calc.engineer / LoRa & Meshtastic / SNR Margin

SNR Margin v1.0.0

Computes LoRa link SNR margin by comparing received power against the noise floor and the spreading-factor-dependent demodulation threshold from the Semtech SX1276 datasheet. Calculates receiver noise floor from thermal noise (-174 dBm/Hz), channel bandwidth, and receiver noise figure. Returns margin in dB and a boolean link-OK indicator. Use to validate whether a LoRa or Meshtastic link will reliably decode packets. Accepts rx_power from link_budget tool output for end-to-end chain analysis.

← from link_budget.rx_power_dbm
Received signal power in dBm (e.g., -110). Typically from a link budget calculation or field measurement.
LoRa spreading factor (7-12). Higher SF tolerates lower SNR.
LoRa channel bandwidth in kHz. Affects noise floor.
Receiver noise figure in dB. Typical LoRa radio NF is 6 dB (SX1276).
Fill in the inputs and Compute to see the structured result.

From an agent (MCP) or the API

curl -X POST https://calc.engineer/api/snr_margin \
  -H "Content-Type: application/json" \
  -d '{"rx_power_dbm": …, "sf": …, "bw_khz": …}'

MCP: connect to https://calc.engineer/mcp and call snr_margin.

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