RTK

RTK positioning device

The RTK positioning device that I’ve designed includes:

• an ESP32-S3 to provide the necessary brains and glue everything together;
• a power supply built around a BQ25895 to manage a single 18650 cell;
• an RAK3172 LoRa module. It’s a technology I’ve not used before, and it’s commonly used for rover-base station communications;
• the Quectel LC29HEA module;
• an MMA8452 accelerometer for us as an inclinometer - if the thing’s mounted on a pole, knowing the amount and direction of any tilt can enable it to compensate for the difference in X and Y location of the base of the pole relative to the antenna;
• an OLED display because it just needs four holes in the PCB at this point and I’m sure it’ll come in useful.

The whole thing’s not much bigger than the 18650 cell in its holder. Battery life should be on the order of 24 hours from a 2500mAh cell without any particular attention being paid to that aspect of the design, and can probably be doubled without much work.

The antenna’s an important part of the whole caboodle. While it’s possible to spend $2500+ on a calibrated survey-grade antenna, I’ve chosen to spend roughly 1% of that on a little helical antenna, dubbed the HX-301A, which someone I found on the internet seemed to think performed reasonably well. We’ll see.

Current status as of 2025-02-12: boards being made, most of the key components which aren’t being assembled onto the boards at the factory on their way with the exception of the Quectel modules - I guess this is the joys of dealing via Aliexpress over Chinese New Year.