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LORA :: LONG-RANGE LOW-POWER RADIO
> It trades speed for range, robustness, and low power consumption.
LORA, LORAWAN, AND MESHTASTIC
The physical radio layer. It defines how bits are converted into a robust chirp spread spectrum signal.
A standardized LPWAN protocol using gateways, a network server, device identities, adaptive data rates, and application security.
An off-grid messaging system where LoRa nodes can relay encrypted packets between users without a cellular network.
HOW THE RADIO SIGNAL WORKS
LoRa uses chirp spread spectrum. During a chirp, the transmitted frequency sweeps across the configured channel bandwidth. Information is encoded through controlled shifts in that sweep. The receiver correlates the received chirps, which allows it to recover very weak signals even when the noise level is high.
This processing gain is the main reason LoRa can work at ranges where Wi-Fi or Bluetooth would fail. The cost is a low data rate and a longer time on air for each packet.
SPREADING FACTOR (SF)
Higher SF = longer range and better sensitivity
Higher SF = slower packets and more airtime
Typical values: SF7 to SF12
BANDWIDTH (BW)
Wider BW = faster packets and lower sensitivity
Narrower BW = slower packets and better sensitivity
Common LoRa value: 125 kHz
CODING RATE (CR)
Adds error-correction redundancy
More redundancy = better robustness, but more airtime
TRANSMIT POWER
More power can improve the link, but legal EIRP limits still apply
A better antenna position is often more useful than extra powerTHE RANGE / SPEED TRADE-OFF
Lower spreading factor, shorter airtime, more network capacity, but less margin at long distance or behind obstacles.
Higher spreading factor, improved sensitivity and link margin, but slower packets and more channel occupation.
WHAT HAPPENS TO A PACKET?
1. The application creates a small payload.
2. The radio adds addressing, integrity, and protocol fields.
3. The payload is modulated into LoRa chirps.
4. The antenna radiates the signal.
5. One or more receivers demodulate the packet.
6. The protocol decides whether to deliver, acknowledge, route, or repeat it.NETWORK TOPOLOGIES
Two radios exchange packets directly. Simple and efficient for a private sensor link or remote control.
LoRaWAN devices transmit to any gateway in range. Gateways forward packets to the network server through IP connectivity.
Meshtastic nodes can rebroadcast packets to extend coverage. Every retransmission consumes airtime, so mesh density must remain controlled.
WHAT LORA IS GOOD AT
- Small sensor messages, telemetry, alarms, GPS positions, and short text messages.
- Long battery life when devices sleep between transmissions.
- Long-distance links with clear line of sight and well-positioned antennas.
- Coverage through buildings where higher-frequency systems struggle.
- Private links that do not depend on cellular coverage.
WHAT LORA IS NOT GOOD AT
- Voice, video, large files, web browsing, or continuous high-rate data.
- Strict real-time control requiring guaranteed low latency.
- Unlimited retransmissions: spectrum is shared and airtime is limited.
- Automatic anonymity: encryption and identity management depend on the protocol and configuration.
SIMPLE STARTING WORKFLOW
[ ] Select the correct regional frequency profile
[ ] Connect the correct antenna before transmitting
[ ] Configure two nodes with the same radio parameters
[ ] Test at short range first
[ ] Check RSSI and SNR
[ ] Increase distance gradually
[ ] Move one antenna higher before increasing power
[ ] Record the settings and test conditions