📡Wireless
LoRa Link Budget Calculator
Calculate the maximum achievable link budget and link margin for LoRa/LoRaWAN links based on transmitter power, antenna gains, and receiver sensitivity.
Formula Explanation
The link budget represents the total signal attenuation that the system can tolerate:
LinkBudget = TXPower + TXGain + RXGain - RXSensitivity
Where:
- TX Power— Transmitter output power (dBm)
- TX Gain— Transmitter antenna gain (dBi)
- RX Gain— Receiver antenna gain (dBi)
- RX Sensitivity— Minimum signal power the receiver can detect (dBm)
The link margin is calculated by subtracting the estimated path loss:
LinkMargin = LinkBudget - PathLoss
A link margin of 10 dB or more is generally recommended for reliable communication in real-world conditions.
Reference: SX1276 Sensitivity by Spreading Factor
Typical sensitivity values for Semtech SX1276 at 125 kHz bandwidth.
| Spreading Factor | Sensitivity (dBm) | Approx. Link Budget (14 dBm, 2 dBi) |
|---|---|---|
| SF7 | -123 dBm | 141 dB |
| SF8 | -126 dBm | 144 dB |
| SF9 | -129 dBm | 147 dB |
| SF10 | -132 dBm | 150 dB |
| SF11 | -134.5 dBm | 152.5 dB |
| SF12 | -137 dBm | 155 dB |