Frequency Hopping Spread Spectrum on LoRa SX1262: Making Radio Undetectable

LoRa is a remarkable modulation scheme. It achieves sensitivity below -140 dBm, delivers reliable links at distances conventional radios cannot reach, and does it all at milliwatt power levels. But LoRa has a weakness that is rarely discussed in maker communities: a standard LoRa transmission is trivially detectable. A fixed-frequency LoRa signal shows up on any spectrum analyser or SDR waterfall display as a distinctive chirp pattern. Its centre frequency, bandwidth, and spreading factor can be