APRS (Automatic Packet Reporting System) is a 2-way packet radio communication.

The main idea for this device is to provide reliable GPS Tracking and 2-way communication, during extreme situation, when existing GSM/Internet network are not available. The device have to be connected to a HAM-Radio unit. The HAM-Radio unit establish the connection to a APRS network. The APRS network mainly contains digital repeaters which repeat the signal, and I-Gates which make connection to the Internet. The APRS network is very flexible if one I-Gate have no internet connection become a digital repeater and repeat the signals to the next node of the network, which provide reliable communication. Using Bluetooth connection to a Tablet and serial console the user can send SMS without GSM coverage, can send e-mail without internet connection. This options needs 3-party software which is not include in this project.

The device is equipped with:

USB port, through this port the device battery can be charged, can be update the software, can be used like TNC Modem

Battery Charge Controller, this module charge battery to exact 4.2V to prevent overcharge.

Battery Discharge Controller, this module prevent battery voltage to drops below 2.8V, preventing battery damage.

GPS module capable to determinate your position very fast. Needs only 6 sek.

Bluetooth module, this module can be used for communication with Phone/Tablet/PC, through serial console can be executed different commands. See section Bluetooth supported commands.

Modem, this module modulate and demodulate the signals to be compatible with existing APRS Analog network.

Temperature sensor based on DS18B20.

Software: The software is based on work of other people in Git-Hub https://github.com/sh123/aprs_tracker

The device use modified galaSAT team "aprslib" , to be possible to be used on the atmega2560 many thank to galaSAT team

Bluetooth supported commands:

All commands work using Bluetooth connection or USB connection, carriage return protocol have to be used.

battery return the battery voltage and percentage

state_battery not work suppose to return is battery charged charging or discharging

bt_reser resets the Bluetooth module

gpsoff turn off the GPS module

gpsno turn on the GPS module

temp return the temperature of DS18B20 sensor

sendpos send GPS position without touching the hardware button

btoff turn off the Bluetooth module available only using USB

bton turn on the Bluetooth module available only using USB

Using metal casing of the device is strongly recommender, high power radio station reset the device some times. This device have some limitations, the APSR network all over the world is owned by HAM Radio Operators to be used is needed license.

Full documentation of the device is available only on Bulgarian language, there no future plans to be translated in English. If you need the full documentation is available on request, just write me.

TO DO:

Searching interested people to write software for similar device but based on LoRa WAN comunication.