LoRa Link Budget Calculator

A LoRa link budget is the calculation that determines whether a signal can travel from transmitter to receiver with sufficient strength. It accounts for transmit power, antenna gains, path loss, and receiver sensitivity to predict communication range and reliability.

Higher spreading factors (SF12) provide greater range and sensitivity but slower data rates. Lower spreading factors (SF7) offer faster data rates but shorter range. Each step up in SF roughly doubles the range but halves the data rate.

Fade margin is extra signal strength reserved to account for temporary signal variations due to weather, obstacles, or interference. Typical values range from 10-20 dB, with higher margins providing better reliability but reducing maximum range.

Different environments have different path loss characteristics. Free space has the lowest path loss, while dense urban environments have the highest due to buildings and obstacles. The calculator uses appropriate path loss models for each environment type.

Wider bandwidths (500 kHz) provide higher data rates but reduce sensitivity and range. Narrower bandwidths (125 kHz) offer better sensitivity and longer range but slower data rates. Most LoRaWAN deployments use 125 kHz bandwidth.

Link budget calculations provide good estimates but real-world performance can vary by ±10-20 dB due to terrain, weather, interference, and antenna positioning. Always include adequate fade margin and verify with field testing.

Typical LoRa receiver sensitivities range from -137 dBm (SF12) to -124 dBm (SF7) at 125 kHz bandwidth. Higher spreading factors provide better sensitivity, allowing detection of weaker signals over longer distances.