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K. Adlington

LoRa Range Warning System

A LoRa link and field unit for high-power rocketry range safety: a tripod-mounted enclosure with a siren and beacon, carrying alerts between the launch site and the range safety stations.

Team project · Third-year electrical engineering design course · 2025

Role
Electrical systems lead — PCB layout, RF front-end and firmware integration
Timeframe
2025

Alerts on a high-power rocketry range have to carry between the launch site and personnel spread across it, and arrive dependably and with low latency; they are what maintains safety compliance and coordinates launch activities. As part of the Third-Year Electrical Engineering Design Course, I collaborated with a team to develop a LoRa-based launch range warning system for that link.

Within the team I led the electrical design and implementation, managing the PCB layout, RF front-end development, and firmware integration. The system was built around the NUCLEO-WL55JC development board, selected for its STM32WL dual-core microcontroller with an integrated LoRa transceiver, which gives long-range communication capability in a compact, efficient platform. I implemented the LoRa communication stack within a C-based operating system and configured it for half-duplex operation, enabling reliable bidirectional data exchange between the launch site and the range safety stations.

The custom PCB houses and interfaces with the NUCLEO-WL55JC, integrating peripheral circuitry for power management, RF connectivity, and system protection. The supply is a switching regulator-based design capable of handling inputs up to 8S LiPo (33.6 V) and generating regulated 12 V and 5 V rails. Power protection uses ideal diode controllers for reverse polarity, along with overvoltage and undervoltage protection to safeguard all onboard electronics. The board also carries integrated siren and beacon switching, and temperature and humidity logging.

A render of the custom carrier board with the NUCLEO-WL55JC evaluation board mounted above it on tall pin headers. The dark green carrier carries a screw-terminal power input at one corner, two large protection devices marked CR1 and CR2, an ideal diode controller and bulk capacitors, with the silkscreen beneath them reading Power Protection.
Figure 33:3D model of PCB and NUCLEO evaluation board
The range warning unit deployed on a sports field at dusk: a black cylindrical enclosure mounted on a tripod, its amber beacon lit at the top. Rugby posts, a treeline and a low clubhouse sit in the background under heavy overcast.
Figure 34:Range warning system on display

The unit is built around a central chassis plate. The control and power regulation PCB mounts to it with the NUCLEO-WL55JC beside it, and the siren and battery sit against the same plate. The display and interface PCB and the power switch go on the front shell, the light dome closes the top and a tripod mount closes the base.

An exploded CAD view of the range warning unit with each part labelled. From the top: the light dome, then the siren and the battery mounted against a central chassis plate, the control and power regulation PCB on that plate, the NUCLEO-WL55JC beside it, the display and interface PCB and the power switch on the front shell, and the tripod mount closing the base. Two curved shell halves wrap the chassis from front and back.
Figure 35:Exploded view of the range warning system

Throughout schematic and hardware development I ran transient load simulations, startup behaviour simulations, and electrical performance analysis to validate regulator response, inrush current limits, and voltage rail stability under dynamic conditions. The target was reliable performance during rapid power transitions and operational stress scenarios.

Transient load simulation. Output voltage in red is plotted on the left axis from 10.5 to 13.5 volts across one millisecond, with the load current step drawn in grey against the right axis. The rail holds at 12 volts; when the load drops from 2 amps to about a quarter of an amp the output overshoots to roughly 13.1 volts and settles back within about two hundred microseconds, and when the load steps back up it dips to about 11 volts before recovering to 12 volts.
Figure 36:Transient load simulation
Startup simulation. The output voltage rises in a straight, monotonic ramp from zero to 12 volts over about four milliseconds and then holds flat, with no overshoot at the top of the ramp.
Figure 37:Startup simulation

Technologies

STM32LoRaC FirmwareSwitching RegulatorsRF Simulation & DesignKiCad

Key outcomes

Designed and implemented a LoRa-based range warning system capable of reliable long-distance operation and stable power delivery under load. The system demonstrated consistent LoRa communication, effective hardware protection, and a scalable power architecture, fulfilling all course design and testing requirements.