GPS tracker on Ham radio APRS network with DRA818 module

The projet

Inspiration : https://github.com/Toni43/MiniSmartTracker

Hardware parts used

• Arduino Nano
• GPS Module (NEO 6M)
• VHF TX module (DRA818V)

Software parts used

• PlatformIO
• QAPRS lib from Lukasz SQ5RWU, forked by me to add PWM
• TinyGPS+ lib
• DRA818 lib from Jereme Loyet
• EasyButton from Evert Arias

The circuit

The Arduino program

The project has one main function : send its GPS coordinate on ham radio APRS network. To accomplish that it has 3 ways :

• With the DRA818V module
• With a Baofeng UV5-R/UVB5 etc connected to the board
• With an external TX by the jack connector

Compile and run

I use PlatformIO insted of the Arduino IDE.

1. Install PlatformIO
2. Run git clone https://github.com/valentintintin/arduino-tracker-aprs-dra818.git && cd arduino-tracker-aprs-dra818
3. You have to uncomment APRS_HW_TYPE_R2R or APRS_HW_TYPE_PWM and comment all the others in .piolibdeps/ArduinoQAPRS/ArduinoQAPRS.h
4. Plug your Arduino nano
5. Run pio run --target upload -e nanoprod

Notes

• There are 2 environments : nanoprod without any logs, nanotest or with log and APRS sended every time even if no GPS locked.
• The QAPRS lib use a R2R resistor network to generate the sound signal or PWM if you change the circuit and small part of code.
• There are many board for DRA818 (by Handiko, by SV1AFN, by HamShop.cz).
• In boards, Low Pass filter is not always included, it's recommended to add one
• To debug I use the button and the TX pin from Arduino with a M5 Stack with my Logger Project

Program flow

1. At the startup, the Arduino try to detect if there is a DRA818 module plugged. If the connexion failed, it goes to the Baofeng mode.
   • The sound (AFSK) is always present on the jack connector and on Baofeng header pins. We don't have to use multiple options at the same time because sound "intensity" will decrease.
   • If you want to start in test mode (no guard for GPS fix or TX rate), keep pressed the button at startup
2. If the GPS is locked AND time between TX is reached ==> send the new location. The time between TX is defined by the speed and two affine functions.
3. Keep pressed the button to send your position (if GPS fix) manually

Photos

Test

I did a real test of my project (65 Km * 2 round-trip). I bought an antenna VHF/UHF Sirio 2070H.

Results from aprs.fi are surprising ! With only 1 Watt, F5ZFL-4 at 81Km of my position received one frame !

The author

My name is Valentin and my callsign is F4HVV. I'm not good in electronics but I can do such project working approximately :)