Welcome to the home of APRS 434 tracker, the 434 MHz LoRa APRS amateur radio GPS tracker that extends range by saving bytes.
Unlike other ham radio LoRa APRS trackers, this tracker aims at deploying LoRa the way it was intended; namely by being frugal about the number of bytes put on air. Doing so, results in a number of benefits:
- Increased battery life,
- Higher chances of good packet reception,
- Hence, increased range,
- Lower probability of packet collisions,
- Therefore, more channel capacity.
To learn more about APRS 434 data link compression, visit aprs434.github.io.
The APRS 434 LoRa tracker firmware is developed for the relatively cheap Espressif ESP32-based LoRa GPS trackers made by TTGO. These are available from Aliexpress, Amazon or eBay.
Supported 433 MHz LoRa GPS tracker hardware:
- TTGO T-Beam v0.7 433 MHz SX1278
- TTGO T-Beam v1 433 MHz SX1278
⚠ Please, make sure to order a 433 MHz version!
The best success is to use PlatformIO (and it is the only platform where I can support you).
- Go to PlatformIO download and install the IDE.
- If installed open the IDE, go to the left side and klick on 'extensions' then search for 'PatformIO' and install.
- When installed click 'the ant head' on the left and choose import the project on the right.
- Just open the folder and you can compile the Firmware.
- You can find all nessesary settings to change for your configuration in data/tracker.json.
- The
button_txsetting enables manual triggering of the beacon using the middle button on the T-Beam. - To upload it to your board you have to do this via Upload File System image in PlatformIO!
- To find the 'Upload File System image' click the PlatformIO symbol (the little alien) on the left side, choos your configuration, click on 'Platform' and search for 'Upload File System image'.
Currently, the APRS 434 tracker is still compatible with the i-gate developed by Peter Buchegger, OE5BPA. However, this will soon change as more LoRa frame compression is added.
We feel confident that trackers with the proposed APRS 434 compressed LoRa frame will eventually become dominant because of the longer range merit. To smooth out the transition, we are developing an i‑gate capable of understanding both formats; i.e. compressed APRS 434 and longer, legacy OE5BPA.
It is strongly advised to install the accompanying APRS 434 i-gate as new releases will be automatically pulled over‑the‑air (OTA) via WiFi.
| tracker firmware |
completed | feature | LoRa payload | compatible with OE5BPA i‑gate |
|---|---|---|---|---|
| v0.0.0 | ✓ | original OE5BPA tracker | 113 bytes | ✓ |
| v0.1.0 | ✓ | byte-saving tracker.json |
87 bytes | ✓ |
| v0.2.0 | ✓ | fork of the OE5BPA tracker with significantly less transmitted bytes |
44 bytes | ✓ |
| v0.3.0 | ✓ | Base91 compression of location, course and speed data | 31 bytes | ✓ |
| v0.4.0 | ✓ | removal of the transmitted newline \n character at frame end |
30 bytes | ✓ |
| random time jitter between fixed interval packets to avoid repetitive collisions | 30 bytes | ✓ | ||
| tracker and i-gate with frame address compression, no custom header in payload |
18 bytes | use the APRS 434 i‑gate |
Currently, the APRS 434 tracker is still compatible with the i-gate developed by Peter Buchegger, OE5BPA. However, this will soon change as more LoRa frame compression is added.
We feel confident that trackers with the proposed APRS 434 compressed LoRa frame will eventually become dominant because of the longer range merit. To smooth out the transition, we are developing an i‑gate capable of understanding both formats; i.e. compressed APRS 434 and longer, legacy OE5BPA.
It is strongly advised to install the accompanying APRS 434 i-gate as new releases will be automatically pulled over‑the‑air (OTA) via WiFi.
| tracker firmware |
completed | feature |
|---|---|---|
| v0.3.1 | ✓ | coordinates displayed on screen |
| reduced power consumption through SH1106 OLED sleep | ||
| button press to activate OLED screen | ||
| ESP32 power reduction |
At first, only uplink messaging to an i-gate will be considered. This is useful for status updates, SOTA self‑spotting, or even emergencies.
On the other hand, bidirectional messaging requires time division multiplexing between the up- and downlink, based on precise GPS timing. That is because channel isolation between different up- and downlink frequencies probably would require costly and bulky resonant cavities.
| tracker firmware |
completed | feature |
|---|---|---|
| add a library for the Xbox 360 Chatpad keyboard | ||
| support for the M5Stack CardKB Mini keyboard |
TBD