Treat this one as a weekend hack: take a Bluetooth chip that normally reaches across a room and push it past four kilometers. RFOXiA founder Moamen Mohamed did that with a module called the MultiNav Pro+, aimed at the same crowd that runs Meshtastic on LoRa boards.
What he built
The board pairs an STM32WB07CC Bluetooth LE chip with a 20 dBm power amplifier and a 12 dB low-noise amplifier, plus a compact 4 dBi antenna. Each module keeps a phone connection and a long-range link alive at the same time, then adds multi-hop mesh on top. The phone app covers offline chat, a GNSS map, a gamepad controller and live sensor readouts. The write-up is at Hackster, and the firmware sits on GitHub under Apache 2.0.
Range versus speed
The trick is Coded PHY at S=8, a Bluetooth 5 mode that trades speed for reach. Short links can hit 2 Mb/s, while the long-range tests ran at 125 kb/s, enough for text, telemetry and control but nowhere near video. His best measured result is 4.6 km line of sight, phone to phone across two modules. The gotcha for anyone copying the idea: your library has to support Coded PHY on both ends, and plenty of cheap BLE modules only speak the 1M PHY.
Parts and cost reality
You will not match 20 dBm of output with a bare dev board, and local radio rules cap transmit power, so check the limits for 2.4 GHz in the Philippines before you add an amplifier. A realistic Saturday goal is smaller: flash two BLE boards that support Coded PHY, send a text string over the link, and log RSSI as you walk away from the other board. Also note the firmware was written with LLM help, so read the code before trusting it.
Spend your Sunday on this
Pick up two ESP32 boards (from about PHP 350 at circuit.rocks), enable the Coded PHY option in your BLE stack, and plot RSSI against distance down your school hallway or campus road. Bring the numbers to your robotics club and compare them with a LoRa module.
Frequently Asked Questions
How does Bluetooth LE reach 4.6 km on this module?
It uses Coded PHY at S=8, which trades throughput for range, plus a 20 dBm power amplifier, a 12 dB low-noise amplifier and a 4 dBi antenna on an STM32WB07CC.
What can you send over the long-range link?
Long links ran at 125 kb/s, which suits text, telemetry and control. Short links reach 2 Mb/s, but video is out of reach.
What will I learn if I build this?
You learn how BLE PHY modes, link budget, RSSI and antenna gain affect range, and how mesh hopping works, all useful for ECE thesis work on wireless sensor networks.
