Open-source SX1280 2.4 GHz FLRC transceiver: Overcoming sub-GHz LoRa bottlenecks for high-rate, low-latency...

Transmitting continuous scientific telemetry over remote distances is constrained by sub-GHz LoRa bandwidth limits and regional duty cycles, which cannot sustain 115 200 bps streams. To overcome this, we present OpenFLRC v1.0, an open-source 2.4 GHz FLRC transceiver platform for dedicated point-to-point links. The carrier board contribution is the system-level engineering required to operate the commercial E28 module as a reproducible continuous-duty scientific telemetry instrument: an open carrier board with a 5-capacitor low-ESR decoupling ladder suppressing 550 mA transients, an unbroken bottom ground plane for thermal dissipation without an active heatsink, and dedicated physical RF-switch routing; paired with a FreeRTOS dual-core firmware pipeline isolating 18 MHz SPI DMA transactions to Core 1 while leaving Core 0 largely available for user sensor acquisition. Controlled laboratory benchmarking against 433 MHz and 915 MHz LoRa validates sensitivity, spectral purity (second-harmonic suppression of 38.5-41.8 dBc), and emulates multi-kilometre links via calibrated attenuation. While sub-GHz links collapse under continuous throughput, OpenFLRC sustains 884.3 kbps ( $\text{PDR}\ge 99.9\text{\%}$ ) at a 1 ms packet interval under laboratory link budgets. All files are released under CC BY 4.0.