What is LoRa, and is it used in industrial remote control?
LoRa is a sub-GHz modulation using chirp spread spectrum (CSS) and it can decode a signal below the noise floor: sensitivity down to -148 dBm is reported on the SX1276 at the lowest data rate, and around -137 dBm at practical rates. The cost is a very low data rate and high air time; that makes it ideal for telemetry and unsuitable for real-time motion control.
LoRa's strength comes from sensitivity. While the typical ceiling on FSK receivers is -125 to -130 dBm, LoRa goes significantly below that at low rates; at the most extreme setting an advantage of roughly 25 dB over FSK is reported. By the 6 dB rule this means, theoretically, a very large difference in distance.
However, in a remote control application the determining factor is not range but latency:
- At high spreading factors the air time of a single packet reaches hundreds of milliseconds; the delay between the operator releasing the lever and motion stopping becomes unacceptable.
- Long air time fills duty cycle limits quickly. A 1 percent duty cycle means a total of 36 seconds of transmission per hour; a remote control sending continuous commands consumes that in a short time.
- Safety functions (stopping) have to be fast and deterministic; a slow channel with variable latency makes this difficult.
The correct distinction of use is this: LoRa is suitable for remote sensor and telemetry links that send small amounts of data infrequently. For real-time motion control, low-latency FSK/GFSK or frequency-hopping solutions are preferred.
Full topic: Wireless remote control installation: pairing, relay, safety