LoRa up close: chirps, spreading factor, time on air and range
· 26 min read
Meshtastic and Reticulum sit on the same physics: a modulation that reads a signal weaker than the noise floor and pays for it in time. This note is about that physics: how a chirp works, where the range comes from, what every knob in the settings does, what the hardware is made of and what gets built on top — from LoRaWAN to drones and satellites.
−20 dBA signal a hundred times weaker than the noise — and it still gets read. LoRa's main trick
−137 dBmReceiver sensitivity at SF12 and 125 kHz bandwidth
32.8 msThe length of one SF12 symbol. Modern Wi-Fi moves a megabyte in that time
4096Possible starting points of one "whistle" at SF12 — 12 bits per symbol