change - is met. |
| Beacon interval | S2APRS sends a beacon when the time specified here has elapsed. |
| Travelling distance | S2APRS sends a beacon when you have moved the distance specified here. |
| Direction change | S2APRS sends a beacon if your moving direction changes more than the angle specified here. |
| Min beacon interval | Once S2APRS sent a beacon, it will not send a new beacon during this interval irrespective of the values in Beacon interval, Travelling distance and Direction change. |
| Ambiguity | APRS position ambiguity. Refer to the APRS protocol reference for more information. |
| Callsign-SSID | Your callsign followed by SSID. |
| APRS symbol | APRS symbol. Only Phone, Car, Van, Jogger, Motorcycle, Bicycle, Train, and Airplane are supported now. |
| Comment | Comment added to the beacon. |
| Always on | Check to prevent the phone from blanking the screen. |
| Server address | APRS-IS server address. You must use a server that has a UDP receiving port. For example, srvr.aprs-is.net, sydney.aprs2.net, texas.aprs2.net.....Many APRS-IS servers only have TCP ports. |
| Server port | 8080 fixed. |
| Passcode | Your passcode. If you are not familiar with passcode, contact me. |
| Debug | Leave it unchecked. |
73 de Oba, JA7UDE